Power loss

[1Rogue]

Hey guys,
Thought I would see if anyone had any ideas on this.

When I have been riding the GZ a little while and I get the appx. 45-50 mph the bike starts occasionally losing power for a split second. It will come right back strong and I don't hear any unusual noises, it is like it justs skips out for a split second. Any thoughts on what may be the problem?

Thanks for all help!

[jonathan180iq]

Does this happen during acceleration (opening the throttle) or just while cruising?

[Badbob]

It could be electrical. A bare wire or loose connection that is only a problem when there is more vibration causing a weak or no spark for a short time.

How long has it been since you changed your spark plug. My GZ250 is very sensitive to this. The plug will look fine but not work very well.

[1Rogue]

Does this happen during acceleration (opening the throttle) or just while cruising?

I think it is happening more when I am increasing throttle.

As for the spark plug, I was told it was changed shortly before I got it, but that is something I will check.

[jonathan180iq]

If this happens while you;re accelerating, I'd think it was a problem with jetting. Did you buy this bike used? If not, where are you located? If someone tampered with the intake or something they could have made minor adjustments to the mid-range jetting that are not allowing proper fuel flow.
If your bike is stock, you might simply have a problem with the altitude where you live.

Aside from that, you may just need to clean your carbs out. Some old gunk could be holding the little moving parts back or gunking up some flow passages.

All gas has detergents in it. These detergents leave residues inside the carb that will collect if the bike ever sits for awhile or isn't used regularly.

Let me know,
Jonathan

[1Rogue]

I did get the bike used but the previous owner only did basic maintenance on it. Oil change, front brake change, brake fluid fill that kind of stuff. He said he did not know enough about motors to mess with anything else other than basic and did not have any modifications done. He rode it regularly until he bought his new Shadow 750 so it didn't sit for any length of time and it has about 4300 miles on it.

I am located just outside of Dallas, TX and the previous owner was in Ft. Worth, so I don't think it is a problem with altitude. He did tell me he was starting to notice something like what I am getting. I am a new rider and until recently I have been riding in lower speed areas getting comfortable with the bike. It is just in the past week or so that I have getting on larger roads with a little higher speeds. I did not get this problem at the lower speeds. It is only when I get in the area of 45-55 that it happens. I was trying to pay more attention tonight when I was riding and it did seem to do it some when I was holding speed and not really throttling up.

You mentioned it might be gunk in the carb. Would running some kind of fuel cleaner through help get any possible gunk out, or will I need to breakdown the carb to clean it? I was also thinking it might possibly be clogged fuel filter. I was going to look and see what it would take to get to that.

I am waiting on the parts to get in but I am going to do the needle shim and 16t sprocket change when they do. Will the shim affect it any or with that area of the carb open could I maybe spray a cleaner or something in that would help at that time?

Thanks for all your help!

[Dupo]

If you want to try to clean out the fuel system/carb ... pick up a can of SeaFoam at an auto parts store. Read the directions carefully and only put in whatever oz per gallon. Run that tank down and that will clean out your carb/jets fuel system better than anything else.

[jonathan180iq]

If it happens more when cruising then I'd say that it's not jetting. It sounds more like a gunk problem. You may just be getting occasional chunks stuck in some important places. (these aren't really CHUNKS, but you know what I'm saying.)

Run some SeaFoam as Dupo suggested and let us know what happens.

Take care,
jonathan

[racinnuts]

I have a similar, but more serious power loss problem. Occasionally my bike will lose power while running down the road at a steady speed. After pulling over it will idle steady and smooth, but will still not have power uned thottle. After cutting off the ignition and restarting the engine it will run fine This may happen two or three times in one day, or go two or three month between mishaps. Anyone have an idea?

racinnuts

[jonathan180iq]

That sounds pretty wierd. Only time that I've ever had anything happen like this was when I let my Ninja sit for about 3 months and I didn't prep it. However, after it stopped running completely one time I just drained the gas tank and cleaned the carbs and I never had another problem.

