Intermittent Lack of Power
 

Hi guys,

I have an issue here. It seems that on random days my bike is extremely lacking in power. I've had this bike for over 6 months and ridden it as a daily commuter, so I know this bike's potential and its limits, and this is a DAILY, NOTICEABLE DIFFERENCE. This is not a placebo effect. There are no surges or putters or anything of that sort. I have run carburetor cleaner (B-12) through two tanks of gas, emptied and cleaned the float bowl, cleaned ALL the jets, cleaned the air filter, changed the oil, adjusted the chain, checked tire pressure, and I have done two valve adjustments over the span of a month to ensure I did it right the first time. Nothing helps. I've also got a float charger on the battery every few days to ensure a fully charged battery.

I thought it was initially due to the cold weather, as they seemed to go hand in hand. But today it is 60 degrees, and coming in to school I could barely get up the same hill at 45 mph that I can normally comfortably pull at 55, and some days even accelerate up the hill. So I don't think the cold is a factor.

Has anyone else had this problem? It's beginning to worry me that maybe my clutch is slipping at high loads, but I've only got 2200 miles on the bike, so I don't think that's the problem.

Anyone with suggestions please chime in, I'm at my wits end!

-Gzlocal

Re: Intermittent Lack of Power
 

Oh yes, I've also checked my spark plug gap and cleaned it, and checked for vacuum leaks with carb cleaner. I'm running Valvoline Durablend 10w-40 for winter, and I usually run Rotella T6 synthetic 5w-40.

A side note, at high RPM's in lower gears, there seems to be some hesitation. I think the best term for it would be a flat spot in acceleration. I know this is common for the bike, but I'm not sure if this would be difficult to diagnose from a slipping clutch under high load. The bike never revs up as in neutral, so again I don't think it's the clutch, but please correct me if I'm wrong.

Thanks in advance!

-Gzlocal

Re: Intermittent Lack of Power
 

Doubtful the clutch is the problem. A different brand of gas might be the solution or try the same brand if you don't already. Different brands may just give you the unwanted power response as some are not as good as others. You need a top tier fuel for best results. Also can you remember if there was any difference in the clothing you were wearing. Wind drag on material might attribute a bit. Mostly though I would think it is a combo of atmospheric pressure, altitude(SP)temp, humidity and a possible unnoticed head wind. Suttle differences can/will slow down a GZ.

Re: Intermittent Lack of Power
 

It's usually very wind-free here on my route to work. My clothing is always the same: Leather harley jacket (no jokes please! :tongue: ) with jeans and riding gloves. Today it was the worst it's ever been, because I had to put myself in a full tuck position to try to maintain my speed going up the hill and it did nothing. Granted, it's a tad bit windier here today due to a front moving in, but it is blustery, not really a head wind. But it isn't just today that the bike does this, it just so happened to be REALLY noticeable today.

I have noticed subtle differences depending on temperature, wind, traffic, etc. But these are seemingly random and feel like I lost 5 hp or something. FWIW, I always run BP gas from a newer station so there isn't likely to be water in the gas from leaky old tanks. And it's not like these symptoms last for an entire tank of gas. It's fine one day, and sluggish the next. Or, even more mind boggling, it can be sluggish on my way to work, then when I leave one hour later, it's fine coming home. :cuss:

Re: Intermittent Lack of Power
 

Just for the hell of it, try and loosen the gas cap and see if that makes any difference and restores power. The vent in your cap could be partially or completely plugged and creating a vacuum and not let the proper amount of gas flow to the carb. If you hear a hiss of air rushing in or the bike picks up power, that could be the problem.

Re: Intermittent Lack of Power
 

That may well be the problem. Why didn't I think of that.

Re: Intermittent Lack of Power
 

Yea! Why didn't I think of that! :lol:

I can actually hear it venting when I park the bike or move it after it has been sitting in the sun. I just filled up with gas this afternoon in expectance of the coming price hike on Sunday and there was no hiss. But when it starts to act up I'll be sure to try that. I just fixed a leaking petcock, so through all my testing I'm very sure I'm getting adequate flow, but I would like to remove as many variables as possible. Thanks for the suggestions!

I think another user Geezer had an issue with his bike in cold weather, that may or may not be related. It sounded like similar issues. I'll try to track him down and see if he ever resolved his issues.

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Re: Intermittent Lack of Power
 

No, this hasn't crept up since the petcock issue. It's fine, I checked it running the bike on prime as well, which bypasses that o-ring altogether and it made no difference. I don't think it is a fuel delivery problem. It's been doing this randomly, basically since I purchased the bike 6 months ago. It's just so hit or miss I never really paid any attention to it and it always seemed to rectify itself just from one ride to the next. Just like today, on the way home, it was perfectly fine. Nothing seemed amiss in the carburetor when I had it apart on my bench. Everything seated normally and it was actually quite clean. I was just wondering if anyone had experienced this same phenomena, and had managed to correct it somehow.

