Mikuni VM32 Air Screw spring and fuel issues

[redhedkids]

I took the carb completely apart yesterday, intalled new needle and seat, flushed all passages and blew out with compressed air, made all adjustments in accordance with the service manual and reinstalled. Unfortunately, I didn't have time to attempt starting because when I got home, there was a fresh foot of new snow on the ground and the kids wanted to go riding.....so off on the X4 Special we went. Hopefully I'll be able to carve out some time today to work on it.

Dennis

[redhedkids]

Another question....on the top of the mixing chamber body, just below the mixing chamber top, and on the air box side, there is a screw hole that has nothing in it. From what i can tell, this may be for a bracket if there are multiple carbs. Should this hole have a screw in it to keep extra air out? I don't see anything in any of the mikuni parts diagrams that show this feature.

[That Girl Racing]

Well???? Is it working?

[redhedkids]

Nope still flooding. So far I've replaced the needle and seat, bowl gasket, air screw spring, and choke plunger. Took apart and cleaned again and everything is set in accordance with the service manual. I plan to take it apart again this weekend to check the floats and give it a pressure test. I may order new main and pilot jets just to make sure. They looked clean when I took them out for cleaning and I didn't see any obstructions. I even set the choke a little leaner to see if that would help. I see that others are having similar problems recently....engine fires and/or runs for a bit, then won't start again due to flooding/fouled plugs. I wonder if I should move the e-clip back to the #2 position. This sled ran good last year although I only got to ride it once for just a short run. Also, can anyone answer my question about the screw hole on the carb that I posted further up? Thanks.....Dennis

[That Girl Racing]

When you say flooding, do you mean fuel coming from the vent lines or that it is running rich?

[redhedkids]

When I pull the plugs they are soaked. No fuel coming from vent lines. When I do get it started its usually with choke off and holding throttle about 1/4 open and feathering. When it dies it sometimes backfires. One thing I haven't done yet is try different plugs.

[That Girl Racing]

Does it backfire through the pipe or carb? Has the motor got good compression and is sealed properly? If you pull the fuel line off the carb and pull it over is there a good squirt of fuel? Have you put new plugs in it?

[redhedkids]

It's backfired through both the carb and the muffler separately. Haven't had the chance to change plugs yet....next on my short list. It feels like it has great compression but I still have to complete a proper compression test. As far as being sealed, there aren't any apparent leaks but I haven't taken the motor out yet to check. Was planning to pull motor and do seals next.

[That Girl Racing]

A backfire through the carb is usually a lean mixture. My guess is the motor is leaking . It looks rich because it is not firing at all and the fuel is laying in the chamber. As i said before, these motors ore pretty forgiving. Give them spark at the right time and a usable fuel air mixture and the will run.

[redhedkids]

Put new plugs in tonight and got it running! Feeling stupid at this point. Still running a little rough so I'm going to fine tune tomorrow in the daylight. I put a set of new BR8ES in as those were the only new plugs I had laying around. Had BR9ES in there before. Seemed real peppy when I ran it tonight although I don't have enough room in the yard to really open it up. After running, the plugs indicated a lean condition (whitish grey). I know the BR8ES run hotter and it is 32 degrees here. Will go to the shop tomorrow and get some new BR9ES. Also, i have the air box on but the metal screen on the intake tube was rotten so I'm running the air box by itself. Is this ok to do? IT still feels as if it is popping a bit and doesn't like to hold idle. When I shut it off, I hear gurgling in the fuel tank like air being released from the fuel line. I'll drain the tank tomorrow to see if the pick up is restricted. I feel like I'm getting there slowly with this sled now so any help is still welcome as this is my first fire series sled. Also, tried spraying carb cleaner around the clutch side seal with no RPM change. I still plan to replace the seals once I get them.

[That Girl Racing]

Good to hear. Gray plugs are difinetly a no no. Check the intake maniflold for leaks also.