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04/05 crf450 bottom end swap

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Hey guys, my bottom ends having some major issues. I can get my hands on a blown up engine (just the top end) for a good deal. Wondering if an 04 crf 450 bottom end will fit into an 05 crf 450 frame. I'd be putting my 05 top end on the 04 bottom end.

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Uhhhh what?! A new crank is what? 200-250 bucks? Switching top ends? Sounds like your trying to save some Money and MAKE some shit work and ya get what you pay for! As in you buy a bomb and that's what your gonna get.. Hobblin around on a set of pegs... That shit don't look fun

Edited by Diggla117

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Uhhhh what?! A new crank is what? 200-250 bucks? Switching top ends? Sounds like your trying to save some Money and MAKE some shit work and ya get what you pay for! As in you buy a bomb and that's what your gonna get.. Hobblin around on a set of pegs... That shit don't look fun

cranks fine.. Tranny. Case and clutch not so much. The new clutch basket cost me 250$ and I'll need two new cases. About 150$ a piece.. And I havnt looked at the tranny yet.. Plus labor fees.. The used bottom end is better than what I have.. And I'm selling the bike once it's fixed ha

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cranks fine.. Tranny. Case and clutch not so much. The new clutch basket cost me 250$ and I'll need two new cases. About 150$ a piece.. And I havnt looked at the tranny yet.. Plus labor fees.. The used bottom end is better than what I have.. And I'm selling the bike once it's fixed ha

Well I think we all frown upon people selling rigged up shi BUT if you have another good bottom end then yea use it. I'm not sure a 04 will bolt up to a 05 but if It does I'd Atleast get a new piston kit for it. There's some good deals on eBay. Also I wouldn't pay anybody to work on it unless you really are not that mechanically inclined. You can find a PDF file online with instructions and torque specs if you really wanna save money on this project and borrow a good torque wrench. Take your time and you should be in business. Edited by Diggla117
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It should bolt up, but I am almost certain you will need spacers at the bottom motor mounts. I think the rule of thumb is you can put a Generation 1 motor in a Gen2 chassis with spacers. You cannot do the opposite. Atleast not without some really weird fabrication

Edited by mrmoto35

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The bike will not be "rigged" perfectly good top end going on a perfectly good bottom end. It will cost less than 300$ to get it all done too :)

It should bolt up, but I am almost certain you will need spacers at the bottom motor mounts. I think the rule of thumb is you can put a Generation 1 motor in a Gen2 chassis with spacers. You cannot do the opposite. Atleast not without some really weird fabrication

is there any way you could find out for sure?

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The bike will not be "rigged" perfectly good top end going on a perfectly good bottom end. It will cost less than 300$ to get it all done too :)

is there any way you could find out for sure?

No I cannot physically verify this as I only have an 02 and an 08 to look at.

 

I just pulled an 04 motor out of an 08 chassis. There were spacers at the bottom mounts. But I am NOT 100% sure the 05 and the 08 chassis motor mounts are eaxctly the same. Gotta see what others say...

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No I cannot physically verify this as I only have an 02 and an 08 to look at.

I just pulled an 04 motor out of an 08 chassis. There were spacers at the bottom mounts. But I am NOT 100% sure the 05 and the 08 chassis motor mounts are eaxctly the same. Gotta see what others say...

Yeah I don't know that they changed much from 05 to 08.. Not sure though

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i put a 04 motor in a 05 some years ago and i remember the bushing in the back was different. no big deal to have it machined the other problem is the front motor mount is different. you will have to machine some spacer's for that one also. other than that it will all line up if my memory serves me correctly.

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i put a 04 motor in a 05 some years ago and i remember the bushing in the back was different. no big deal to have it machined the other problem is the front motor mount is different. you will have to machine some spacer's for that one also. other than that it will all line up if my memory serves me correctly.

how about the top end of my 05? Will that all line up with the 04 bottom end?

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how about the top end of my 05? Will that all line up with the 04 bottom end?

Yes that while bolt straight on. If you walk into the dealer and buy a new cylinder they are going to give you part number 12100-MEN-671 which fits '04 to '08  http://www.partzilla.com/parts/detail/honda/HP-12100-MEN-671.html

 

Same with the head. They will give you part number 12200-MEN-850 which is the 06 head http://www.partzilla.com/parts/detail/honda/HP-12200-MEN-850.html

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Yes that while bolt straight on. If you walk into the dealer and buy a new cylinder they are going to give you part number 12100-MEN-671 which fits '04 to '08 http://www.partzilla.com/parts/detail/honda/HP-12100-MEN-671.html

Same with the head. They will give you part number 12200-MEN-850 which is the 06 head http://www.partzilla.com/parts/detail/honda/HP-12200-MEN-850.html

awesome so I got the bottom end.. Working on swapping my top end over.. How do I get past the cans and everything just unbolt it all? I have it at tdc and the cam chain tensioner is removed

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awesome so I got the bottom end.. Working on swapping my top end over.. How do I get past the cans and everything just unbolt it all? I have it at tdc and the cam chain tensioner is removed

First you have to remove the cam gear. When you do you want to use a zip tie or a length of wire to hang the cam chain so it doesn't fall down into the bottom end. If for some the chain does fall down into the bottom end you can fish it out with a coat hanger. Once you have the gear off and the chain hung you need to take clean rag/s and cover up that entire passge that the cam chain goes through so that none of your shims fall down there into your bottom end when you pull the cam holder assembly off. Then just remove the 4 bolts from the cam assembly and very gently lift it out. I say gently because there is a small shim the sits on top of each valve. Sometimes they stay on top of the valve. Sometimes they stick to the lifter/bucket. Sometimes they drop into the head

Edited by mrmoto35

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^plus mark or keep track of which shim came from where if you want your valve clearance to be correct when you get it back together.

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