I need some engine advice guys

[neJeff]

Sorry to bring this to you guys but I need fresh thoughts from XS’sers. This pertains to my GS550. Quick history: Bought from original owner for cheap ($125). What’s been done: Carbs have been through full tear down with replacement of o-rings, ect, carb boots replaced, new air filters & breather filters, valves adjusted (3 were out of spec). Here’s what is going on. Having trouble getting the idle set correctly ( this is also affecting doing a proper carb sync but they are very close), does not idle down much when shifting ( I pull the clutch on the 11 and it drops to idle rpm in between shifts, this bike hangs up quite a bit, if I shift at 3,000 maybe drops to 2500). The bike engine does not feel or sound “comfortable’. This is where I lose people. It’s hard to explain. You know how your bike feels when its ready to shift, this one doesn’t like to be much over 3500 rpm’s. I have run it up to 5500 but feels like it could blow its top off. Feels like it doesn’t “breathe” well, feels tight if that makes any sense. It feels like its one twist of a wrench to get this running great, but I am flat out of ideas. The Suzuki guys that own this same bike say it really runs best between 4,000 and 8,000 rpms and higher is not unheard of at all. I have done nothing electrical with the bike but all seems to operating correctly. Plugs look good, all cylinders heating up. I am grasping for straws but was thinking maybe exhaust plugged (don’t see how this could happen), stuck valve, petcock plugged? Any ideas guys would be appreciated. I'm missing something!

PS A little choke it starts easy, throttle cable looks/works fine, can’t find any vacuum leaks anywhere

[old_chopper]

What a coincidence, I have an XS11 and a GS550 too. These little engines do love RPM's.
Did you bench sync the carbs? Very important step.
You said new intake boots, are these the carb to engine?
New orings there too?
The hanging idle is almost always a vacuum leak.
Have you ran a compression test? Maybe a weak cylinder.
You cleaned the carbs, are you certain all passages and jets are clear?
Check the mechanical advance to make sure it's freely moving.

One thing I can almost guarantee you is that it is something simple, seems it always is! Keep us updated.

[neJeff]

What a coincidence, I have an XS11 and a GS550 too. These little engines do love RPM's.
Did you bench sync the carbs? Very important step.
You said new intake boots, are these the carb to engine?
New orings there too?
The hanging idle is almost always a vacuum leak.
Have you ran a compression test? Maybe a weak cylinder.
You cleaned the carbs, are you certain all passages and jets are clear?
Check the mechanical advance to make sure it's freely moving.

One thing I can almost guarantee you is that it is something simple, seems it always is! Keep us updated.

Yes bench synced carbs, new orings in the new boots (intake boots), every orifice clean & clear. I guess I am at the point where the carb rack needs to come back off (real fun on the 550's right) and do it all over again just to make triple sure. I do need to do a compression test, will go get tester today from HF

[mharrington]

On my XS750 the advancer unit was gunked up and would not snap back to home postion. Sometimes at a stop light it would idle so high I had to release the clutch enough to bring it down some.

[neJeff]

Thanks for the hint. What exactly are you calling the advancer unit?

[rpgoerlich]

RE: Advance unit, It's under the RH front engine cover. Sits below the pickup coil plate. You have to remove the rotor and pickup coil plate to get to it.

I'd try syncing the carbs first...

[neJeff]

RE: Advance unit, It's under the RH front engine cover. Sits below the pickup coil plate. You have to remove the rotor and pickup coil plate to get to it.

I'd try syncing the carbs first...

Will try these things and see if it improves. Thanks guys!

[Shacknasty]

A bench synch is not a replacement for a proper synch done while the bike is running. I would not mess with anything until you synch and set idle mix and synch again with a fan blowing on a warmed-up motor.

[neJeff]

I've done both syncs but bike idle was rough and I think it affected the sync. Going to do it all over again and also add a new throttle cable

[Hippie_Dave]

Too lean on your mixture will make your idle not drop between gears. Does it get better or worse as the motor heats up? Good luck, be sure to post any solutions you come up with.

[DiverRay]

I've found that the longer the bike sat, the worse the advance unit is! I would pull the cover, pull apart and clean/grease the advance as a first step. It may not move much, and stick when it does move. That could cause a LOT of problems.
Just my $0.02, as I need to try and help!