1997 polaris xpress quad engine problems.

[hotroddal]

ok i have just recently put a new wiseco piston, rings, and gaskets into a 87 polaris xpress quad, and after i have put the new parts in it is making a funny noise like a nocking,just wondering if anyone has any ideas on what it could be.

[wheelie king]

I have heard that noise before on an old quadrunner I rebuilt, it turned out to be a "blowby" noise that was actually a whistle, or rush of air. Is everything sealed properly???

The noise on mine ended up being an exhaust issue that I finally hand to break out the mig welder for. I am just sharing my experience cause it was the last thing I was expecting.

[Wickedfinger]

... is it a 300 or 400?.

[hotroddal]

oops i ment it was a 1997 polaris xpress not an 87, and wickedfinger it is a 300cc.,o and by the way i lost one of the exhaust springs so i had to put a diiferent type of one on and it doesnt fit realy tight where it meats the muffler.

[Wickedfinger]

The Robin/Fuji/Subaru motors in the Polaris pingers are known for having their fair share of rattles and especially a low knock. Thats the oil pump though - it gives off a low thump. If its a new noise - I would suspect either a wrist-pin knock or more likely piston slap. This could be caused by either a bad overbore or you not getting an overbore out to .10 when you really needed one and just installed a std. sized piston. Rod knocks are rare in those motors, as with 2-strokes in general - unless it has super high mileage. The wrist-pin is an easy fix - but - you need to make sure you definitely replace the pin as well as the needle cage, because if it was bouncing around in there, its out of spec and unreusable even if it looks fine.

[hotroddal]

ok ill give ya guys the rundownb on everything that i did to this previously- ok i first bought the machine witha hole blown in the top of the piston, so i honed it and bought a new wiseco piston, rings,wrsit pin needle bearing and gaskets and cleaned the carburator and thats all id di to it i do not know if it made this noise or not before i got the machine becuase i bought it with a hole in the piston, so all i did was rebuilt the top end i notices a noise coming from the motor, but the more i ride it i am suspecting that maybee the clutch on the side of the engine is going bad because it oesnt have much for a takeoff and takes a while for it to get up to speed, so what i am planning on doing is taking the clutch cover off and inspevt the clutch.

[hotroddal]

ok guys i have found out the problem and i just want to tell you guys, it has bad crank bearings and seals and it blew a hole in the top of the piston from it sucking air from the seals and bearings.

[Wickedfinger]

Runnin lean. Well, the good thing is, the motor is a sinch to work on - once its actually out of the machine (thats another story). Its nice not having any tranny to deal with.

[hotroddal]

hey i have another question are the crank bearings pressed in?, i think they are, but i wana make sure, i have a press that i custom built so i can do the job myself, just wanted to know if there pressed in or not, im planning on taking the engine out sometime next week and tearing it apart again.

[hrc85250r]

you can install crank bearings by putting them in the freezer and putting your engine cases in the oven at 350 for 20 mins or so....at least thats how i did my R's mains...

[hotroddal]

i have a press to press them out so i will not have to do that freezer trick, but its a neat trick.

[mbg75]

like wicked said, it's a pain in the a** to get the motor out!

[hotroddal]

why is it a pian to get it out, when i put the new topend in it it looked like it would come out pritty simple.

[Wickedfinger]

..... you just have to take off alot of parts to do it, thats all. Its not like on an older 250R, where you could literally swap an engine in and out in 30 min.

[hotroddal]

ok i get it now