Valve adjustment for the GZ250

[Chris]

I've mentioned that I have a friend who used to be a motorcycle shop mechanic and has had several promotions since then so he is a national motorcycle maintenance expert. This guy is a real resource for motorcycle information and a lot of other things. And a good friend.
Today he came over to adjust my valves and I said in this forum that I would report back on what he said and did. He said that most people had no idea if their valves needed adjusting or not. If they are too tight that is bad and too loose is bad. If they get out of adjustment it could toast your engine and most people simply would never know it was coming.
So how do you know if they need adjusting? You never would. He said to make the first adjustment at about 5000 miles (mine has 5400 right now) and about 5000 miles after that. Best is to get it done about 5000 and then every 5000 miles. Sometimes you go in there and they don't need any adjustment, but then you are sure it is right.
He says this has a very small effect on performance and even on valve noise. Too quiet is bad as the valves are probably too tight (mine were).
I offered to ride the bike to his house, but he said that it takes the engine so long (2 hrs.) to really cool down that it was easier for him to just come to my house. I won't tell everything he did, but it started with taking the gas tank off. Then the chrome cover on the left side where the spark plug is. My spark plug was loose, but no damage had occured. My plug looked great. Then he tried to take off the small plate on the left side of the engine to be able to move the piston to TDC. But the plate would not budge so rather than bung up the plate we put the bike in 4th gear and by moving the bike that moved the piston (without the plug there was no compression so it was easy) back and forth until the piston was at TDC. It comes to TDC twice and you want it at TDC on the compression stoke. Hard to know when this is, but when the valves are loose that is it (valve caps are off. Labeled #1 and #2, put them back the same way).
Loosing the nuts and adjusting the "valve adjustment screws" and tighting the nuts was tough. There are two valves: exhaust in the front and intake in the rear. He adjusted both and put everything back together. I videoed all of this so I can do it the next time.
Honestly, this was pretty hard to do and I don't think the average rider should attempt it.
Probably $100 at a shop. With my video I think I will do it, but just starting from scratch I don't think anyone should try this. Unless you have done this on other engines.
So it went well and I owe him a big favor. Just thought you would want to know.

Chris, retired, Atlanta

[mrlmd1]

No pictures? Can you capture any stills from your video? Or post the video somewhere?

[mr. softie]

Thanks for the post Chris. Your remarks at the end made me think a bit on some of the advice I have given on this forum. It is true that if someone has little or no experience at something it is much more difficult for them. I have 53 years of experience (since I was 5 or so) of wrenching on my own "bikes". I have totally rebuilt a number of vehicles, motorcycles and cars, including engine and transmission overhauls, as well as working as a professional mechanic for a good while. So while it is easy for me to say "just do it", I realize it is not that easy do do without the experience, tools and know how I may have accumulated over the years. To me doing a valve adjustment on the GZ is about as hard as putting a band aid on a cut would be for a surgeon. You don't want me doing surgery though, believe me! Even if I had a video! :lol:

[Easy Rider]

He said that most people had no idea if their valves needed adjusting or not. If they are too tight that is bad and too loose is bad. If they get out of adjustment it could toast your engine and most people simply would never know it was coming.

Honestly, this was pretty hard to do and I don't think the average rider should attempt it.


:plus1:

Great post. I agree with all of it. Important parts above. :tup:

Knowing that it is somewhat of a gamble, I still think that I will only check mine every 10K or so....but he (and the Zuki) manual are correct that they really SHOULD be done more often.

[JWR]

Well said mr. softie.

My father was a mechanic all his life.
He kept a small school with about 8-10 buses running for 10 years.
In the 50's and 60's you did everything hand, and rebuilt all that you could.
Dad would buy cars and trucks that did not run, rebuild them,paint them, sell them.
I was the clean up boy on the engines, scrape off the old gaskets.

The real lesson we both got is when we began a trucking operation as owner operators.
I have fixed flats on everything from a bicycle to cars, trucks, tractors, and of course big trucks.

The only tire that I could not change by hand was a golf cart tire, too wide to get a grip on.

This is why I would rather do it myself. I care, but does the tech??

Well said mr. softie.

This is why I would rather do it myself. I care, but does the tech??


