1987 yz125 build

[broncomitch]

got this yz125 a few weeks ago as my next project.

Got it non running but the guy said it would with fresh fuel cus its been sitting a few years...

The bike was a grease factory and someone spread silicone on every single section of the motor..removed the head and found this..

The piston and cylinder are in pretty good shape, it's bored over to 57.0mm,not sure if I'll replace it or not..but I will be splitting the case and check everything out and give it a much needed gasket kit and replace the clutch's..

I will pretty much be braking this bike all the way down and going through it. this will be a slow project due to other hobbies (bronco) lol

 

[broncomitch]

 

[Rot Box]

Cool! Should be a fun project

 

[Jeromy]

Looks like fun. I'm thinking something similar for my nephew to work on when he visits.

 

[broncomitch]

Wish I could get it going faster... but need a hole new ignition setup for the bronco and new tires and I might try and enter ITTC this year...

But I expecting to have this completely rebuilt under $1000.

 

[idahoyj]

I might try and enter ITTC this year...

DO IT! Cheston needs some competition for 2nd place!

 

[broncomitch]

Ordered parts

 

[broncomitch]

So in preparation of parts coming (and get away from the wife) I decided to start taking the motor apart.

Cinda bummed cus the clutch looks bran new and I ordered a fancy race clutch from EBC.

Looking in the case everything is nice and clean and in grate shape. Super stoked.

 

[anderson750]

You are into it this deep, you may as well put a new clutch in it. Hold onto the old one.

 

[rholbrook]

You are into it this deep, you may as well put a new clutch in it. Hold onto the old one.

And bearings

 

[anderson750]

And bearings

^^^^Agreed. With crud that was in the cylinder, you don't want to reuse the crank bearings that were in it.

 

[broncomitch]

You mean the bearings on the connecting rod?

Ordered a hole new rod assembly as well cus the one in it feels like crap.

 

[rholbrook]

All the bearings in the motor, not just the connecting rod.

 

[broncomitch]

Cinda regretting this now.
Need a few special tools I really don't want to buy and I'll need to have the crank sent into a shop...

 

[anderson750]

Cinda regretting this now.
Need a few special tools I really don't want to buy and I'll need to have the crank sent into a shop...

What do you need? Are you having the crank rebuilt? I have to rebuild the crank on my boys bike about every 60 hours and use Andrew Cooksey out of Texas to rebuild them. He specializes in KTM's but I am sure he could do Yamaha. From looking at his website he would charge under $200 to rebuild the crank and he makes sure it is balanced and true before sending it back.

 

[broncomitch]

I need a crank instalation tool.
I guess worse case I'll make something to press it on the bearing..

Yeah, I already got a connecting rod that comes with the press in section...but obviously I don't have the equipment to do all that...
I would like to use someone locally but we will see..

 

[anderson750]

I need a crank instalation tool.
I guess worse case I'll make something to press it on the bearing..

Yeah, I already got a connecting rod that comes with the press in section...but obviously I don't have the equipment to do all that...
I would like to use someone locally but we will see..

I have one of these I will loan you. I will be coming up north next week and we could work out getting it to you. Lindsey Machine will take care of that rod for you for around $100 probably......that seems to be about the going rate for removing and pressing in a new rod.

 

[broncomitch]

Called them today, $75 out the door. Should get the rod tomorrow and I'll drop it off.

I appreciate that!
I might try and heat up the bearing and freeze the crank, the guy at Lindsey said that's pretty much what they do...

See how impatient I get lol
Really want to get this this thing going.


Tho, my clutch showed up and and they sent the wrong one... so we will see how that return goes..

 

[broncomitch]

Okay, case put up a little fight cus it was pookied shut but got it open and everything is in awesome shape and got the crank out and dropped the crank and rod kit off at LMR and shout get it back next week.
Also ordered all new bearings and seals and a bunch of other stuff.
Sadly most of it won't get here till next week..

 

[broncomitch]

Need some creative advice.

My goal with this rebuild is to make it look like a newer bike and I think I'm on the right track with that but I can't decide what to do with the motor and frame..

The frame and motor are black and I don't like that, stock the frame was white..

I can't decide if I want to take the motor to a natural alum finish (or paint it)

And can't decide what color to paint the frame.. blue, aluminum, or black.

Thoughts?