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whats the point of a bigger carb?

Posted: Fri Jul 11, 2008 11:31 pm
by PimpinSpree
whats the difference between getting a bigger carb and just putting a bigger main jet in a stock carb?

Posted: Fri Jul 11, 2008 11:47 pm
by burnt_toast
Better flow and adequate supply of A/F to a big bore engine.. bigger carb not needed on stock block

Posted: Sat Jul 12, 2008 12:04 am
by PimpinSpree
so if i do i big bore do i def need a bigger carb?



what about a spree carb with a bigger jet on an se50 elite motor

Posted: Sat Jul 12, 2008 12:20 am
by Kenny_McCormic
Spree carb on SE50 will be underpowered at best.

Posted: Sat Jul 12, 2008 1:41 am
by GN Racer
PimpinSpree wrote:so if i do i big bore do i def need a bigger carb?
Not necessarily, but you will need a larger jet for sure.
PimpinSpree wrote:what about a spree carb with a bigger jet on an se50 elite motor
Open up the carb a bit with a grinder (after disassembly). Not too much though. You can open it up to the stock SE50 size, or larger. I used to run an opened up Spree carb on my '87 Elite engined Aero with a 62cc Proma kit. I think the jet size I used was a 90 or 95

I later upgraded to a 18mm Mikuni w/Kitaco manifold, but I don't remember if there was an improvement in performance. It's still on there so I know that it didn't hurt performance.

Posted: Sat Jul 12, 2008 2:07 am
by PimpinSpree
what do you mean open it up? I've never heard of doing this, so i can only guess. Like grind off some aluminum where the butterfly opens up?

Posted: Sat Jul 12, 2008 2:40 am
by GN Racer
Yes, grind, file, Dremel to flow more air. Not too much though, and definitely not on a stock bike with no mods. Also FYI, there's no butterfly, there's a slide.

Although it's pretty easy, I would not recommend doing this if you've never done it before. The carb has to be completely disassembled, and you have to be careful not to overdo anything.

If you do run the Spree carb, don't forget to swap out the slide as well. It will be different. Also, don't worry about the bystarter; Just leave it unplugged. You will not notice a difference. Don't forget to re-jet! Always better to be rich than lean!..

When modifying your bike, do ONE modification at a time whenever possible. That way you can determine if it made a difference or not. It also makes tuning much simpler...