Engine dies when slowing down

[Hoperator]

Hey guys,

This site has a wealth of knowledge, so this might have already been answered but I think im using the wrong search terms.

I have an 81, rejetted, pod filters, just cleaned the carbs, and I'm using a 12v 0.8ah battery, with simplified wiring (i.e. headlight, taillight, pamco). The problem is the engine dies when I slow down aggressively. It'll kick over after this loss of power, but when I give it some throttle it dies again. I let her sit for a 3-5 minutes (while I sat on the curb and searched this site on my phone for answers ) started her up and this time, she ran like normal. My guess is electrical/charging issues? Help!

 

[sparky01]

breaking hard splashes fuel from the float bowls flooding it out floats my be to high

 

[Hoperator]

breaking hard splashes fuel from the float bowls flooding it out floats my be to high

Thanks for the reply Sparky. I took her around the block right now and noticed that the issue disappears when I set the petcock to PRI. Would that be related to the floats/fuel issue?

 

[sparky01]

I do not think so chk your gas cap is it venting

 

[xjwmx]

It could be any number of carb or petcock issues. But if it's always there on run and never there on prime it might be a clogged vacuum line. The petcock actually has an air jet in it that might be clogged too. That could let the fuel in the bowls get low and cause what you're seeing, especially when you slap on the throttle and it dies. Prime bypasses the whole vacuum thing. I don't think it's a big leak in the vacuum, else you'd be seeing something all the time. You might want to take the petcock apart and examine and clean it and carefully put it back together. When you finish make sure it doesn't flow gas on run, unless you're sucking on the vacuum tube at which time it should flow.

If that doesn't help, examine all the carb parts, float valve and seat, o-ring, diaphragm. Make sure your jets are stock or something reasonable. Clean the bejezus out of the whole thing.

 

[kerno]

My pal had the same problem and it was vacuum and petcock problem. Check vacuum pipe for leaks and get petcock repair kits with new wee diaphragm or change to non vacuum petcocks should cure it.

 

[Hoperator]

thanks guys! I'll check out the petcock issues

 

[Hoperator]

oops. Double post

 

[Hoperator]

Update for future searchers because I hate coming upon a thread with your same issue and the OP doesn't say if the suggestions worked:

So i switched to a manual petcock effectively eliminating the possibility that it's a vacuum issue. She was doing fine until I REALLY had to aggressively come to a stop (stupid intersection light), at which point her idle dropped fairly low and I noticed a hesitation when blipping the throttle. Good news, she didn't die this time. Pulled the choke and she seemed fine. Carbs have been cleaned thoroughly, then cleaned again, and then again. 145 mains. 45 pilots. pod filters. shorty cone mufflers. valves set. cam chain set.

My guess is the idle screw needs to be futtz with and maybe I'm using my manometer wrong. Stay tuned.

 

[Hoperator]

Final Update: played with the sync screw and air/fuel mixture screws while following this youtube vid on manometer operation. Needless to say I was using the manometer wrong (was only paying attention to idle levels & not what happens when you rev it). Now I'm officially ready for this riding season. Thanks again to all who helped. Keep two wheels to the floor and lets ride tomorrow!

 

[weekendrider]

Hoperator,
Thanks for coming back. Had you not posted I would have guessed sparky is right on with the float out of adjustment.

 

[Hoperator]

Hoperator,
Thanks for coming back. Had you not posted I would have guessed sparky is right on with the float out of adjustment.

You know now that I think about it, it could've been the floats as well. I adjusted the tang a little bit while wrist deep in my third carb cleaning. It was probably a cluster of all these issues put together.