Yamaha Starbike Forum banner

1 - 13 of 13 Posts

·
Registered
Joined
·
207 Posts
Discussion Starter #1
After modifying my exhaust (1 1/2" hole saw) and removing the AIS I still had some backfiring on deceleration. After lots of reading on here and in the KB I figured I'd remove the carbs and drill out the brass plug so I could adjust the PMS. Anyway, I read something that said not to separate the carbs when I had them out and I don't plan on it but I discovered they were very loose not tightly held together. The two long bolts had backed out some. I see a gasket between the two carb bodies, is there some sort of balance tube between them or what is it? Since the carbs were loose, could this be the cause of it being lean? I put lock washers on the bolts and tightened everything back up. Front PMS was @ 1.5 turns out and rear was just a bit more than 2 turns out. I've set both @ 2.5 turns out to start. Waiting to put the carbs back on until I get some feedback on the loose issue.

BTW, this is on an '03 1100 Classic all stock except for the exhaust mod.
 

·
Registered
Joined
·
1,471 Posts
if your getting popping on decelleration its because you drilled your pipes the bikes come lean from the factory and the popping is muffled by the stock pipes. the kb calls for two turns out mine was set stock at 1 and 3/4s you might be a little rich .i would check your plugs in 500 miles might be a bit tan
 

·
Registered
Joined
·
207 Posts
Discussion Starter #4
Thanks guys, from what I've read, I'm fairly confident I can get the PMS adjusted properly. It will just take going slowly. My main concern was the issue with the carbs not being tightly secured to each other and any problems that may have caused if any.
 

·
Registered
Joined
·
166 Posts
3.5 turns would be too much for stock intake and simply drilled exhaust. I would reset to stock, then go out a 1/4 turn at a time till you're good.

I don't know about the carbs being loose, I'd call a local shop and talk to their mechanic.


Sent from Motorcycle.com Free App
 

·
Registered
Joined
·
207 Posts
Discussion Starter #8
I finished up my spring maintenance on the bike this morning which included checking valve adjustment. Intake valves were in range (.003-.005") but the exhaust were tighter than the .007" spec. I didn't check what they were but they had very little movement. I adjusted the intakes to their max spec of .005" and the exhaust to .007" and then reinstalled the carbs. Bike started right up without using the choke and after it warmed up I reved it up a few times and no more popping on deceleration. Everything seems ok, so it's time for first ride of the season.
 

·
Registered
Joined
·
171 Posts
Did you find out any info about the loose carbs? I've never read anywhere in the rejetting instructions not to separate them. I separated them to get extra clearance for a wrench when rejetting my carbs.
 

·
Registered
Joined
·
207 Posts
Discussion Starter #12
Roblox84.... not sure where I read that, but in searching here someone posted a link to instructions and that's where I read about not separating the two carbs. Since you did, is there a air passage between the two carbs or are they just bolted together?

Nick57.... I got those specs from the KB where I printed out the procedure for adjusting the valves. Intake .003-.005" Exhaust .007".
 

·
Registered
Joined
·
171 Posts
Roblox84.... not sure where I read that, but in searching here someone posted a link to instructions and that's where I read about not separating the two carbs. Since you did, is there a air passage between the two carbs or are they just bolted together?

Nick57.... I got those specs from the KB where I printed out the procedure for adjusting the valves. Intake .003-.005" Exhaust .007".
There was no air passage between the two carbs. I also saw a custom build where Tim from metric magic separated the two carbs to put them on both sides of the bike.
 
1 - 13 of 13 Posts
Top