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Eyewitness89

04 Foreman trx450fm

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Ok... so I know in my intro that my 450 smokes bad.. definitely needs rings at minimum.  My wonderful devious mind just thought of a quick temp fix. I actually have 2 other 450 engines sitting here.. should I swap the jug and piston till I rebuild one of the motors to swap? Or am I tired and not thinking of everything?

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As long as there is no trash in the bottom end (sunk submarine) a top end rebuild should be all that's needed. Pretty much the same thing. If the internal parts look good a set if rings, hone the cylinder, valve seals, lap valves and some gaskets and you done. 

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I'm planning on rebuilding one and over boring. I'm talking straight swap as is just so I can still ride while I rebuild the other. In 3 hours I'm straight outta oil. Burned off currently 

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What kinda shape is your crankshaft in on your installed engine?  Any play in the connecting rod?  Does your piston wrist pin fit tightly or any rock play in it?  If these tests are not good you may think twice about a top end swap..... 

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Do the other 2 motors run or what wrong with them? I would do a complete motor swap vs trying to use a top end without any new parts or gaskets.

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I'd be using new gaskets.. both motors ran. But I did take one down after the idea this morning and that's a no go.. other motor I picked up temporarily from a friend cause he needed cash.. kinda like a pawn shop deal.. he wants it back eventually if he can, but I'm free do do whatever with it.. he said it needed to be timed before it would run

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If one of the 450 engines you have in your shed I'm assuming. If it's out of the same year, why don't you swap the engine for right now, ride it then rebuild the original when you have time? Just a thought I had.

Edited by F250 guy
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1 hour ago, toodeep said:

Do the other 2 motors run or what wrong with them? I would do a complete motor swap vs trying to use a top end without any new parts or gaskets.

That's what I said lol, trying to steal my thunder haha.

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Ok, well.. I'm gonna start this thread since I've already begun tearing apart the parts bike(well it was already mostly tore apart). Plans are to clean (lots of walnut blasting) the case. Rebuilding internals. Possibly going to remove the rectangular frame rails from parts frame, and weld them directly on top of my frame for a slight body lift. (Haven't decided on that yet). Definitely doing an oil cooler relocate since I'm 90% in mud and water. Hooking a toggle to the engine fan so I can kill it while in water and mud. Aside from these things, I will remain mostly a stock bike. 

I'm DEFINITELY open to ideas and suggestions. Remember this is a mud bike.

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I took a frame cut off a 450 and stacked it on top a 450 frame and it is a clean fit , I think it would be an easy frame lift to complete , I have it sitting there and can take a pic , I have some pic on another thread of what it looks like 

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This should give  you an idea , the frame section is straight so stacking them should be easy 

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I might just attempt it.  Would be a bunch of grinding and welding.  But doesn't look like it would cause much of a problem. Except maybe on the steering end.

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it looks like if you were to cut off the original steering tower off  and use the one on the frame section , then it might line right up , then with an extension welded to the steering shaft it would work out , then use the fenders , tank and seat mounts of the upper section and leave all the suspension and exhaust /muffler mounted to the bottom section  -----longer cables and wires might be the hardest part 

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Considering I have 2 steering shafts this may be very doable. Time will tell.. this may become a 3 year project like my last race car was lol

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Thanks. The rims were already on this bike when I bought it. It had 28" itp tires, but they were bad. So I found these 29.5 outlaws. At 1st I got them to try and trade for some 28 vamps, but I really liked how the outlaws fit and performed in the mud. Let me see if I have a pic of the bike prior to me starting my OCD trip on it

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as long as the connecting rod is good in any of those engines ?, then i would just swap motors. BUT !!!, if the rod is bad ?, your wasting your time and money.

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i am NOT  mud person ( just ask anyone on here that knows me ! ) , but i envy ya on this build !.

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2 hours ago, shadetree said:

as long as the connecting rod is good in any of those engines ?, then i would just swap motors. BUT !!!, if the rod is bad ?, your wasting your time and money.

Agree with ya. 😁

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Update *** bottom end seems good so far on parts motor aside from the goopy oil water mix oozing out, stripping it and rebuilding it

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If it were me , I wouldn't put a used jug and piston with new rings in my motor unless money was an issue , for about $200 and some change  , you send your jug to G+H , they will bore it to match a Shindy piston , they give you rings , wrist pin , clips , all seals and gaskets to do the job , it does take about 2 weeks turn around time from your door and back 

 

I just clicked a list off Partzilla , rings , wrist pin, clips , head gasket , base gasket , valve stem seals , tensioner gasket , and what I can think of to do that job that comes with the G+H deal and it is $102 with shipping , so for another $100 you get all that plus a new piston and the boring of the jug from a one stop shop ----then it is all fresh 

 

Did that reduction show up ? There is no grinding required with that 14.5% which is a good thing  , the 34.5% was a lot of grinding and I was afraid of going thru the case as it is really thin now 

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I'm actually going to attempt to bore an hone the cylinder myself (cringes). If that doesn't work I will send the other cylinder out to shop and was looking at either weisco piston or the namura piston kits. 

If anyone knows anyone that can do the machining work to make the 26T primary gear fit. I'd love to know, I dont have a lathe so I won't be able to bore out the gear properly.

3 motors for 2 450s, I have a little room for error. 

I know the 26T primary has to be machined out and the stock primary needs to be broken to get those really soft brass bushings out to fit into the 26T that's been freshly machined. I just don't have the tools to do that.

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