Yamaha Starbike Forum banner

1 - 6 of 6 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
my father and i just picked up the bike in maryland today. when at idle and sometimes driving it has a pretty bad backfire to it. it has straight pipes and i guess its been jetted. was hoping for a couple of suggestions that would help me get rid of it. thanks
 

·
Registered
Joined
·
49 Posts
From what I know, 2 things will cause backfire: an incorrectly sealed exhaust to where air gets into the exhaust near the engine, or an incorrectly jetted/configured carb setup.
 

·
Registered
Joined
·
923 Posts
I took my 1100 around the neighborhood for a spin yesterday and had backfires quite a bit. The guy I bought it from told me he had done a carb rebuild and "tweaked" the idle. I'm thinking I might have to "un-tweak" what he's done.
 

·
Registered
Joined
·
1,530 Posts
+1 on what Karnal said. Also the AIS is a controlled leak into the exhaust.

Jarhead do you have non-stock pipes? What do your plugs look like.? Usually a PMS adjust (open about 1/2 turn) will cure along with AIS removal for non-stock pipes.
 

·
Registered
Joined
·
923 Posts
+1 on what Karnal said. Also the AIS is a controlled leak into the exhaust.

Jarhead do you have non-stock pipes? What do your plugs look like.? Usually a PMS adjust (open about 1/2 turn) will cure along with AIS removal for non-stock pipes.
Fulltilt I have stock pipes. The previous owner had rebuilt the carbs because he had let it sit through last season without any fuel stabilizer. Carbs gummed up so he rebuilt. Before rebuilding he tweaked the idle thinking that was the problem.
 

·
Registered
Joined
·
1,530 Posts
a back firing is a known problem with straight pipes. Its usually cured by a combination of things. An adjustment of the PMS about a half a turn on each carb. If this is the first time they have been adjusted 1) they weren't cleaned very effectively and 2) you'll have to remove the brass plugs covering them from factory. On the left side carb it is on the under side aft of float bowl and right side same place but fwd side of bowl. Removal of carb is necessary. I'll send you links for how to in morning. The other thing you can do is to remove and plug AIS. If you have additional questions, ask away.
 
1 - 6 of 6 Posts
Top