Xr100 in MX Frame

[GrottoNZ]

I'm thinking about putting an XR motor in an 80/85cc MX frame.

As my skills are limited, I was wondering which is the easiest frame to choose.

I've googled and it seems Yamaha, Honda, Kawasaki and Suzuki are all options, and all have their own issues but is one easier than another?

As it's the first build I've done I'm not hugely concerned about appearance, but have seen dome where you have to remove the foot peg to kick start it (would like to avoid that) and some where you have to cut and weld the tank (also don't wish to do that).

Also, I've read that an XR75 motor and XR100 are the same external dimensions -is this correct. I've got an XR75 spare which I thought about using until I source an XR100.

Thanks

[Wild Alaskan]

if you don't have any fab background, its probably no the best idea to try and do a motor swap.

[GrottoNZ]

I haven't built bikes before, but I've rebuilt a good few, have a lathe and welder (not expert with either but get by).

I know it's not straight forward, but want a bit of a challenge. I've gained most of my knowledge by doing stuff I've never done before, made plenty of mistakes, but I seem to learn best doing it that way.

I'm doing it with my 12 year old son so he gets a few skills and expect it to take a long time. I'm not counting on getting it right first time but may do another using what we've learned.

[Go Big Red]

I haven't built bikes before, but I've rebuilt a good few, have a lathe and welder (not expert with either but get by).

I know it's not straight forward, but want a bit of a challenge. I've gained most of my knowledge by doing stuff I've never done before, made plenty of mistakes, but I seem to learn best doing it that way.

I'm doing it with my 12 year old son so he gets a few skills and expect it to take a long time. I'm not counting on getting it right first time but may do another using what we've learned.

Thinking out loud you may have some challenges.  Number one, the XR100 is not a full perimeter frame and the engine is part of the stressed structure.  to fir the CR motor, you might have to fab in the rest of the frame.  a better idea might be the XR motor in a CR frame.  then you could put a 120 kit on the xr motor, cam it, head work, exhaust....  holy crap that would be a sweet scrambler for a 12 year old.

 

as for insider knowledge, I haven't heard of anyone throwing the smoker in the XR frame.  but as they say, anything can fit in anything.  and if it gets jacked up, those frame are not expensive to start over,

 

keep us posted.  I like the idea.  ?

[GrottoNZ]

Thanks, but I'm doing it the other way around - XR motor in CR/RM/YZ frame.

I'm not sure which MX frame is the easiest to modify to fit an XR motor, or if they are all about the same hassle.

Cheers

[pscook]

Try this:

http://acsracing.tripod.com/mxracing/id1.html

 

Also google for xr100 cr80 hybrid

or

XR100 CR80 conversion

[GrottoNZ]

Thanks,

I've done some googling and it looks like CR frames are the most popular. It seems that down this way there aren't many CR80 rollers. A few RM80’s around with seized/blown motors, but not too sure if it's more difficult yo fit an XR100 motor in an RM80 frame.

Maybe I'll just wait until a reasonably priced CR80/85 comes along, or buy a runner and sell the motor.