Giving a Bezoat a Second Chance

[DeanFHobart]

Albert,

Perfect….I have always liked NAPA. Back in the day they had magneto parts for KG4’s and 20H’s…. I bought dozens.

You have a really nice outfit there… Congratulations on the outcome….. Probably one of the best restorations I have seen.

Dean……………………………

[Albert]

Quick update for anyone looking for one.
The fall got busy in a hurry with us welcoming a new daughter to my house and my work being very very busy. Time has flown and the Bezoat is tucked away for winter. There is some work due in the spring. A small leak at one of the seams, and a new motor plate in the back with captive slots for the motor mount bolts.
While my basket case motor worked fairly well this year I did pick up another Y80. It's bone stock and had been hoarded away for many many years by a local who kept it for a back up for his lake runner. It's stock down to the prop shaft and early style carb. I will give this motor a once over and re-ring the other motor before spring to hopefully have a good runner and a back up/loaner to help get another local on the water.
I am still on the hunt for some cut sleeves or a cut shirt as I hope to make it to Maine in the spring and put some names to faces.
3AE72AE6-E4A2-4F22-BF07-438ECF8FA527.jpeg

[Albert]

Well the snow is melting and the order has been placed for some y80 parts.
Time to get to work if I want to try the new motor out in late May.

[ZUL8TR]

What parts are you getting for the new stock Y80? Among the parts will you be doing the prop shaft from metric to 9/16"?
Where is the seam leak you note in 12/9/21 post on boat or engine?

[Albert]

What parts are you getting for the new stock Y80? Among the parts will you be doing the prop shaft from metric to 9/16"?
Where is the seam leak you note in 12/9/21 post on boat or engine?

Just going to re-ring the motor and have a look and make sure everything is ok. This motor was never really raced from what we can tell, it was a back-up for a lake run boat for the last 20 years. Also yes going to switch to the 9/16 prop shaft. It was heavily fogged based on what we saw with the other motor that came with it and a look down the plug holes.

As for the leak in the boat we're unsure if it's leaking from around the air trap of the transom. The boat will come down off of the storage racks in the next couple weeks and we're going to try and find the leak and make sure the bottom has remained perfectly flat.

Lots to do.

[DeanFHobart]

Just going to re-ring the motor and have a look and make sure everything is ok. This motor was never really raced from what we can tell, it was a back-up for a lake run boat for the last 20 years. Also yes going to switch to the 9/16 prop shaft. It was heavily fogged based on what we saw with the other motor that came with it and a look down the plug holes.

As for the leak in the boat we're unsure if it's leaking from around the air trap of the transom. The boat will come down off of the storage racks in the next couple weeks and we're going to try and find the leak and make sure the bottom has remained perfectly flat.

Lots to do.

When you take it off the rack it will obviously be dry…. So with the boat right side up, pour some water in it and watch where it drips. Simple…. It works every time.

[Albert]

Ok,
Time to come clean. When I put this motor together last year we all knew it wasn’t perfect. I ran all last year with stock sized rings on .015 over pistons. Truth be told every time the motor was out my ring gap that started at 0.08 was growing and growing. Compression was dropping and so was power. There were also some things I’ve learned since that I just plain did wrong. Time to give the basket case 80 some love for getting me through the summer. It will be better and good practice before I tear into my hopefully nicer “new” motor.

54B36A6C-C9B6-4A6A-B01A-52654529D628.jpeg

[Albert]

Sigh,

68CF39AB-5B1E-476B-A560-C7A18C5663B6.jpeg

[bill hoctor]

[Albert]

Bill,
I’ve had a night to sleep on it and you know what? This is as good as it could have of gone. I wasn’t able to get out to test a final time last fall. We knew it got hot and I ran it one more heat. Thankfully only one more. The cylinder is fine, new rings and a good used piston and this will be back together with a hone.
I am going to have the cylinders measured to be sure they are still round…but I think it will be ok.

Obviously I’d rather not have to deal with this. When you build a motor from spare parts and leftovers you have to expect things won’t be perfect. This motor needs to be good enough to lend to a local racer later this summer for a weekend. Maybe not win but be reliable. That’s the goal.

[ZUL8TR]

Is there any aluminum on the cylinder wall, might be hard to see? If so remove it (not with sand paper) before a deglaze. If cylinder still round that would be amazing considering age and use! If out of round a spring hone not good for that could make bore egg worse. For deglaze I use ball hones for the Mercs (haven't done my Y80 yet), they do zip on the metal removal if not excessive, just get the rpm and stroke right and do CW 1st then CCW to finish and lots of outboard oil. That piston is not that bad the ring lands not folded and look ok per pic. I have reused pistons with light score like that with a light clean up using 1000 or 1200 wet paper in circumference direction. Based on your stated goal for the engine might consider a reuse of that piston since already fits the bore with lots of hot cold cycles, a used one could be a worse fit or not any better? Just get the right rings and end gap on them.

[Albert]

Zul8ter,
Im not sure what the acceptable spec is on the cylinder. I was just going to see a friend with a dial bore gauge and see if it was “close”.
This piston was replaced when I did the crank as the original piston played pinball with some bearing material.
My first thought was to wet sand the piston smooth but I was worried about it having been weakened.
If I get both kids down for a nap at the same time today I’ll try and clean it up real well and have a better look at it.