I'd suggest the usual; carb clean, maybe a valve adjustment, and check for any leaks or faulty hoses. It's also possible that BadBob's suggestion might be happening to you.

Removing the carbs and studying them really helps you understand how they work and it gives you an opportunity to inspect for possible worn parts.

Sorry I can't be of more help.

Take care,
Jonathan

[racinnuts]

I bought washers to shim the carb, so I will clean the carb and adjust the valves when I install the washer. I have checked the electrial connections, wires, etc. and installed a new spark plug and battery but still have the problem ocassionally. I forgot to mention that this normaly happens in the morning on the way to work. Maybe my GZ is trying to tell me something!

Thanks for the input,
racinnuts

[Easy Rider]

on larger roads with a little higher speeds. I did not get this problem at the lower speeds. It is only when I get in the area of 45-55 that it happens. I was trying to pay more attention tonight when I was riding and it did seem to do it some when I was holding speed and not really throttling up.


This sounds like the classic case of plugged gas cap vent. Vacume in the tank cuts gas flow down to a trickle and doesn't keep enough in the float bowl to support sustained high speeds. Also could be improperly set float, gunk in needle valve or partially plugged screen(s) in the petcock or tank.

Good luck!

[1Rogue]

This sounds like the classic case of plugged gas cap vent.

Well I got and used the Seafoam and figured I start with that. Any tips on how to check the gas cap to see if it is the culprit. If these don't work I guess I head for the carb and the tank workings.

Thanks for all the great info everyone. I'll keep ya posted.

Oh, yea - if I find it is the cap. Is there a way to clear it, or do I have to buy another one.

[racinnuts]

You should be able to hear a sucking sound and fill the vaccum when you take the gas cap off if the vent is plugged. I can hear my cap venting after my bike has been sitting on a hot day and I lean it from side to side if the tank is pretty full.

[1Rogue]

This sounds like the classic case of plugged gas cap vent. Vacume in the tank cuts gas flow down to a trickle and doesn't keep enough in the float bowl to support sustained high speeds.

I'm about 3/4 through a tank of gas with Seafoam. I have seen no noticeable difference. I thought I would address the plugged fuel cap vents next. It doesn't suck air when it is parked and I open it, but being as it only happens at upper speeds I don't know how to test it. Is there a way to clean them out, or do I have to buy a new one. I really hope it is not the latter, that looks like about $60-$70.

[Easy Rider]

This sounds like the classic case of plugged gas cap vent. Vacume in the tank cuts gas flow down to a trickle and doesn't keep enough in the float bowl to support sustained high speeds.

I'm about 3/4 through a tank of gas with Seafoam. I have seen no noticeable difference. I thought I would address the plugged fuel cap vents next. It doesn't suck air when it is parked and I open it, but being as it only happens at upper speeds I don't know how to test it. Is there a way to clean them out, or do I have to buy a new one. I really hope it is not the latter, that looks like about $60-$70.

Just went out and looked at my cap. It's a pain in the ass compared to the "flip caps" on most other bikes I've had. It doesn't seal until it is completely closed SO.......If you have an extra key, I would think that with 1/2 tank or less you should be able to leave it open 1/4-1/2 inch without fear of it coming out (mine is very tight until I get it all the way out) or any appreciable splashing.....if you ride mostly straight up with no sudden starts or stops. It looks like it comes apart with 2 screws but I decided not to look inside mine!

If that turns out to be the problem, I think I'd soak the whole cap for a while in some carb cleaner before dis-assembly or replacement.

If that is NOT the problem, the next thing I'd do is check for a vacume leak in the line going to the petcock, then check the screens. Think I heard they are on the fuel pickup inside the tank at the top of the petcock. Next would be float levels.


Good luck!

[1Rogue]

If that is NOT the problem, the next thing I'd do is check for a vacume leak in the line going to the petcock, then check the screens. Think I heard they are on the fuel pickup inside the tank at the top of the petcock. Next would be float levels.

