one cylinder wont fire!!!!! please help

[bolty16]

ok so what i have is a 95' polaris xlt. i recently rebuilt this old girl to rip. so i finally got her back to the start stage and pulled on it and fired. super pumped. only one problem is that the PTO or clutch side cylinder will not fire and is blowing fuel back out the carb. spark plug is NOT wet and spark is great. also i cant even spray ether into the carb and get it to fire. it is like the ports are plugged with something and it is pushing the air/fuel out rather than pushing it into the intake ports. here are my specs that i have checked. if there is one that i forget let me know so i can get this thing goin.

compression: 121, 120, 120
carbs are cleaned and rebuilt
sparkplugs: BR8ES
newer rings and pistons

so please any help or other questions about the sled let me know. or heck if anybody is around the portland, OR area and wants to buy one of these let me know. its for sale.

pm me or post. PLEASE

 

[retiredpop]

I think the crank has twisted so it is out of phase. In other words when the spark comes the piston is not in the correct position to fire. You would still get a good compression reading on that cylinder. In one crankshaft revolution each piston reaches TDC once separated by exactly 120 degrees of rotation from the previous one.

 

[bolty16]

ok that makes sense. any way to check at home? and if it is twisted is that new crank time or send it out and have it repaired? i have never dove into the game of crankshafts. please ladys and gents out there any more help would be greatly appreciated.

 

[retiredpop]

This is just an idea on how to check it as I have never done it. Get a degree wheel so you can stick it on the drive clutch cover. Make a pointer and fasten it so it points at the degree wheel. Then using a dial indicator gauge find TDC on one cylinder. Either rotate the degree wheel or set your pointer so it indicates 0 degrees. Then move your dial indicator gauge to the next cylinder and see if it points to 120 degrees (or 240 degrees) at TDC. Similarly check the third cylinder. That should tell you how it's doing.

There is probably a more sophisticated way of doing it and maybe someone else will chime in here with more info.

If it is twisted then you can get it repaired depending of course how bad it is. If I were you I would get hold of indydan on here if you need repairs. Do a search by user name on this link to get hold of him.http://www.snowestonline.com/forum/search.php

 

[FEZ]

oops, re-read the post.


continue.

 

[Super Dave3]

The easiest way to check crank phase is to bring the mag side piston to TDC. Then take two equal length screwdrivers and put one in the center cyl and the other in the PTO cyl. The tops of the screwdrivers should be at the exact same height.