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89 piston and crank in an 86 jug
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Posted by: superevil

Can you run an 89 longrod crank and the 89 piston with an 86' jug?

Posted by: rustyATV

Yes, but you'll want to be wary of how much time you put on that piston because, as the piston wears, it can rock in the bore, making it more likely the skirt will lodge in the intake.

A better situation is to use a base plate and the '86 piston.

Posted by: superevil

Why would the 89 be more dangerous to run than the 86,i was under the impression that they were the same except for pin height

Posted by: C-LEIGH RACING

School time boys.
Neil

Posted by: superevil

quote:
Originally posted by C-LEIGH RACING
School time boys.
Neil

What do you mean?

Posted by: rustyATV

quote:
Originally posted by superevil
Why would the 89 be more dangerous to run than the 86,i was under the impression that they were the same except for pin height

No, they are not the same design; see the below image. On the left is the 86 and earlier piston, on the right is the 87-89 piston (never mind the crack on the intake skirt

).

Anyway, in addition to the 5mm pin height difference, the extra skirt of the later piston can wedge itself inside the intake of the early cylinder, and will, if the piston develops enough play from wear.

http://img.photobucket.com/albums/v11/hoppy/100-0001_IMG-1.jpg

Now, I have run a late piston in an early cylinder for a whole season of XC racing (including practice) without a catastrophic failure, but I did notice quite a bit more wear on the intake skirt of the piston when I did a top end job, than what I got from the late cylinder.

So, like I said, you can do it, but you'll want to make sure you service that top end at a reasonable time. If you think you're going to be a little lax in doing so, do yourself a favor and get a base plate and the early piston.

Posted by: superevil

Well the main reason im asking is im wanting to run a +4 stroker crank in my 86 cylinder,but i can only find the stroker crank with a longrod,so i wanted to run the stroker with the 89' piston so i didnt have to space the cylinder so far

Posted by: rustyATV

In my opinion (not speaking from experience, just theory), a stroker crank increases the possibility of the late model piston becoming lodged in the intake, due to higher side loading from the longer stroke. I'd re-think this motor, if I were you.

Posted by: deathman53

you are also aware that stroker motors require the port timing to be changed(re-ported).

Posted by: superevil

What if i ran the long rod stroker crank/with an 86 piston.
I could run a spacer plate for the added rod length and have the head milled for the added stroke length.
Porting will definitely be involved in al this

Thanks for all the help btw

Posted by: C-LEIGH RACING

Why I said school time, because I can read in your post you've never done this before & your going to need a bunch of help.

First off, what your thinking about doing with the stroker cranks not a bad idea, just one that who evers doing the work needs to have done one before or at least helped in the process.

An engine set up like this takes a god auwfull amount of work, that is if its to perform like its suppose to after the build.

Spacing the cylinder for the added stroke, you can do it that way & it will work to some extent, but remember this, performance, since thats what your after to begin with wont be prem or at least one thats easy to handle.

Any 2 stroke engine build, what ever it may be or size, the ports need to be down low at the bottom of the stroke BDC.
Only way, it will work spacing the cylinder so the piston comes up flat with the deck, is if your intending the engine to be a drag race output engine.

One more thing to take note of, if the cylinder your intending to use has had any porting done to it at all, in the end after the build it will be an even more drag race engine.

Neil

Posted by: superevil

quote:
Originally posted by C-LEIGH RACING
Why I said school time, because I can read in your post you've never done this before & your going to need a bunch of help.

First off, what your thinking about doing with the stroker cranks not a bad idea, just one that who evers doing the work needs to have done one before or at least helped in the process.

An engine set up like this takes a god auwfull amount of work, that is if its to perform like its suppose to after the build.

Spacing the cylinder for the added stroke, you can do it that way & it will work to some extent, but remember this, performance, since thats what your after to begin with wont be prem or at least one thats easy to handle.

Any 2 stroke engine build, what ever it may be or size, the ports need to be down low at the bottom of the stroke BDC.
Only way, it will work spacing the cylinder so the piston comes up flat with the deck, is if your intending the engine to be a drag race output engine.

One more thing to take note of, if the cylinder your intending to use has had any porting done to it at all, in the end after the build it will be an even more drag race engine.

Neil

Well i have decided against the stroker.
Im just going to have the cylinder ported to work well with the ftz pipe and 38mm carb. Im running stock port/stock carb/and a curtis sparks mx pipe right now,so even without the stroker crank its going to be a big difference.

I just came to the conclusion that i dont want to deal with a really complicated setup on a play bike.

Can you recommend anyone to me for porting a 250r cylinder?
I dont want a full on drag port,but i will need an aggressive enough port to work well with the ftz pipe and large carb.
The cylinder is a stock port stock bore 86'

Posted by: gojk

quote:
Originally posted by superevil
Well i have decided against the stroker.
Im just going to have the cylinder ported to work well with the ftz pipe and 38mm carb. Im running stock port/stock carb/and a curtis sparks mx pipe right now,so even without the stroker crank its going to be a big difference.

I just came to the conclusion that i dont want to deal with a really complicated setup on a play bike.

Can you recommend anyone to me for porting a 250r cylinder?
I dont want a full on drag port,but i will need an aggressive enough port to work well with the ftz pipe and large carb.
The cylinder is a stock port stock bore 86'

Send it to Neil(c-leigh). Never have used one of his cylinders, but from what I understand, you won't be disappointed.

Posted by: cdrookie

c leigh is who you want to send it to! and i'd stick with the sparks pipe over the ftz

Posted by: C-LEIGH RACING

quote:
Originally posted by superevil
Well i have decided against the stroker.
Im just going to have the cylinder ported to work well with the ftz pipe and 38mm carb. Im running stock port/stock carb/and a curtis sparks mx pipe right now,so even without the stroker crank its going to be a big difference.

I just came to the conclusion that i dont want to deal with a really complicated setup on a play bike.

Can you recommend anyone to me for porting a 250r cylinder?
I dont want a full on drag port,but i will need an aggressive enough port to work well with the ftz pipe and large carb.
The cylinder is a stock port stock bore 86'

Good choise.
You will enjoy keeping it a simple build in the long run & next time it needs working on, just regular parts will fit. Probably be cheaper as well.
Neil