Giving a Bezoat a Second Chance

[ZUL8TR]

Luc
Yes to the Kaizen way to make improvements. Interesting the tower seal retainer came off, that is an interference fit? Good on the flattening of the gear case to tower surface. You can always add a thin coating of silicone to the outer part of the seal perimeter case that fits in the gear case recess bore for additional protection to prevent water entry. I just use a thin coat of wheel bearing grease (with molydisulfide additive) on both sides of the gasket that aids seal to prevent water entry. I do the same on the powerhead to tower gasket for better air seal and easy remove with no gasket stick and a ruined gasket.
Pete

[ZUL8TR]

Luc

Nobody has ever worked on my Y80, just me and not blue printed just a stocker with things done below. Yes 150 is a healthy engine but both cylinders need to be darn close.

I received the engine in 1977 from distributer McKean Marine in Texas through Yamato rep and racer/ boat builder/prop maker and dear friend Harry Pinner (RIP). At the time I did nothing except have a 9/16" prop shaft put in, didn't know about the ignition timing or carb settings, did set up testing with Pinner 3 blade prop. In 1978 the Y80 was a probationary engine in the new class 20SSH (hydro) and 20SSR (runabout), I ran 20SSH and did well. I did align the block, exhaust outlet to the tower as noted in the manual and properly torqued the bolts. Also adjusted the tower tuner to have a great seal to the powerhead/exhaust. Cleaned and adjusted the carb. Head pulled off on occasion to clean any carbon (none in combustion chamber but always some on piston crown. Put in 18 to 14mm spark plug inserts. Adjust timing often since the Y80 has trouble keeping it right on due to poor top bearing selection and difficult to get oil up there. Recently replaced seals and ball bearings in the gear case. To this day basically a Japan stadium raced engine with same rings and pistons stock bore. I have std after market rings and when ready to replace will just do the top rings. I use more oil than manual states at 25:1 like 16 - 18:1 synthetic blend Pennzoil XLF with 87 E free and that extra oil does accumulate in the tower/ tuner but figured so what it runs great.

Pete

[Albert]

Curious is your motor stock/as stadium raced? Or was it worked over by someone ?
I was told to shoot for 150+ for a healthy motor.

And your right on the oil. 15:1 here I come.

[ZUL8TR]

Here's to your success on that engine, may the Yamato God's be with you!
To keep tabs on all my engine's internals I do cold (keeps temp about constant) compression checks throttle wide open and keep track of the "same gage" readings each pull, and log in all readings. On the Y80 4-5 rope overs reaches max. psi, shouldn't be more than that for good bore, piston and ring seal. I look for a high 1st pull # that indicates a good suck air-in compress breather. On the Y80 I get 95-100 on 1st rope and 3-4 more ropes to get 150), darn near the same (+/- 2-3psi) for each cylinder. This std. bore Y80 engine has the same rings and pistons from when I bought it in 1978 and raced back then with testing + these days at AOMCI meets. Might re-ring it one of these days? Must be oil is cheaper than parts! ;-)

[Albert]

Pete,
I took the cylinders to a pro and experienced kart engine builder.
He checked for round and did the hone using a really neat 2 stone hone with two wiper stones (4 stone set up). I don't have the exact measurements for the bores as I wasn't standing over his shoulder the whole time just when the hone was done. He informed me the bores were in good shape but had some wear and they looked perfect after a hone.
As for the gap I'm aware is quite tight, the builder who did the cylinders even recommended 0.003. I know TJ recommended 0.006. A local builder who has done Yamato's recommended 0.003 as well.

Based on how much the last set of rings opened up in short order I think by the time these break in they will open up to .005 or similar.

The two engine builders I spoke to, shared pictures with and one of whom had the parts in his hand agreed that my engine problems came from excessive ring gap (almost 0.03 on one of the rings removed) this allowed a ring to push out and snag a port scuffing the piston.

I think on a freshly sleeved and bored motor/or one with little to no wear you would probably want to go a little looser but with some cylinder clearance . ****

*You know I didn't want to delete this thought, but it clearly shows a gap in my logic since the ring gap is set to cylinder diameter not piston diameter...



In short I have gone from one extreme to the other and its possible I have passed the happy medium. This may bite me in the butt just like having the larger ring gap did.

[ZUL8TR]

Luc

I know from previous posts you have had power loss and increasing ring end gap issues starting at 8 thou and growing. With this new refresh have you checked the cylinders for true round and any taper? If out of spec that will cause many issues. What are you honing the cylinders with? I use a ball hone to knock the glaze and cross hatch the walls.

That ring gap of 4 thou is very tight to start compared to what I have done and come across. Where did you get that #?

Wouldn't want you to have an issue with rings.

Gene Stillwell uses 5 to 7 thou Post #14 here
https://hydroracer.net/forums/forum/...to-302-rebuild

Ric Montoya recommends 12- 14 thou with after market rings, here:
http://www.yamatoracing.com/technical_entry.php?pid=2

[deeougee]

Discontinued Hastings ring. Going to try Cabors for a Husqavarna chainsaw. Unfortunately only good for stock bores. Have a contact for custom rings also. Hard to find rings with the same bore for the 80 and 102. Most of them you will also have to surface grind to get the right thinkness.

[Albert]

I keeping with the motors Japanese roots let’s do a little kiezen and fix two other little issues.
Remember when the foot wouldn’t come off last year? Well it has been off a few time since. One of those times the seal retainer ring at the bottom of the tower that holds the driveshaft came off with the foot!
So tonight I removed that brass bushing, cleaned up the bore and the bushing and applied some retaining compound to make sure it stays in place. While it was out I took a piece of flat bar and gave the foot mounting surface a quick flattening…it’s not perfect but it’s better and should be fine with a gasket.

[Albert]

Pete,
No mark for top or bottom. Looked to be a generic cast iron ring. I gapped them to 0.004 .

[ZUL8TR]

Were they generic rings or OEM which have a mark for how they face? What did you gap them at?

[Albert]

Bill, I kept at it and got a few more pits out . It’s not ideal but it’s way better than last years.

[bill hoctor]

A lot of HOT Spots!

[Albert]

New rings arrived from TJ tonight so I gapped them and threw the cylinders on.
Just last time but now it will have a better head and better ring gap.
16EC8A53-AE9E-45C0-9DF3-2A607B49398E.jpeg

[Albert]

It’s really coming along now.
8DE26A91-19D7-4AB6-97F4-5F8D053D5D33.jpeg

[Albert]

Dean,
It was built by Steve Carruthers in 1986 and won the Canadian nationals that year.
My brother bought it last summer from an gentleman who had owned it for 15 years, before that we don’t know where it was for a decade.
The coaming and look are definitely Bezoat inspired ( I don’t think Steve would mind me saying that) but the more I look at it the more it’s different on the underside from my boat and the black Bezoat you’ll see on earlier pages.