killed the ox66 250 this weekend

[Circusboy]

played with the motor today. runs fine, but seems to be down on power a little. so i did a compression test

VST filter side top to bottom

20 psi
110 psi
110 psi

Starter side top to bottom
110 psi
109 psi
110 psi

This confirms what I heard and felt. I guess that means a rebuild

[StrokerSmoker]

ox66 250s are a great reliable motor Hydro-Tec not only rebuilds Yamaha they have some great bolt on's for some extra hp and a great warranty

[javelin90]

It's your money, as mentioned the OX 66 are great motors and I'll run mine till the outlaw a 2 stroke. Cost just under what a sho rebuild cost. I work on cars all the time and what I like on 2 strokes is they are easy to work on and at least if mine develops an oil leak I can fix it. Long live the OX66's!

[Circusboy]

FYI. I decided to rebuild the OX66 :)

[jdwo2212]

Good! Hope it all goes well.

[Circusboy]

Got the word today, motor is toast. Something about input and output bearing on the crank were messed up along with the case and the crank shaft was broken in half. Looks like i'll have some parts for sale soon :(

[5bites]

That absolutely stinks. Back to four stroke shopping?

[Circusboy]

found a 1999 merc promax 300 locally. don't know much about them but it has my intrest. not a 300x. anyone got any info on these? will it work on an alum. bay boat lol.

[Circusboy]

or keep saving for a 4 stroke lol.

[StrokerSmoker]

or keep saving for a 4 stroke lol.

HYdro-tec can still fix it....They have block cores and cranks and anything else that is broken in-stock.....Its what they do.

[ClarkBird]

Got the word today, motor is toast. Something about input and output bearing on the crank were messed up along with the case and the crank shaft was broken in half. Looks like i'll have some parts for sale soon :(

id be curious to know how you got the compression #s you did with the crank broke in half? That’s a head scratcher

[Circusboy]

here is the damage

[CJ1]

I have seen lots of engines run with broken cranks. Had a 6 cylinder diesel break one just behind the #1 rod journal. Boss argued with me until we tore it down. When the flywheel moves back and forth and the damper does not and nothing is loose you only have 1 problem. Like Paul is saying Hydro Tec will build you one up with a good block and crank for 1K extra. That is what I did and been very happy with it. CJ

[Circusboy]

I'm signing papers on a brand new F200 in the morning. Just in time for our 100% chance of rain this weekend lol. excited can hardly wait

[aus10b50]

My 2 cents, I had mine rebuilt last fall after pushing a rod through the side of the block. Got it back, tested it out, taking off it bogs down at about 2800 RPMs once it works past this it runs well, it kicks in and goes. I have spent an additional 3000.00 chasing this gremlin and gone through 2 new mechanics. In retrospec I wish I would have just bought a low hour used motor. Maybe if you have a reputable mechanic you won't have this issue but my 4k job has now cost me 7K and i still don't have a properly running engine.

[ClarkBird]

I have seen lots of engines run with broken cranks. CJ

I was keying on the "broken in half" comment.

[CJ1]

I was keying on the "broken in half" comment.

I believe Mike Lohn's was broken when HT tore into it and it still ran fine. If they fracture and the pieces lock together the will run fine. Seen it on a couple of large diesels personally and one race car. Cj