Big Red 250es motor question?

[boogie5184]

Well I finally got my 1985 250es running with fenders, brakes and all of my switches working. And wouldn't you know it, the motor goes out. The question I have is , What else besides the 250es Big Red motor is an exact fit? I have been told that the 250trx and the 250sx motors are the same. Is this true? I don't know if I want to just buy another motor or rebuild mine. I really don't know much about these motors, any suggestions?
:TrikesOwn

[bigredhead]

First find out why the current one quit running.

then consider your options depending on cost.

Yes the SX motors will match up, 85 to 87.

The 85 and 86 have different driveshaft and axle / swingarm setups.. but interchange within the same year models.

I do not know about the TRX tho. sorry.

[boogie5184]

thanks big red head. My motor has a dropped valve, rings are gone (will need to hone or bore out , new piston etc..) and the cam chain seems to need replacing.

[bigredhead]

As long as the tranny/clutch/entire bottom end is ok.. heck.. for the price of a USED motor , wich will probably already need all this in the end..

Get a new timing chain. both valves with seales, a new cam if it needs it, and springs piston ring one size over.. etc.. .. ... and you got a motor that will run another 20 years.

[firefirefire90]

i dont think the trx motor will fit...it is a chain drive. Im guessing yours is a shaft driven.

[freewheel3]

I agree with BRH, if the bottom end, clutch & transmission are OK, rebuild the top end & then you know what you got. As my dad used to say, buying a used motor is like buying a cat in a bag.

[BIGCRIP28]

i think you should rebuild the top end.
i do have that 85 big red engine still though, if you want it

[boogie5184]

Thanks guys. I don't know what I'm going to do. Right no wI think I'm looking for the cheapest way out. But I don't want to regret it later either. Big crip , p.m. me about that motor. How much do you want for it and how does it run? Thanks again guys!

[brapp]

no you guys the trx 250* is the exact motor as athe 250es and the 250sx its actualy the big red?es motor due to its silver color the sx motors were black. but it is a direct bolt in.the only diffrenc eins the 87 250sx carb and thre 87 trx carbs are diffrent but will work with earlier models. i am lookign at all 3 repair manuls right now.

[boogie5184]

thanks brapp, thats what I was thinking, just didn't know about the different carbs!

[Howdy]

There is a difference in the TRX250 motors. If you look at the output shaft housing you will see they are a little different. I found out the hard way ( via putting a 250es motor in a TRX250 ).
Howdy

[brapp]

i have done it before and it worked for me, but had a slight scraping due to a handmade universal joint and yokes.