And if it's not a matter of care, it may be one of ability/experience. I think Alan alluded to this kind of thing on another thread when he talked about how dealerships put inexperienced techs in place b/c of the high turnover rate. Unfortunately for folks like me, who did not grow up wrenching on bikes, cars or anything else, we're kind of at the mercy of the mechanics, dealers, etc. The best you can do is try to educate yourself at least somewhat (like with this forum), but if my mechanic says I need to do something, in the end, you have to take a leap of faith. That's why I try to form a relationship with a mechanic and then be loyal as hell and send him business. We all do this, really. You have a doctor or a dentist? Same thing. Pilot of an airplane? Same thing. Amazing how we put our lives in other people's hands all the time.

kk

[JWR]

A good tech that you know and trust is a good thing. Get their knowledge.

Just going to a shop......is the tech having a bad day? bad week? bad life?

Yes, boards like this, is very valuable to everyone. Each person is not going to have the same problem, so we can all glean some information from each other.

Most machines are not that different.
Air, fuel, and combustion is all it takes.
Now the hard part is to get them to all work at the right time.

Jerry

[mr. softie]

....is the tech having a bad day? bad week? bad life?

Probably! :lol:

[Chris]

No still pictures. ANd I have no idea how to get my VHS tape online. I thought of taking still pictures, but thought the video would help me better in the future. I got the video with his audio comments, etc.

Ride safe, ride long.

Chris, Atlanta Just waiting on warm weather.

[alanmcorcoran]

Chris,

Is it a digital video camera? Or analog? What size tape? Or, what is the make and model of the camera you shot it with?

Video can usually be easily converted to a computer playable format, but, like mechanical stuff, you have to have the right tools. It's sometimes easier (but not cheaper) to take it to a video shop.

[Chris]

My camcorder is an ancient VHS tape model. Works well, but now with a new grandbaby I need to upgrade to a digital model. But for the moment I still have a VCR and my camcorder works just fine. I am old enough not to like it when the world moves to new technology. My camcorder is at least two generations behind and today you cannot even buy a VCR!
My bike is now in tiptop shape and I am just waiting on warm weather. Time for me to oil up the chain and set a new speed record! 76.9mph on the last one, but I know I can do better than that. The guys online talking about 90mph are just lying. Unless they change the gearing, etc. a stock GZ250 would never do that. Maybe off a cliff!

Chris, retired, Atlanta

[alanmcorcoran]

Chris,

Given how far behind you are (I'd say at least four generations) your best bet is to take the tape to a video shop and have them make you a CD with an .AVI or other PC compatible file. For a while there, there were digital Hi-8 recorders that could read an analog tape (I have an old Sony TRV350 I've kept around for that purpose.) My unit will convert the analog to digital and transfer it to a PC via a Firewire port. I'm not sure they had any digital recorders that wrote to the full size tapes - but there were a lot of different options over the years.

Since yours was made there has been:

Analog on Video8 and Hi-8 tapes (a little bigger than a music cassette)
Digital on Hi-8
Digital on mini DV (probably the most popular format today)
HD digital on mini DV
Various "tapeless" contraptions that use flash memory, hard drives, and DVD-R's

Don't worry,as soon as you buy a new one, it'll be obsolete.

[music man]

You can use a program/plug in like this, I have never used this or any other program to do this, but I have a couple of friends who say it isn't all that hard to do.


http://www.easyvhstodvd.com/

[kaput]

Can someone tell me 2 things about the valve adjustment?...

1. How do I know when I am on the compression stroke?

2. Which 2 valves are intake and which 2 are exhaust?

This knowledge is in preparation for the arrival of my "special tool" tomorrow.

:rawk:

[Easy Rider]

Can someone tell me 2 things about the valve adjustment?...


Do you know how an engine with valves actually WORKS?
Not so sure it is a good idea to be adjusting the valves without at least rudimentary idea of what is going on in there.

Do you have a shop/repair manual? There is one available here for download.

The manual should help a LOT.......including the answer to your two questions.

[kaput]

I had a 65 VW bus for many years so, yes Easy, I have adjusted valves before, many many many times , not rocket science :2tup:

This is however the first time I have ever worked on a motorcycle.

The manual says to adjust the valves on the compression stroke, it does not explain how to get there other than going to TDC which will not put you on the compression stroke every time.

