Question about carb cleaning

[alke46]

VM carbs. I have been experiencing some carb issues, namely a hanging idle and a pilot air screw on carb #2 that does not respond to any adjustment.

I am dipping them now and have found that the Bleeder (pilot jet) has some restriction to full flow. I am getting them cleaned out with a very small wire. Could this be the cause of the non-responsive pilot air screw?

Also, I have seen somewhere but can't find it now, a cut away view of the carb passageways. Anybody know where it is located? I just want to be sure I get all the passages clean with the dip and the carb cleaner and compressed air. Just don't want to leave any stones unturned and have to re-do this later.

I have placed my order for new O-rings and intake rings as well but since I just put new ones in about a year and a half ago, the ones now in there still look to be OK. The intakes also look very good so I figure I could just wait and install the new O-rings at a later dip.

Another question, when doing the bench synch, is it OK to use a paper clip (straightened) as the stopping point for the slide assemblies?

Thanks in advance,

Larry

 

[Steve]

As far as cleaning passages, if you see one, clean it. After the dip, spray a little carb cleaner in the EXIT of that passage, then blow some compressed air through it, also backward from normal flow. If there is something stuck in there, going backward stands a better chance of un-wedging the crud.

Personally, I prefer to not use ANYTHING solid as a gauge for carb opening. I just hold the carbs up to a light and look through them from the engine side. Adjust the idle speed screw until you just barely see a sliver of light under the slides. Adjust the sync screws so they all show that same small sliver of light. You may have to adjust the idle screw a time or three, but it helps the accuracy.

When you are done, back off the idle screw until it is not touching the mechanism. Turn it back in until it touches, then go two full turns. That should get you pretty close, but it will need some fine-tuning.

.

 

[hannibal]

I have two VM guides beside the rebuild guide on bikecliff's site. Found a link to one and will upload the other when I get home.
http://www.mikuni.com/pdf/vmmanual.pdf

What causes the hanging idle? My bike has started to do this and I just cleaned the carbs in May.

 

[geol]

The hanging idle can be cause by three things. 1. rubber pads on enrichener plungers are shot and allow air leaks. To check this, jiggle the "choke" arm while the hang occurs. If it comes down as a result, the plungers need replaced or the pads themselves can be replaced. 2. Pilot circuit dirty; use new pilot jets and this will likely fix the problem. Spray carb cleaner w/nozzle straw into pilot air jet. You should see it come out the small hole in venturi. 3. cables not adjusted; too tight; make sure there is slack in the cables where they will deflect with your finger when you push on them.

 

[alke46]

As far as cleaning passages, if you see one, clean it. After the dip, spray a little carb cleaner in the EXIT of that passage, then blow some compressed air through it, also backward from normal flow. If there is something stuck in there, going backward stands a better chance of un-wedging the crud.

Personally, I prefer to not use ANYTHING solid as a gauge for carb opening. I just hold the carbs up to a light and look through them from the engine side. Adjust the idle speed screw until you just barely see a sliver of light under the slides. Adjust the sync screws so they all show that same small sliver of light. You may have to adjust the idle screw a time or three, but it helps the accuracy.

When you are done, back off the idle screw until it is not touching the mechanism. Turn it back in until it touches, then go two full turns. That should get you pretty close, but it will need some fine-tuning.

.

Steve, have you noticed the restriction in the Bleeder (pilot jet) that I referenced? I don't know if this is common or if mine are just crudded up. I can ream it out with a small wire but even after dipping, it still seems to have too much resistance to a small wire. I am using a wire from a bread wrapper twist tie.
Thanks,

Larry
P.S. I will look you up at the Ozarks rally to pick your brain a little more.

 

[Big T]

If you hold the pilot jets up to a light, you should see the same size hole in each one and it should look all shiney brass inside

Rather than poke at it with steel wire, I put it in a film canister with some spray carb cleaner and carry it in my pocket, agitating it every so often. The agitation is very effective

 

[hannibal]

The hanging idle can be cause by three things. 1. rubber pads on enrichener plungers are shot and allow air leaks. To check this, jiggle the "choke" arm while the hang occurs. If it comes down as a result, the plungers need replaced or the pads themselves can be replaced. 2. Pilot circuit dirty; use new pilot jets and this will likely fix the problem. Spray carb cleaner w/nozzle straw into pilot air jet. You should see it come out the small hole in venturi. 3. cables not adjusted; too tight; make sure there is slack in the cables where they will deflect with your finger when you push on them.

Thanks. I trust my pilot jets are clean since I cleaned them twice and didn't have the problem until I started riding the bike. I'll check 1 and 3.