Honda MB5 - CR8X engine swap

Thinking of swapping a running MB5 engine with a CR80 (or 85) engine. Googled all the performance mods for a mb5 engine and it doesn't seem mods are all that $$$-efficient for squeezing more torque/top speed. pipes are top-end focused and unrideable in traffic, HPI CDI upgrade seems to be both pricey and lacks a decent accessory coil. from what i've gathered, VM20 + reeds + unrestricted intake seem to be the way to go for having a half rideable MB5. All I want is to slap an appropriate engine for that heavy MB5 frame, and zip zap around town

has anyone in recent history done this engine swap? all i've got to go on is this thread from 2012.

goal is 60-70 and to get there reasonably fast. open to fabbing mounts etc (edited)

Re: Honda MB5 - CR8X engine swap

Dirty30 Dillon /

If you can fab engine mounts, than any motor will probably yield more power per dollar than modifying the MB5 motor.

If 60-70 was your goal, an AM6 motor would be a great option, with the ability to be modded basically into orbit, your speed and accel would only be limited to your funds.

Or you could just source am MBX80 and do 60-70 in complete luxury on a stock bike with liquid cooling and 6 speeds.

Re: Honda MB5 - CR8X engine swap

i was gonna say, the AM6 is a better bet. CR80 doesnt fit like at all, so both are pretty equivalent effort building mounts. Dos might have some MB/MT80 stuff if you ask em, they used to have some but doubt theres any still.

But if youre goin CR80 you're lookin at effort pretty equivalent to any other engine swap, why not go by whatever's available. probably find a YZ motor and fit a lighting coil or somethin. like in that thread they made the whole cradle and everything.

Bobby swoops put an am6 in a ysr and that was insane fast, like 80s? and another atl fella did a YZ swap in his, also batshit fast.

The lifan motors are a pretty lame option but the nicer 190's should do 70.

Also, I got a cheap kit, HPI and homo pipe, VM20 and intake from NS and it's solidly 60. not much over but it's very ridable and keeps up unless youre tryna go on the highway. I feel like thats a pretty realisitic expectation of an MB5

Re: Honda MB5 - CR8X engine swap

Moped gp east mb5 w/ cr80 transmission parts and plenty of handmade parts.

Adam Cramer built the bike and has raced it in vintage class for a number of years. He's on facebook and this is his site:

Very knowledgeable guy from pa. He said this build was 65mph at loudon nh. (edited)

mb5 cr8.JPG
mb5 2.JPG

Re: Honda MB5 - CR8X engine swap

I did a swap from a 1980-1982 air cooled CR80. The initial hope was to do a transmission and top end swap into the MB5 cases but the transfers and skirt diameter wasn't going to work out. I cut the cradle off the CR80 and grafted it to the MB5 frame. Used a combination of the MB5 and CR80 ignition parts to get lights and spark. Hand built an exhaust. It was stupid fast but not super reliable. I think it ended up in Arizona or something. Read this thread when you have some time.,2797082


Re: Honda MB5 - CR8X engine swap


decided to keep the stock engine with the mods i added before. should be good to keep me satisfied until i get a realdeal motorcycle haha

appreciate all the help

Re: Honda MB5 - CR8X engine swap

EH 📣FCC of the QCB /

The ReAL tHiNg? Your bike is fake?

Re: Honda MB5 - CR8X engine swap

I can applaud people giving up their mb5's for bigger bikes if it means we can keep buying back their mb5's for cheap with new parts.

Re: Honda MB5 - CR8X engine swap

my bike will go on the market and i can only hope that the next guy will have as much fun with my go-fast parts as i will have. last guy left me with an athena kit, carbon fiber reeds, and a proma gp. i plan on leaving it in a better state than the last guy :) ride on folks

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