I haven't really noticed it anywhere else, because on my daily commute that one hill is the largest and steepest I have to climb. I don't know GZ Rider how familiar you are with the Charlotte area, but the large hill on highway 29 at the speedway? That's the one I'm talking about, which I guess is a bit steep for any vehicle with less than 8 cylinders, but it is a good reference point for measuring my bike's "attitude".

As far as opening the throttle too far to lose power, I can actually attest to the fact that once you run out of throttle on the GZ, you run out. You can open it farther, but you don't go anywhere. That's kind of the situation I find myself in everyday on the same hill, it's just that when it decides to act up, the bike doesn't hold its speed. When running normally, if I run wide open in 5th up the hill, I'll at least maintain the 55mph I started at. When being a little pissy, I just watch hopelessly as the speedo drops to 50, then 45....

I guess my GZ is like my girlfriend. She has her good days, and her bad days. But she's always fun to ride! :curse:

Thanks for the suggestions guys! Lovin' it here!

Re: Intermittent Lack of Power
 

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Re: Intermittent Lack of Power
 

Correctamundo! That's the beasty! :rawk:

Thanks for all the suggestions, I appreciate all the help on this forum. I'll have to try the gas vent just in case. Thing is it's hard to tell whether or not it's going to do that until I start climbing the hill. So I'd have to stop, shut off the bike, remove the cap, go back down the hill, get up to the same speed and try to climb it again. Based on its behavior, it could very well have resolved itself at that time and climb the hill fine. I wouldn't know if it was because it was happy again or because of the cap. I'm telling you it has a personality!

Re: Intermittent Lack of Power
 

Um... I'm no expert on the mechanicals of the GZ, but I'd be interested if, before each trip, you would check wind speed and direction on the internet. Lots of weather sites have them. I've found that when I'm riding I can barely notice wind at all unless it's practically gale force, but I do notice it on the speedometer.

Some days on the same stretch, I can barely keep it above 50 in 5th, and some other days I'm flying at 60-65. When I go back and research, there was a wind. It may be from the north or from the south, but it was there. It really annoys me. Oh, and I'm a commuter, too, but not daily. More like twice a week or so.

Re: Intermittent Lack of Power
 

You don't have top remove the cap completely, just crack it open to break any vacuum. If that's the problem you will notice an immediate difference in the engine picking up revs.
If you are losing power going up a long steep hill, just shift down to 4th gear to maintain your power. You may be running out of torque to maintain the speed up a long hill in 5th, and this is a characteristic of the bike, or any low powered vehicle.

Re: Intermittent Lack of Power
 

Yea, I usually lose a few MPH's going up the hill, but some days it's very noticeable. I know it was very windy, so maybe there was a wind I wasn't sure about, but I don't think the wind direction would have been south to north, the front was moving in from the west. But I'm not sure. I can't look it up now, all the forecasts I can find are from today onwards.

I can't explain all the other days. It does feel like it has an all around lack of power, but I can't really confirm it until I hit that hill, so I can't accurately say if it was windy all those other days. I did think about that as a factor, but I don't recall any particularly windy days. They are usually just blustery, not really constant winds here.

I guess I need to find a way to fit a Chevy 350 inside it. Anyone got a shoehorn? :lol:

Re: Intermittent Lack of Power
 

Do you have the problem with a loss of power if you are riding along a flat road at 60-65mph or only when you go up that long hill?
There may be absolutely nothing wrong with the bike.

Re: Intermittent Lack of Power
 

It seems to have more difficulty getting past 55. I can normally twist the throttle under normal circumstances on flat ground and accelerate in 5th relatively quickly. But when it acts up, it's much more sluggish. I can twist the throttle and there's nothing left.

Re: Intermittent Lack of Power
 

So don't forget to ride with your spare key in the fuel cap lock. :whistle:

Re: Intermittent Lack of Power
 

Exactly what I was thinking quietly to myself.... :retard:

Re: Intermittent Lack of Power
 

one way I've found to test the wind effect... after struggling on the freeway for an hour and a half trying to maintain 55+ I'll suddenly get to the city and I'll be surrounded by cars and big rigs galore, so the effective wind break is super magnified. All of a sudden, I can cruise at 75mph with no problems, and that is all uphill, downhill, every single direction. The only difference I can see there is that it isn't just me against the wind.

Even if there isn't wind, if you're on a wide open road, you're fighting your own wind resistance unless you have a truck or something in front of you to break it up.

