Mikuni VM32 Air Screw spring and fuel issues

[redhedkids]

Good day,
Somehow I lost the air screw spring for my Mikuni VM32 off my '83 Sprintfire. If someone has one or can provide me the length of the spring so i can make a temporary replacement, please let me know. I'm having trouble dialing in the idle on this carb and I think that by not having the spring, the 1 3/4 turns out is a little on the restrictive side because the spring gap between the carb body and the screw isn't being accounted for. I feel that the carb is throwing too much fuel on starting because the plugs are extremely wet after trying to start with choke on. The sled is barely firing and won't hold idle once i start it. The only way I got it to start the other day was by feathering throttle with choke off while a buddy was pulling it over. Very good spark and compression and I've thoroughly cleaned the carb. I even adjusted the float arm tab to try to get the floats to engage the needle a bit better. I haven't vacuum tested the carb...yet. All settings on the carb are in accordance with the service manual.

I'm ordering a new needle and seat tonight from New Breed. This is my first sled with a Mikuni as my other two sleds are a JDX4 Special and a '74 300. If you have any experience and advice you could provide, I'd certainly welcome it. Thanks in advance for your help.

Dennis

[Matt]

Dennis, I don't have the spring handy to measure but I can order you one in to go with the needle & seat. They are $1.85. It would take me a few extra days to get the spring before I can ship your order.

Matt

[redhedkids]

Thanks Matt! Please include the spring with my order. Order should be submitted tonight. If possible, I'd like to have the items that I order that you have in stock sent as soon as possible and the others when they come in. I don't mind paying the extra shipping/handling. Dennis

[redhedkids]

One last question....should I add the power jet kit to this carb?

[Matt]

I just added the spring to the store's listings. That's no problem, I'll send the needle/seat right away. No, you don't need a power jet kit, it just complicates things and doesn't help much with performance.

[redhedkids]

Order submitted but I didn't see your reply about the spring in the store's listings before I placed the order. Can I PayPal you directly for the spring?

[Matt]

Sure. I'll let you know when I get them in, should be Thursday.

[That Girl Racing]

No doubt you need the spring. But I seriously think that is not the problem

[jdrob]

Dennis did you by any chance check the jets to see if they are stock for the sprints? Also the Needle that goes through the Valve body. Where is the e-clip set? should be in the middle setting. Also do you know if the oil injection is working properly ? thats a couple places to look at. And of course crank seals. but usually 1 side will run lean and the other side rich ! hope this helps !

[redhedkids]

Rob, I just finished taking the carb apart to install all of the new parts I received today from Matt (Thanks Matt!) I've had the carb apart recently but never took the needle out of the slide to inspect. Lo' and behold the e-clip was in the second ring down from the top; not the middle as both you and the service manual direct. Jets look to be correct. Hopefully I'll be at my buddy's garage later to install everything. A foot of snow scheduled for tomorrow so I need to get this thing running good!

[That Girl Racing]

2nd clip is leaner than the middle position. You will richening up the idle even more

[redhedkids]

Although I only have very limited experience with the Mikuni carbs, does the needle really have much effect on idle? It was my understanding that pilot circuit ran everything at idle and that the needle (and jet) start working at about 1/4 throttle and up.

[That Girl Racing]

All circuits in the Mikuni carb overlap each other. If they did not the sled would bog during the transistion from idle to full throttle. Put a 700 main jet in the carb and see what happens.

[redhedkids]

Isn't it a big jump going from the stock 165 jet to the 700? What is the benefit as i don't have any experience with jetting? Sorry for my ignorance, but I'm just trying to gain a good understanding of the tuning of a Mikuni. Thanks for your assistance.....Dennis

[That Girl Racing]

What I was trying to demonstrate is that if the main and idle curcuits were independent of each other, putting in a 700 main or changing the tube to a cc-5 would not effect the idle of the sled . I can assure you either on of those would kill the motor. There is something you are missing in the carb, dirty pilot jet, leaking intake, leaking needle/seat. These motors are not that sensitive, get them close and they will start and run fine.