backfire

[heatonmt]

Just got the new bike back from deal after 600 mile service. It seems to have a back fire when deceleration. He said it was set lean from factory and he adjusted. Am I wrong or does this bike not tend to backfire when it is running lean. If he set it richer should that take care of the back fire

[BOO]

Just got the new bike back from deal after 600 mile service. It seems to have a back fire when deceleration. He said it was set lean from factory and he adjusted. Am I wrong or does this bike not tend to backfire when it is running lean. If he set it richer should that take care of the back fire

 

Not sure what the dealer could have done. There's really no adjustment on the Carb for making it leaner or richer. From other post on this forum the backfire condition could be coming from the Carbs not be Sync'd properly or an exhaust leak or ? Some say to disconnect the so called pollution device but you shouldn't have to do that if the bike is right.

Do some searching on this forum and I think you will find numerous posts about this condition.

BOO

[V7Goose]

Your dealer is incompetent (and that is the absolute NICEST thing I could say about him). These bikes absolutely will NOT have any afterfire or popping from the exhaust if completely stock and set up properly. "Set up properly" means proper carb sync and no vacuum or exhaust leaks. Opening up the mixture screws will help the bike run better, but is not necessary to stop the problem.

 

You can very quickly see if they even touched the mixture screws by looking under the carbs with a flashlight - if the brass cone-shaped caps are still on the mixture screws, they could not have touched them.

 

If the bike was not doing the popping before you took it in, then the dealer either totally messed up the carb sync, failed to replace the caps on the intake vacuum ports, or probably cut one of the AIS vacuum hoses when they tried to get them off to do the sync (those hoses always are stuck real bad the first time from the factory). If it was doing the popping before you took it in, then you may have one or more leaks at the exhaust Y pipes.

Goose

[kevin-vic-b.c.]

I had issue with my '86 at one point backfiring on deceleration. I found that the small tapping that is used to connect the carb cync equipment should have a small rubber cap over it. That cap had somehow vanished. I used a small vacuum hose line with a screw in it re-cap the port. No more backfire..... maybe the mechanic forgot to reinstall one of these or it popped off somehow after service.

 

This all being said assuming the newer engine is similar to my '86.

[heatonmt]

Well I look at the carbs and the vac line look OK one small nick but not through hose. Caps are on I looked for brass cones but did not see any I did see so brass screws on each carb is that what is under the cones not sure how to tell if there is a leak at the y on the pipes?

[buddy]

Mike,

When you was riding with us in the Eureka Springs hill Country your bike never did backfire nor did it sound off beat !! It was in perfect form as for idle and running down the road!!! so it sounds like he or they did something to cause this problem. Take it back and make them synchronize the carb. and look for vacuum leaks ETC. if you can watch them do it:cool17: they hate it when customers watch them

because most of the time they have no clue whats going on and it will show:doh:!!. keep us up to date as for whats going on and what caused the problem...

[heatonmt]

OK I went out to the bike and checked vac hoses,caps (turned to make sure all were tight, pulled the choke out and push it back in. Got up today and took bike to work no back fire. got off work took out on hy. no back fire not sure were the back fire went but glad it gone? You Got Me.

[V7Goose]

My bet is that you actually have a cut in one of thode vacuum hoses that is all the way though, and your playing with it has it pushed on far enough at the moment to block the hole.

 

Glad your problem is gone for now anyway -

Goose