starts at 3k

[Guest]

the carbs have been dipped and have new o-rings. so after battling with it for a day or two I have finally gotten the bike to start up, but it jumps right to 3k. putting any choke on kills the bike. I kept turning the screws out half turns till it got to a normal 1100 idle, was 5 complete turns. I blipped the throttle, it hung but returned to 1100 again. as it warmed it began to rise again to between 3 and 4k.


So I think I have a couple problems here. one is an air leak, wondering how do I track this down? second is the carbs themselves. the pistons with the needle jets seems to hang. I thought it may be dirt or something so I hit them very lightly with 1k grit sand paper. they fell okay the first couple times then began hanging again. maybe a weird vacuuming issue? I dunno, you tell me.

I am about to walk this bike to the Delaware and push it in . seriously though, I've done a lot of work on this thing and this is the last mile of getting it done. any help would be greatly appreciated.

thanks for your help

[tom203]

Did you bench sync the carbs ?- the throttle plates will just be open a sliver, too much air slipping under plates would produce erratic idle. But increasing rpms as bike warms up sounds like air leak at boots or boot/head interface- did you replace the boot o-rings?
Sticking/hanging vacuum pistons- did you inspect diaphragms for pinholes?

[Agemax]

check the throttle cable has free play so the carbs are actually shutting properly. also make sure the cable isn't kinked or dirty. try removing the cable completely from the carbs and make sure they snap shut.
have you tried adjusting the idle adjuster to control the idle?
squirt some wd40 or similar around the intake boots and see if the idle note changes, that will confirm an air leak around that area

[chuck hahn]

If all the adjustments have been made and double checked as far as no hung up throttle cables, lubed up the grip ends of the cables, all the bolts that hold the slides on are tight. and new intake boot orings..etc etc. I would conclude its a running lean issue.

Also to add to Toms reply. If the butterflies on carbs are not perfectly centered in aech of the throats, one can be hanging up and not allowing them to fully return to the right closed positions. Loosen the screws a tad and resettle the butterflies in and work the hem a little to see that nothing is hung up.

So here is what I would do to the bike...and in this order.
1..Check that the intake boot rubber itself is in good condition..not torn free or cracked thru.
2..Recheck the point gaps and timing.
3..Revacuum sync the carbs.
4.. Reset the mixture screws to a richer condition. If the carbs are VM style, you would turn the mixture screws ( on the side ) IN to make it run richer. If they are CV carbs, you would turn the mixture screw ( on top and at the back ) OUT. Go 1/8 turns at a time and be ready to readjjust the idle so it is at around 1500 to 2000 . Get it so the idle drops back well at this RPM range and then use the big idle adjustment knob to set it lower after the symptom is cleared.

Keep a few fans blowing on the front of the engine to keep her cool while doing the work.

[81gs1100]

May want to check your pilot jets, either replace, or go up a few sizes. I was having the same problem, the idle would shoot up about 5 seconds after the bike started.

Are you running it with or without the air box? Did you go from an air box to pods? Both of these modifications would require a richer pilot jet.

[detorn]

okay to answer some questions.

throttle cable is good. snaps back just the was it should I assumed the hanging throttle was from the hanging pistons.

there are new boot orings and hex bolts from Mr. Barr on it, but one of the manifold is a replacement I bought as a part of a set in which the other one was bad, so I'll put the original, known to be good one back on today and see what that does.

the idle adjustment screw isn't even in play yet, it was not making contact with the carbs at the time of this test

the diaphragms are in great condition.

the butterflies snap back fine, I assumed it was the the pistons hanging causing the throttle hang. i'll go through the bench sync DIY again today to make sure I did it right.

I do not know what checking the point gaps and timing even mean. I am also not set up to do the vacuum sync, I'm trying to get it running well enough to get it to duanage's house so we can do it there. I'll do 1 and 4 from your list though

I am running it with the original airbox. no mods have been made to the fuel air system.

the pilot jets, aside from one being on the verge of being stripped, looked okay. I cleaned by dipping, then wire brush needle, then checked by spraying carb cleaner through to see if it passed through cleanly.

thanks for the advice everyone, I'll let you know what happens in about two hours

[detorn]

just reread the bench sync diy, I was way off... i'll do that and the boot swap and let you know

[detorn]

okay, re-bench-synced the proper way... any thoughts on the hanging pistons before I put these back on the bike? do you think its not a part of the problem?

[detorn]

swapped the intake boots. with that and the resync the bike now climbs to 3k instead of just starting there. I sprayed the boots no change in rpms. choke still kills it. condition doesn't change with the air mix screws.

[tom203]

Are the pistons hanging up in just one carb ? Are these the original needles and mainjets, and in original spot (not switched from left to right ) ? Is idle stop screw doing anything ?

[detorn]

duanage came over to inspect my work. we found the bowl floats weren't right and adjusted them. this solved the 3k problem, but there was what he called a slow systems problem... he took the carbs with to inspect closer... I'll let you know what happens

[duaneage]

I reset the pilot idle screws and lubricated them a little before setting them 1.5 turns out. I increased this to 2 on the bike. The bike needs new boots, if the carbs are leaned or moved the vacuum changes and speed as well. I used a vacuum gage to test with.

[detorn]

update. So I got new, actually new not just new to me, intake boots. still not quite right. as I was searching the GSR for the next step to take I found that the choke cable needs orings where they connect to the carbs. part 37

http://www.buymotorcycleparts.com/OE...011/5602630011

there wasn't one there when I took them off so I never noticed. going to test this out today. will update with results

[detorn]

it was the choke plunger orings. never even knew they were there. thanks to spryug in this thread I found it. did I need to spend the $90 on new boots? we'll never know. but thanks to those rings and a vacuum sync, the fuel air mess seems to be over.

(Just posting this for search results. no one ever finishes a thread)

[nejeff]

it was the choke plunger orings. never even knew they were there. thanks to spryug in this thread I found it. did I need to spend the $90 on new boots? we'll never know. but thanks to those rings and a vacuum sync, the fuel air mess seems to be over.

(Just posting this for search results. no one ever finishes a thread)

Those choke plunger orings got me once too. Glad you got her going!