runs only at idle

[Kuba]

Hi Guys!

I already replaced head gaskets, rebuild tensioners, new belts in, timing set up correctly. Carbs were taken out and cleaned (not separated). All the jets were cleaned, floats set, needles and diaphragms was all nicely working... coils and cables withing spec.

Initially bike was only running with choke on or with throttle open, couldn't stay running, was dying time to time and was reving up on it's own. I thought maybe there's some more residue in carbs... Backfired as crazy... I let sea foam into the carb and sit overnight and then drained the bowls and run bike on fresh gas with seafoam. Didin't wanna start and I found out there's no spark on one plug. I replaced all the plugs and I have spark on each one. Coils and cables installed as they should.

Now bike is running without throttle on it's own, I managed warm it up and sync the carbs. After a short warm up it runs nicely without the choke, but dies on throttle!

I have a brand new fuel filter, no residue in tank, new air filter. Also it doesn't matter if the air filter is in or the box is all open. I thought maybe there's some vacuum problem. I disconnected vacuum line at that T connector and nothing changes.

Any advice?

[OldguyGlen]

More info? Can you creep it up in RPMs and eventually get faster speeds? That might be sticking slides, or still some plugged jets.
If it dies on sudden throttle, then the accelerator pump is not working, or the tiny jets in the carb throats are plugged. You can look into the throats with a mirror in the airbox while you pump the throttle..

[Kuba]

I can put it into higher rpms other than using choke. But then it revs up like crazy, 3000-4000rpms. When I open the throttle slowly it dies withing a couple pf seconds. Nothing helps.

I think I should spray some ether around vacuum stuff and intake elbows. Maybe there's a problem...

I also noticed that right after exhaust manifolds when it meets mufflers, previous owner cut mufflers in two places to kinda make then wider? Idk. The think is I have a small gaps, I mean maybe 3/16"x1/2"... Can this be related to this problem? I need to do something with it anyway. Probably will weld some longer pipes to manifolds to make a decent overlap.

[OldguyGlen]

If the only way to get higher RPM is the choke, then you have carb trouble. Plugged jets, or stuck slides. Manifold leaks would interfere at idle more than interfere at open throttle. At idle feel (carefully) the exhaust headers. Looking to verify it has gas & spark on all 4 cyl. If it is idling on less than 4 cyl, that might give you some clues where to start looking.

[Kuba]

Checked headers before. Run on all 4.

When I cleaned the carbs slides were good. I cleaned main and pilot jets. Set the floats height.

I had to miss something. Will pull them out again.

[lcdrjoe]

If you haven't taken the carbs back off yet, you might try this. Maybe the seafoam loosened up stuff that then clogged up the main jets. I'd try taking the slides out, open the bowl drain, and spray some carb cleaner into the hole the slide needle goes into, using the straw on the carb cleaner to get right into that hole. That might just clean out the main jet and whatever has it clogged would go out the drain. Do this at your own risk of course, but it's probably what I'd do before taking the carbs off again.

[Kuba]

I got bike running today quite better. It runs on throttle now. Each time I put this to sit in the garage I take the fuel line of the tank and I connect it to the funnel and make bike run on pure seafoam and them turn on off when I now there's only seafoam in the carbs. Then next time I start it, I drain the bowls prior and then run it. I have decent amount of seafoam in gas, too. I took air box off and was spraying seafoam spray in carb separately. I noticed 1st and 3rd cylinders smoke much more on it and cylinder 4 spatters, kinda backfires back into the air box.

I'll keep continue doing it for a few days in row to see if this will still make it better.