Some help

[ACOLDTO1L3TS3AT]

I just purchased a 1994 stock banshee, only mods it has is a top end sprocket and pinion, and its never had any work done on the engine, so im planning on working on it asap... now im not to familiar with these banshee engines...

 

... The compression on it is so low its not even funny, like you can push the kick start with your hand low, but it starts on first kick every time and runs like a beast, but you can just tell that the compression is not there though... I mean its a 1994 never worked on.

 

So im planned on getting:

Some new pipes (undecided between fattys and t6's)

V force 3 reeds

Milled/shaved cool head

Wiseco pistons

New gasket(s)

then getting it ported along down the line

 

Now, what I know is pistons and heads come in different options(0.03/0.06/0.08, etc.), what size head and piston should I get since its a stock motor, also, should it help the compression at least a little? Im not too familiar, so bare with me, I just know your basics.

 

Thanks.

[crustydemon]

I just purchased a 1994 stock banshee, only mods it has is a top end sprocket and pinion, and its never had any work done on the engine, so im planning on working on it asap... now im not to familiar with these banshee engines...

 

... The compression on it is so low its not even funny, like you can push the kick start with your hand low, but it starts on first kick every time and runs like a beast, but you can just tell that the compression is not there though... I mean its a 1994 never worked on.

 

So im planned on getting:

Some new pipes (undecided between fattys and t6's)

V force 3 reeds

Milled/shaved cool head

Wiseco pistons

New gasket(s)

then getting it ported along down the line

 

Now, what I know is pistons and heads come in different options(0.03/0.06/0.08, etc.), what size head and piston should I get since its a stock motor, also, should it help the compression at least a little? Im not too familiar, so bare with me, I just know your basics.

 

Thanks.

 

First off you really need to read up on two stroke engines or just take it to someone who has experience with them, it's not like a four stroke at all and you cant determine low compression by how easy it is to move the kicker. Granted it probably is low if its not had a top end for a long time. As for your question, bore the minimum. You gain little if any power by the overbore and all you do is shorten the usable life of the jugs.

[ACOLDTO1L3TS3AT]

First off you really need to read up on two stroke engines or just take it to someone who has experience with them, it's not like a four stroke at all and you cant determine low compression by how easy it is to move the kicker. Granted it probably is low if its not had a top end for a long time. As for your question, bore the minimum. You gain little if any power by the overbore and all you do is shorten the usable life of the jugs.

Yeah, I def. know about these engines, just not every little meticulous thing about them as this is why im here asking. Ive had a raptor for a minute, and I built go carts for a living, but thats beside the point. Im planned on doing everything besides the pistons, I already have a shop that I talked to that will do it for me, also whats the different in the sizes of the bore of the pistons? And im getting a compression tester just to check, but I just know its too low, its just too easy to turnover...

Edited September 12, 2010 by ACOLDTO1L3TS3AT

[crustydemon]

Yeah, I def. know about these engines, just not every little meticulous thing about them as this is why im here asking. Ive had a raptor for a minute, and I built go carts for a living, but thats beside the point. Im planned on doing everything besides the pistons, I already have a shop that I talked to that will do it for me, also whats the different in the sizes of the bore of the pistons? And im getting a compression tester just to check, but I just know its too low, its just too easy to turnover...

 

Sorry man, I think I misunderstood your post, anyway I dont know exactly what your asking about the piston sizes. .020 is 20 thousandths overbore .030 is 30 thousandths over etc. You may also find them marked in millimeters such as .25, .5, 1, or 2. Anyway you dont have to worry about any of that, your macine shop will determine what is necessary to "klean up" the cylinders. Hope that helped, if not someone else can jump in.

[ACOLDTO1L3TS3AT]

Sorry man, I think I misunderstood your post, anyway I dont know exactly what your asking about the piston sizes. .020 is 20 thousandths overbore .030 is 30 thousandths over etc. You may also find them marked in millimeters such as .25, .5, 1, or 2. Anyway you dont have to worry about any of that, your macine shop will determine what is necessary to "klean up" the cylinders. Hope that helped, if not someone else can jump in.

Basically, can I accidently get one that is too small or too big? And whats the difference as in performance output?

 

Thanks for your input though.

Edited September 13, 2010 by ACOLDTO1L3TS3AT

[smith]

Im no expert so correct me her if im wrong anyone. Im doing the topend on my banshee right now I have the pistons on order right now. Im going to send my pistons over to the machine shop with my jugs thats how they will know how much to bore out my cylinders. Like I said Im by no means an expert.

[midlifecrisis]

Smith is correct as well. You take your jugs to the shop, allow them to mic your cylinders to let you know what size to buy, then once they arrive, the shop will take out the correct amount of material to maintain the size of your cylinders for as long as possible. Boring them too big will only shorten their life, and cause you to have to source out a new set earlier, or have them resleeved.

 

You can only buy new pstons up to 2.5mm over the original 64mm bore (this translates into .100" over) .25mm roughly equals 0.010"

[Balzout]

It's a little risky to order the pistons before you have your cylinders looked at by the shop that is going to do the work. They will put a bore guage in them to check for out of round and can tell by looking, about how deep the scratches are to be sure they will be cleaned at a certain overbore. Most times it works just to get the next size bigger piston, but why risk it.