I need help......

[kevin-vic-b.c.]

No not that kind of help...... well maybe

 

2002 Venture, 48,000 km (30,000 mi ) I have a backfire problem on the Right side.

 

I have done a carb sync... I think it made it worse

I replaced exhaust gaskets on right side

I changed the plugs... that's fun... they were all nice and golden brown color

When I had exhaust apart I noted that the rear cylinder pipe was clean the front was blackened

Valves to the best of my or PO knowledge have never been adjusted.

I have run hi test fuel through with Seafoam in it

 

I need help.... what now.

 

thanks much

[muffinman]

Make sure you have good spark on the back plug wire I have changed a few bad coils on the right rear cyl for no spark problems

 

 

 

 

Jeff

[kevin-vic-b.c.]

Make sure you have good spark on the back plug wire I have changed a few bad coils on the right rear cyl for no spark problems

 

 

 

 

Jeff

 

All the plugs were in great shape when I pulled them, nice golden brown. Backfire on deceleration when engine gets warmed up.

[SilvrT]

Have you checked for any cracks in the exhaust pipes especially at the Y pipe area as I seem to recall this being a problem on some of the 2nd gens.

 

If there is any crack, it will suck air in and cause the spent gasses to explode. I had a similar problem on my '85 and it was caused by cracks in the collector. Once I welded them up, no more backfiring.

[Dave]

I can tell you I had same problem at 28.000 miles and had valves adjusted at the start of this season and that took care of it for me. Also did carbs at the same time.

[Yamamike]

Hey Kevin,

Do you have OEM mufflers on your beast? I read on another thread that the OEMs apparently have something built-in to them to prevent this. If your plugs are a nice chocolate brown, she must be running great!!

[dfitzbiz]

If the carb sync made it worse you should check the vacuum hoses and caps where you attach the carb sync tool. A leak there may cause your problem. Good luck.

[kevin-vic-b.c.]

Well Mick Kyte connected with me on Facebook and suggested disconnecting the AIS, I followed a thread started byFreebird, so far so good.

[Miles]

Kevin, that is one of the reasons that I removed the entire AIS system completely off my '06 RSMTD. Zero backfire after that.

 

But, I think one of the others may have suggested the real problem, in that after you sync'd the carbs, it made it worse. I would check the rubber caps and vacumn lines for the ports to where the carb sync tool connected. You may have a vacumn leak.

 

Thta is very easy to diagnose...just get the engine VERY hot...spray carb cleaner all over the engine..., and if it does not catch fire...but does raise the engine RPM's, then you have a vacumn leak.

 

 

[kevin-vic-b.c.]

Yes they are stock mufflers, I have checked the exhaust while I had it off and seemed to have minor leakage around the Y of the right side, I used some steel putty stuff around it just in case.

I have checked that I put the vac tubes back on securely also but yes I am going to spray check the intake system.

I am thinking a bit of cause and effect here, the AIS disconnect is 90% cure, a couple little pops out of it on way home tonight running it very hard. I can smell a bit of raw fuel someplace so although it is much much better I don't think this is the end of the investigation.

I know very little about carburetors, even working on cars for years I never did carbs but something is still not correct I think.

I am going to get the valves checked in the off season, not willing to try it myself alone for first time during riding season, so a mechanic I know is always good about fair rates in the winter when his shop is dead quiet.