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So i have a spare 2002 cr125 frame, i want to fit a engine with more than one cylinder.. ideas for engine conversion?

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Ive posted this on SuperMotoJunkie but no one seem'd intrested so i thought id make a new thread here..

Basicly i bought some motocross spares recently and in with the deal there was a 2002 cr125 frame. Now rather than sell it me and a engineering friend would like to make a moto 450 or supersingle style bike out of it but rather than a single cylinder mx engine we would like to use a road bike engine what would make more reliable power and last longer without maintenance.

http://www.rolandsands.com/bikes/super-single

Anything is possible, so im not looking for answers like why bother etc etc my friend is an awesome fabricator so any frame chop is do-able.

I know kawasaki er6n conversions are possible on aprilia sxv's as its been done a few times:

now idealy id like a honda engine to match the honda frame, but im still open to suggestions for engines from other manufactures..

At the moment were thinking a honda cb500f engine is the way to go (honda's er6 equivalent) if we can get one. but im realy intrested to hear other peoples ideas first before we buy a engine and start cutting

thanks matty

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thought about a banshee or rz350 engine but there realy hard to get over here, unless someone could ship me one over :thumbsup::ride:

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I would be going with the engine out a 1995 yamaha R6 , tons of power , low maintenance , and is an extreamly simple motor.

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I would be going with the engine out a 1995 yamaha R6 , tons of power , low maintenance , and is an extreamly simple motor.

i think an r6 will be to wide with it being a inline 4 cylinder

vfr400 NC30 motor might fit in there ? or an Aprillia rs250 Vtwin twostroke

a vfr400 was my first thought but i need to find out if the rear cylinder will fit between the frame?

at the moment im thinking of just using a er6n engine as its the most simple and has decent power, the honda alternative is a cb500 engine but they dont make as much power and dont look as good.

honda dont make enough inline 2 cylinders!

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honda dont make enough inline 2 cylinders!

agreed on that .

The Rotax twin being used in the 800 BMW's is a lovely motor but might be big $'s ,,, well big pounds over there I guess. or what about an RC51 motor or the lesser tuned super Hawk motor not sure what there called in the UK.

But I think that Kawasaki engine would be the cheapest option and lots of fun ..

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If all you have is the frame, save yourself a lot of trouble and just sell it. By the time you get the rest of the bike together with any engine, you'll have spent a lot more than if you'd just bought a complete 125 and parted out the bits you don't use.

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agreed on that .

The Rotax twin being used in the 800 BMW's is a lovely motor but might be big $'s ,,, well big pounds over there I guess. or what about an RC51 motor or the lesser tuned super Hawk motor not sure what there called in the UK.

But I think that Kawasaki engine would be the cheapest option and lots of fun ..

i can get the rotax 650 thumper found in the pegaso and earlier bmw650s pritty cheap only problem is the chain drive is on the opposite side which sucks

If all you have is the frame, save yourself a lot of trouble and just sell it. By the time you get the rest of the bike together with any engine, you'll have spent a lot more than if you'd just bought a complete 125 and parted out the bits you don't use.

i think i can build it up much cheaper this way and im after gettinh ohlins forks and rear shock of a TM racing bike and a aprilia swinger so id have to sell most of it off anyway along with 17" super moto rims.

How about an xr 400 engine ,for an updated super green lane bike ?

and xr400 is do-able as its been done but if im going to do it i have to put a 650 engine in it atleast.. lately i have been thinking the easyist option would be the 650 rfvc engine found in the honda xr, honda dominator/nx650 and the honda slr650, only problem with this engine choice is it may be abit tight in between the frame spars.

if anyone has any links to previous builds with a xr650 engine post them here!

Edited by McGoo 69

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i have also thought about the rd 350 engine, they normaly go for a pritty penny over here but i did miss out on a untested rd350 engine what went cheap the other week.

theres only one reason im against it and thats because i dont want to put a yam motor in a honda.. it just wont look right..

i am thinking of doing it in the future though on a yz chassis

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hopefully picking up a xl600 thumper engine tommorow, its done a few miles and i dont know if it runs but its cheap so atleast i can start fabrication and worry about that later.

Ive collected afew parts already so hopefully itll fit! haha

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Progress so far,

Cut up the cr125 frame to alow engine to fit

Engine has been fitted in the correct position (tempory)

Problems so far

Not alot of room for twin carbs, may have to convert to single.

Engine is Bloody HEAVY!

if i can get a carb to fit then the project is do-able, if i cannot come up with a solution then ill have to give the idea up, i will upload some pictures later

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Honda had a shaft drive bike...Oops .I just realized as I was typing that it mightn,t be usefull

Anyhow its a CX500 roadie

They were a good V Twin

Just gotta figure out how to get the shaft on the rear sprocket

Sorry for wasting your time mate :banghead:

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What about the oil tank ?

ill worry about that once ive got the carb fitted, ill either run a oil cooler or make some sort of header tank.

Honda had a shaft drive bike...Oops .I just realized as I was typing that it mightn,t be usefull

Anyhow its a CX500 roadie

They were a good V Twin

Just gotta figure out how to get the shaft on the rear sprocket

Sorry for wasting your time mate :banghead:

i think the cx500 would be to wide, and too much hassle

im going to stick with the RFVC engine i have and see if i can make it work, if not itll be back to the drawing board.

im going to make a new thread with the progress i have made so far so i will link this thread once ive done so.

matty

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