Well, it isn't the vents in the cap. Just got back from trying your leave it open suggestion. I even had it completely off on a couple of the long straight aways. It still was skipping out. I'm going to hit the manual and see where the line the petcock is you suggested to check. I'm guessing I am going to go ahead and break the tank down and check the screen and all inside.

[Easy Rider]

Well, it isn't the vents in the cap. Just got back from trying your leave it open suggestion. I even had it completely off on a couple of the long straight aways. It still was skipping out. I'm going to hit the manual and see where the line the petcock is you suggested to check. I'm guessing I am going to go ahead and break the tank down and check the screen and all inside.

Alas, you are rapidly eliminating the easy things.
If the fuel flow is not restricted, then it would seem that you are left with a low float level or an intermittant (heat related?) electrical problem.
Good luck. Sounds like you'll need it! :sad:

[1Rogue]

Alas, you are rapidly eliminating the easy things.
If the fuel flow is not restricted, then it would seem that you are left with a low float level or an intermittant (heat related?) electrical problem.
Good luck. Sounds like you'll need it! :sad:

Two questions here. - Is a special tool required to check the float level or is there a way to do it without dishing out cash for a special tool? Also, is breaking down the carb difficult? (Remember your dealing with a newb here.)
I think I am going go for broke. I should be getting the 16t sprocket in today as well as the extra washer to do the shim. Since the tank is off and I'll be going into the carb anyway, I figure I may as well break it down and clean it.

I got this bike hoping it would be a good beginners way to learn how to work on them. But not a crash course! :mad:

[jonathan180iq]

If you're gonna do this, don't let the carb intimidate you.
If you don't take off parts that shouldn't be taken off, you'll be fine.

I have one favor to ask. Since you are already torn down, would you mind measuring the inlet diameter and total circumferance of the carb intake? I haven't gotten there and probably won't for some time.


http://upload8.postimage.org/588733/carb.jpg (http://upload8.postimage.org/588733/photo_hosting.html)

You're watching part number 20 in this pic.
Here is a link that I used a looooooong time ago.

http://771doug.netfirms.com/float.html

If you don't feel confident with this procedure or with the help of the service manual, I'd suggest takin' it in.

Needless to say, carbs are pretty important in the function of the bike. You don't want to screw something up.

[1Rogue]

If you're gonna do this, don't let the carb intimidate you.
If you don't take off parts that shouldn't be taken off, you'll be fine.

Needless to say, carbs are pretty important in the function of the bike. You don't want to screw something up.

Thanks alot! I wasn't intimidated, but now....

Just kidding, the Serv.Manual is pretty step by step. I would be happy to measure the carb intake if it will help. I know everyone's helped me out a ton <this forum rocks>.
You have to remember I am a newb and I didn't see anything in the service manual carb schematic labeled carb intake (this may be where you roll your eyes and say nevermind). I am guessing you are not referring to where the fuel hose slips over the inlet into the carb so, if you can give me an idea where we are referring to I'll get the measurements to you?

[jonathan180iq]

I appreciate your willingness to help me out. No problem with being a "noob". We've all been there.

The part that I need really isn't see-able on the pic that I'm attaching, but it's the reverse of what I have outlined.

It's, simply put, the part of the carb where the air comes in from the air box.


http://upload8.postimage.org/593600/intake.jpg (http://upload8.postimage.org/593600/photo_hosting.html)

Like I said, it will be on the reverse of this photo

[Easy Rider]

Two questions here. - Is a special tool required to check the float level or is there a way to do it without dishing out cash for a special tool? Also, is breaking down the carb difficult? (Remember your dealing with a newb here.)
I think I am going go for broke. I should be getting the 16t sprocket in today as well as the extra washer to do the shim. Since the tank is off and I'll be going into the carb anyway, I figure I may as well break it down and clean it.


No special tool; just a small ruler. Other posts seems to indicate that you have a shop manual. It should have the spec. and proceedure for setting the float.

