2003 xr80r vs. xr/crf100 land speed record question

Ok, I'm counting on you guys. I have a 2003 xr-80 motor that has been de-stroked and sleeved to a 50 for a land speed record. It is supercharged and the supercharger runs off of a pulley that is attached to the flywheel. I would like to take a 100 motor with me so I can just change motors and enter the 100 cc class also. (only $150 for a cross class pass) Will I be able to use a xr or crf 100 motor with my flywheel or do I need to get another xr/crf 80 motor and bore it (I think the max is 95cc)?

The big thing is I need to use my flywheel, it was quite expensive to have made. You can see the bike at www.theworldsfastesthonda50.com



I checked the part numbers (by doing a buy it now) and found the XR80/CRF80 to be the same and different from the CRF100.


Sounds like the XR80/CRF80 is the way to go.

The shorter the stroke the better anyhow. Maybe the CRF100 has bigger valves and will fit the XR80/CRF80 bottom end????? Or maybe the cylinder and head will fit (with some case boring)???

Good luck, hope you make it.


Yes you can swap the flywheels.

Thanks socalxr, I had a feeling it might fit but as salsa found out the are both the same and different when looked up by part number.

I guess I'm looking for a crf 100 motor.

Plan A: anybody want to loan me their XR/CRF 100 motor?

Plan B: Anybody have one for sale?

Plan C: Ebay/Craigslist

Here is some land speed record advice: Come up with a budget, multipy that number by 4, build the bike, total up what you have spent, multiply THAT number by 4, then you are almost ready to go! Fortunately I have a very understanding wife. (I hope the credit card company is understanding also)!



I wish I could help, I would lend you any XR stuff I had but I'm in Ont. Canada.

:)This is the most intriguing post in years.:thumbsup:

Please keep us posted and Lots of pics!

Yes, please let us know how you make out!! :thumbsup:

sound like a fun project. Id like to know more about it. good luck bro. your website needs practice though. they have bolt-on twin-cam heads available in japan. why didnt you consider the new Honda dream engine?


I thought about using a dream engine and in retrospect I should have just bought a whole dream50, it would have been cheaper. I had a little bit of remorse taking the sawsall to the XR-80 that I paid $750 for, I can't imagine cutting up a cr50r!

I wasn't aware that you could buy a twin cam head for the 80, I've seen the Takagawa head for the xr50 though. I would be really interested in the twin cam head, do you have any contacts or web sites?

Only one month to Bonneville!



labrat, I looked everywhere for the link but I lost it, it was all japanese and Im pretty sure it was a Takagawa head kit. we cant get them unless we can speak japanese anyway. I know I saved a pic though, I'll keep looking for ya.

found it:



also a 4-valve head


and check out this twin-engined chopper


ya gotta love the Japanese!

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