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1985 Yamaha YZ490 motor into a 2008 Yamaha YZ450F frame?

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yep that means the exhaust port is angled to one side. can you put

 

I race a 1982 490 in post-vintage; they are tough and durable motors for sure!

in good-traction conditions, they can out-drag modern 450's . . . the secret is "good traction".;-)

i must ask, what is your jetting at?

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i must ask, what is your jetting at?

Well, I know there is the stock main jet in it (#440) which works well.

Needle position and pilot, I don't know. (I traded a fellow racer my '83 yz250 for it; he had the jetting sorted pretty well.)

It's a bit rich at low throttle openings, so I'll check pilot and float settings, and needle# and position

when I get in there I'll let you know.

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Well, I know there is the stock main jet in it (#440) which works well.

Needle position and pilot, I don't know. (I traded a fellow racer my '83 yz250 for it; he had the jetting sorted pretty well.)

It's a bit rich at low throttle openings, so I'll check pilot and float settings, and needle# and position

when I get in there I'll let you know.

thanks a ton dude! :)

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Spend some time reading up on the motors. Getting the head cut correctly is key. The details are well published on the web. Pretty simple if you have the tools. Porting seems to just be extra, the head is mandatory and cleans up most of the problems to a fully acceptable level. 

 

You're right the hard part is the pipe. You'll need to mod the frame in the yoke area one way or another. I would lean toward moving the yoke up to make room for a center pipe or down to make room for the side pipe. Don't just hack on it to clear. Then you'll need to make the rest of the pipe work. I was thinking about 490 in a modern frame a lot last year. I suspect the highboy pipes would clear the rearward part of the frame (not the subframe) better on a YZ250 frame than on a 4T frame. Figure out what tank, seat and side panels to run and how to mount them.

 

Or you'll need a custom low-boy pipe built. Which would likely be the easiest solution, but you're trusting a lot of money to a pipe builder, and hope he gets along with the stock porting or your engine builder. All very complicated to manage. 

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I didn't see what year steel he measured. I'm assuming 450 steel. I'd bet the old bikes had lighter frames than the early 00 thumpers. The 490 I think was around a 250lb bike like most modern 450s. The problem is the weight was all of the components like the wheels, that lump of a motor etc. Now everything is oz here and there. The 490 in a thumper frame I'm guessing will be heavier which is what I'm saying. You could get the old bikes down around 225 with trick parts. Trust me I have tried to do some oddball swaps. 701 vxr jet ski motor in a fzr chassis. It would be cool but I don't think worth the time and money personally. There are some 700cc w stroke motors out there(atk I think). Now that would be a swap.

Aluminum frame is lighter. At the time of the switch most articles were claiming 5 lbs lighter.

MXJosh did a frame swap on his bike and weighed the steel and aluminum frames side by side. Steel = 24.2 lbs, aluminum = 18.4 lbs, for a weight savings of 5.8 lbs.

http://www.thumpertalk.com/topic/496051-actual-weight-differenceaf-vs-sf/

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I didn't see what year steel he measured. I'm assuming 450 steel. I'd bet the old bikes had lighter frames than the early 00 thumpers. The 490 I think was around a 250lb bike like most modern 450s. The problem is the weight was all of the components like the wheels, that lump of a motor etc. Now everything is oz here and there. The 490 in a thumper frame I'm guessing will be heavier which is what I'm saying. You could get the old bikes down around 225 with trick parts. Trust me I have tried to do some oddball swaps. 701 vxr jet ski motor in a fzr chassis. It would be cool but I don't think worth the time and money personally. There are some 700cc w stroke motors out there(atk I think). Now that would be a swap.

His swap was 01 (?) YZ250 to aluminum YZ250.

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Ha ha, sounds like you got the Junkman's Itch.  

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His swap was 01 (?) YZ250 to aluminum YZ250.

 

01 and a frame designed in the 70s will weight a little different:) 

 

OP if you have the 83 and start breaking it down i would be interested in what the frame weighs and what the motor weighs compared to the 450 frame.

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01 and a frame designed in the 70s will weight a little different:) 

 

OP if you have the 83 and start breaking it down i would be interested in what the frame weighs and what the motor weighs compared to the 450 frame.

