CC gains after cylinder boring?

Hey guys, I'm wondering if anyone knows that CC displacement gains I would get from boring my 244cc engine out .0010? .0020? .0030? or .0040?

I'm sure there is a mathmatic way to figure that out but math was my worst subject!

Overbore vs Big Bore

You have your decimal point in the wrong spot... instead of .0010... you mean .010

(and that is technically incorrect anyway.. its rounded off from 1/4 of 1mm.. which is actually .0098)

anyway.. even at your ".040".. (1mm) overbore (the largest overbore Honda will offer for it)... you are only up to 256cc... not much at all ...7cc

Soooo... if you really wanted something... see if Wiseco offers a big-bore piston kit ... which could put you at 280cc.

This is all based on a bore and stroke of 73mm x 59.5mm (if thats what you've got)

I was guessing its the same as the Honda XR250 (it may not be, but it should be close)

Re: CC gains after cylinder boring?

well I got a formula if you want ...use the constant .7854 x bore/ squared x the stroke will give you the cubic inches and your only at roughly 15 cu in now(14.89) ... so you can only get so much ..... but if your going for power your limited to torque anyway because your tranny is limited to a certain speed .but you might get there a bit quicker.......Rog

Re: CC gains after cylinder boring?

No matter what the over bore is, you should see a gain in performance if you are needing to rebore your cylinder due to a lack of compression. I am a little lost on the amt of gain you are looking for. If you are looking for a huge gain, you might want to see about installing a sleeve and boring it out to a new cylinder size (not really worth it, you can gain in performance in so many other ways). Are you having current compression problems? The newer cylinders are so well designed that they can handle a lot more stress. Look into the exhaust, carb, porting and other such stuff. A good 250cc engine can really produce some power. Some of the smaller bore engines can give more torq and Hp than the larger ones if worked correctly!


Re: CC gains after cylinder boring?

Ok, I saw the earlier posting. You have a Honda Elite, I remember some of your other postings. Go for the performance exhaust. You would have trouble getting much perf increase by boring the cylinder. There wouldn't be enough room in the cylinder wall to go too much over standard. I'd go for quality work!! With the over bore, you can get a good quality job that would give you an increase over standard. It isn't alway how much over you go, it can also be the work itself. Everything is designed around a good ratio, Transmission, engine and exhaust. Open the exhaust, Let the motor get some air and fuel. Make sure your transmission is up to grade and you'll see a scoot that smokes new ones off the show room floor (after break in).


Re: CC gains after cylinder boring?

Hmmmm, Now you guys have me thinking ...Larger displacement is what I'm after. It seems the cheapest way to gain power. My scooter doesn't need a rebore but I figured since I have the jug off I'll never be any closer to doing it. Plus, I'm in no hurry because in NY it's below freezing so I can't really ride it anyway.

The only aftermarket (malossi) exhaust that I can find for my scooter is $300! They told me it was a "touring" pipe made for the helix and would offer only a slight increase in performance and a little less weight.

That doesn't sound like a very good bang for my buck.

I like the wiseco big bore Idea. I'm guessing a big bore kit would cost about the same as hondas .040 kit or even less. Going as large as 280cc would be awesome but would it open up whole new can of worms? Would I have to change anything else like the carb or the valves, the exhaust? Or is it just a simple bolt on package. Would my MPG suffer a lot? I'm getting 60-70 MPG now.

I'm fine with the scooter being limited on the top end as someone said on this thread. I have had my last 250 elite up to 75 MPH on the highway. It was completely stock. That was not a comfortable speed for such a short wheelbased scooter. If I could get up to 65MPH a couple seconds faster than a stock 250 elite that would be more to my liking. :)

Thanks for the advice.

PS - my bore and stroke is 72 x 60.

Re: CC gains after cylinder boring?

First thing... go to Wiseco's website where they have an online catalog ... see if they offer a big- bore kit for it.

They offer them for the XR250... for 280cc... but thats not the same motor as yours... its a 4 valve... yours is a 2 valve.

And ... going to the 280 kit would be the best way to get more acceleration.

Its fairly cheap too.... However... it also means your cylinder has almost no more room for another overbore if anything happens.

Re: CC gains after cylinder boring?

I went and they do not list anything for the CH250 elite. There was one that was with .5 mm of my stroke though. And the bore was 3 or 4 mm larger.

Re: CC gains after cylinder boring?

Hey Don, I was just going to put my 2 cents in on your exhaust but I see you already found it..... performance exhaust for a 4 stroke wont do squat for horsepower. you might get a pony or 2 out of it but, ususally its not worth the money, unless its a big bore twim and they look good hanging off the side, ie lotsa chrome... but not for an elite (wish I had one too)......exhaust is real important on a 2 stroke and can make a huge difference but not on a 4 stroke...Rog

Re: CC gains after cylinder boring?

Since going .040 over will only net me a few CCs and they dont offer a big bore kit for my scooter I guess I'll be leaving it stock. No sense in spending another $100 for a couple CCs.

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