Re: Intermittent Lack of Power
 

Yea, I try to hunch up when I approach hills to make it as easy as possible on the bike, but it seems to make little difference. It seems fine everywhere else. I stay well away from large trucks because they tend to throw me around a lot. I'm 6'0" and 160 lbs, so I get thrown around a lot on my tiny bike. I may invest in a small windshield and duck behind it, but I've heard some folks say it helps and some say it hurts MPG and top speed. So I haven't decided yet. I'm really wanting to wait until that magical 4000-5000 mile interval when the "true" break in period ends. This is when most people say they gain a lot of pep in their GZ, so I'm waiting until that happens before I do any carb mods or alter anything on the bike that may affect performance.

Did any of you guys experience a smoothing out, gain of pep, top end, etc. at the 5000 mile interval or thereabouts?

Re: Intermittent Lack of Power
 

By the way alantf, I've been meaning to ask you since I got on this forum, what in the world is that furry mammal in your avatar? Is that like a mutant guinea pig? :skeptical:

Re: Intermittent Lack of Power
 

It is a rabbit standing on his hind quarters.

Re: Intermittent Lack of Power
 

Go to "My Avatar" in off topic chit chat (Oct 10th, 2011) :)

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Here is the link for anybody that wants to know:
viewtopic.php?f=14&t=5083
:) :cool:

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Yea, I'm very easy on my bike as well. But there is this one spot in Charlotte that when you have a gap you have to take it, so sometimes I have to give it all she has, and that's when I noticed the hesitation on the top end. I can't say I remember that when I first got the bike, but I was probably too afraid to rev it that high before. Time flies by for me at this time in my life, so it's hard for me to be sure about anything anymore.

Gz Rider, have you done any carb mods to either of your bikes? What difference did you see if you did?

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Re: Intermittent Lack of Power
 

I rebuilt my carb with a bigger Main jet (#132),shimmed the needle,and adjusted the idle mixture.The biggest change I seen was much easier starting cold,as the bike was running richer,which I would contribute to the idle mixture adjustment.Before I done the adjustments,the bike was hard to start when the temperature dropped below freezing.After modifying the carb the bike started much easier hot or cold,idled smoother,with no fluctuation and was more responsive.
:) :cool:

Re: Intermittent Lack of Power
 

... I love big trucks, the bigger the better. Yes, it's true, you do get buffetted, but nowadays the buffeting is like music to my ears. Once I'm in that little buffer zone behind the big rig, my speed changes from a top speed of about 55 in 5th gear to an easy 65+ and I don't even need wide open throttle. It makes all the difference in my commute, but then I commute almost 2 hours each way, so every little bit counts. I do stay at least 2-3 seconds behind them. I'm crazy, but not *that* crazy. :P

The reason I still think it's wind (I've never noticed any difference in hunkering behind the windshield, myself) is that I used to experience the same thing. One day it's quick, the next slow, and everything else seemed equal. That's when I looked at the windspeed and direction on the computer before leaving for work and it all adds up.

If you have a flat stretch, and it's a particularly slow day on the bike, try making a u-turn. I did that once, and one direction I was struggling to get to 55 in 5th, and when I turned around (there was construction blocking the road) I was suddenly flying at 75 on the same flat road. So, that cinched it for me that even if I can't see any blowing in the trees, that the wind is still my constant friend/enemy.

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Oddly enough, I never have an issue anywhere else but on the hill. Even on bad days, although it is slow to get there, I could do 60-65 no problem. Thing is, the speed limit is 55, and I don't speed, EVER. So it's hard to test the top speed since it is in excess of the speed limit and I refuse to go there unless it's on the interstate where I can safely test it, and I tend to stay away form that particular path. It just scares the hell out of me with all the construction in the area.

It's not so much a top speed issue as it is a maintaining issue. I get the analysis with the wind, and more than likely it is a major culprit of the behavior. Weather conditions change too rapidly around here to get an entirely gut measured reading of power, especially with such a low powered bike.

Re: Intermittent Lack of Power
 

So after I recently passed 2400 miles on the odometer, the bike started to wake up a bit. I haven't had the issue on the large hill anymore since then, it was very happy to maintain a constant 55, and then a few hundred miles ago, it magically decided it would ACCELERATE up the hill! I couldn't have been more pleased. Unfortunately, the bike was up for sale when I found a really good deal on a new local CBR250r, and I was in too deep to back out. So, sadly, my GZ is getting ready to leave to a new happy family. But, being my baby, before I sold it to them I did a background check, learned a bit about them, checked where they lived, yearly income, other vehicle conditions, social security number, what their breath smelled like, favorite movies, traffic tickets... :lol:

So if your GZ lacks a bit, wait a couple thousand miles for it to wake up a bit before making the mistake of upgrading too soon! I already miss the bike and it's not even gone yet.... :cry: