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wroom

WR400F -> 440cc kit, and other things.

10 posts in this topic

I am in final stages of completing the auto-decomp mod after reading hundreds of pages of happy customers on TT. :lol: :lol: What's left is timing, and putting it back together. New shims won't be in until Tuesday :bonk: . The bike has been great so far :) but dicking with manual decompression was never fun.

After doing more research I have noticed that bunch of you guys have updated the crank pin, and some went with the 440cc route. Followed Powroll link and they want $400 to rebuild crank, and another $800 for all the parts ordered through the dealer. Local builder would charge another $300 to fit this all together. :p

Is this a normal price for 40cc bumpage? :p I can buy whole another WR400 with the +40cc kit already installed for $1400... :banana:

Now, regarding the crank pin -- I have to ride 40miles to get to any better trails, but sometimes I run 200 miles on the pavement. Usually cruising at comfortable 55+ mph. :lol: :lol:

Thanks for your input!

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you can buy a 426 crank for the 400 bux poweroll wants to rebuild your 400 crank (saves you the cost of the rod kit). You will need to buy a primary drive gear and balance shaft drive gear as well, as the 426 gears are splined rather than keyed like the four hundie. Going from 426 to 444 costs about 500 bucks for the cylinder, piston and gasket kit. Add another hundie for bottom end gaskets and crank bearings, and you're looking at a grand to do the work yourself (it's not that hard!)

Is it worth a grand? On an 11 or 12 year old bike? Only you can answer that...If you spend another couple hundred and replace the valves/cut the seats and replace the timing chain, you will have a brand new motor that you know all about...

On my son's '02 250, I just dropped about 2k in a big bore kit, stroker crank, complete head rebuild, etc, etc, etc. It was a lot cheaper than a new(er) bike, and he already has the suspension, controls, etc pimped out and set up for him...plus, here in Cali, it's plated (legally!). For him (us) it was worth it as it's a DS he can ride for a long, long time...

Oh, by the way, the power you will get from those 40 cc's (especially if you go hi comp on the piston) is unreal!

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Quick update: I am shooting for realibility, and leaving the displacement stock would seem to be the way to go.. however.. the pin is what scares me. Also, if you have an oil cooler on WR400 please post a picture!

Thanks again!

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you can buy a 426 crank for the 400 bux poweroll wants to rebuild your 400 crank (saves you the cost of the rod kit). You will need to buy a primary drive gear and balance shaft drive gear as well, as the 426 gears are splined rather than keyed like the four hundie. Going from 426 to 444 costs about 500 bucks for the cylinder, piston and gasket kit. Add another hundie for bottom end gaskets and crank bearings, and you're looking at a grand to do the work yourself (it's not that hard!)

Is it worth a grand? On an 11 or 12 year old bike? Only you can answer that...If you spend another couple hundred and replace the valves/cut the seats and replace the timing chain, you will have a brand new motor that you know all about...

On my son's '02 250, I just dropped about 2k in a big bore kit, stroker crank, complete head rebuild, etc, etc, etc. It was a lot cheaper than a new(er) bike, and he already has the suspension, controls, etc pimped out and set up for him...plus, here in Cali, it's plated (legally!). For him (us) it was worth it as it's a DS he can ride for a long, long time...

Oh, by the way, the power you will get from those 40 cc's (especially if you go hi comp on the piston) is unreal!

hi there! just a short intro of me and the place i'm in. i own a wr 400 and that bike is one of those bikes that had been barely made street legal 10 years ago. only recently do they get the wr450 2009 street-legalised. if i get it, it'll cost me about US$18k. all i wanna ask from you is this. will it be much better to pimp my wr 400 that has already been fully paid than getting a new wr450? the choices over here are rather limited. :smirk:

and another question, i know that wr 400 can get rather hot. if i changed it to a 444cc, can the bike handle that excess heat? or will a 426 upgrade be enough? me being a noob, i had just overhauled my engine last year, due to a cracked connecting rod. my mech told me this story that the stock conrod is not that good and i must use aftermarket pipes and jet it properly to release the internal pressure acting on that conrod. i don't know if i should believe his story or not. :lol:

I am in final stages of completing the auto-decomp mod after reading hundreds of pages of happy customers on TT. :lol: :lol: What's left is timing, and putting it back together. New shims won't be in until Tuesday :usa: . The bike has been great so far :smirk: but dicking with manual decompression was never fun.

After doing more research I have noticed that bunch of you guys have updated the crank pin, and some went with the 440cc route. Followed Powroll link and they want $400 to rebuild crank, and another $800 for all the parts ordered through the dealer. Local builder would charge another $300 to fit this all together. ;)

Is this a normal price for 40cc bumpage? :p I can buy whole another WR400 with the +40cc kit already installed for $1400... :cheers:

Now, regarding the crank pin -- I have to ride 40miles to get to any better trails, but sometimes I run 200 miles on the pavement. Usually cruising at comfortable 55+ mph. :lol: :lol:

Thanks for your input!

u fix the auto decomp on your own? where do you get the parts from? i'm thinking of fixing it on my bike as well. but i have no idea where to start from. especially about bringing it to my place.:ride:

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I ordered the cam through a friend who has a bike dealership.

The kit is in, the new shim pads are in. It's kind of hard to decompress the engine. I can feel when the notch touches the bucket.. It's not easy by any means. Is that normal?

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I had a 400 with a 426 jug bored 2mm over, that's 444 13:1 it was wicked fun, ran on pump gas. The piston was a custom one and I'm not sure who it came from, wiseco I think, and getting them may be a problem

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Just got back from a nice 100 mile ride. I guess the more it runs the easier is to start. I just need to run her in more.

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On the side note, I am getting about 35 mpg at 200 feet above sea level, hot and humid day. :banana:

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just do the good old big bore start drill, get it to TDC and then one hard kick, once you learn the drill you can start anything

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