Carb Rejetting - Snowmobile Forum: Your #1 Snowmobile Forum

Shades · 02-02-2005, 09:09 PM

I removed the dual 32mm carbs on my '77 Pantera 500 F/A and replaced them with dual 36mm carbs. Both have 350 main jets. How much bigger of a main jet will I need to go to get the air/fuel ratio back? Also, what is the factory rating for HP and how much more power should I expect with the upgrade?

Thanx

600SE · 02-02-2005, 09:40 PM

-Someone who likes the classics...

I don't think the bigger carbs will make a huge increse in power...Maybe noticeable...not sure about rejeting....

Now all you need is to get it bored, balance the crank, port polish, shave down heads, tuned pipes, stud track, stud track again, put on carbides, some fancy race stickers, Drill 3 million holes in everything to lighten up the sled, fool around with the clutch a little, add NOS, turbo charge, use high octane fuel(aviation fuel)........

Shades · 02-02-2005, 11:05 PM

IS THAT ALL! And I thought I would have alot to do... I would be happy with a bit more of a paddle than thefactory 1/2-3/4 POS...maybe a little better suspension...

Snow Freak · 02-03-2005, 05:00 PM

Shade i woudnt do any of that, because there goes the reliability!! And i would deffinately not drill holes in everything because there goes the strength!! Why do you want to change them? i dont think changign any of that will give you a lot more noticable power either.

Shades · 02-03-2005, 06:02 PM

...ummm... I dont plan on doing any of that. Never did. All I am gonna do is rejet the carbs. Swapping an Arctis Cat 500 F/A into a '76 Mercury T/T was enough work! I thankfully did it right and can put the original 440 Kohler back in if I get so inclined...I might just sell it... Hey, anybody want a 440 Kohler?

BC_Dan · 02-04-2005, 01:05 AM

Engines are basically an air pump. By adding bigger carbs, you allow more air to go in, but it is at less velocity, so it won't go past the needle jet as fast and won't pick up as much fuel. In order to make more power with bigger carbs, you have to work at getting more air IN and more air OUT. This involves porting, pipes, and other magic things. It's voodoo.

You may get your jetting to work at low end, then it will be a fight to get it working at high end. Expect to change out a lot of needles and jets in the process. And with the change, there won't be any helpful books laying around anywhere to guide you.
You may learn a few new words in the process.