I am curious, how have you guys connected bigger carbs to your motors? I have a 96 300 Xpress that I have ported and polished. It has done remarkably well. It is basically a completely different engine now. However, it is time to replace the modified stock carb with something bigger and better. I have looked all over at work(Polaris/Yamaha Dealer) to find a company that sells oversized boots that connect the carb to the motor. I haven't found one yet.

I have alot of friends who have all kinds of extra carbs laying around. I'm sure I can come up with a bigger carb. The problem will then be getting it connected and sealed to my motor in a sturdy way.

If you were to buy a bigger carb from Aaen or HPD, do they send you the different mounting pieces you'll need to hook it up?

I'm sure that I could figure out a way on my own but was curious if anyone else could offer any helpful insight.

 

Both the 39PWK sold by HPD and the 38TMX sold by RCR fit the OE boot on the 400. I would suspect the 300 comes with the 34mm carb? If so either of the two above should fit the boot, however you might run into clearance problems with the tranny and or adapting it to the air box.

I've run both the 38TMX and 39PWK with the OE boot on my 400, but scraped the air box long ago.

Honestly you should call Rick he'll square you away.

 

elroy,

No problem, it is simply a matter of stretching the manifold to fit. I wouldn't go too wild on the carb though. A 34mm should fit fine. If you have the money, you might try the new 35 mm PWK from HPD. Anything you put on it wil be an improvement compaired to the miniscule VM30SS you have on it now.

A friend of mine, Jack, went to a 38mm TMX carb on his 300 and said he lost most of his low end and didn't gain much on the top. I would guess that's too much carb for his machine.

 

I find it puzzling to think that a bigger carb will even go into my boot. The inside of my boot measures 30mm. If I were to stretch out the lip of my boot to squeeze in a bigger carb, does that mean that the rest of the boot will stretch out to the same size as the bigger carb? I can see where a bigger carb will push into the stock boot lip but I am not so sure the inner part of the boot will stretch out to the bigger size.

I don't want to put a 35mm carb on and still be drawing threw a 30mm intake. This does not seem as a real good benefit.

 

As you can see in my list of parts on my TB i have a 34mm carb on it an it helped alot an I am getting a 35mmpwk for it this winter.

 

Elroy ,
Look in the Parts Unlimited Snowmobile book down at the shop you work at. Look at the manifolds in there . You may find a manifold that may match up and do what you want from a smowmobile .

 

I did exactly what Rick suggested for my 44mm carb. The sled boots work great.

 

Rick,
Thanks for the idea. I never thought about looking in the sled book. I did check all the atv books we had but not the sled books. I'll try to check it out today but I have to watch the parts counter along with my service department today because the parts guy went to the nascar race this weekend. It is going to be a long day.

 

elroy,

Not only does the lip stretch, but the manifold itself stretches along the length where the carb is inserted. Trust me, the manifold will be plenty wide enough to flow what a 34mm carb can give it. You may need to force it in or use the tried and true method of lightly coating the carb and manifold with something slippery (i.e. grease), but it will work.

Also, I don't think that the idea of a snowmobile manifold will fly with this particular motor. You are talking about a piston port motor in the 300, not a reed valve motor. Most sleds (now and in the past) have had reed valve motors. I really do wish there was some way of putting a reed valve on these motors with out an extensive (and expensive) retrofit.