xr 100 to xr 80

[smoothoperatorsfreestyle]

will a 100 motor fit inside of an xr 80?

[PlanetMinis.com]

[firepower354]

Yep. The 80 has better gearbox ratios though, and a smaller combustion chamber, so those parts on the 100 motor work great.

[smoothoperatorsfreestyle]

awsome i have an 80 with a blown motor i found and a 100 with a cracked frame

[firepower354]

I just put a 118cc XR80 together for the neighbor kid. Runs like mad. I lightened the crank and flywheel, ported the head, WebCam, etc. Lots of fun!

I'm doing a 150cc one for myself. Let me know what you have left over...

[smoothoperatorsfreestyle]

wow, you can do a 150?

i would be very interested in that

[xr100man]

Sounds like a blast post some pics!

[firepower354]

I made the mistake of rounding up parts before I measured stuff. It's amazing how much is different. Rod length, jug height, cam and crank sprocket tooth count, crank weight, compression height. Ford could have done it with less confusion. It was supposed to be a quick case bore and drop on a 100 jug.

Mine's going to get a 12mm stroker and 60mm bore for 160cc. The stock head isn't great, but unless I can steal a Tak/Kit head it will have to do, ported and o/s valved of course. I need a tourquer since I weigh about what the average mini and rider combined do.

[LANG421]

if you buy the 115 takegawa stroker kit....does it fit on the 80?

[guardian327]

^^^ no, oil paths on cylinder are different. if you want to run a good stroker /w head, get the kitaco 145 kit.

[LANG421]

does that fit on the 80?.....one of my friends has an 80 and he is a big guy and wants a little more power, ive done everything i can to it and he likes it but i would like to get him some kind of kit for it. then modify that kit

[firepower354]

I'd run a 145 Kitaco if I had money falling out of my butt Maybe I can find a blown up head on the cheap and rebuild it.



I'm eyeing other bigger bike heads for a future conversion too. Maybe an 84-85 4V XR200 topend. Adapter bolted to the cases with countersunk screws, tapped for the bigger bolt pattern studs. Long rod, no sleeve hanging out the bottom like the Tak new stuff, short skirt piston. Too much free time...



I'm not running oil through the jug at all on mine anyway. I've tapped in to the main gallery, running to an external oil filter, cooler, then a splitter to the crank and head bleeder port. Lots of cool fresh oil to the head and crank. Ridding myself of the stupid sheetmetal slinger too with a longer drilled crank pin.



On the kid's 80/118, I JB Welded the stock vertical supply hole in the cases and redrilled it to match the 100 jug with the big sleeve. I spun the porky 100 crank to 150g lighter than the 80 piece. 100 cam sprocket and longer chain too. Revs great and pulls like mad. I might see if the 100 5th gear fits the 80 shafts for a litte more overdrive.



I'm redrilling the mounting holes in a knockoff IRK next, since the Tak/Kit ones are only for the different 100 mounting pattern and they're big bucks.