Taking the carb. apart is EASY. The hard part is getting it all back together! :roll:

Why are you shimming the slider? Have you already mod'ed the pipes and air cleaner?
That is a "package deal" and the carb mods should NOT be done with stock pipes and air filter.

If you HAVE already done the pipes and filter, then it's likely been running lean. That may be the WHOLE source of the hesitation problem or you may be burning up the plug. For a couple of bucks, I'd put in a new plug while you've got it apart.

There is a simple way to check the fuel level in the bowl (and by implication, the float level) without taking the carb. apart........but by now, you probably won't find that useful.

Keep us posted. :cool:

[1Rogue]

Why are you shimming the slider? Have you already mod'ed the pipes and air cleaner?
That is a "package deal" and the carb mods should NOT be done with stock pipes and air filter.

There is a simple way to check the fuel level in the bowl (and by implication, the float level) without taking the carb. apart........but by now, you probably won't find that useful.

:??: OK, I guess I missed something in my reading. My understanding was that the shim was a recomended mod like the sprocket and I figured it was only a couple bucks for an extra washer so why not. I did not catch that it came after the pipes and filter. I have not meddled with those, they are still stock, so I'll put the brakes on that mod.


There is a simple way to check the fuel level in the bowl (and by implication, the float level) without taking the carb. apart........but by now, you probably won't find that useful.

Looks like I'm trying to jump the gun all over the place. I pulled the tank and the checked the screens last night and they looked clean and clear, so I assumed the next step would be to clean the carb. All I have done is buy the new o-ring and carb cleaner, so if there is a way to avoid breaking the carb down for now, I'm all ears. But, being that the hesitation is only happening at 45-60mph would checking the bowl while not moving be effective? There is no hesitation at low speeds.

[Easy Rider]

But, being that the hesitation is only happening at 45-60mph would checking the bowl while not moving be effective? There is no hesitation at low speeds.

Yea, the fuel level shouldn't vary by much regardless of speed, as long as the line to the tank isn't restricted......which it appears that you have pretty much ruled out.

See that black tube going from the bottom of the carb down toward the pavement? It is a combination overflow (should the float stick open) and manual drain tube. It becomes a drain for the bowl if you loosen the screw just above the top of the hose.

To check the fuel level in the bowl, you need to (temporarily) replace the black hose with one that is the same size but CLEAR. Open the drain screw and let some fuel out in a can, etc. Petcock must be at PRI. (Come to think of it, just draining/flushing the bowl might help if it has accumulated some water). To check the level of fuel in the bowl, loop the clear tube UP past the carb. being careful not to kink it. Open the drain screw and watch the fuel in the tube. The level in the tube will be the same as the level in the bowl. BIKE SHOULD BE UPRIGHT IN NORMAL RIDING POSITION.

So, at this point you ask what is a normal level? I don't know for sure but my guess is that the bowl should be almost full and certainly not less than 1/2 full.

To recap: What year bike? How many miles? Is that 45-60 mph in top gear?
Noticed any hesitation in lower gears at high RPM?
HAVE YOU CHANGED THE PLUG YET?

[Water Warrior 2]

Just a thought from my old memory here. Is the float a hollow metallic design or a solid material than has a given weight ?? Have seen the hollow floats develope a pin hole and partially fill so that they sink lower than specified. Also have seen the solid types get saturated with gas and sink due to their weight. This is probably the opposite of the actual problem but maybe useful for future trouble shooting.

[Gadzooks Mike]

I did the needle shim with the stock pipes and air box. It has improved performance, as it was running too lean before. I didn't need to purchase a washer, either, as the one that's there can simply be moved down in the stack and works fine.

The OTHER mods (air box and drilling out the plug to get at the mixture screw) should be done only with the new exhaust.

At least, that's the way I read it. Anyone know any different? I have been wrong before and will be again - and it's only 8:30am!

[1Rogue]

To recap: What year bike? How many miles? Is that 45-60 mph in top gear?
Noticed any hesitation in lower gears at high RPM?
HAVE YOU CHANGED THE PLUG YET?

