Base Plate Motors for the TRX250R

A description of what base plate motors are and what they are for.

Do you need a base plate motor? That depends on what you're trying to do. You should discuss with your engine builder what you want out of a motor and whether you need to go this route. There's nothing special about it, just more to keep track of.

Remember, when building base plate motors, when you turn the base studs out for better thread engagement on the nuts, put some blue (medium) thread locking compound on them so they will stay put. Do NOT use red (heavy) thread locking compound, as you will never get those studs out again.

Category:

Autos & Vehicles

Tags:

• Honda
• TRX250R
• Base
• Plate
• Motor

[quadkindaguy]

hey is their a bigger difrence with the 3.5 space plat and the yz piston or is it not worth it

[rustyATV]

@quadkindaguy What I've been told is that you can get TRX pistons in most any size you want now, so the YZ piston isn't really necessary, and that this was something that was done mainly before larger pistons were readily available.

[RBSTI3]

Hi Rusty, i have a baseplate motor, i bought a new 87-88 crankshaft and rod, and an 86 piston kit, is there any difference in the crankshafts between years? I thought it was just the lenght of the crank rod? I hope im correct? can you help me by answering this?

[rustyATV]

@RBSTI3 The only difference in the cranks is the rod length. Stroke is the same.

[hondatrx450rguy]

nice video rusty! you said .120 over bore was a 68.5 piston. wouldnt it be a 69? wiseco makes a .140 overbore piston and its 69.5. i might be wrong but by looking at their website thats the way i read it.

[rustyATV]

I believe you're right. Looks like I'll have to put in a balloon!

[slrrman88]

@hondatrx450rguy actually now you can get a 70mm piston but i would never go that far

[slrrman88]

@trikes4life8256 not sure if you found a spacer plate but Eddie Sanders Racing makes them

[trikes4life8256]

Where do you find the base plates, i just tried putting a new wiseco top end in my 86 250r and didn't realize the guy before me had put a hot rod stroker crank in it. And my piston is hitting the head.

[86trx250rrider]

i found that with my spacer plate i had to get the head chambered because i was making so much compression, i actually blew a base gasket with about 3hrs on the new rebuild. i went from 220lbs to around 165