High and Hanging Idle

[notrocketscience]

After about 7 months of sitting around, I finally built up the courage to put some gas in my bike and see how it started. To my surprise (and after a lot of cranking) it finally shot to life and could sustain itself at idle.

While that's all great, I'm having an issue where the lowest I can get it to idle is around 1800 to 2100 RPM. My idle screw is no longer in contact with the throttle body (idk the technical term for that little springy guy on the carbs) and even then I'm still running high.

I've also noticed after revving up the engine, the idle will slowly drop and tend to stick around 5 or 6k.

I thought it might be a throttle cable issue, but the cables feel loose when I mess with the throttle. I was thinking it could be a mixture screw issue, but I'm not sure if I should increase or decrease the fuel ratio.

I've got many more issues with this beauty, but I figured this might be something the gurus have seen before. I'd appreciate any advice

[ducatiman]

synch issue, IMHO

[Triple Jim]

After looking into what ducatiman suggested, another possibility is air leaks between the carburetors and engine.

[ducatiman]

Originally Posted by Triple Jim

After looking into what ducatiman suggested, another possibility is air leaks between the carburetors and engine.

certainly could be a cause for synch issues

[notrocketscience]

Originally Posted by ducatiman

synch issue, IMHO

Thank you for the advice - I haven't gotten the bike running well enough to do a proper vacuum sync between carbs. I can putt around on it, but after taking a lap of my apartment complex the bike tends to idle down and die. It'll come back if I give it time before trying to restart it.

However, I did just pull my carbs off and checked them with a sewing needle. The right butterfly valve is slightly more open (barely even noticeable) than the left.

I'll keep screwing around with it, but for some additional context, I'm around 2,000ft above sea level, have a muzzy exhaust, and threw on some cheap pod filters. It's definitely the best my bike has ever run, but it still isn't road worthy.

[Triple Jim]

In case you haven't found it, there's a black idle speed adjustment knob on the left side near the carbs.

Valves that need adjustment can cause a guy to fight carb problems forever.

Pod filters can cause carb tuning headaches.

If the starting enrichers aren't fully closing they'll cause an overly rich idle so it stalls when the engine is warm.

[Bhudson]

I have been dealing with a similar problem with mine, most of the issue for me was caused by vacuum leaks in the petcock and the coasting enricher. It might be worth trying to disconnect and cap your vacuum lines and try syncing the carbs again to see if you get any closer.

[notrocketscience]

Originally Posted by Triple Jim

In case you haven't found it, there's a black idle speed adjustment knob on the left side near the carbs.

Valves that need adjustment can cause a guy to fight carb problems forever.

Pod filters can cause carb tuning headaches.

If the starting enrichers aren't fully closing they'll cause an overly rich idle so it stalls when the engine is warm.

My idle speed adjuster was at a point where it wasn't in contact with the throttle body anymore when trying to reduce the idle so I figured something was weird. I ended up pulling the carbs again (stripped a bolt but we won't talk about that. I'm calling it weight reduction until I can figure out helicoils).

After pulling the carbs I noticed my coasting enricher wasn't properly sealed so I fixed that before reinstalling.

During the reinstall, I replaced the throttle cables and then noticed my choke cable had no play. I measured it out and I think it was constantly open by ~5mm so I was glad to see your comment. Ever since then it's been running better. I'm still messing around with it and planning a longer ride today to better understand what's going on.

I appreciate the help, thank you!