The bike is a '05. It has about 4500 mi on it. Yes it is 45-60 in top gear. No there is no hesitation in gears 1-3. No have not changed the plug yet. It was changes before I got it and didn't think to worry about it. After reading the post last night I pulled it and figured to go ahead an get a new one.

Do I have to go to the bike shop to get the plug or are they pretty common?

[Easy Rider]

I did the needle shim with the stock pipes and air box. It has improved performance, as it was running too lean before.


Experience is the best teacher! I stand corrected.
While it might be beneficial with stock pipes, the shim and idle mixture adjustment are probably REQUIRED after pipe/airbox mod. 'cause then it would probably be running WAY lean.

[Easy Rider]

Do I have to go to the bike shop to get the plug or are they pretty common?


If there's an auto parts shop close, try there but I've not had much luck anywhere but a bike shop. Any bike shop (except Harley) will probably do, as most stock a wide variety of plugs.
I would check the book first to be sure to get the right one (don't automatically assume that the one in there is correct).

You've just about got me stumped now. The only thing I have left is a real long shot.
I have seen cases where an arching plug wire or boot will only affect performance at (relatively) high RPM and under load. Do you have a garage or other VERY dark place?
Fire it up and LOOK for corona discharge around the plug and wire.

[1Rogue]

Well I did it...
I replaced the spark plug (the original in there was very loose so I thought that might be the the skipping problem). Broke down the entire carb and cleaned it, as well as adjusted the float level. Changed to a 16t sprocket. Did the needle shim. And Finally sprayed out the petcock screens with air to make sure they were clean.

I got it out on the road and couldn't get it over 35. So I broke it back down and found the edge of diaphragm was kinked and put it all back together

I hit the road got it up into 5th gear and... it is still skipping. :cuss: So, I just got home kicked the tires a few times and said a few (ok, alot) choice words at it and gave up. There is a bike shop in the next town over I may take it to. Hopefully they can find find the problem and it will be cheap. Can't afford to spend much more on it till next month. I think I've gotten and addressed everyone's ideas and I just don't have a clue what else it could be unless it is electrical and then I am really clueless.

Jonathan - your measurements are: 16.2 cm around the outside and 5 cm across the center.

[Easy Rider]

I think I've gotten and addressed everyone's ideas and I just don't have a clue what else it could be unless it is electrical and then I am really clueless.


What about this one.....from a previous post:
You've just about got me stumped now. The only thing I have left is a real long shot.
I have seen cases where an arching plug wire or boot will only affect performance at (relatively) high RPM and under load. Do you have a garage or other VERY dark place?
Fire it up and LOOK for corona discharge around the plug and wire.

After that, I give up too.

[1Rogue]

I went to a bike shop today and spoke to one of the mechanics. He said it sounded like 5th gear may be going out and to change the oil and see if metal was in the oil. I did, (no metal) when I took out the oil plug a large spring and what looks like a metal plug of some sort, both which appear to be part of the oil plug area, fell out after. These did not appear in the manual or in the description on how to change the oil. They fell out in a way that I couldn't tell how they went back. Can anyone tell me how these go back in? I put them back in the way they looked like they may go (spring, then metal plug then oil plug bolt), but then it wouldn't start. I hope I didn't mess anything up.

Easy Rider I read your last post and was going to try it after I changed the oil and it got dark out. Haven't quite got that far yet.

[Dupo]

I don't ever remember a spring and a plug falling out or being anywhere near the oil plug drain. Better check engine schematics layout and see where the heck that fell from.

[1Rogue]

http://mysite.verizon.net/resogrx4/the_bolt.jpg

This is it. The metal slug and spring above the bolt. Anyone seen this before? I hadn't seen anything like it before. In the book it is called the gearshift cam stopper :??: It looks like I had it in the right spot just not the right arrangement. And the reason it wouldn't start :blush: low battery. Now I can continue on with the original problem.

