rebuilding a 2 stroke

[ryan 83]

I am getting ready to rebuild a polaris 90 2 stroke for the first time. should the wrist pin be very tight or should I be able to tap it lightly and it pop out? it seems very tight is this something I should worry about. my plans were to have the cylinder bored and a over size piston put in. 7 years old and never been touched internally.

Thanks for any info

Is this in the old piston?? It should just slide in if its new. The oil probably heated up and made the pin rough to get out. Just push it out but dont use enough force to bend your rod. Please let us know how your doing.

[ryan 83]

I got the wrist pin out it was very tight. I am looking for a place to bore my cylinder and pick up an oversized piston and rings. what are some of the more economicals ways to produce more power out of these engines?

Here is a list of accessories we have on it. Any advice would help.

-hetrick pipe
-aftermarket cdi from hetrick
-clutch kit from hetrick
-31 tooth rear sprocket
-16 inch snow hogs

My 8 year old drag races this bike and did very well, but we need a little more power/speed.

Thanks for any help

[ryan 83]

ANY INPUT- NEED SOME ADVICE!!!

Have you thought about a 54mm kit ported and polished?? You can use gearing to get where you need since having enough power to pull many varieties of sprockets. It is a very storong set up if its done right

[ryan 83]

What kind of expense am I looking at compared to a normal rebuild? Can I use a stock carb or do I need a larger one?


on the oil injection do I leave the mechanical part of the injector bolted on the engine? is there a block off plate? or do I cut the hose which has the spring protection around it and plug it? I removed the entire system but now there is a hole into the engine not sure if this is correct.

THANKS

[wv racer]

Does anyone have any more info on this issue? oil injection block off,cylinder bore and piston kit

you can leave you injection part mounted till you get a block of plate.

[wv racer]

how much more HP is 54 mm kit going to give me over a standard cylinder bore and oversized piston kit, also how much more expense?

What kind and how big of a carb can I use and get results from with a stock bored cylinder or a 54mm ported and polished kit.

Thanks in advance for your time I am new at tring to make these little cvts run.

I just want to ask what are you trying to accomplish. Trail riding, racing, or??? I need to know what application you after then I can answer you in the appropriate way. I don't want to steer you in the wrong direction not knowing what you are wanting. Please let me know and I will do my best to steer you the right way. Thanks

[wv racer]

MY 8 year old is drag racing (300ft) on dirt.

the currently has on it - hetrick pipe
- cdi form hetrick
- clutch torsion spring, rollers and springs from hetrick
- 31 tooth rear sprocket

I have the entire bike tore down to paint and repair a few bearings and thought since it was 7 years old it was do for a rebuild. had no issues with it still run very strong we are just needing a little more hp (speed) to compete competitively. I have the cylinder removed I finally got the wrist pin out (very tight) and removed the piston. I am now looking for ideas of what to do next bore the cylinder or get the 54 mm kit. I am also looking at the expense.

Thank you for your interest in helping me.

Ok if you use a 54 mm you can run a taller gear to get more mph than you can from your stock motor now. The bigger the piston will infact give you more power than your current motor. Changing to a 45 mm full circle crank would also help you and make a bigger cc machine. It would be a power house anything over a 45 mm crank mean case machining. So a 45 54 motor would indeed if done right would be a monster of a mini. It would have one heck of a take off as long as your clutch is set up right. So I hope this helps.