More carb questions

[RobTx]

Ok, what cause the engine to stay at around 3000 rpm when you shut the throttle and then slowly go down to idle at 1300 or so?  At least I've got it where it'll start, but can't get it to idle steady or settle down to idle very quickly.  It also won't pull redline in any gear, missing badly above 5 or 6000 rpm.  I don't know if the problems are related, I might have an electrical problem too.  It was running better before, then on day it wouldn't start.  I pulled off the carbs and took them apart.  The YICS is not hooked up because it leaks internally and externally.  Thanks for any help.
Rob

[Humber]

I had this problem in my bike. I may not be right since I am not carb freak but for me it sounds like unadjusted air mixture screw.

Mine did exactly the same until I put some special locking compound (for this particular use) on the threads of the screw - just a little bit. Then I adjusted it and forgot.....


Maybe the same is with yours.....

[Lucky]

You describe clasic symptoms of a vaccume leak.
try the following:

- ?cap off the fuel pump vacume at the intake, see if that helps.

- do the same to the petcock vacume line.
if either of these help, you have a leaking diaphram.

next try caping off the flapper vac line & the small round filter lines.. ?this really shouldn't do it, but it's worth checking.

if all of these check out, double check your carb adjustments. ?if you still have the problem, that leaves only the intakes themselves, or intake gaskets leaking, (cracks on the outsides do not nessacarily mean leaks) ?or and internal carb problem, (gaskets, loose venturi, etc)

You can check the intakes by removing them & "C" clamping a couple of metal or plastic sheets on eather end of the intakes, caping off the 2nd vac line, and appling vaccume ton the intake with a 'mity vac' and watching the guage.

it may not be a vacc/carb problem, but i'd be very surprised if it wasn't.

let us know what you find, i'm very interested in your results.
Good Luck! --Lucky

[RobTx]

Thanks for the tips.  I'll double check the mixture screws and vacuum lines.  I just had the carbs off and they weren't doing it before.  I should just replace all the vacuum lines, they're old and I've been taking them off and on a lot since I got the bike.  Vacuum hose is cheap.  If that doesn't work, I'll check the intakes and other things Lucky suggested.
Rob

[RobTx]

Ok, no luck finding any vacuum problem.  :(  I'm gonna take the carbs off again and go over them with a fine tooth comb and let them soak a while.  I figure I can't make things any worse at this point.  I replaced the vacuum lines as well.  Except for the fork seals the bike is ready to go, so I'm getting kind of frustrated.  I want to ride!  Hmmm.... maybe this Briggs & Stratton in the edger will bolt up to the frame...
Rob

[RobTx]

Ok, I took off the carbs and dipped them again and cleaned them cleaner than they've been since new, I bet.  Put it all back together and voila, it works!  Any gear, any RPM, whack open the throttle and it pulls, pulls, pulls.  I was shifting at 10, 000, but it would have pulled right through it if I let it.  No flat spots at all.  I'm still having a problem with the idle, but I think re-syncing the carbs and fine tuning the pilot screws will solve the problem.
Rob

[Lucky]

I swear, 99% of all carb problems are due to dirty, mis-adjusted carbs, the other 1 % are bad hoses.
It's been my mantra all along: "Clean! Clean! Clean!"
And no, it's not unusual to dip them 2 or 3 times to get them properly clean.

Feels good though don't it? Now you truly know why we love these bikes.  It's like when you tell your kid the same thing, over & over, and one day, BAM! he finaly gets it!

Enjoy1 --Lucky

[Cdnlouie]

Rob, just tossing another 2 cents in.  Is your tank clean? Are you using an inline filter to keep those carbs nice now that you have done all the great work?

Why not get that YICS repaired as well?  It takes 3 minutes to cut the thing in two and about 15 to wash it up with lacquer thinner (in & out) and use some JB Weld epoxy (coat both sides and up the middle & clean off the old gasket by sanding flat on a piece of emery cloth) for the final solution (or do it Lucky's way).

By the way, what kind of jetting are you using?  Just kind of interested in the numbers (air & mains).

Louie  ;)

[RobTx]

I have a Kreemed tank and an inline filter.  130 jets on top for both carbs.  122.5 front main and unreadable rear main.  It is running great right now, I can't imagine it running any better.  I'm going to repair the YICS today.  I would have to sand down 4mm or so to make it flat, since it is a tongue and groove joint.  I'm just going to clean it and JB weld it together like it came apart.  If that doesn't fix it, I'll just leave it off until I run across another one cheap.  
Rob

[Cdnlouie]

Don't worry about the groove, just clean off the old gasket so the epoxy can get a firm grip on some roughed up material.  A reasonable coating on both sides just enough to get the seal but not enough to run all over the place inside and spread some around the seam on the outside for the finishing touch.  The gray JB weld blends in quite nice.

Glad to hear about the jets.  That combination seems to be working really well.