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Discussion Starter #1
Has anyone retro fitted a dirt bike motor in a cafe? I'm thinking of attempting to put a Cr250 2 stroke motor, forks, wheels and brakes on my 72 CB350.
 

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That engine would be better served in something lighter, like a CB125 or CB200. Air cooled is the way to go, radiators and plumbing just muddy up the works on a bike that has no provisions for mounting such. Additionally, there is the small problem of the charging system, or lack thereof, on the CR engine. It is a solvable issue, but something to think about.
 

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Right, it has been done/can be done, but it will be a lot of work and depending on your state regs, you may not be able to get it through a S.I.
But you'll have a pipey little street bike with long forks and marginal brakes.
 

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What is your intended purpose for the bike?
What is your mechanical skill level?
Is the CR liquid or air cooled?
Why have you selected these pieces to put together?
What is your budget?


Ken
 

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Discussion Starter #5
I have the skill level to build it. I wanted to build something fresh and rarely seen if ever. I'm a dirt bike freak and love cafe's so I figured I'd mix the two. I've been shopping for an older 2 stroke "air cooled". Don't really have a budget or a time frame. Want to build what I want. Does anyone make a turbo for cb350?
 

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Any time I put a dirt bike motor in a cafe the patrons complained about the noise and smoke. Something about not being able to drink their coffee and carry on a casual conversation.

Putting a dirt bike motor in an old bike however can end up one of three ways:

1) you use a modern chassis to get a two stroke race bike feel. But then people wonder why you underpowered a gixxer slingshot one thousand.

2) you stuff a 90 hp built motor in a frame designed to have 20 hp, and you get a death trap with no brakes or handling, which is ok cuz it spends its life trolling hipster hangouts at 3 mph.

3) you build one of Roland sands spec racers out of a kit. It does everything flawlessly but isn't street legal and looks nothing like the hipster bait you want it to be. But it works.

What are these skills you speak of? I see nothing here that passes for an intro nor any indication of skill other than you know what a cb350 is and you don't know what aftermarket exists for it (hint, it is a pretty small aftermarket).

We're this my project - I would go find a ninja 250 with a blown motor and put a kx250 motor in it. Then I would buy race bodywork and paint it like the old GP 500 two stroke race bikes from the 80s. Then I would have something really cool and not gay. But what was your idea? Cb350? Um yeah....
 

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In that case, I would look for an MT250 since it was basically a CR with a lighting coil. Maybe you could fit an MT ignition to a similar year CR. I would get a flat track down pipe from Circle F and put the whole thing in a CB350 frame. I would use the complete CB rolling chassis since the CR wheels, brakes and suspension are just wrong in terms of size and performance for the street. I would look for an early CB that had the fork springs on the outside of the tubes since I like the look of those forks and front fender. Then just get the tank seat and rearsets on there and you should be good to go. Note that the charging system on the early honda 2 stroke enduros are 6v and the CB lights are set up for 12v.

Ken
 

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By the way....telling someone you generically have "skills" is like telling people "I'm famous on the Internet". Even if it is true, nobody cares and most people don't believe you anyway.
 

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Big Rotax engine in a Gen 1 Ninja 250. Was in Motorcyclist Magazine fifteen, twenty years ago. Four-stroke though.

I'd like to do an SR/SRX with a big IT/YZ engine, but those bikes are too really nifty to screw with. Had an SRX-6, got the engine (YZ490) and downtubes (bolt-on) and fabbed up plates, but never installed it. Engine was seized, never rebuilt it, and some skinny kid offered me stupid money for the SRX. Also, I never figured out how to get around the necessity of being in the ONLY county in the ONLY state in the U.S. to require motorcycle emissions testing - although in order for a two-stroke to fail, it would have to be coal-powered. Alas, the SRX was in the system as a four-stroke, so pleading ignorance wouldn't do.

I'm still of the mindset that a big-power engine in a flimsy chassis would be a barely-controllable hoot, as long as one knew what they were getting into - the vulnerability of the chassis to be tied up into a big tubular knot upon liberal application of throttle - like a AA/Fuel Altered. I'm thinking a KX500 in my H-D Aermacchi sport 50, perhaps?
 

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Discussion Starter #12
Thanks for the input. Looks like I should go invest in one of those mechanics tool sets. Duck tape and zip ties too!
 

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If your going to do it, use a YZ490 motor in a Lambretta chassis (I knew a guy in Britain who used to do the conversion)[8D] :D
Don't mess about with 250 MX motors for street bikes
I'm still on the lookout for a cheap XR500 motor to fit in CB360 chassis
 

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quote:Originally posted by bmartin

I like Geeto's idea using a Ninja 250 frame but I'd like to stuff a hopped up Bansee 80hp+ motor in it. Stupid - yup
I have seen several RD350 powered ninja 250s over the years, never an RZ/Banshee powered one though. I had a friend in neworleans who stuffed a gast h2 motor in a zx750r chassis as well and that bike was retarded to ride.

I thought about a T500 mill in a 250 ninja, but not sure if that is an upgrade.
 

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Look up 'CR500 Sportbike - Project Street Racer' and you'll see what this guy is doing with a dirtbike. There are 13 parts to it I think, so very informative.
 

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Just find a usable Bighorn 350 lump and send it to somebody like Scott Clough. He'll get about 60 horse out of it if you've got the snap. Put that in your Honda and smoke it.

;)
 
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