[Easy Rider]

http://mysite.verizon.net/resogrx4/the_bolt.jpg

This is it. The metal slug and spring above the bolt. Anyone seen this before? ..................And the reason it wouldn't start :blush: low battery. Now I can continue on with the original problem.

After consulting the service manual and inspecting the bottom of my engine (I haven't changed my oil yet), it would appear that the reason nobody else has seen those parts is that most people don't remove that bolt because it is NOT the oil drain plug. :roll:

The oil drain plug is in the middle of the "sump cover" which is not in your picture because it has been removed......along with the drain plug.

Thanks for sharing this 'cause I might have done the same thing without the benifit of your experience! :tup:

And now back to the movie...........
It is possible that a charging system problem (or bad battery) is causing your original complaint. Not likely but possible. In the process of checking that out, be sure to check the main cable connections, both at the battery and at the other ends.

Oh yea....and I think the "mechanics" idea that 5th gear is "going out" is a bunch of crap. It is possible that the clutch is slipping in 5th only where the load is greater but your original description didn't sound like that. You do have a tiny bit of free-play in the clutch cable, don't you?

[1Rogue]

After consulting the service manual and inspecting the bottom of my engine (I haven't changed my oil yet), it would appear that the reason nobody else has seen those parts is that most people don't remove that bolt because it is NOT the oil drain plug. :roll:

The oil drain plug is in the middle of the "sump cover" which is not in your picture because it has been removed......along with the drain plug.

Thanks for sharing this 'cause I might have done the same thing without the benefit of your experience! :tup: :oops:
You know, I wondered about that, and why they made this bolt so hard to get to with everything around it. But, all the oil came out so I assumed it was the right one. Oh well, live and learn. Maybe others can benefit from my mistake, or at least get a little laugh out of it.

I'm going to check for the corona discharge you mentioned tonight, and I'll check the battery connections at that time as well. I'm pretty sure the battery was weak because I had forgotten and left the key on for a while earlier that afternoon. I pretty much dismissed the 5th gear idea when the oil came up clean and I talked to the previous owner and he said he saw nothing in the previous change right before I got it from him. (He also mentioned never seeing a spring and metal slug come out after the oil plug...go figure.)

If nothing else, I found a Suzuki dealer with a service dept. about 30 min ride from the house I may take the bike to on Saturday. I think I am going to avoid the bike shop service dept that suggested the 5th gear failure.

[1Rogue]

Update:

Some dealerships really bite! :cuss: Well, I took my GZ in to see if they could diagnose the ongoing prob. They said it would be $75 to diagnose it and if they could fix it in that same hour it would be no extra charge except parts or they would call me and see if I wanted to pay extra if it would take longer. They kept it for a week then called me and told me three different things.

There is nothing wrong with the bike. Then, there is no hesitation in fifth. Then, oh...that, thats how these bike react to those speeds. The rest of the time was spent getting me off the phone or out of the building. :curse:

Then renewed faith: I found another dealer and called to see if they could at least check my electrical since the first shop said they cleaned the carb and adjusted the valves and everything was to spec. He said he could do it all day but why don't I explain the problem and see if could give me some ideas. I did. He said to please bring it in and he would have a technician ride it and see if he could diagnose it. I asked what that charge would be after being burned the last time and he said "why would he charge to ride it...thats fun!" So I did. He had a mechanic ride it for about 15 minutes and was pretty sure he had it figured out in about 30 min total. From everything he saw and felt it had to be the clutch starting to go out (probable a warped plate) and it would be $125-250 depending on if it is a plate or the whole clutch needs replacing. They said that while you are hitting the same rpm at all gears the reason it is only happening in 5th is that is where the highest stress is when reaching toward the bikes top speed, plus he could feel a little surge at the end of the hesitation like it was re-engaging. It makes some sense. We'll see what happens, i made an appointment to take it in, in two weeks. Thats how far back were booked.

