Bike Trouble - classic MX, custom project

[live4horsepower]

Now, don't flame because this is on a car forum but I know you're a bunch of top blokes and tbh, I couldn't be stuffed signing up to anything else.

Now, heres the problem. I've got a 1979 XR80, only the frame is a XR75 frame. I'm aware i can swap up to a 100 engine into an 80 with no mods but what about the 75? Is it only the early XR's that are interchangeable or can I go as modern as, say, an '03 XR100 engine?

It's a ripper of a bike and with the shortened straight through pipe it sounds like a beast, though I feel its about to die out and needs a bit of modern tech.

Cheers

[JCY 74]

Not sure about the difference between the xr75 and xr80 frames but as far as the motor goes, I don't think the xr motors have changed much at all since they were first concieved so an 03 model should fit IMO.

[rocketa9x]

OzVMX - The home of Aussie Vintage Motocross
Try here, Im sure you will get the correct info.

[motodevo]

you shouldn't have a prob, the only issue you might have is the top of the motor clearing the tank(nothing a 10mm spacer wont fix) and airbox wont fit carb so get a mini pod filter. Sounds like it'll be a ripper, you can get alot of big bore stuff for the 100's, alot more than the 80's as the 100's are very popular in the US. Got a soft spot for xr80's, had a few over the years and still have a 99 xr80 in the shed, i'll take one of these over a chinky pitbike anyday. Actually i have a soft spot for any Honda minibikes, i have 5 z50a's, 1 z50J1, 1 mr50, 1 ct70, 1 ST90,the xr80 all in various states of disrepair. Its a sickness

[live4horsepower]

@motodevo You have a great collection of bikes mate! i love the old hondas, my dad owned this one back when he was my age and it basically sat in his shed for probably 20 odd years, new spark plug and it went first go. i also found a great american site full of old 80 gear. If all else fails it will be my final resort

I'm also thinking of getting a longer XR100 swingarm and mounting a single rear shock with additional brackets welded in place for strength. I'd then have to remove the airbox because the only place to fit it is under the seat, so a pod filter would come in handy and look BADASS! also planning a custom seat, low, thin and streamlined so it doesn't look like it has a fat ass anymore

[live4horsepower]

Here is a quick mockup i did. only decent photo i could find. missing a few parts and the exhaust is basically 6 inches shorter now
[IMG]http://i776.photobucket.com/albums/yy42/HemiBoy95/Cars%20and%20things/XR751.jpg[/IMG]

[fordbaden]

my first bike was a 1980 xr80, sooo much. good luck with the project mate!