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Discussion Starter #1
My 01 660 was running fine. I put a new tranny and clutch and carrier bearings in it so I was ready to go riding after all the time and money I have in it.



It starts and idles like it is brand new. You can start to rev it up and o ce it hits a certain RPM it hangs there and backfires/sputters/pops/bangs/throws fire out the pipe.


I pulled the plug and it was BLACK.

Thing is,that the carb was jetted for the pipe and air filter I have and ran fine before...the plug looked perfect and it ran great.

I checked and the problem is not one of the rev limiters. I tore the carbs down and they were spotless and everything was set as it should be for my elevation and mods as far as jetting specs.

I've TRIED EVERYTHING AND THINK IT JUMPED TIMING...Does anyone think it is possible that it jumped time and would cause it to run like it does.
 

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If it jumped timing it'd likely be hard to start and run rough at idle.

Have you looked at the inspection points and checked timing?
 

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Master of the Electron
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Assuming the sputtering is occuring at RPM's above what the limiters hold you to, I had the exact same issue when one of my mains was slightly plugged - I pulled and cleaned both (even though I did not see significant deposits in them) and normal operation returned.

1) are you certain the limiters are not causing this? (i.e., the RPM where it occurs is way, way above idle would say they're not.)
2) is it throttle related, not RPM - i.e. 3/4 to WOT only? If throttle, most likely carbs.
3) Bottom line - something has changed... any changes you have made recently, or anything you've overlooked telling us?
 

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Discussion Starter #4
I checked all the rev limiters. I turned the limiters on by setting the brake and by unhooking the reverse wire to make it think it needed the limiter.Those kick in at a lower RPM...so I unhooked them and went from there.

I took out the carbs and cleaned them...they weren't even dirty but I took them apart just to make sure NOTHING was clogged.

I have a full exhaust and the mod for no airbox lid...Icarbs set 146 main left,148 main right,clip on the needle is set 3rd from bottom or 4th from top on both carbs.

It ran fine before,then one day while I was riding it just decelerated and started backfiring and sputtering,I was able to get it home by keeping it low RPM's.


And It occurs at certain RPM's and not throttle position.It starts to rev,hits a certain RPM and stops.I can put it 1/4 throttle,1/2 throttle,full throttle and it does the dame thing.
 

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Discussion Starter #5
And QM...the only thing I have changed recently was that I put a new clutch in...I don't see how that would affect this...not even like I really tore into,it was just pates and springs.
 

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Master of the Electron
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Thanks for all the detail, it makes helping so much easier.

So, did you clean the carbs before or after this occurred, your timeline is not obvious.

Did you test the two limiters (reverse and PB) separately or together? They actually limit at different RPM's, reverse being somewhat higher - so doing both at the same time will give you the lower of the two only... try unplugging the reverse wire only, if you haven't already, and see if THIS is the same RPM you are having problems at.

Does your reverse light work normally? If so, any chance that the light is flickering slightly when this happens? Vibration induced by certain RPM's can cause the reverse switch spring connection to break contact briefly, turning the limiter on intermittently - try grounding the wire and see if the problem goes away. (I'd guess, from info so far, that this is the most likely culprit)...
 

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Discussion Starter #7
I cleaned the carb after the problem started.

And yes,I tested the limiters separately.My reverse light works normally,and I tried grounding it out and there was no difference.

When I unhooked the cable for the reverse limiter,my light came on...then I grounded it to the frame and the light shut off.
 

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Discussion Starter #9
Thats a hard one... what do these beasts redline at? I'll go from there.
 

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Discussion Starter #11
I'm guessing that it is about 3-3.5k RPM
 

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Discussion Starter #13
Well,I was guessing RPM's

Plus I tripped the reverse limiter by unplugging the wire and when it kicked on,it was at a lower RPM then where my problem is at.
 

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I am unique
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Well,I was guessing RPM's

Plus I tripped the reverse limiter by unplugging the wire and when it kicked on,it was at a lower RPM then where my problem is at.
SO how much higher then about 3500 rpm do you think the problem starts.........
Did you drive this bike after your clutch job, or are you just blipping the throttle.........
If you are driving it, what speed in 4t or 5th gear does the problem start..........
 

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Discussion Starter #15
I drove it once after I did my clutch. I ran it down the road in front of the shop It ran great everything it worked as it should...pulled hard in every gear through all RPM's

I would say that in 5th gear down the road on flat I was going about 35MPH.
 

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Master of the Electron
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Keep in mind, that if the reverse limiter is being turned on intermittently by vibration at the connection, the RPM that it settles to may be higher than if the limiter were on continuously.

I'd suggest grounding the wire and riding, to see if the issue has gone away. Simple test that may find the problem... if not, at least we've eliminated one more possibility.
 

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I drove it once after I did my clutch. I ran it down the road in front of the shop It ran great everything it worked as it should...pulled hard in every gear through all RPM's

I would say that in 5th gear down the road on flat I was going about 35MPH.
You have lost me, you said it pulls all the way in the RPM range but what happens at 35 mph in 5th.........
IS this where your problem starts.........only in fifth........
 

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Discussion Starter #18
I grounded out the wire and it still cuts out at a certain RPM.

Willy.I rod it once and it was fine,then I went to ride at my friends house it started running like crap.

It will pull hard when it's really low rpms. then once it gets so far it cuts out.

I can punch it 1st gear,it will pull for a split second,cut out.

I can shift to 2nd,punch it,it pulls for split second,cuts out.

Shift to 3rd, pulls slightly,cuts out.

4th,pulls slightly,cuts out.

5th,pulls then cuts out.

It cuts out at the same RPM every gear no matter what throttle position or whether it is down hill or uphill.
 

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Great, you answered all I wanted to know, and you think that is above the reverse rev limiter RPM, So what I think you should try first is go right to the CDI unit and ground the green and white wire directly, just in case the wire is broken somewhere throughout the harness........
 

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Discussion Starter #20
When the limiter kicked on it would rev so far,then I grounded it,it would rev a little farther,but still cut out.
 
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