Switched to the darkside...

[rider250ex]

Hey, I have been big on 250r's for a while now. last season was my first season racing and i was won my 265R. I decided over the winter i was going to build a Hybrid so here is what i have. I have a complete R (only thing stock is frame and swinger). i Just bought an LSR N0-link frame, motor mounts, yz400F motor, carb, and all electronics. I have a few questions for you. I know i am going to need to buy a no link swinger and shock now, I can get an LSR airbox really cheep off my friend, but i know there is alot more into these bikes than bolting them up and going. How many problems do people usually run into building an LSR based hybrid? Is there alot of working getting the intake to line up right?(airbox to carb)? Will the YZ450F cylinder bolt right up the the 400 bottom end? is there a difference in cams, gear ratios, and strength of the bottom end between those bikes? I know most of these questions have been asked before but i have looked around and couldnt find many clear answers. Thank you for any help you can give me. Here is a picture of my R before i tore it down to build my hybrid.

[stocktires]

Nice quad, You'll face the usual intake and exhaust problems. As far as the YZF motors go, I'm not all that knowledgable about them. I know there are some big differences though.

[CrackerboyLV]

I think a yz426 cyl. will bolt directly to a yz 400. The 450 is a different animal. You can bore the 426 to a 444 with a 97mm piston (available as a 12.5:1 or a 13.5:1). I heard a rumor that baldwin has a 14:1 custom made, but I dont know if that is true.

[gtilley45]

Like stocktires said, there might be problems finding an intake setup that isn't a cobbled up mess. I'm in the proccess of trying to find something better for my LSR/CRF now. I also think CrackerboyLV is right about the YZ cylinders. Seems like I have heard that the 426 cylinder will bolt up, but the 450 won't.

I was talking to Norris from Quinn Motorsports about my hybrid and from what he told me, the LSR no link hybrids are damn good hybrids once you get them dialed in. He said that he feels like the no link rear end is as good of a rear end there is until you start jumping REALLY big jumps. The no link works very well in whoops and rough, choppy stuff. I feel like you can't beat a properly built hybrid as far as MX goes. As far as problems with LSR hybrids, I can't think of any I've heard about that would have anything to do with it being just because it's a LSR. In my opinion, a hybrid is only as good as the person who built it/maintains it.

[stocktires]

You'd get better answers about the motors here www.thumpertalk.com
That's what I use for CRF450 info.
I've HEARD the 446cc or 444cc big bore on a 426 cylinder isn't a great idea and it slows the revs. These high-tech bike motors are built to be the size they are and perform the best at that.

[CrackerboyLV]

I am a newly converted two stroke guy, so I don't know if a 444 revs slower than a stock bore 426. I've never ridden any 4 stroke except the 444.

You are right about the no link - it works great in my sons hybrid cr125 powered kasea (250r rear -4", yfz 450 front) but I went through about 10 springs before I found one that worked correctly. The geometry of the design (on his bike) causes the spring rate to ramp up fast in the last 2" of travel, so it can be a little more work to get set up, but it rides very nice once dialed in.

I have a cr500 link in my Laeger and like that also, it is easy to set up and adjust but it did add a little weight. (Linkage and slightly longer shock). I don't think you can go wrong with either setup.

[gtilley45]

Yeah, the CR500 linkage is supposed to be better for the big jumps. Norris Quinn told me that and he has had both setups. He said the no link was great but the CR500 linkage (which he has now) is better once your start jumping really big jumps.

[kendog57]

they cylinders are not interchangeable. they all have a different designs so don't try it. you can overbore them if you want more power but make sure your motor is getting good air flow. have fun

[rider250ex]

hmmm...i read that right after opening the box to the 426 cylinder i won on ebay.

[rider250ex]

so i should be getting the motor any day now. i am going to start to tear it down and see how the cylinders compare. if the 426 cylinder wont fit forsure what do you think i should do. bore, port and polish, higher compression piston, cams, and ss valves, or stealth 417BB with ss valves and Port and polish? oh and cams. also what cam does everyone suggest?