No Power at Higher Rpms

[Buckethead]

Hey-

I am at wits end.

I went for a good muddy wet ride two weeks ago on my 24,000km '89 KLR. I dropped the bike once at low speed with no damage. I stopped for fuel when I was back in town. A few minutes later on the freeway I noticed a power loss at higher speed. The bike would not go above 5000 RPM (110km/h). Bike starts and runs fine.

I assumed that I had gotten bad fuel and drained the tank and float bowl and refilled with new gas with carb cleaner added. I pulled the petcock and checked the screens - clean. I connected another line to the vacuum post on the petcock. It appears to be working fine.

No joy.

I replaced the spark plug, and checked and cleaned electrical connections. Checked air filter -clean.

No Joy.

I pulled the carb, dissasebled and cleaned. Main jet and needle looked good. No sediment or debris visable. I inspected the slide diaphragm. It looked okay, but I replaced it. (Thanks Harley)
No Joy.

I pulled the carb, dissasembled and cleaned. I inspected the slide diaphragm. The new one looked okay, and well seated, but I pulled it out, and reseated it. Cleaned the main jet and needle again. Checked valves - A little tight, but still within spec.


No Joy.

I have run out of ideas. Thoughts?

Thanks,
Matthew

 

[edzzed]

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air filter?? longshot. how is the power going up thru the gears.

 

[Buckethead]

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good thought, but that was one of my first checks. The engine pulls fine untill about half throttle, then loses power. It is most noticable at highway speeds.

 

[joker650]

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A friend had a small rock get stuck on the carb that limited the throttle movement. But u had the carb appart....right.



It craps out at the same rpm in every gear?

Does it crap out at the same RPM if reved up in neutral?



EDIT:

I just re-read ur post. is the tweety exhaust pluged?

 

[Buckethead]

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I haven't checked the exhaust. I'll pull the pipe tomorrow and give it a shake.

Vents are all good.

The power loss shows up under load, regardless of gear. It revs fine in neutral.

Thanks for the ideas.

 

[Loz]

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I think it might be something on the ignition side. The symptoms you describe can be caused by an ignition fault such as a tracking HT lead or plug.

 

[Buckethead]

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Loz wrote:

I think it might be something on the ignition side. The symptoms you describe can be caused by an ignition fault such as a tracking HT lead or plug.

I agree. It does sound a bit like weak spark. I have cleaned all of the contacts, and it didn't make any difference. Any suggestions on how to dignose this without simply buying new parts?

Thanks

 

[Loz]

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I'd just start with new plug and maybe the lead and cap.

 

[Buckethead]

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Loz wrote:

I'd just start with new plug and maybe the lead and cap.

I replaced the plug early on. I don't really like using the "known good part" method of diagnosis as it can get expensive, but I might be at that point.

 

[Loz]

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I agree. Maybe borrow a coil and lead to try. But then whats the hassle factor worth compared with a used item? I reckon it has to be on the HT side of the system.

 

[Buckethead]

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Eagle Mike figured it out. I had given the timing a casual look when I checked the valves, but gave it a closer inspection today, and sure enough, it was off by a tooth. Re-timed it, and after the other carb, ignition, and exhuast work the bike runs better than ever.

Any thoughts on why it would jump a tooth?

Thanks, all, for the advice and help.

Cheers,
Matthew

 

[BMWNut]

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Buckethead wrote:

Eagle Mike figured it out. I had given the timing a casual look when I checked the valves, but gave it a closer inspection today, and sure enough, it was off by a tooth. Re-timed it, and after the other carb, ignition, and exhuast work the bike runs better than ever.

Any thoughts on why it would jump a tooth?

Thanks, all, for the advice and help.

Cheers,
Matthew

I had a friend with a jeep that ran fine. He drove it through a deep puddle in Vancouver, spun the wheels a bit , got out the other side and the motor quit. After much diagnosis time and a lot of swearing we found the timing had skipped a few teethwhen the drive train unloaded and loaded back up againand was too far out to run. Could this have happened with you in the mud?

