OCD

[davo231481]

after the ride yesterday i found the engine mounts had loosened up a bit. Not getting any vibrations through the bars just in the seat..... maybe its the wood i get when its rolling along. Ive swapped over the exhaust to the stubbie tht came with the 4-1 with a stiffer bracket. Checked the exhaust nuts as well and nipped them up a tad. I could be up for the CR spanner day on sat if i get the directions so ill have another set of eyes and ears have a listen to it to point out any issues. The clutch is a bit rattly but i expect this is typical for this era as my 84 gsx 1100 sounded like a handful of marbles in a coffee can and that was spose to be the norm.

[davo231481]

the bike has been giving me a bit of grief. over revving, slow fuel flow, poor idle, slow to back off. I resealed the inlet manifolds using locktite 515, changed the air screw o rings, cleaned slides using thinners very carefully, retensioned springs for diaphrams. still playing up. slow fuel flow when turned to prime. there seem to be no vacuum leaks. could it be the fuel tap? i looked at the tank cap breather because it hissed at me when i took it off the bike as tho air was slowly reentering the tank but ran it with the cap open and it made no difference. Im open to some ideas. Can i use rubber grease on the fuel tap diaphram o ring on the vacuum side to let it move easier?

[Gosling1]

Over-revving and slow to return to idle - still sounds like air-leaks at the manifolds to me ? Maybe the actual rubbers are cracked ? Have you done the aero-start test while the bike is idling - give all the rubber manifolds a hit. This will tell you straight up.

Slow fuel flow out of the tap - the internals sound blocked. It should literally piss out in the Prime position.....the fuel cap breather might need a bit of a blast with some compressed air as well.

I would also check the small diaphragm in the tap - if this has any pinholes it won't work properly.

Is the small vacuum line from the inlet manifold to the fuel tap hooked up OK ?

[davo231481]

hi gos. yeah tried the aerostart again and made no difference ( sort of wishin it would). when i disassembled the filler cap the breather looked clear but will give it another hit with compressed air. Im thinking its in the fuel delivery and the taps clogged with shite or as you have suggested the diaphram has developed a hole. its very frustrating and after doing a search i saw that the surfer was having a similair problem. Im stripping down the tap tommorrow to see whats going on there but fuel just dribbled out like it had a prostrate issue.

[Gosling1]

hopefully getting the fuel tap sorted will fix the fuel issue.......not sure about the revs hanging though, I know you have been over the carbs/manifolds several times now....I guess the cables and routing etc, throttle housing - all check out OK ?

[Jonno]

Internally collapsed fuel line?

Just a stab in the dark.

[davo231481]

hopefully getting the fuel tap sorted will fix the fuel issue.......not sure about the revs hanging though, I know you have been over the carbs/manifolds several times now....I guess the cables and routing etc, throttle housing - all check out OK ?

yeah thats what is so frustrating. carbies snap back via cable nicely and not a hint of rev increase with hairy start. ill be replacing the fuel line just to eliminate that area

[dickfaber]

this may help (or maybe not)
when the throttle shafts wear, they allow small but significant air leaks, and also mean the throttle plates sometimes dont shut completely. when this carby is a cv style (reliant on mainfold vacuum signal for slide/needle fuel delivery) it causes all sorts of issues; just like the ones you describe.

i learned this from my days stuffing around with gpx250

solution (probably not the best, but it was the most effective) - machined the throttle shaft to a common fulll size, reamed the carby body throttle shaft hole to a common full size; ensuring it was actually round. then machined some nylon to the appropriate sizes and fitted them. instant sucess!

point is, check the slop in the throttle shafts at the carby. at idle, give them a strong wiggle and see if idle changes, and give them a squirt of wd to see if that changes idle quality

[Gav]

Hey mate.Earlier in the post I suggested that you completely reco the fuel valve / petcock.This little item is crucial in the fuel flow/distribution.My 550 had the exact same issues as yours..ie dodgey idle,and seem to be running on two cylinders.Also it would rev up but slow to go back to any sort of idle.I got a reco kit online and had it fitted. I also had the carbs recoed and have pod filters on it.My 550 purrs like a kitten now and when its running you can hear the valve/diaphram ticking quite loudly through the tank. Good luck.

[davo231481]

im ordering a new diaphram today

[davo231481]

Fitted up the new tap kit. Replaced the vacuum lines. Started it up no probs. went for a quick spin outta town and it went well with no farting or carry on but the revs are still a bit slow on the return. It pulled quite well through the revs but i haven't opened it up all the way just yet.I have noticed in the 20 times I've taken the carbs off that the butterfly isn't completely closed. They all stay open about a poofteenth. Would this be to allow air through on the idle? Speaking of the idle I've wound that back to about 1200. The clutch lets me know it's still there with it's rattle but everything else sounds happy.

[Gosling1]

yep, the butterflies need to be cracked open that poofteenth for the idle. 1200rpm sounds pretty high for an idle ? I would have thought closer to 1k would be about right ? For this rpm, the balance has to be *perfect* otherwise the motor will hunt a lot......

Did you re-do the manifold rubbers yet with the new gasket goo ? Its the shizzle matey

[davo231481]

yep. a big improvement. see the pm I sent ya.