Bigger sporty motor..... - Harley Forum

street bob · #1 11-02-2008, 09:39 PM

What can be done to a sportster motor to make it bigger?
Are kits available to build them out to 80" or maybe 84"?
My wife loves her scoot and doesn't want to hear about going to a "big" bike.
I don't blame her(to much) because she is so used to it that she has no issues at all about getting on and going for a week at a time.
I'd like to get different flywheels, have them balanced at Balance Masters and build her something with more power.
Do they make kits out there for this?

Catmechanic · #2 11-03-2008, 08:30 PM

NRHS makes 88" & 90" big bore kits. According to their website the cases need to be bored.NRHS - High Performance for your Harley Twin Cam, Evolution, Sportster or Buell! (303)702-1600

I haven't bought anything from them but a 90" Sporty sounds mighty interesting. Some of the folks over at XL Forum have good things to say about them.The Sportster and Buell Motorcycle Forum - Powered by vBulletin

Jim S

street bob · #3 11-03-2008, 10:03 PM

Catmechanic.......... Thank you very much.

hotrodsporty · #4 11-03-2008, 10:29 PM

I took my 883 up toa 88 ci with axtel. love the results. had to machine the case. and rebalance the fly wheel for the larger pistons.

street bob · #5 11-04-2008, 08:00 PM

Hotrodsporty..... How long ago did you do the build?
Was there alot of difficulty in the build?
How has the motor held up since the build?
Any break downs or difficulty in long distance rides?
Did everything fit back to the stock frame?
Sorry about all the questions but just thinking about an 88' sporty trips my trigger!

hotrodsporty · #6 11-04-2008, 11:17 PM

bob, no prob with the questions.... I did the build about a year and a helf ago, had a great mechanic to help with the extras, the motor is still holding strong, and in fact I have only found one bike to beat it on the quater mile, and everything fit in the stock frame. But the bike is not only a racer, I tour with it and travel a thousand miles in a weekend on it. SO far I have put 8000 miles on it, and it is still runnin strong. Im on the road right now, but when I get home at the end of next week Ill pm you on all the different parts I put on it and you can consult with your mechanic and see what you can do with yours.

street bob · #7 11-04-2008, 11:56 PM

Thanks Hotrod.......... I'll look forward to it.
I'd do the build myself. I'm a journyman machinist and have my own shop.
Actually I have partners in the business, anyway, I'm no stranger to Harley building and wrenching.
I went to the NRHS website and looked at the different kits. I'd love to take my wifes bike apart and do this upgrade. Very cool.
Thanks for your input and I look forward to hearing from you.

sportsterpaul · #8 06-09-2009, 12:06 AM

My '00 XL1200C sports a 89" kit from S&S. It's about the largest size obtainable with the stock,(modified), cases. Some of the smaller kits when assembled with proper componants can give you all the power most riders would want. S&S to name one offers a 100" engine for those wanting to step it up, however its not certified for "street" use, and I'm sure no one would ever consider running one of these on the street, right? Have seen two other Sporty's sporting 127" and 131" respectfully, they should offer all the excitement that one could want.