Boring out a Tri-zinger

[Cert88]

I was wondering if there is any piston I could buy that would work in a tri zinger that is at its max bore. It it possible to bore it out more and put a different piston in.

Yamaha over makes two bore sizes over std. And it doesnt look like there is a sleeve you can replace, once its at max. So a new cylinder is the only option if another piston/ big bore will work.

I have a cylinder at .50 over std now.

Anyone know anything about this?

Thanks!!

[Vealmonkey]

You can try using a cylinder out of a pw50, it will just bolt in. Then you should be able to use a standard yt60 piston.

[Cert88]

Thanks Vealmonkey

Does the pw50 cylinder have to be bored to the yt60 standard bore? cause it is too small at standard correct?

[Vealmonkey]

Yes, that is correct. A hop up for the pw50 has been to bore to the yt60 piston. Hopefully you can find an unmolested pw50 cylinder. You might have a better time finding a new pw50 cylinder at the dealer if you have to.

[Cert88]

Ok cool, thanks.

Say I get a new pw50 cylinder... (one on ebay now, for $70, with piston, rings, head etc)..... Could I just use that complete top end? I dont see why i couldnt correct? The heads are swappable too?

Yea I will have less power, but I can bore it couple times, than I can install the yt60 piston after it is past the pw50 pistons... So I should be good for a lonnnng time than.

Thanks for all your help vealmonkey!

[Vealmonkey]

That sounds like a game plan. Your child really won't notice much difference in performance and you will have several bores so it should last a while. Also the big thing to check is if the cylinder is out of round or tolerance. You might be able to get away with a slight honing and just a new set of rings if you stay on top of it mechanically. The heads are the same head. If you get another head, you might want to experiment with removing some material from the head, it will up your compression, meaning a little more power. If you have a friend that is a machinst, you might want to see if he can "deck" the head for you. It's been along time since I've done any performance work on a zinger, so you might only want to shave a couple thousandths off it at a time, like 5 thousandths or so and sneak up on something that will work for you. Remember to check the cylinder pressure with the stock head and every time you shave it down for experimental purposes. Make sure you have clearance between the top of the piston and spark plug and be careful, you can really bump up the compression pretty quickly and make the zinger hard to pull start. If you start running the compression up too much, you might have to switch to a higher grade of gasoling. Also, I would highly recommend pre-mixing your oil. I never trust 20 plus year old 2 stroke oil pumps. Just find a nice premium pre mix of your choice and follow the makers oil ratio and you should be in good shape. I can't remember what yamaha recommends for the zinger ratio. Just make sure you run enough that you don't have a meltdown but it's only a zinger, right? I hate to tell you all the tricks we did to the old zinger to get them to run. And then what we did to modify them. I'm talking new cylinders and heads and the whole she'bang! All the modding we had to do cause of that crappy intake system to get them to make good power. And those modding tips have all but long since disappeared. Have fun.

[Cert88]

Sweet... thats what i'll do.

Thanks Again!