Author Topic: Misfire under load again  (Read 1278 times)

Online Greybeard

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Re: Misfire under load again
« Reply #45 on: 15.02. 2019 09:30 »
I keep seeing this kind of reference:

I had the same problem with overrun on one of my bikes.  It turned out that I had slightly overtightened the carb mounting bolts and distorted the carb body, thus binding the slide from quickly returning to the idle position (also only when warm).  Try loosening the bolts and just tightening them enough to eliminate any air leaks.  Hopefully this will help!  I agree with A10gf on the float level being off on the stalling on the sidestand.

Seabee

Offline bsapete

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Re: Misfire under load again
« Reply #46 on: 15.02. 2019 11:06 »
Thanks but this is without the carb bolted up to the head so not a case of distortion and also the old slide was moving fine.
62 A10S Spitfire Scrambler
54 A7 Star Twin (sold on)
61 Jaguar E Type FHC Flat Floor
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Offline coater87

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Re: Misfire under load again
« Reply #47 on: 15.02. 2019 11:17 »
 I would buy a new carburator.

 Sanding is just making it easier for air to leak around the slide.

 Really the best you can hope for is the throttle does not stick open when your riding it.

 Lee
Central Wisconsin in the U.S.

Online Greybeard

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Re: Misfire under load again
« Reply #48 on: 15.02. 2019 12:02 »
...the old slide was moving fine.
That may only mean that slide and body are both distorted, or that the old slide was so slack that the distortion of the carb body didn't matter. If you put the old slide in are you able to rotate it freely? If not, that would indicate ovality in both parts.

Offline bsapete

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Re: Misfire under load again
« Reply #49 on: 15.02. 2019 22:52 »
Yes the old slide is a nice fit and will rotate through 360 degrees without binding. I’ve achieved the same with the new one with light sanding.
62 A10S Spitfire Scrambler
54 A7 Star Twin (sold on)
61 Jaguar E Type FHC Flat Floor
99 Jaguar XKR Coupe

Offline trevinoz

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Re: Misfire under load again
« Reply #50 on: 16.02. 2019 01:41 »
Maybe you should have sent the carby away to have the body bored and the slide sleeved.
Probably wouldn't have cost much more than a new slide.

Offline bsapete

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Re: Misfire under load again
« Reply #51 on: 16.02. 2019 23:53 »
Maybe you should have sent the carby away to have the body bored and the slide sleeved.
Probably wouldn't have cost much more than a new slide.
[/quote]

It cost me $30 for the slide, I doubt I’d get much done for that
Carb is reassembled and back on the bike. Started second kick after a good tickle. Idle was high so screwed the idle screw out to settle it. Took it for a ride and once warmed up it pulls well. Certainly a marked difference with the correct 290
main jet and the 3 1/2 cutaway slide.
62 A10S Spitfire Scrambler
54 A7 Star Twin (sold on)
61 Jaguar E Type FHC Flat Floor
99 Jaguar XKR Coupe

Offline coater87

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Re: Misfire under load again
« Reply #52 on: 17.02. 2019 23:28 »
Maybe you should have sent the carby away to have the body bored and the slide sleeved.
Probably wouldn't have cost much more than a new slide.

 I had that done, I dont know if they did it wrong or if never being able to change slides is a side effect.

 They bored the body than sleaved the slide to fit the body.

 A new slide is much to small a diameter.

 Lee
Central Wisconsin in the U.S.