bike stumbling at idle?

[reddevilmedic]

bike is stumbling at idle, dropping down in rpms, them back up. over and over. bike is warm. i replaced the plugs, relatively new wires, new to me tci. any ideas?

[safetyguy]

What shape are the carb diaphragms in?

[Trader]

Seafoam!

[Yammer Dan]

Seafoam!

 

 

 

 

I got Help!!!!:sign yeah that:

[V7Goose]

bike is stumbling at idle, dropping down in rpms, them back up. over and over. bike is warm. i replaced the plugs, relatively new wires, new to me tci. any ideas?

Stumble or surge - I guess it all depends on what you view as the baseline. Anyway, what you describe is classic for too rich idle mixture - very easy to cause this by just having the choke a tad bit on when it is fully warm.

Goose

[reddevilmedic]

definately a stumble. carb diaphrams are good. just replaced 2 of them. seafoam keeps fouling out the plugs.....i have the choke off. it definately "smells" like its running rich.

[reddevilmedic]

i believe it to be the voltage regulator. anyone know where i can get one?

[dingy]

i believe it to be the voltage regulator. anyone know where i can get one?

 

Okay, I'm gonna ask, how did you get voltage regulator as your final answer & did you call a friend or do a street shout out?

 

I just don't see the regulator making it smell rich!

 

 

Gary

[JoeKanuck]

First thing; sync the carbs. I just did a bunch of stuff to the carbs and it idled like a horror show before I synced the carbs.

 

It makes a tremendous difference.

[reddevilmedic]

i did a sync with carbtune pro. once bike gets hot, it hestitates like a fuel issue, but volts on dash drop also. it was a shout out. doesnt do it while cruising, mainly just idling.

[dingy]

If the rpm's drop the voltage will also drop. The stator is putting out less current.

 

Pull the headlight fuse out of the fuse box & see if that makes any difference.

 

Check the connector from the regulator for melting issues. Three cond. connector near the rear shock damper knob. Three white wires into it.

 

Gary

[bkuhr]

i did a sync with carbtune pro. once bike gets hot, it hestitates like a fuel issue, but volts on dash drop also. it was a shout out. doesnt do it while cruising, mainly just idling.

 

Suggest get battery load tested. If volts drop during idle, as they should, enough to affect idle preformance-likely ignition, then I suspect low capacity battery.

A new regulator will not help with a low capacity battery, as it does not charge at idle anyways. Need to be above ~2000rpm for charging.

[reddevilmedic]

the battery is a week old AGM. i pretty sure the stator is original to bike. i bought from second owner who never had the opportunity to work on it. i did already replace the connectors to the stator. i was considering replacing both, stator and rectifier. rectifier is yamaha part, probably original also. is ricks the way to go with stator? how bout rectifier?

[bkuhr]

Before throwing , I usually do some testing first.

My first question would be, what is battery voltage when measured with a quality digital multimeter (DMM) measured directly across the battery posts during...

a. prior to start key off

b. prior to start key on

c. during starting/cranking

d. during idle-~900rpm

e. during high rpm ~3000rpm.

 

Based on these readings we may determine if no electrical problem at all, weak battery, or problem with charging system.

 

If needed then additional electrical tests can be completed, again with a quality DMM. If you don't have one that would be the first place I would spend , but likely can find a local friend with one.

[reddevilmedic]

thanks, i dont have one, but ill get one tommorrow and post results.

[reddevilmedic]

well, i didnt get a dmm yet, but i put the battery on a trickle charge and noticed it was down 3 amps. doesnt the stator keep the battery charged?

[bkuhr]

I went out and preformed the same test I am asking you to do.

should be close, 83strd vs 83 royal.

I turned off my added fog lights and radio. Headlight Low beam. Think only major item different is I have no CLASS powering up. Running Batteries Plus AGM. Has not been run or charged for 1 week.

 

key off=12.44v

key on=12.06v

cranking=10.8v started real quick, but lowest # I saw

idle=13.1v after stable for about 1 minute

high idle=13.9v

 

We can compare #s when you get yours, and try to figure out if you really have electrical problem, and if so where to start looking.

 

As for DMM, dont waste on cheap $10 at harbor freight. Plan on at least $40. Make sure leads come with both probes and gaterclips. If you have the money and want the best I like Fluke 77 series, but Sears, Radioshack, etc sell some decent ones.

Almost all meters have, but make sure DC volts, AC volts, OHMS, DC amps/miliamps, AC amps/miliamps. Quick test in store: lowest OHMS scale, short the leads, very low (.1) steady reading, repeat for same reading. May or may not be adjustable to zero the reading out. If so zero it and repeat.

[JoeKanuck]

When your bike is idling, slowly rev up and note when the volts come up. My volts drop just under 1000rpm and level off at around 1300.

 

One thing to note is when the brake is on, not only are your powering the brake lights, but the anti dive as well. My volts drop to 12 at idle if the brake is applied.

 

As for your rough idling, a bad spark will do that. You only need one bad plug, wire or coil to give you a rough idle and that cylinder will definitely run rich.

 

You can try adjust your low speed jets as well.

[bkuhr]

When your bike is idling, slowly rev up and note when the volts come up. My volts drop just under 1000rpm and level off at around 1300.

 

One thing to note is when the brake is on, not only are your powering the brake lights, but the anti dive as well. My volts drop to 12 at idle if the brake is applied.

 

83 does not have electric antidive

[reddevilmedic]

im trying to borrow a dmm first, just in case i need to buy some parts. tight budget. like i said, plugs are a week old, changed them with oil. wires are 4 months old, custom. battery week old agm. bike wasnt doing this before. just in last couple days. took it for a ride yesterday. didnt notice problem while riding, but stopped at lights, rpms drop the jump back to norm. with or without brake. driving lights off. i tried leav ing the choke on a little, still did it.

[mralex714]

I know this post is 2 years old but did you ever get a good resolution on it? I am having the same issue with my 86 and looking for a fix.

[Peder_y2k]

I'm thinking vacuum leak at the carb mounting booties, the pilot screws could use some tweaking, and the carbs need a thorough cleaning - especially the emulsifier tubes. The SEAFOAM treatment may help if done correctly. Also, clean dry spark plugs can do wonders.

-Pete, in Tacoma WA USA

'83,88

[mralex714]

I'm thinking vacuum leak at the carb mounting booties, the pilot screws could use some tweaking, and the carbs need a thorough cleaning - especially the emulsifier tubes. The SEAFOAM treatment may help if done correctly. Also, clean dry spark plugs can do wonders.

-Pete, in Tacoma WA USA

'83,88

 

I sprayed around the engine looking for vacuum leaks and found none. Carbs were done in January. I had a new slide and diaphragm and swapped it with one with a chip in it. Idle has improved, I think I'll change the other 3 diaphragms.

[reddevilmedic]

ended up being stator, replaced stator with Ricks Hot Shot, and Shindigen R/R. It ventually just died and wouldn't restart, within a week of this happening. Do the stator tests, if that's it, replace the r/r with it.

[mralex714]

ended up being stator, replaced stator with Ricks Hot Shot, and Shindigen R/R. It ventually just died and wouldn't restart, within a week of this happening. Do the stator tests, if that's it, replace the r/r with it.

 

I'll do the stator checks. I'll do them after the bike warms up, because that seems to be when I have my issue.