 

A few posts before your first one someone mentioned using a 99+ YZ250 frame. When you came in saying steel was lighter than aluminum the YZ250 post was still in my mind, that's why I posted up what I did. Re-reading, I see you were talking a different direction! Yes, a spindly 1970's frame most likely is lighter than today's over-built stuff. I worked with a guy that raced enduros for Penton in the early 70's. He claimed their extremely modified bike weighed in under 190 lbs and made a touch over 30 hp. He also said it was flexier than a cereal box, overheated if you looked at it wrong, etc etc.  Not sure how true all the stories were, but he was extremely knowledgable, and even in his mid 60's on on a quad he could lay a whooping on guys half his age.

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Frame and suspension design wasn't a strong suit back then:). If it were me I'd probably start with the 490 and updated the suspension and wheels, brace the frame and clean up the stock plastics:). I live frankenbikes as an excercise in engineering but this seems like a , it might be cheaper to put this motor in, deal. Could be wrong though.

A few posts before your first one someone mentioned using a 99+ YZ250 frame. When you came in saying steel was lighter than aluminum the YZ250 post was still in my mind, that's why I posted up what I did. Re-reading, I see you were talking a different direction! Yes, a spindly 1970's frame most likely is lighter than today's over-built stuff. I worked with a guy that raced enduros for Penton in the early 70's. He claimed their extremely modified bike weighed in under 190 lbs and made a touch over 30 hp. He also said it was flexier than a cereal box, overheated if you looked at it wrong, etc etc. Not sure how true all the stories were, but he was extremely knowledgable, and even in his mid 60's on on a quad he could lay a whooping on guys half his age.

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Found the project I was thinking of - a Yamaha 465 in a Suzuki frame = Yamazuki.


It's on cafehusky - I tried to cut and paste but I'm old = it didn't work.


google 'yamazuki 465'


Edited by xxxbranham

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So my '08 YZ450F went turnoble on me, so im looking at buying a yz490 and putting that motor into my 450f frame... Good idea or bad? I hear the suspension sucks on the stock 490 frame, but apparently- the engine was decent... so i'm thinking it would be an awesome idea! Opinions? 

yz465 is a better choice, the 490 is a step back....poor head design detonates to high hell & is a pig to start cold

better still put in a cr500  engine

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yz465 is a better choice, the 490 is a step back....poor head design detonates to high hell & is a pig to start cold

better still put in a cr500 im one of those (cant stand hondas) type of guy, i love yamaha born and rasied with it, there no way ill ever put a honda motor into a yamaha frame

 

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you should put a blaster cylinder. on your mx175. it will bolt right on i think. and i like the wr500 idea, it would haul ass. I know a guy that lives in pefferlaw that did a swap like this. he put a honda cr250r motor into a yamaha frame with Race suspension front and back, Applied racing triple clamps and bar mounts, eline carbon fibre pipe guard, pro circuit Silencer, D.I.D gold Xring chain, boyeseen racing ignition cover, Works connection rad braces, 100% gripper seat Cover, o6 plastics and new fender decals, Acerbix hand guards, O.D.I lock on grips. I could ask him to help you out if you want guy.

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you should put a blaster cylinder. on your mx175. it will bolt right on i think. and i like the wr500 idea, it would haul ass. I know a guy that lives in pefferlaw that did a swap like this. he put a honda cr250r motor into a yamaha frame with Race suspension front and back, Applied racing triple clamps and bar mounts, eline carbon fibre pipe guard, pro circuit Silencer, D.I.D gold Xring chain, boyeseen racing ignition cover, Works connection rad braces, 100% gripper seat Cover, o6 plastics and new fender decals, Acerbix hand guards, O.D.I lock on grips. I could ask him to help you out if you want guy.

i already told that retard denney that a blaster cylinder would fit ohh and its not that i need someone to help, its that im issing the profits i need

Edited by TTR230KING

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005.JPG 003.JPG 004.JPGIt is fun to ride. All that new handling with alot more power.

Hot damn! Is there a build thread on this? If not mind sharing some of the problems ya ran into with the build. Beautiful bike!

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015.JPGthanks for the complement. it is so plain jane most people don,t even realize what it is. The transfer was easy i just had to figure out how to i wanted to modify the down tubes. And the rest was make engine mounts. The easy one is a 2002 and up yz250 2stroke frame i can do it in about 3 hours. I have done several of those. And i am finishing up a 07 250stroke conversion. I can answer any questions you might wonder about.

And i do ride the bike and with the group i ride with it has to be reliable and the vibration is almost none since i run stock tripple clamps and bars. It is in the carb and the pipe.

The yellow bike is a 98 yz250 with a 490 built years agoin cluding hyd. clutch. I borrowed the pipe from it to dial it in So i do have to get a pipe made.

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