Two Stroke Motocross

Two Stroke Motocross Forum => Technical => Topic started by: dijaydave on August 01, 2011, 06:48:03 AM

Title: YZ144 2005
Post by: dijaydave on August 01, 2011, 06:48:03 AM

Hi Guys!

I have some troubles with my Bike. It`s a Yamaha YZ125 05 with a Athena 144 Kit.
In fact, the headgasket is the problem. I got the old cylinder with the two o-ring.

The problem is that the inner o-ring is always braking. I've changed the o-ring 5 times. And now i have to revise the cilynder cause the coating comes off!

Has anybody some experience with the Athena 144?

Thanks & Greets!

Title: Re: YZ144 2005
Post by: Charles Owens on August 01, 2011, 07:11:06 AM

Welcome to the site!

The last YZ I built before our project bike I used an Athena top end kit. (Stock Bore)
I never had a problem with the inner O-Ring, but I have read quite a few problems with it.
Are you using a light coat of grease when you install them? Do you have to stretch it to get it to seat in the groove?

Title: Re: YZ144 2005
Post by: dijaydave on August 01, 2011, 11:24:48 AM

Thanks for the welcome!

No i haven't used any grease for installing them. The O-Ring fell easily in the groove of the cylinder.
I have bought the bike used this year in February with the 144 kit already installed. The guy gave me a lot of o-ring with the bike. (Now i know why).
The O-ring were original packed so i think they should be ok. I never stretched them.

After changing the o-ring the last time, i saw that the coating from the cylinder comes off, right up there were the head fit the cylinder. So maybe the coating wasn't good from the cylinder.

I'm also not happy with the 2 piece head. The new generation of the 144 kit has only a 1 piece head. (no changeable dome)
I think the head doesn't fit that good to the cylinder and the compression is really high (14:1). It seems that the explosion in the head can reach the o-ring. (Maybe in combination with the bad coated cylinder) But that is just speculation.
Athena didn't gave me any feedback to my questions.

I wonder what will happen when i use Hylomar instead of the o-ring?!

greetz!

 

Title: Re: YZ144 2005
Post by: 2T Institute on August 01, 2011, 02:39:43 PM

Rub the top of the cylinder on a sheet of glass with some wet and dry paper on it, I think you will find the top of the cylinder has sunk a bit around the exhaust port.

Title: Re: YZ144 2005
Post by: riffraff on August 01, 2011, 10:16:42 PM

If you can get Dow-Corning DC55 it's formulated to make an "O"ring swell slightly to provide a better static seal.

Title: Re: YZ144 2005
Post by: dijaydave on August 02, 2011, 12:38:17 AM

Thank you guys for your replys!

The cylinder returns from the workshop in about 2-3 weeks.
In the meantime i will organize some DC55 and check the head.
I'll keep you guys up to date!

Does anybody know if the "new" Athena head fit to the "old" Athena cylinder?

Greetz!

Title: Re: YZ144 2005
Post by: SachsGS on August 02, 2011, 06:22:18 AM

2T Institute X2.

Put a dial indicator to the barrel and head and you'll see that the mating surfaces are moving (ever get the 144 hot?).

Title: Re: YZ144 2005
Post by: dijaydave on August 02, 2011, 06:45:38 AM

Yes i think it ran definitely hot! :(