400 426 conversion question

for those that have done 400-426 job, did you replace crank?

i'm right now looking at some specs of the 450 and 426 and it states the bore /stroke is 95mm /60.1 and 95mm/63.4

i checked part numbers and the rings are the same part numbers as even the 400 (duh 95mm) so only the stroke is different?

so getting a 426 barrel may not make any difference without 426 crank????

am i not getting something here?

anyone?

ive done a search... and cant find any info on bore / stroke.

anyone know any more?

400 = 92 x 60.1

426 = 95 x 60.1

I rebuilt my 400 to a 426 this past winter.... I went to the 426 crank, cylinder, rod and piston. I stuck with the 400 head due to the $$$ of the 426 with all the titanium goodies. In doing my research I was told the 400 crank will work with the 426 rod, piston and cylinder. I swapped the crank due to the cam chain gear on the crank that you can't replace.

Good luck!

I'm in the process of doing mine, and got the 426 crank, cylinder, and piston...mostly because my big end bearing was bad, so I was going to have to replace the crank (or rod/bearing) anyways...

however, with the 426 crank you get a more reliable (larger) small end and splines instead of a woodruff key on the drive gear (also more reliable)...

If you don't want to replace the crank, I would just go with one of the various big bore kits available for the 400... Luke's Racing for instance...

now, let me get this straight.

after 6 months of homework, i was under the impression that by using a 426 rod and piston i would eliminate the 'small end' issue.

is this so?

i believe that the 426 rod is up to 2mm thicker in the point that had been known to be the weak link and by using it i would improve the long term reliability. am i getting close?

now, let me get this straight.

after 6 months of homework, i was under the impression that by using a 426 rod and piston i would eliminate the 'small end' issue.

is this so?

i believe that the 426 rod is up to 2mm thicker in the point that had been known to be the weak link and by using it i would improve the long term reliability. am i getting close?

That's what I was led to believe also...I guess my wording was a little off...by replacing the "crank", I meant "crank assembly", as in crank, rod and bearings...

Since it would've cost me just as much to replace only the rod (since you have to disassemble the crank), I opted for replacing the whole assembly...

thanks for that JJ

let us know how you go when it all together.

do you think you will need to perform any other adjustments to allow for it being a larger capacity, eg jetting.?

i've never had the carb off mine and wondered if i would need to do any other jobs to other components on the bike.

cant wait to get the rest of my bits

these are the other bits i'm getting too

http://www.jp-parts.com/confirm/0706/180706/180706-001.html

I'm still waiting on parts, hopefully it'll get going soon...I hate having her in a million pieces :thumbsup:

I'm pretty sure the jetting might need an adjustment...you should probably compare stock 400 with stock 426 jetting, and see if they're the same...

My bike has a Leo Vince pipe, and I'm getting the HotCams (Auto-DeComp!)...so I'm definitely going to need some sort of re-jet...

thanks again JJ

i'll check those jetting specs. i may even get to see what a jet looks like, but then again it will probably be safer if i leave it up to the guy who does all the spanner work on my bike.

i'll do a search on stock 426 jetting, i'm sure there will only be 6 million threads on jetting.

stay in touch on your progress and we can have a virtual drag once we are all back together.

thanks again. good luck with yours.

p.s. did you like the prices from my quote?

fairly reasonable

thanks again JJ

i'll check those jetting specs. i may even get to see what a jet looks like, but then again it will probably be safer if i leave it up to the guy who does all the spanner work on my bike.

i'll do a search on stock 426 jetting, i'm sure there will only be 6 million threads on jetting.

stay in touch on your progress and we can have a virtual drag once we are all back together.

thanks again. good luck with yours.

p.s. did you like the prices from my quote?

fairly reasonable

I will definitely be updating my thread, once things get going again...I hate waiting for parts!

I did look at the prices, but didn't do the currency conversion due to laziness...I tend to compare everyone to the TT store, as they're VERY reasonable...

PISTON (STD) (5NG1) 5NG-11631-00-00 AU$46.94 1 35.726 USD

GASKET CYLINDER HEAD1 5JG-11181-00 AU$26.75 20.3594 USD

ROD, CONNECTING 93306-30633-00 AU$58.28 44.3569 USD

cam CHAIN 94591-50120-00 AU$48.71 37.0732 US

JJ this is how some of the prices compare.

I'm very happy with them.

g'damn, that's cheap...I tried to get a quote from them, but I think they ignored it because of my USA address :thumbsup:

was the shipping reasonable too?

yep $25

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now