Need a little help in making my decision. I'm going to go with a Hetrick cylinder kit soon and can't decide between the 52 or 54 kit. In my area their not strict on cc size so that wouldn't be a problem if I went with the 54 kit. I know the price will be a little higher with the 54 because I'll have to go to a larger carb (currently have 20mm). My biggest problem is I've always hated when someone ran a larger cc bike/quad than the class their in and they get away with it because it still has the 50/70/90 sticker on the side. It's just the principle staying under 90cc when you're in that class.

If you guys have any other pros and cons I'd appreciate it.

 

You should check with Hetricks, but I believe I've heard that a 54mm will not hold up as well as a 52mm. But like I said check with them about their experience.

 

Maybe you think bigger is better. Ask newnick. His motor is 50mm and I bet it'll keep up with any 53 or 54mm cylinder.
The 20mm carb is sufficient IMO.

 

We went with a bigger carb (30mm)on our bigbore stroker and it made a world of difference over the 20mm Keihin in lowend and topend power. If you have no cc restriction, a 5 or 6mm stroker crank will make much more power difference IMO than a 54mm over a 52mm cylinder. A properly ported and setup 109cc mini outruns a 89cc bike everytime in a straight line but at our MX track the better rider will win with even 70ccs.

 

Hey Jack, it'll be 50.5 mm if I ever get a chance to put it back together. We're still trying to get straightened out after the huricane around here. I agree with the last post about the rider making the biggest difference.

 

I should have added that Lt 80 said it right that a 20mm Keihin is big enough. Our 20mm ran awesome on our old 89cc motor and was snappy and easy to jet we just used a bigger carb and it worked better for us on the 109cc kit. But I love the 20mms..