I HAVE downloaded the Manual and I can not find this information.

Please answer if you know the answer, if you don't know, don't bother.

Thanks!

[music man]

2 valves on the exhaust side and 2 valves on the intake side.

[kaput]

cool, so the 2 in front are exhaust and 2 in back are intake.
Thanks for the help.

[patrick_777]

I HAVE downloaded the Manual and I can not find this information.

Please answer if you know the answer, if you don't know, don't bother.

http://www.tacogod.com/images/tsr/CatHiss.gif

[Easy Rider]

cool, so the 2 in front are exhaust and 2 in back are intake.
Thanks for the help.

OK, that is true but how did you deduce THAT from this:

"2 valves on the exhaust side and 2 valves on the intake side." :??: :shocked:

As to the other question:
Take the spark plug out. It makes the engine MUCH easier to rotate.

You want to find TDC on the compresssion stroke. That occurs when the piston is coming UP and both valves are closed. They both stay closed as you go past TDC for a ways.

The other time the piston is at the top, the exhaust valves will be open (starting to close) and the intake valves will be closed and starting to open. That is NOT the spot you want.

If you have trouble telling what the piston is doing:
Drop a LONG soda straw or something similar into the plug hole. This will tell you the relative position of the piston. Be sure you use something long enough that it won't disappear into the chamber.

I'm guessing the straw trick won't be necessary as the marks probably only line up at the two above points......which are pretty easy to tell apart just by watching the valves.

Good luck!

And I'm not trying to be a smart ass but anybody who has really worked on 4 stroke gas engines much at all should know that already. They all work the same regardless of the size. :tup:

AND I am just trying to keep you from getting in over your head and making things worse......really. :cool:

[5th_bike]

cool, so the 2 in front are exhaust and 2 in back are intake.

Yes, our GZs actually have 4 valves. There are several web sites with "motorcycle specs" that maintain that GZ250s have two valves, even when informed otherwise.

It may seem beyond comprehension yet even THIS site is one of them...

[kaput]

Thanks Easy,
I appreciate your time and explanation. I will not argue the differences between my old vw and this little suzuki or express my feelings of "The Manual" :)

I am sure this will send me in the right direction.
thanks again,
-=kaput=-

[patrick_777]

It may seem beyond comprehension yet even THIS site is one of them...

Whatever do you mean?? :whistle:

[adrianinflorida]

I HAVE downloaded the Manual and I can not find this information.


The procedure is on pages 2-4 thru 2-6 (Pages 19-21 if you're looking at the page numbers displayed in the PDF reader)


Below is the text, but USE THE MANUAL so that you can follow the diagrams calling specific parts out.

VALVE CLEARANCE
Inspect initially at 1 000 km (600 miles, 3 months) and every 5 000 km (3 000 miles, 15 months) there-after. INSPECTION
• Remove the front seat. (See p. 5-1.)
• Remove the fuel tank. (See p. 4-1.)
• Remove the cylinder head cover left cap
• Disconnect the spark plug cap and remove the spark plug. 09930-10121: Spark plug socket wrench set
Remove the valve inspection caps The valve clearance specification is different for intake and exhaust valves. Valve clearance adjustment must be checked and adjusted, 1) at the time of periodic inspection, 2) when the valve mechanism is serviced, and 3) when the camshaft is re-moved for servicing. Valve clearance (when cold): IN. : 0.03-0.08 mm (0.001-0.003 in) EX.: 0.08-0.13 mm (0.003-0.005 in) NOTE:
* The piston must be at top dead center (TDC) on the compression stroke in order to check or adjust the valve clearance.
* The valve clearance should only be checked when the engine is cold.
* Remove the valve timing inspection plugand generator cover cap
Rotate the crankshaft with a box wrench to set the piston at top dead center (TDC) on the compression stroke. (Rotate the crankshaft until the "T" lineon the generator rotor is aligned with the triangle markon the generator cover.) Insert a thickness gauge into the clearance between the valve stem end and the adjusting screw on the rocker arm. 09900-20803: Thickness gauge
If the clearance is out of specification, adjust it to specifica-tion as follows.

