[ggarsen]

can i swap motors ,can i put a 300ex motor in a 250 big red without mods

 

[Helmut]

Welcome to the forums. No, the 250 big red is shaft driven and the 300EX is chain driven. Also, I'm pretty sure the mounts wouldn't line up.

 

[ggarsen]

the guy i bought it from said it came out of a 300ex it was sitting in a 250 sx frame and it was shaft drive

 

[Helmut]

the guy i bought it from said it came out of a 300ex it was sitting in a 250 sx frame and it was shaft drive

A 300EX is chain drive.

 

[TheRealFatShady]

You mean the TRX300 2wd model, 1988 - 2000. I belive you need the output shaft from the 250 engine to line up with the driveshaft/rear end of the stock Big Red.

 

[Helmut]

You mean the TRX300 2wd model, 1988 - 2000. I belive you need the output shaft from the 250 engine to line up with the driveshaft/rear end of the stock Big Red.

Yeah, that might work.

 

[ggarsen]

output shaft

You mean the TRX300 2wd model, 1988 - 2000. I belive you need the output shaft from the 250 engine to line up with the driveshaft/rear end of the stock Big Red.

when i take the casing off with the shaft do i have to be careful cause i read on another forum that something falls off the shaft while removing it,im not quite sure what happens inside the engine because it wasnt explained too well

 

[Helmut]

You mean the TRX300 2wd model, 1988 - 2000. I belive you need the output shaft from the 250 engine to line up with the driveshaft/rear end of the stock Big Red.

when i take the casing off with the shaft do i have to be careful cause i read on another forum that something falls off the shaft while removing it,im not quite sure what happens inside the engine because it wasnt explained too well

When you pull that output shaft out of the engine, the gears on the shaft fall off and down into the engine. You will have to split the case to put them back on.

 

[ggarsen]

tks for all the info helmut,what kind of job am i looking at to split the case,im not sure how to start,maybe i should bring it to a professional,any suggestions??? tks

 

[Helmut]

tks for all the info helmut,what kind of job am i looking at to split the case,im not sure how to start,maybe i should bring it to a professional,any suggestions??? tks

The engine has to come out of the frame. The head and cylinder have to come off and both side covers have to come off. The flywheel has to come off. Both clutches will have to come off, as well as the primary gear and timing chain. Everything has to come off to split the case. It's a pretty big job, but it can be done as long as you have a lot of patience and time. A good service manual is helpful.

Before you attempt all this, make sure you talk to someone that has actually done the conversion to make sure it will actually work for what you are trying to do. That would be a lot of work for nothing.

 

[dr. feelgood]

I think there is some work to that swap... on the 3wheeler forum I frequent people have put TRX 300 engines in their Big Red 250s or 250sx trikes, and I don't think it was as straightforward as you would think.

Rob

 

[ggarsen]

i decided to cut off the bottom brackets and i moved the engine over about 3\4 of an inch,it lined up perfectly and now the machine must do close to 70 mph, i love it