400 cylinder different to 426???

have been getting quotes on bits to rebuild 400 and have just been told that the 426 cylinder wont fit the 400.

i have been working off this http://www.powroll.com/P_YAMAHA_YZFWR426F.htm

using the part numbers etc and have been advised to get 400 cylinder bored and recoated. can anyone shed some light on this?

has anyone put a 426 cylinder onto a 400 case?

down to ordering bits and i'd like to know before i get the $$$ out.

any input would be appreaciated


Give Eric Gorr a call. I was talking to him a few days ago about using a 426 crank and rod but never asked about the cylinder. I was under the understanding that it was a bolt on as well. Post your answers for us.

Eric Gorr/Forward Motion

1531 Bourbon Pkwy.

Streamwood, IL, 60107

Direct Phone Line for Eric Gorr

Call 1-630-289-5645

I'll be answering the tech line from 7am (U.S. CST) to 10pm Monday-Friday.


yeah thats the site i was working from, i got it from one of your old posts. maybe the guy i called makes more $ boring or resleeving the old cylinder than supplying a new one but he seemed certain it wouldnt fit.

i have found another supplyer in victoria here who can bore and electrosil(nicasil) the bore and am waiting for some quotes to come back.


I'm going to go the 426 option and during my research i found this site but something seems a little um not quite right.... not sure.


bit dodgy on sending over $1000 on an unknown.

you can just put the 426 rod cylinder and piston and use only the oem parts

it works very good.

let us know what the quotes are, im in melbourne too


here is quote

note that all info was sent on the same day and the first one to reply was in japan. ok it was a public holiday here but we will see how long good aussie service takes.


seems pretty competitive but we will wait and see compared to local suppliers.

there's a thread here that has the exact part numbers to order, so do a search.

i'm rebuilding my wr400. it's fast enough for me so i'm stickin to stock bore and compression. wiseco kit ran me 125.


i have learned through research on here and through various yamaha 'people' that the small end is weak and that the 426 rod will eliminate this problem.

the 400 has plenty of power for me too, but i'm after long term reliabilty and the extra 26 cc cant hurt in sand and in the case of low end putting around.

besides my mates have 450 without yz timing and a 426 with yz timing should see me eating a rock or two less maybe.

I just wish i was able to keep it a secret to surprise them, but its too exciting to keep under wraps that long.

I just recieved a quote from a local supplier and it is twice as much as the prices quoted from jap supplier.

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