ADJUSTMENT The clearance is adjusted using the special tool and offset wrench.
• Loosen the locknuts
• Insert a thickness gauge between the valve stem end and the adjusting screwon the rocker arm.
• Adjust the valve clearance by turning the adjusting screw using the special tool while holding the locknuts
09917-14920: Valve adjuster wrench
CAUTION Both the right and left valve clearances should be as closely as possible.
• After the adjustment is completed, tighten the locknut se-curely.
• Rotate the crankshaft 720° with a box wrench and check that the clearance is within specification.

[kaput]

Thanks Adrian but I had that already. my real problem was finding the compression stroke.

I found it and confirmed it with my neighbor.

I got the "Special tool" wrench and adjusted the valves, took me about an hour but I think next time will be way quicker. I put them at midway in the specs and it is a bit Klacky but my Idle and Stalling problems are GONE! I think I may tighten them to minimum specs next weekend to get the noise down.

Bike also starts faster and the choke is not needed at all (here in sunny San Diego).

By the way, if anyone is scared to do this job, don't be intimidated. Its really not as hard as some folks may have you believe and is extremely beneficial.
:2tup:YOU CAN DO IT! :2tup:

The hardest part is getting a tool that will remove the generator cover cap and finding TDC on the compression stroke. (2 of the things the Manual does not cover)

-=HINTs=-
* I found the the compression stroke was easily found if you leave the spark plug in, you will feel resistance just before you hit TDC.
*Also the 2 valves in front are the Exhaust and the 2 in back are Intake

the rest is covered in the manual in the pages that Adrian quoted.

Thanks for the help and good luck to anyone trying this fairly easy job.
-=kaput=-

[5th_bike]

Whatever do you mean?? :whistle:
:rawk: You FIXED it !!! :2tup: :banana:

[alanmcorcoran]

Maybe that's why my problems went away as well. Adjusting the valves was on of the things they said they did (the third time.)

[kaput]

:rawk: OH yeah! its my birthday :2tup:

Always a great feeling to do it yourself.
and you know it has been done correctly too.

I would be willing to bet $$$$ that was your problem alan.

[Easy Rider]

my Idle and Stalling problems are GONE

Glad everything went OK.

It is VERY rare for valves to be far enough out of adjustment so that it makes a noticeable difference in how the engine runs and performs. That difference "might be" just a coincidence.

If you really did get them set to the middle of the spec., you probably should leave them there......since having them too tight is MUCH more dangerous (to engine life) than too loose.

Since this was your first run doing the adjustments, it might be a good idea to check them again soon just to be sure they are set where you think they are. :2tup:

[Easy Rider]

I would be willing to bet $$$$ that was your problem alan.

I'll take that bet. How much? :biggrin:

A valve lash difference of .001-.003 inches will NOT affect engine operation enough so that you can notice; it just won't. NOW, if your valves were WAY out of adjustment, all bets are off.

Alan: Did they really mention valves on your LAST ticket? I don't remember you saying that.

[alanmcorcoran]

Yes. When I got it back the first time, I indicated I suspected that they hadn't really done the 3K service as detailed in the manual because there was no itemization or charge for a valve inspection/adjustment. (I also found oil in the drain tube from the air box and it was obvious no one had looked at the spark plug.) They claimed they "HAD" done one for "free" but I didn't really buy it. The second "fix" was a complete eff-up, they just basically said, "Yep, it's f*cked." But, the THIRD time, it really was fixed - carb clean, emmisions, valve adjustment. Not sure what actually fixed it, but it's running real good again. Idles real nice and no stalling. I can drop the choke off after a few minutes or so, and only need half choke to get it started. No funny racing around and idling drift.

[Easy Rider]

Idles real nice and no stalling. I can drop the choke off after a few minutes or so, and only need half choke to get it started. No funny racing around and idling drift.

Yep, that was mine last year. Hope the new air filter fixes it; will know tomorrow as the temp. is supposed to near 70 and the shop called to say the new filter is in. Got lots of errands to run after being gone all weekend.

[Canuck]

Im getting the Valves adjust tomorrow...

Im NOT SURE if it will be the solution but after taking the week old spark plug out it is sooty black around half the threads, around the ring and is greywhite on the little metal thing on the very top...

