How reliable Wr400 bored to 460cc

11 replies to this topic
  • nin73

Posted January 17, 2006 - 11:13 AM



Looking at buying a WR400 supermoto that has been bored out to 460cc when it had a rebuild. Is this pushing things a bit, or will this engine cope with this amount of tuning?

I will be using the bike on road.

  • steve lemley

Posted January 17, 2006 - 11:28 AM


how much is the boring kit and mods to make it run again. I have a wr400 and am interested... Thanks.

  • nin73

Posted January 17, 2006 - 11:32 AM


Sorry, got no idea mate. Looking at buying the bike with the work already done. Bit of a wally when it comes to mechanics, i have chosen my friends wisely though!!

  • rockieman

Posted January 17, 2006 - 12:58 PM


I am by no means an expert but I just rebuilt my 400 with the OEM 426 parts, cylinder, piston, crank etc. But if you look at the rebuild kits offered by the most notable ones (Maxpower etc)....they take the 400 to 420CC, the 426 to 440CC and the 450 to either 470 or 490. I would question any kit that took a 400 to a 460 :thumbsup:
My two cents.

  • xr_man

Posted January 17, 2006 - 01:17 PM


AGREED ......dont think there IS a kit to 460cc for the 400 ....some ones spinning you a line me thinks :thumbsup:

  • nin73

Posted January 17, 2006 - 01:30 PM


wel, i have asked the guy what kit he used. So we will se what comes back.

Think i might just buy the 625smc i was looking at aswell anyway. Sounds safer!!

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • bluebike1999

Posted January 17, 2006 - 01:31 PM


frostbite has the 430 kit and recently cracked something in the head, but his environment is not what you'd call average and possibly contributed to it.
he has had it for a while i believe. may pay to summon the snowman.

  • R_Little

Posted January 17, 2006 - 01:33 PM


My WR was a a 444 with a 426 rod. It seems to run fine. The WRf is a reliable motor.

KTM 625 is a much larger bike ...big time low end power but vibrates like krazy. Good for short rides.

  • nin73

Posted January 17, 2006 - 02:29 PM


just had the response back from the dealer. He stated that it was from an offical yamaha dealer and fitted by a proffesional.

not sure what to say???

  • steve lemley

Posted January 17, 2006 - 02:37 PM


sounds like he's running around giving you a straight answer... Beware. Theres a lot of bikes out there.....

  • nin73

Posted January 17, 2006 - 02:40 PM


Would it be best to ask him what kit it states on the reciept?

  • TallBoysWRF

Posted January 17, 2006 - 03:44 PM


I would be cautious about that bike. If the guy doesn't want to give you a direct answer (not giving the type of kit as you asked) that should be a red flag right there. I also have never heard of a 400 being punched out to a 460. The things to keep in mind is that the crank has to be able to handle the extra power. If it has a 426 crank you are better off, but I still would be careful. Another thing to keep in mind is that you have a thinner cylinder wall now, AKA a weaker wall. That's my two cents.


Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.