Rough idle

[TexinMaine]

Just purchased a 1981 XS1100H. The PO said he did a rebuild on the carbs and that they just needed syncing. The problem is at low rpm's it runs horrible, chugging, popping, etc. Over about 3000 rpm it runs fine and has plenty of power but starting off in first gear it lags and chugs until the rpm's come up. Sorta does the same in second and less in third. Does this sound like just a sync problem or should I look for something else also? Also one one small problem is the left turn signal, when I turn it on it just stays solid, the right does blink so I'm not sure it is that turn thing by the fuse block. Thanks ya'll!


Tex

[BA80]

Rough idle is pilot jets plugged or just dirty. Turn signals are most likely the signal relay. It might snap out of it after a little use but if not you can put a 2 prong automotive flasher ( plugged into the 2 brown wires) and it'll work fine but no self cancelling feature.

[DiverRay]

Yeah, I'd go for pulling the carbs and going through the pilot jets just to be sure. You will then need to sync the carbs again, but you could also check the valve clearance while it was apart, just because....
The turn signal is PROBABLY a bad ground, and looking at the front and rear signals, find the one that seems to not light. Or, you can just clean up ALL the grounds, including the ones under the tank. I use anti-seize on the grounds to keep them from rusting or oxidizing.

[motoman]

Just purchased a 1981 XS1100H. The PO said he did a rebuild on the carbs and that they just needed syncing. The problem is at low rpm's it runs horrible, chugging, popping, etc. Over about 3000 rpm it runs fine and has plenty of power but starting off in first gear it lags and chugs until the rpm's come up. Sorta does the same in second and less in third. Does this sound like just a sync problem or should I look for something else also? Also one one small problem is the left turn signal, when I turn it on it just stays solid, the right does blink so I'm not sure it is that turn thing by the fuse block. Thanks ya'll!


Tex

Stating PO did a carb rebuild and trusting that is part of the problem. Float heights being off, partially plugged pilot jets, and finially, incorrect idle mixture settings along with poor or no carb sync done. Likely, the way it's running at low rpm, incorrect float levels is a good start. Next, remove and inspect pilot jets CLOSELY. Lastly would be idle mixture settings and carb sync, in that order.

[Radioguylogs]

Wrong Pilot Jets Possible?

Tex:

When the PO rebuilt the carbs, is it possible he used the 'bad' pilot jets in the K&L rebuild kit?

It happened to me.

Mine ran really rich and would not drop back down to a normal idle speed after revving.

Mikuni pilots fixed my problem.

Good luck with your problem.

[TopCatGr58]

ALL good suggestions, ideas. Aside from the RE-Cleaning and ensuring that the PILOT circuit is clear/clean, jets are clean, and are the correct type(MIKUNI) and not K&L junk.

Another thought is that it's an 80. That was the transition year for the bastardized carbs that "sometimes" has the sharing tunnel between the MAIN and PILOT jet towers, and if so, then it needs the pilot jet tower plugs/caps....otherwise it's sucking in TOO MUCH fuel directly from the bowl instead of getting it's proper share from the MAIN JET TOWER TUNNEL source instead.

Also, does it still have the PILOT Idle Screw tunnel sealing plugs in place on the top front of the carb bodies? IF so, then you can not ensure that end of the pilot jet circuit is clear as well as being able to properly set the idle F/A mixture for proper tuning. You'll need to remove the caps, and then the pilot screws...watch out for the little metal and rubber o-rings/washers down in the tunnel that are supposed to be at the end of the pilot screw.

Aside from the possibility of corroded grounds on the turn signals....the actual fixtures grounds to frame, the ground strap INSIDE the fixture to the bulb socket and the socket itself can form corrosion....check and clean as needed. ALSO verify that the bulbs are the right power/wattage....stock actually is 27 watts for turn signal, but folks have used automotive replacements that are lower ie. 24 watts or so, and that can cause the turn signal flasher to not develop enough heat to cycle the flasher due to insufficient load!

But you may also want to take apart the signal switch and check the reed switches for corrosion and proper tension and contact during the throw action.

T.C.

[TexinMaine]

Thanks for the replies and tips everyone. I figured it would be more that just a sync. I do have a box of extra parts for the carbs and brakes and the are all K&L. I'm not sure if he changed the jets he just said he rebuilt the carbs. I didn't have time to get into them today but I did go ahead and adjusted the cam chain tensioner. I thought it sounded like it was loose inside. So I released the lock nut then the stop nut. I didn't really hear it move but it looks like it may have. Anyway after tighten the nuts and putting that cover back on I started it and it seemed a bit better. Still a little rough but no where as horrible as the other day. Took it for a ride and it was definitely smoother taking off in first gear. Also should there be a plug or something on the end of the tensioner?

[TopCatGr58]

Hey Tex,

Yes, there's a rubber coated plug that is supposed to be on the end. There's no oil PRESSURE there, but it will drip when it's not sealed. A variety to techniques have been improvised to seal it, from sticking a bottle cap over it with gasket maker sealant, RTV, etc, since you've already lost the plug. Others have taken a piece of hard rubber, fashioned/cut it to approximately fit in the larger opening, and again applied sealant.

I still had the plug, so I just cleaned/degreased it and applied the sealant OVER it. Don't mind the other oil/dirt, that's from the valve cover and such!



T.C.

But, WE really do highly recommend you get an ACCT or perform the manual MOD to your OEM unit, see this thread for info and how to.

http://www.xs11.com/forum/showthread...nute+cam+chain

T.C.