Turbo WR426??

3 replies to this topic
  • carbonbody

Posted September 25, 2003 - 07:55 AM


Ok, I posted here not too long ago that I was building a roadracer with a WR426 engine. I've searched the rule book and can not find any reason I could not put a turbo on it. Now... my question is, has anyone seen or heard of a turbo charged Yam 4-stroke engine besides the raptor? I've found plenty of info on turbo banshee and raptors, but nothing on the 400/426/450 engines. I'm wondering if there is some reason no one has done it yet.

By the way, I just received my 426 engine. Zero miles on it! Found it on ebay. Got the rads, cdi, coil, wire harness, decomp lever, pipe, and all the hoses. I sat it beside my TZ frame last night and it looks like I could tilt it forward a lot. Makes it look like an R6 engine with 3 cylinders chopped off. I wonder how far I can tilt it before I run into oiling problems. I havent taken the oil pan off yet to see how it picks up oil. Hopefully I can tilt it some to produce more downdraft and to move the weight lower and more to the front.


  • DesertChris

Posted September 25, 2003 - 09:32 AM


These might not help a bunch but...
The 426 uses a dry sump setup, you will need an oil tank, if the oil pickup(s) are in the right place you could tilt it pretty far.

The 426 runs a 12.5:1 static compression. I don't have a vast knowledge in turbo charging gas engines but from what I understand so far the seems high before any boost is applied.

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  • jwriott

Posted September 25, 2003 - 09:44 AM


Haven't seen a WR turbo but here's an XR650R turbo.

XR650R Turbo Link

  • NEV YZ

Posted September 25, 2003 - 09:50 AM


The only other yamaha (i think it's a yammie) is the seca turbo street bike you might want to check the specs on it and see if it's close in terms of compression, rpm range, oil usage, and wastegate vacuum needed.


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