[KiwiGZ]

Hi there

I have an 04 GZ with only 2850 miles on the clock, and in the last month or so it has starting doing exactly the same as yours, always seems to be first thing in the morning on the way to work, and usually when I am trying to merge with traffic on the motorway - not a good time to lose power! It is quite intermittant, most days fine, then suddenly does the lose power thing out of the blue. I thought it might have been related to the colder weather, but I usually have ridden for 5- 10 minutes before getting onto the m'way so should be warmed up by then.

It seems to always lose power at around 80km/hr (I think that is about 45mph!?) then will pick up after about 30-40 seconds. Also had a few episodes of backfiring when I release the accelerator in 5th gear when slowing down or coasting downhill.

It is coming up due for the 3000 mile service so will get the bike shop to check it out. I certainly hope it isn't the clutch at this low milage!!

[Easy Rider]

It seems to always lose power at around 80km/hr (I think that is about 45mph!?) then will pick up after about 30-40 seconds. Also had a few episodes of backfiring when I release the accelerator in 5th gear when slowing down or coasting downhill.


Sounds to me like it is due for some carb. cleaner.
Since it is still running good most of the time, you probably can get by without a tear-down of the carb.

[KiwiGZ]

Thanks for that tip, I will give it a go first before asking the dealer.

[jonathan180iq]

I had a similar problem on an older bike and it turned out to be a pinched diagphram(sp) over the jet needle. May want to look into that. This would make sense, as the area that you are talking about is in the mid-range, which just happens to be the area afftected by the needle.

[Badbob]

it would appear that the reason nobody else has seen those parts is that most people don't remove that bolt because it is NOT the oil drain plug. Rolleyes

I'll fess up. I did this before. Talk about puzzled.

I think the reason lots of people have done it but they are just to shy to admit it.

[1Rogue]

Well, finally got it in and out of the shop. They tested it for several things and broke into the clutch and adjusted a couple of things they said weren't in correctly, but to no solution. It is still doing the same thing. The service manager said the only place left it could be is in the transmission itself. They said that could run around $950 and that they would put the labor charge I paid for the clutch work toward that service. That is still around $800 and I dont think I want to put that much more into the bike.

So, new question. Has anyone rebuilt their transmission on the GZ250? If so, how difficult is it and do you need all the special tools that the service manual shows? I may try it myself.

[Badbob]

I sure would like to know why they think its the transmission. I can't imagine a transmission problem that would do this without some hard shifting or crunching and grinding.

Ignition system problems can cause surging. I had a bad connection in a connector that would do this at almost exactly the same speed. The vibration was causing the connection to break and shunting down the ignition system. When the vibration subsided the ignition would come back on. I got home by riding slow to keep the vibration down.

[1Rogue]

I think they came to the conclusion by process of elimination.

I did discover a potential source of the problem on my own last night riding. My foot was close to the shifter lever and I felt it bump my foot right before the engine skipped in fifth gear. I started monitoring the shift lever and it would slowly creep downward until the engine skipped, it would then pop back up into place. It is still only happening in fifth around 48mph and up but found if I kept firm upward pressure consistently with my foot it didn't happen. It wore my leg out pretty quick but it didn't skip once when I did that. I don't know where the origination of the problem is stemming from, but it is the closest I have come to a symptom besides the skipping.

Any ideas anyone. The dealership's mechanics don't seem to be helping any. I have been through 3 of them now.

[Water Warrior 2]

Sounds like some type of return spring or the like has given up. Obviously internal but could be an easy cheaper fix than the whole tranny. Of course what do I know, but do keep optimistic.

[LoneRyder]

I realize this is very old thread, but, did you ever discover the source of this problem ? This is what my bike is doing. Runs fine at 50 mph in 4th gear but in 5th it surges and stumbles like it is popping out of gear or starved for fuel as I go from 45-55 mph. used berrymans carb cleaner, checked air filter, checked exhaust. otherwise runs fine. just on the high way as i shift to 5th and accelerate it stumbles and surges. very annoying. my bike is a 2007 with 1000 miles on it with 600 miles over the past two months.