 

[Guest]

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Buckethead wrote:

Eagle Mike figured it out. I had given the timing a casual look when I checked the valves, but gave it a closer inspection today, and sure enough, it was off by a tooth. Re-timed it, and after the other carb, ignition, and exhuast work the bike runs better than ever.

Any thoughts on why it would jump a tooth?

Thanks, all, for the advice and help.

Cheers,
Matthew

Did it backfire even slightly ?



Or is the timing chain stretched and not adjusted properly?

My friends old street bike backfired, and that caused it to skip.....not sure why, but it did....ya, its a long shot, but just a thought I had.

 

[Buckethead]

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BMWNut wrote:

I had a friend with a jeep that ran fine. He drove it through a deep puddle in Vancouver, spun the wheels a bit , got out the other side and the motor quit. After much diagnosis time and a lot of swearing we found the timing had skipped a few teethwhen the drive train unloaded and loaded back up againand was too far out to run. Could this have happened with you in the mud?

It's possible.

The only other thing that stands out about that day was another riding error that I made. I braked too late for an unexpectedly deep cross-ditch, missed the downshift, and had to power back up the other side from a near stop in second gear. I expected the bike to stall, but it didn't.

Thanks for the ideas.

Matthew

 

[Buckethead]

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mcfly wrote:

Did it backfire even slightly ?



Or is the timing chain stretched and not adjusted properly?

My friends old street bike backfired, and that caused it to skip.....not sure why, but it did....ya, its a long shot, but just a thought I had.

Hey-

No backfiring, and the adjuster and chain appear to be good. Did you ever get that long doo spring you were looking for?

Thanks,

Matthew

 

[Guest]

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Buckethead wrote:

mcfly wrote:

Did it backfire even slightly ?



Or is the timing chain stretched and not adjusted properly?

My friends old street bike backfired, and that caused it to skip.....not sure why, but it did....ya, its a long shot, but just a thought I had.

Hey-

No backfiring, and the adjuster and chain appear to be good. Did you ever get that long doo spring you were looking for?

Thanks,

Matthew

I heard it should need a shorter spring to keep tension on it...so I will pull it this winter while not riding, and see how short ( if any) of a spring I need to use on it.

 

[Buckethead]

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mcfly wrote:

I heard it should need a shorter spring to keep tension on it...so I will pull it this winter while not riding, and see how short ( if any) of a spring I need to use on it.

I have both the long and short spring that come with the doo kit. If you need one, let me know and I will drop it in the mail for you.

Cheers,

Matthew

 

[Guest]

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Buckethead wrote:

mcfly wrote:

I heard it should need a shorter spring to keep tension on it...so I will pull it this winter while not riding, and see how short ( if any) of a spring I need to use on it.

I have both the long and short spring that come with the doo kit. If you need one, let me know and I will drop it in the mail for you.

Cheers,

Matthew

Awesome thanks....I likely will take you up on that offer. :hb:

 

[_scooter_]

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Hey Guys

new here. I am having very similar problems, minus the wet ride.

I ran out of gas coming down out of the squamish valley on saturday, tipped my bike

on it's side and got it started again. Once we got down to Squamish and on our way

back to the north shore it started to sputter and backfired a couple of times, only

at about 100 kmh with the throttle all the way open. Did it a coulpe more time before

I got home. I have a clymer, but have never done any repair work myself. (this is my

first bike, 02 KLR)

Is this an easy fix or should I justtake it to a shop. If so any recomendations of

where to take it (lower mainland)

thanks

brian

 

[_scooter_]

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well

somehow I've managed to fix the problem. I'm still not sure what happened.

I just started on buckets list. pulled the fuel valve, cleaned it. checked all the lines

and tank vent, drained the float bowl. Just got back from a rip on the highway and everything seems fine. I was sweating taking the carb apart.