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Discussion Starter · #1 ·
So, I described my problem (serious backfiring letting off the throttle, crappy idle) and most seemed to agree that the ACV valve (i think?) was no good. So I opened the carbs today, blocked up that little bypass hole with a piece of bicycle tube, put everything back together, runs just the same. I checked the diaphragms too before putting everything back together and they looked fine.



Now, it didn't occur to me until now, but I had a similar problem some time ago that balancing the carbs seemed to fix. I think the problem was like this. But my question is why would the balance go out of wack a year or so later and only 1000 or so miles? Maybe I didn't tighten the screw down enough once I got them balanced? Something else? Maybe it isn't a carb balance problem at all?



I'm kinda stumped. Luckily to check if it is a balance issue just requires a length of plastic tubing and some spare oil. I LOVE having that little nipple that a tube slips nice and snug on between the carbs and the cylinder
. GLs and later CXs don't have that do they?



Should I try balancing first? Should I check the mix screws? Should I check something else?
 

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Looking at my carbs before I went to Matts and balanced them, there was something like a drip er so of some yellow looking lock-tite covering both the adjusting screw and the lock nut. So, it seems as though that just the vibration of the motor running could loosen up the lock nut after awhile.



This could also mean that the idle mixture screws are too lean. Could try fattening them up a quarter to half a turn a ride (trial and error, ya know) and see if this clear up your problem.



OR?, it could be a little of both, but you should get the idle mixture set as close as possible before balancing.



Hope this helps.
 

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Nick,im not with Bearman on this.i dont believe your carbs would fly out of balance for no good reason.nor,do i believe,if the carbs were a bit off balance,it would show your symptoms.

whip your carbs off and visually balance them,use an 1/8 drill bit[you need 2]put one under each butterfly,see how far they are out,not far i suspect




if[and i say if] your carbs are clean,then i believe you have an air leak.

bike on main stand,ticking over[fast idle]

spray a fair bit off brake/carb cleaner in and all around all six joints.any change in revs,up or down show a leak...you,l need to address it.



backfireing is also a symptom of an exhaust leak,check for that also
 

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Discussion Starter · #4 ·
that all makes an awful lot of sense. I've got to pull the whole exhaust off to change the oil (yea, wrapped MAC 2in1, oil drains right onto the pipe, soaks the wrap - stupid) so I'll go through it then to see if there is any trouble there. Although I think it's more likely one of the boots between the carb and the cylinder. one is clearly cracked and the rubber is hard, so that might be the culprit. the other one is nice and soft and looking good. wonder what those boots cost.



so, of course the weather has turned again and there's rain in the forecast for the next week. this year better not be like last year, cold and rainy all the way through June. Yuck!
 

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that all makes an awful lot of sense. I've got to pull the whole exhaust off to change the oil (yea, wrapped MAC 2in1, oil drains right onto the pipe, soaks the wrap - stupid) so I'll go through it then to see if there is any trouble there. Although I think it's more likely one of the boots between the carb and the cylinder. one is clearly cracked and the rubber is hard, so that might be the culprit. the other one is nice and soft and looking good. wonder what those boots cost.



so, of course the weather has turned again and there's rain in the forecast for the next week. this year better not be like last year, cold and rainy all the way through June. Yuck!
Used heat resistant plastic in front of the drain bolt to redirect the oil away from your header.



I thought you said you had worked on your carbs ... not that they did that all by themselves. That was why I told you how to re-balance them.
 

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A piece of something to divert the oil is always a good idea. I have the same exhaust and given up caring but my parking lot has a pretty good angle on it so i put the bike on the centerstand facing downhill and oil only gets on about 2 inches of the pipe.



Hell if you had a piece of saran wrap at the time of oil change or even a garbage bag you could wrap the exhaust.
 
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