CRF 250 PROJECT

Brian Degulis · Posted: Tue Dec 04, 2012 4:27 pm Post subject:

Well figuring out how to make this engine fit has been a challenge. My seat needs to be back a lot further than Howies so as the seat widens in front it's hard to clear the oil filter. This engine is considerably wider than a 2 stroke. Suprisingly it's only 13 lbs heavier than the Pavesi it's replacing.

I think I have it worked out pretty well and I'm surprised that off setting the seat more doesn't make it feel weird.

Now on to making the mount.

Brian

paul rees · Joined: 06 May 2007 Posts: 264

Brian Degulis · Posted: Thu Dec 06, 2012 7:02 pm Post subject:

OK fuel pump set up. The round pump has 4 hose barbs. pulse, fuel in, fuel out and ?. On the pavesi the forth barb was the return to the tank but you guys are talking about putting in a Y in the out line and using that for return. What is the 4th barb for? Does that serve as a return? If not should it be plugged if a Y is used?

Brian

Howie Idelson · Posted: Thu Dec 06, 2012 11:57 pm Post subject:

plug it and run the Y from the feed to the carb back to the tank.
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Brian Degulis · Posted: Fri Dec 07, 2012 5:33 am Post subject:

So I guess if the pump has 2 outlets the only purpose to using the Y instead of just returning the second outlet to the tank would be to get full flow closer to the carb before splitting for the return?

Brian

Brian Degulis · Posted: Sun Dec 09, 2012 2:23 pm Post subject:

Well I'm up and running. I tried it in the neighborhood and it's a wild ride. Pretty cool not having to be in a narrow power band.

Now the coil and spark plug boot are incorporated so there is no coil wire. How did you guys get a Mychron to work. Where or how did you hook up the tach wire?

What's good operating temperature?

How is it on a bike they have no instrumentation? How would you know your not over revving or over heating??

Brian

Brian Degulis · Posted: Thu Dec 13, 2012 12:14 pm Post subject:

WA LA CRF250 On the cheap!!! Runs Awesome!!!!

Brian

paul rees · Joined: 06 May 2007 Posts: 264

The thing it does need, is a chain guard. That's a lot of steel to have swinging around looking for some meat to munch on . Nice build though, one question though is that a twin muffler set up?

Benn Herr · Joined: 18 Jul 2001 Posts: 1580

The muffler looks like a Cherry Bomb! Cool

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Brian Degulis · Posted: Thu Dec 13, 2012 2:08 pm Post subject:

Yes the lower is a glass pack silencer with that alone it was still very loud. The upper is a 2" Thrush cherry bomb car muffler that quieted it down a lot. I have no idea how they effect performance they're both larger diameter than the OEM bike silencer and both straight through glass packs? And yes chain guard will be made just couldn't wait to give it a try.

Brian

Chris Reinhardt · Posted: Thu Dec 13, 2012 7:25 pm Post subject:

I wouldn't worry about the back pressure so much, but you have a really, really, really long pipe on there!!!!

You could find yourself on OEM canister muffler off a sport bike before they starting going with the shorties and undertails. Most guys threw them away, try your local bike shop, most likely pretty cheap, $50 or less.

CR
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Howie Idelson · Posted: Thu Dec 13, 2012 9:29 pm Post subject:

I have an unused Pro Circuit titanium prototype muffler I will let go of. PM me if you're interested.
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Brian Degulis · Posted: Fri Dec 14, 2012 12:00 pm Post subject:

paul rees · Joined: 06 May 2007 Posts: 264

The length pipe does come in to play for tuning. A good after market Sportbike muffler will work great. I picked one at a swap meet for $5.00 it had two small scrapes from parking lot drop.