Carb swap?

[motoXman]

Id like to upgrade my carbs to something newer off a more modern sled. Anyone know what will interchange and still work with the stock JD airbox?

[ljm]

May I ask why you want to change?

New carbs are not much different

[ihengineer76]

You are not going to notice much difference seeing how the architecture of the round slide Mikunis have not changed much over the years. You could go with a flat slide, but you would only notice a slightly better throttle response and not much else over a properly tuned original carb. The hassle and price of new carbs is probably not worth the money and could probably be better used elsewhere on the sled.

[motoXman]

My carbs work ok, but they pretty worn and I think a new set of carbs would help with the overall reliability of the sled.

[ljm]

What is worn?

Mikuni carbs have very few wear points

[motoXman]

The needle and seat. Its not a big deal, Id just like to upgrade them. What are the specs on the stock carb, does the size of the slide matter? anyone know the mm of the motor side and airbox side of the carb?

[ljm]

you can upgrade them if you want. Just lots of expense for little gain.

They are Mikuni VM 36 carbs with powerjets.
All you would gain by getting new carbs would be to go to non power jet carbs. This would decrease fuel effeiciency in the low and midrange.

New needles and seats are less than $20 each. I would take them to a shop and have the old carbs redone.
New carbs will be well over $100 apeice and it will be some trial and error getting the jetting right. To bad you were not closer I would gladly fix your carbs for you.

[motoXman]

Do you by chance happen to have a good ignition coil to spare? I think mine is breaking down

[ljm]

pm sent

[motoXman]

Will this VM36/4 Carb work? I see its lever style choke, but I assume that I can unscrew that and thread in my cable choke assembly. The jetting Im unsure about. I like the idea of brand new carbs. Nice and fresh, should help the overall reliability... that alone makes the upgrade worth it to me. Anyone know the specifics that will matter for this upgrade? Thanks

http://catalogues.kimpex.com/Snowmobile ... 594/zoomed

[motoXman]

Has anyone switched from Mikuni VM36 Power jet carbs to VM36 NON Power jet carbs?? I need some advise here. I'm seriously considering buying the Mikuni VM/4 non power jet carbs brand new.

The stock main jets in these things are 350. What am I supposed to do with that? 350 has to be way to big. If I go non power jet 150 will be too small since theres no acutal power jet so that fuel has to be compenstated correct? So maybe I add 150 to the 110 power jet and put a 260 ish main?

What about the needle and seat? I know the needle is also a different number. I need some advice here before I take the plunge. I can get 2 new Mikunis for $208.. not bad IMO.

[ljm]

Not many machine have had non powerjet carbs put on them. I think you are on the right track with adding the two jets together. I would stay at about 240-250. It will be richer mid throttle and leaner full throttle than the powerjet carb

a 1.5 needle and seat will work
An Indy 400 is very similar hp carbs jetted similar to them might be a start.

There are alot of factors that affect jetting. Be careful and keep a close eye on the plugs. You don't want to be too lean

[motoXman]

Can anyone tell me what Im losing by going to the non power jet carb? Do they even make a VM36 Power Jet model anymore?

[TASKY]

Can anyone tell me what Im losing by going to the non power jet carb? Do they even make a VM36 Power Jet model anymore?

Sounds like $208.00

I dont know why you would be willing to introduce so much uncertainty to a proven concept. It is all engineered and pre-packaged. All that you have to do is clean the carb and inpect the jets and make sure they match the prescription. They even have a temperature and elevation chart to go buy. I would spend some money on a finetune manual or download it for free from vintagesnow.com I just dont understand why you would want to gamble when all of the guess work has been done for you.

That felt good, anyhow Good Luck.

[motoXman]

And I may just go that route But I like the idea of new carbs. I wish they still made this carb. The plastic fittings are all brittle, the slides are worn and scored, the jets are tarnished and the needle and seat are worn out. $208 didnt seem unreasonable for 2 shiney new tight carbs. But unfortunately the new VM36 is non power jet. Why would they not sell it WITH the power jet? I see they sell add on kits for 22 bucks to convert them. But maybe the power jet is not that big of a performance increase to be worth it on a production carb?