Yamato 321 top cylinder temp

[Bipolarboater]

Cooked same motor over the weekend.....7/8s down, 1/2 in tuck. And now on a 302 tower. That is the second time in a year for this 321 head. Temp was around 450 on the mychron5.

[Ericwienczak]

Id give it up until the sorc makes a change. We tried everything in the book with minimal improvement

[sutton99]

try taking the the tuck out

[Bipolarboater]

Update....crank is twisted and bottom bearing may be seized...more to come

[ZUL8TR]

Cooked same motor over the weekend.....7/8s down, 1/2 in tuck. And now on a 302 tower. That is the second time in a year for this 321 head. Temp was around 450 on the mychron5.

Which cylinder? What max revs are you doing ? What oil type brand and mix are you using? Since you say you cooked the same power head and I assume repaired it, did you change the piston clearance? Is too much water being released from the top of the head tell tale? Maybe its your boat and /or prop?

[Matt Dagostino]

Contact your local rep and the SORC Chairman for answers................that's what they are there for , to solve problems............................our 321 tower is on the rack to stay due to the same issue you have. We now run a 302 tower in 20ssh and barely cool with that. Have fun.......

[deeougee]

Have you tried moving down one or two heat ranges with the plugs? Running platinum plugs will help. Have you also tried to run richer? More fuel helps cool the combustion chamber and cylinder. Platinum plugs will help with fouling if you go down in heat range and run a richer fuel mixture, 26:1 produces the most HP on any 2 stroke engine, this is dyno proven. You may have to run richer though to help with cylinder temps. Your cylinders also have to be perfectly straight, any high spot will create a hot spot and increase cylinder temp, same with piston rings. People may not think these things make a big difference but they do and the dyno proves it when you add it all up. Yes cooling water is part of the problem, but this motor was not designed to run the heights we are running so you have to compensate in other ways. Just thought of a couple of other things, retard the timing a bit also and you may want to check your pipe for cracks and make sure the cone hasn't come off, these will also affect engine temps.

[ZUL8TR]

Have you tried moving down one or two heat ranges with the plugs? Running platinum plugs will help. Have you also tried to run richer? More fuel helps cool the combustion chamber and cylinder. Platinum plugs will help with fouling if you go down in heat range and run a richer fuel mixture, 26:1 produces the most HP on any 2 stroke engine, this is dyno proven. You may have to run richer though to help with cylinder temps. Your cylinders also have to be perfectly straight, any high spot will create a hot spot and increase cylinder temp, same with piston rings. People may not think these things make a big difference but they do and the dyno proves it when you add it all up. Yes cooling water is part of the problem, but this motor was not designed to run the heights we are running so you have to compensate in other ways. Just thought of a couple of other things, retard the timing a bit also and you may want to check your pipe for cracks and make sure the cone hasn't come off, these will also affect engine temps.

Which dyno, what engine, do you have a link to the tests? That 26:1 on a 2 stroke water cooled is different than what has been reported with back up.

[deeougee]

That stuff was written up back in the mid 70's and there's been lots more to back it up since. 2 stroke theory is 2 stroke theory regardless of the application, bike, kart, boat etc. it's all the same, look it up. The same mathematical formulas apply for all. One of my mentors started racing Kawi triples back in 71, won back to back titles. Did Karts after that, dominated there, boats same result. Here's some more advise, take the Y321 spray shield and throw it in the garbage because the rules say you can, all the baffling in it is restricting air flow into the carb. Take your temp gauge and do the same with it and learn how to read your plugs. The temp gauge is the same as the idiot light in your car, it's to late by the time it comes on. I've run some Yamato's at 10:1 to keep the motor from burning up, which is what you are trying to prevent right? Want to know why you should go to platinum plugs? The melting point of platinum is 1774 degrees celcius versus 1535 for iron. So its less likely to melt, has a thermal conductivity 18 times greater than iron and will not oxidize. Translation, platinum plugs are less likely to foul so you can drop in heat range which will help with the cylinder temp and can withstand the harsh environment better.

[squirrelboydeluxe]

This is a fascinating thread- particularly for a rookie-
But why is it in the for sale section?

Maybe it's here to scare potential 321 buyers away...it sure has me scared to death
squirrelboy

[Bipolarboater]

My bad...in the wrong place....ps don't be scared,of a 321 as it is the only option we have for a new engine.....learning,today is that crank is twisted and the bottom bearing is bad. Many 321s run well with no drama.,, something went afoul here. Root cause still being investigated.

[deeougee]

Didn't realize this was in the sale section. You could also save yourself from all this and run 300SSH. Get yourself a nice boat and work on your driving and starts. If you need parts or work done you might want to ferret out the Kart guys, they are light years ahead of where we are at. Luckily for me I have the 2 top guys in North America in my immediate area. Their company build engines from a sheet of paper. I get a lot of machining support from them.

[Ram4x4]

Was the intake hole drilled out on this engine as per the new rule?

[HydroKyle93R]

In rare cases, overheating a motor will dry-out and damage the rod bearings. I have seen this happen three times in the last three years, first hand. Three times may not seem so rare, but from my perspective, I've seen 302's and 321's overheat, or stick, dozens of times in the ten years I've been racing C Stock Hydro. Good luck with the rebuild, Bipolarboater.