The Idle mixture screw is set to 2.75

It is idling much better then it was and when fully warmed is not stalling as far as i have seen...

Im going to adjust the throttle to its manual specs and tomorrow see how the valve adjustment goes...

Last time i had it done was around 10,000 kms and I've done some pretty long trips and have been riding all winter long...

Ill switch to 92 octane as the manual suggests (I have been always been using 94 octane)

I've also been considering getting a compression test just to make sure its operating at full. If not then I will start to look for exhaust leaks where they bolt onto the engine.. As ive posted before i have rusted bolts and have never had the gaskets changed...

couldnt hurt? except if those bolts snapped off!

*sigh*




See how it goes, wish me luck

[alanmcorcoran]

It is possible that you are not getting the choke completely shutoff. That would explain your fouled (new plug) and the racing. Not sureit would actually cause a stal though. When they adjust your valves, have them check and clean the carb.

[roncg41677]

Chris, thanks for the info. I'd love to see that video! I've had some VHS stuff transferred to DVD before at a video shop, and it's not expensive at all. Might be worth it so you could easily copy it on a computer and pass it along ;).

I'd love to learn how to adjust the valves. I've learned to disassemble and clean the carbs. I have a good friend who built race cars for many years and works on his cars/boats/engines with the precision of a surgeon. He showed me how to take apart the carbs, what was what etc. It's so valuable to have an experienced friend to help. The guys here are the NEXT best thing :biggrin: .

All the talk about novices not messing with engines got me thinking though. Can you practice some of these things on a much smaller engine, like a lawn mower? Finding a cheap non-working one would be easy, and if you mess it up in the process you're not out but $20 or whatever.

[adrianinflorida]

Mine's ready for the valve adjustment and carb cleaning tomorrow morning. Got the gastank off, fixed the clutch position switch wire that was giving me issues a while back and will do the 'teardown' of the carb and valve access covers when I get up.

[Easy Rider]

Im getting the Valves adjust tomorrow...


As I posted in anothe thread, PLEASE tell the shop what problems you have been having and ask them to FIX it. Your spark plug report still points to a major carb. problem.

[kaput]

Easy Rider,
Do not be scared to do your own repairs!
And please do not scare others to do what they should be doing.
Why would you want to stop folks from improving their bikes?
You accused me of never working on an engine but the first thing I know from working on my VW bus is you must check the valves, the carb, and the spark.
I checked these things and now my bike runs perfectly.
Either you are an idiot or I am a genius.
-=kaput=-

[Easy Rider]

Easy Rider,
Do not be scared to do your own repairs!
And please do not scare others to do what they should be doing.


Oh God, here we go again.
Let's see if I can do this without a pissing contest.........

I know about engines. I rebuilt my first one when I was 16....about 45 years ago.....a twin thumper John Deere.....with some help from my Dad.

Just because you and I can do it doesn't mean that EVERYBODY can or should be doing it.
If I have assessed your skills incorrectly, I appologize.

The fact remains that some people just don't have much mechanical savy or skill. You can usually tell that after only a few posts. I do not think it is a prudent to encourage someone who apparently doesn't know which way to turn a bolt to remove it to do his own repairs. Do you, really??

I usually assume that people have a bike because they want to RIDE it.
If they bought it as a project to learn engine mechanics, then that's a WHOLE different story......but this is a RIDERS forum and not an online course in engine mechanics.

[alanmcorcoran]

I usually assume that people have a bike because they want to RIDE it.

That's me. For the record kaput, Easy and others encouraged me to change my own oil. I'm not stupid or interested enough to try and adjust my valves. I know the basics of an internal combustion engine, and I've had the head off my moped, rebuilt lawnmowers and so on, but the last GZ problem I had, even the the dealership needed three tries to fix it.

I think if you look back through the threads, Easy and the other mechanic types (softie, tryke, JWR, etc.) generally encourage "maintenance" things like tightening, lubricating, adjusting (idle, f'rinstance), even plug cleaning/replacement but discourage mechanical newbs from major repairs. Even though it sounds condescending, I think it's good advice.

[Easy Rider]

Even though it sounds condescending, I think it's good advice.

Thanks for helping to clarify. :tup:

Condescending......me??......never!!.....well, good comment, actually.
Something to keep in mind.