[T-Dub13]

Mine was worn 1/2 way off also. You could find a sleeve to put over it to take away some of the looseness. Maybe a piece of copper refrigeration tubing. Or grind the weld off and replace the pin with a new 8mm bolt. Or better yet, replace the entire thing with an allballs roller... That's what I ended up doing, but I had to move mine anyway because of the added travel.
But yeah, that's how it goes together. Washer, roller, washer, nut.

 

[JKLNHDE]

So just to clarify, pic 1 is the post on my frame. To make the roller functional, I should drill out the bad post and tack weld in a bolt in its place roughly the diameter of the center hole in the roller (pics 2 and 3)? NO bushing is needed? How does the roller not just grind itself to pieces with no bushing present? I guess Im missing something but no bushing is mentioned as being part of the roller. Thanks.

 

[T-Dub13]

Exactly. Refer to the original bolt and that will answer your question: It will grind itself to pieces. But bear in mind that it took 30 years haha. I would bolt or tack weld in a new bolt and use a piece of copper tubing for a bushing and grease it. Should last a good 10 years until it saws through the new one.

You can find a washer that fits inside to tighten up the wobble, but as far as I know, that's the way they're built. Maybe someone else knows better...?

 

[JKLNHDE]

Engines at the builder. Can anyone tell me what the stock, standard bore is on the 81 YZ60 ? Thanks.

 

[T-Dub13]

Stock bore is 42mm
1st OS = 42.25mm
2nd OS= 42.5mm
3rd OS = 42.75mm
4th OS = 43mm

(And I found the following in comments on youtube)

"The KX60 stock bore is 1mm larger than the YZ60. The piston deck height is the same and they both use a 12mm wrist pin. The KX60 piston has a flat piston skirt on the intake side while the YZ60 has a window cutout. I made a template of the YZ60 intake, centered it on the KX60 piston and then used a dremel to cut it out. I first used a cutoff wheel and made three cuts to remove most of the material. Then I finished with a carbide bit and did final shaping/chamfering with a sanding drum."

Good luck! There's also a bunch of pistons and rings on ebay right now.

 

[JKLNHDE]

current bore is 43.00 and it needs to be cleaned up. Looks like Im looking for a +1.25mm piston. Tons of pistons on ebay but no +1.25mm- ugh.

 

[JKLNHDE]

Is there such a piston size as +1.25mm made by Yamaha or is it time for a custom Wiseco @ 43.25mm? Thanks

 

[T-Dub13]

Wiseco doesn't offer anything for the YZ60. But the KX60 piston should work from what I've read, seen and heard. Never done it myself though. I went with a 1981 YZ80 top end since mine was shredded when I bought it.

Make sure that you ask about the bore material when doing this retrofit! The KX bore is a nikasil bore and yours is steel. No problem for the piston, but the rings may want to be a different material. See how the oversize pistons call for a sleeve but the stock 43mm piston call for an electrofusion bore? I'd definitely ask them about this. It may be a common practice to do this retrofit. See below.

Wiseco produces high quality American made FORGED pistons, that stand up to the test of extreme racing conditions. Every Wiseco product is engineered with the most advanced technologies, for the ultimate performance and durability in all forms of PowerSports!

	Part Number	Price	Boresize	OverSize	Attributes
	648M04300	$97.29	43.00mm	STD	Displacement: 60cc Stroke: 41.6mm Notes: Electrofusion Bore
	648M04350	$97.29	43.50mm	0.50mm	Displacement: 61cc Stroke: 41.60mm Notes: Cylinder sleeving required, Cylinder replating required, Electrofusion Bore
	648M04400	$97.29	44.00mm	1.00mm	Displacement: 62cc Stroke: 41.60mm Notes: Cylinder sleeving required, Cylinder replating required, Electrofusion Bore
	648M04500	$107.02	45.00mm	2.00mm	Displacement: 63cc Stroke: 41.60mm Notes: Cylinder sleeving required, Cylinder replating required, Electrofusion Bore

 

[T-Dub13]

Looks like you've got plenty of cylinder thickness left, even on the spigot since yamaha filled the void with aluminum outside the liner on the spigot. This is a pic of mine, I forget what the bore was. The 60 is on the left side.

 

[JKLNHDE]

Im getting out of my depth here on the Electrofusion bore, etc. In calling Wiseco, am I inquiring as to whether the rings will seat on a steel bore/sleeve that the YZ60 has? If I need to ask anything else please let me know. Thanks

 

[Bohon]

Here is mine just ordered a kx60 piston and rings. Still need to

get it bored

 

[JKLNHDE]

I called Wiseco. The tech said that the rings would seat on a steel sleeve. Anything else I should be aware of ??

 

[JKLNHDE]

Bohon - which piston kit did you go with (43.50mm?)? Aside from a a little dremeling on the piston itself, is there anything else you must do or be aware of to retrofit this into the YZ60 jug? Thanks

 

[T-Dub13]

That's a cool looking DG replica there Bohon.

JKLNHDE: I'd ask wiseco
1) if they've heard of retrofitting the KX60 piston into a YZ60. Tell them yours is a steel bore and ask what the differences are for fit and ring material.
2) Ask what rings should you order if theirs is for electroplated only.
3) Also ask what the ring end gap should be for their rings.
4) and the piston / bore clearance.
5) ask if the KX60 piston is domed or flat top. I think the YZ was flat top or close to it, so there may be a significant compression bump if the KX60 has more than a slight dome. Also might need to machine the head to have the correct squish band and combustion chamber.

Your engine builder will need this info.

 

[JKLNHDE]

I hate to ask this of you but would you mind calling and posting your findings? Im out of my comfort zone on this one. If not, no big deal. I just wont be able to navigate the conversation on my own. Wiseco 1-800 321-1364, option 2 is technical assistance. If you have time it sounds like others would benefit. Thanks very much.

648M04350 Product Detail Information - Wiseco Piston Inc.

 

[Bohon]

The cylinder is at 42.5 and the stock kx60 is 43 so im going to have them bore it to fit the piston. I hope it works ill see. Ill keep you guys posted. From what i have read it should work

 

[JKLNHDE]

Other than cutting a window into the piston is there anything to do? Any issues with ring seating , etc? Thanks

 

[Bohon]

Not that im aware of

 

[Bohon]

Here it is with the cut out.

 

[Bohon]