After carb cleaning, engine wants to run at open throttle.

Great site, couldn’t have cleaned my carbs without your helpful posts. So thanks in advance for your help in getting my first bike running and on the road.

I just completed a carb cleaning and upon reinstall and start up, my bike wants to run mid to full throttle, 5k to 6k rpms. To a point where I need to hit the kill switch in fear of doing some serious engine damage.
Some background- I bought my '82 650 maxim about a month ago. The bike had sat for a year and to the owners knowledge, never had the carbs cleaned.
When I first got the bike home, I could only get the bike to start and idle for about 5 seconds. It was clear, I needed to clean the carbs.
Here's what I've done up to this point:
* Read through pages of tips and instruction on this site.
* Pull carbs- they are the Hitachi version.
* They where indeed dirty, with plugged jets etc.
* Decided not to split the rack. (too much to takeon and wasn't sure it was necessary.)
* Pulled all the components from the TB and organized them to insure they went back into their original carb.
* I did use the boil in lemon juice and water technique to do the majority of the cleaning. This worked out better than I expected.
* Used compressed air, carb cleaner, pins, needles, etc to make sure all passages where clear. Even sprayed carb cleaner into my safegoogles a few times. Thanks for the tips! Saved me a doctor bill.
* Enrichment valves where stuck to the cylinder walls; removed them, cleaned and polished them, then Clunk tested and passed.
* reassembled and used WD40 on metal parts and silicon on the rubber diaphragms for lubrication.
* I replaced the gasket bowl seals, but did not replace any other carb parts.
* Put the carbs back on the bike.
* Air intake boots are in good shape and were reinstalled correcly, seated and align correctly.

First start after reinstalling carbs.
* When gas was allowed to flow from the pet cock via “Prime” it appeared the #4 &2 carb dripped gas. Turned petcock to “on” to prevent this. Also rapped the carb with a wooden handle, hoping the vibration would free up a stuck float. This seemed to do the trick.
* I needed some starting fluid to get the engine to pop and draw gas. It first fired up nicely, with the choke on it was running at 2500 rpms for about 30 seconds, then I gave the throttle a twist and the engine rev’d to 6,000 rpms and stayed there. Hit the kill switch. I made sure throttle cable was not stuck, tested the throttle linkage and enrichment linkage on the carb to ensure it was moving freely, backed off the choke and restarted. Started up at around 3000rpm then started to climb. Tried adjusting the main idle setting, to see if this would correct the open throttle condition. No success with this. This morning with the bike cold, I started the bike and it immediately started in full throttle mode. Hit the kill switch within in seconds of starting to avoid damage.

Where do I start trouble shooting this?
What’s causing this open throttle condition? Bad Float settings? Enrichment valves Stuck? Not sure where to begin.
Thanks,
Dale

 

Have you backed off the idle screw to see if that makes a difference? If so, check your throttle linkage for any binding to start. Once it gets going, can you push the throttle down between #1 & #2 and get the idle to go down. If so, something is probably pushing the throttle up.

Could be other things, but that is as good as any starting place.

 

Re: After carb cleaning, engine wants to run at open throttl

Found the problem!!!

The #2 carburetor hose clamp was preventing the throttle from returning to the idle position.

I discovered this problem as I was removing the carb from the bike. None the less, I removed the carb anyways so I could do a proper bench tune. Then reinstalled it and presto, problem solved.

She runs great!
Thanks