Rough Running Problems

[m-cman]

I have read almost every post on the site and haven't found a definitive answer to this problem.

My newly purchased 1997 with stock carb/exhaust/air filter runs fine when first started. As it warms up, it starts running rougher and rougher. When at full operating temp, it won't idle and runs very rough until above about 3 - 4000 rpm. Have to keep reved up and is difficult to take off from a stop without stalling. It seems to get worse the longer I ride it. :sad2:

The bike is not over-heating. The fan never comes on and the temp guage never gets above the half-way mark. The charging system is fine. (Passes all tests as outlined in the shop manual including the 14v at 5000 rpm test). ullhair:

Hopefully, someone here is familiar with these symptoms. :th_help:

 

[maleko89]

Are the mixture screws plugs drilled out?

You're running rich....rich condition gets worse as the bike heats up. 3-4000 rpms is still in your idle circuits so it's time to clean those with some Seafoam fuel treatment. Make sure your floats are set to either all 16mm or 17 mm. Do the Peashooter and see if that helps. Then, adjust your mixture screws one at a time and re-sync your carbs. Since running rich one of your pilot air jets is probably plugged. There are two...one at the top of each carb and one behind the slides.

How is your air filter?

Mark
#1098

 

[m-cman]

Thanks for the response. I have already tried the Seafoam. The mixture plugs are drilled out and all are between 2 and 3 turns out. Air filter is clean. Thought it might be a low to mid speed jet/carb problem since high rpm seems ok.

What is the "peashooter" treatment? What is the proper/best way to clean the pilot air jets? Are there "how-to's" on these fixes here on site?

Thanks again,

Don
VMOA #782

 

[maleko89]

Here's the Peashooter: http://home.comcast.net/~onlyone12/carbs1.htm

Another option is the Shotgun. Go to vmax.lvlhead.com and it's under Tips.

Mark
#1098

 

[m-cman]

Thanks Mark. Will check out.

 

[KINGmax]

I'm having the exact same problem.......very rough idle only when fully warm. All electrical checked out fine. Did the peashooter and/or shotgun method work?

 

[4gasem]

I'm having the exact same problem.......very rough idle only when fully warm. All electrical checked out fine. Did the peashooter and/or shotgun method work?

I would also check your carb sync... :thumbs up:

Running a can of Seafoam in it wouldn't be a bad idea...

 

[jfeagins]

:ummm::bang head:

I, too, am having these very same symptoms -A'FREAKIN'GAIN! The bike starts missing only after it warms up, only mine IS in the spark system. I've been through new plugs, new plug caps, new plug wires. I've double, triple, and quadruple checked all neccessary connections for all the above. Still I experience a wandering spark here and there (after warm up) The warmer the weather, the worse the problem. I'm wondering if my problem isn't some sort of microscopic cracks in the coils. I sure can't see anything wrong with them though.

If on the center stand, and after dark, you can see the occasional spark jumping off the darn black plastic trim which sits on the valve cover. Usually it is one of the rear two cylinders jumping. I've tried lots of fixes. The wires are new. They don't have holes, cracks or other. They are clean, and they have been attached properly at both ends.

I finally pulled the black trim clear off and got enough relief from the symptoms so that the South Dakota trip went well enough. I thought I'd just leave the plastic trim off and enjoy life, BUT IT'S back again even without the trim on the bike.

Anyone with ideas, please chime in. Hurry. It takes the fun out of riding my Max. I hate to spend any more money on parts if it aint' going to fix the real problem.

Sure wish they had released that new model. Now would seem a great time to trade, but I don't want to part with the '85 until I can get one that goes even faster. Heck, at this point even the big Stratoliner is looking pretty good.
:confused2:

 

[4gasem]

:ummm::bang head:

I, too, am having these very same symptoms -A'FREAKIN'GAIN! The bike starts missing only after it warms up, only mine IS in the spark system. I've been through new plugs, new plug caps, new plug wires. I've double, triple, and quadruple checked all neccessary connections for all the above. Still I experience a wandering spark here and there (after warm up) The warmer the weather, the worse the problem. I'm wondering if my problem isn't some sort of microscopic cracks in the coils. I sure can't see anything wrong with them though.

If on the center stand, and after dark, you can see the occasional spark jumping off the darn black plastic trim which sits on the valve cover. Usually it is one of the rear two cylinders jumping. I've tried lots of fixes. The wires are new. They don't have holes, cracks or other. They are clean, and they have been attached properly at both ends.

I finally pulled the black trim clear off and got enough relief from the symptoms so that the South Dakota trip went well enough. I thought I'd just leave the plastic trim off and enjoy life, BUT IT'S back again even without the trim on the bike.

Anyone with ideas, please chime in. Hurry. It takes the fun out of riding my Max. I hate to spend any more money on parts if it aint' going to fix the real problem.

Sure wish they had released that new model. Now would seem a great time to trade, but I don't want to part with the '85 until I can get one that goes even faster. Heck, at this point even the big Stratoliner is looking pretty good.
:confused2:

Sounds like a bad coil or ignition unit...

 

[KINGmax]

I would also check your carb sync... :thumbs up:

Running a can of Seafoam in it wouldn't be a bad idea...

Thanks for the advice. Here's my set-up details and what's been done so far (problem has been around since I bought it in November '06).

-1998 all stock except for exhaust (two bros. slip-ons)
-no info on if carbs were re-jetted when slip-ons were added.
-bought about 1 yr ago (with 2400mi).
-owner before me only put only 300miles on it in 3 years
-I've put 4,000+miles on it and I'm sick dealing with the rough idle/lack of idle problem when it's hot.
-seafoam - run through 4+ tanks
-carb sync @ shop
-pilot screw adjust @ shop
-new regulator/rectifier (replaced twice @ shop)
-new battery
-electrical testing at shop found one bad coil and plug wire (they were replaced)

I'm currently waiting for one of the shops I've been to to get their Dyno fixed so they can test my air/fuel mixture to see if carbs need to be rejetted/rebuilt. They're thinking it's a lean condition that's getting worse when the bike is fully warm. What I don't understand is that it seems to be somewhat based on the weather as well. For example, problem is much worse when it's hot outside and good luck trying to ride in traffic on an 80+ degree sunny day. Runs much better in cold weather but problem still surfaces occasionally:bang head:

I have not taken a close look at night when to see if there are any sparks dancing on the wires. I'll check this out soon.

Any suggestions are greatly appreciated! Thanks.

 

[maleko89]

I wouldn't take it back to that dyno shop.....lean problems get better with heat...rich gets worse.

I would remove your carbs and see exactly what you got...if it's not stock then it needs to be changed to stock.

PAJ1: Mikuni 90
PAJ2: Mikuni 170
Mains: Mikuni 152.5
Float level: all four the same...either 16 or 17 mm

Check the electrical link on this site and troubleshoot your charging system. Stock battery sucks....get a maintenance free gel battery like the Odyssey PC680. Also, solder the stator to R/R connection and the crimp connection under your seat near the battery. Mine used to get a rough idle when it got hot because the fan uses quite a bit of juice. Oh, check all 3 grounds...frame, R/R and engine by oil filler cap.

Mark
#1098

 

[KINGmax]

Thanks Mark,
All electrical checks out fine based on both shops it's been to. I know that the crimp connection has been soldered, but the R/R connection has not. I will do that soon. I will also check all three grounds. --Chris

 

[KINGmax]

I also meant to say that I don't have the experience and/or know-how to pull the carbs. I'll have to leave that to a bike shop. I've priced it out and it costs anywhere from $500 to 700 just in labor to rebuild these carbs. I'll definitely check the electrical connections first.