[ZUL8TR]

I doubt if weakened, not enough scuff to cause that but inspect carefully for small cracks outside and inside. Don't get to aggressive with the 1000 or 1200 wet paper in the circumference direction just cleaning up here. Might help to put the paper on a flat stick and roll along the arc as you sand this keeps your fingers from digging on the paper. Never been into my Y80 but on the Merc racers I get the piston largest OD dimension about 1/2" up on the skirt at 90 degrees from the pin and compare that to the smallest ID in the bore at the same relative running orientation position of the piston in the bore to get the tightest the engine will deal with. Note there is no piston to bore clearance listed in the Y80 manual but in the 102 and 302 they list 0.003" clearance, I think a bit tight. If you get 0.004" OK

Maybe other HR guys will step in here on Y80 piston clearance and other suggestions?

If the bore is egged a lot use the smaller bore ID and the largest piston OD at the specified OD measured location.

Here is a video of measuring done on a 2 cycle Yamaha with OD mic and a bore gage (he has expensive accurate tools). Note with his tools all that matters is the difference of the Piston and bore measurements for the clearance which he explains.

https://www.bing.com/videos/search?q...6FORM%3DHDRSC3

Pete

[Albert]

F0E790BB-0ECD-4E95-A906-077B1D0A9C29.jpeg C52ADAE2-BEE7-4E26-9814-47A9E08EE8A3.jpeg


If I had to race tomorrow I wouldn’t hesitate to put this in and run…the question is do I trust it long term. Some 1500 wet then a finish pad cleaned a lot of it up quite quickly.

[ZUL8TR]

Luc

If you go the used piston route measure same as old to make sure the piston to cylinder clearance you will measure is ok. What happened that the engine suffered a cooling issue?
Good travels with your engine work
Pete

[Albert]

I'm going to get the cylinder measured today or tomorrow depending on when I can sneak away from work.
As for the Piston I'll measure it when it arrives.
The motor definately got hot, real hot. We tried raising it to 1/2 below and by the time I came in from two laps it was pumping steam. Hopefully not enough to warp the bores...but I'll know soon.

I sure wish Yamato had used an off the shelf piston.

[ZUL8TR]

That is a good question as to why certain parts are not off the shelf, in cars as well and other things!!
Just to know what oil mix ratio and brand/ type (full syn or dino) were you using that steamy engine day?
Hope the bores are OK.

[Albert]

So I stopped by a local engine builder this morning, we had a look at the piston and cylinder. He did spot two small spots of aluminum in the bore but said they would clean up with a hone. Otherwise he said he wouldn’t hesitate to reuse the piston and he agreed the lines visible in the cylinder wall are minor and will clean up.

He immediately asked how big my ring gap was and I told him too big. He agreed.

Pete,
I was running 18:1 Lucas semi-synthetic for injection oil.

[ZUL8TR]

Keep us posted with pics on your progress. This is a great thread.

[Albert]

Thanks for the words of encouragement Pete. I know this is stuff some experienced racers have been going through for many years. But it’s new to me, and I figure it may answer some questions for other rookies along the way.

Maybe the lesson to be learned here is start with good gear. Or don’t hack a motor together. Or don’t be a mechanical masochist. Or that you can start with garbage and end up with a pretty nice set up if you have helpful friends, are willing to read a lot and don’t place value on your own time invested in a project.

[ZUL8TR]

Luc
You are welcome. March on with the work it will be worth it and a great accomplishment. I look back at all the people along the way that helped me and pass on what I can to others.
Have a good day
Pete

[Albert]

51753BCF-F06E-49D6-8A56-60DD43871401.jpeg OK,
So since no one seems to want to recast and machine heads for an 80 and replacement heads seem scarce it was time to get creative.
Step one consult the manual:

27. It is legal to re-machine squish band area to the following measurement: angle 15° ± 2°, 2.350 ± 0.015. No changes may be made to the combustion chamber. There must be a visible ledge surrounding the squish band.


I assume there is also a minimum cc for cylinder head but I don't see it in the apba manual.
Regardless my squish band needed love and my by hand grinding job last year left a lot to be desired.

If only I had something like this die to work in some valve grinding compound to repair the squish band without putting it on a lathe or mill.

[Albert]

Just re-read it appears it must be measured on the motor with motor at tdc…sounds messy.
I assumed there would be a spec for the head chamber itself.

[ZUL8TR]

No spec on CC's for just the head chamber. To measure with head + gasket bolted on block and head horizontal is not messy but must have accurate way to measure CC's of liquid you put in and remove all trapped air.

[Albert]

Need one of those cylinders with a degree.
You know a graduated one!



I’ll show myself out.

[pav225]

Tom Johnston may be able to clean up that cylinder head.

[deeougee]

That’s ok Mike, we can handle it in house, we have the technology. It’s actually an easy fix. We could even make them scratch if we really wanted too. The head dimension rule delete helped significantly with that but we could do with or without the dimension rule.

[Albert]

Tom Johnston may be able to clean up that cylinder head.

I would imagine he could, I’ve been told through the grapevine that he’s quite a competent machinist.
A skilled mill operator could make it perfect again. A good welder could even build up the dome with minimal warpage and then have it re-machined back up to original.

I am not a machinist, and I’m a lousy welder, but I think my tool will grind the band smooth, then a caliper can ensure both chambers are quite close and then measuring the volume of the heads as Pete pointed out will make sure the cylinders are balanced and legal.

I could have sent this head off to get fixed for 3-500$ Canadian. (200-350usd) but I wouldn’t learn much, and I wouldn’t have a tool to help me fix this problem if I need it. Or to help a friend fix a head in a pinch.

I do have a friend whose a bit of a cad/cnc nerd I’m sure he could make me a new head. But dropping 2k on a billet head wasn’t really in the cards for me right now.