I recently took my engine apart in my 03 polaris sportsman 700 because it had been sitting for 2 years and needed to be cleaned out. When I took the engine apart, I forgot to mark the timing gears so I lined up the factory timing marks. When I first cranked the engine over it started but I could hear a knocking noise coming from the engine, as if the timing wasn't right. The engine soon died and now all the engine will do is crank over, but will not start. I can't figure out where to start with the knocking issue, or what could be causing it. Any insight would be greatly appreciated.

 

Compression check first. If the cam gear,counter balancer and crank sprocket weren't timed right bent valves could be the result. Knocking could be anything,if the double cam sprocket came apart and jumped a tooth,this could be the source,but I'd be mighty suspicious of a bad rod bearing also just from my experience with them.

 

Thank you for our help. I'm gonna try to work on it this weekend. Not sure what a rod bearing is. I guess I'll start with a compression test and then move to the cam gear

 

Crankshaft is a complete unit on the 700 and parts not offered by Polaris. Can get expensive if it is a rod.Dirt Cheap Yamaha, Honda, Arctic Cat & Polaris OEM Parts & Accessories – Cycle Parts Warehouse

 

Will the camshaft journals cause a knocking issue if they are excessively worn? The oil relief holes in the journals are worn down and are now about 1/2 inch long rather than just a circular hole.

 

Possible,but you need to measure the cam shaft journal OD and the case bore ID to make sure. If you have as manual it's under engine specs,if you don't here's a cheap 5 buck pdf service manual.2003 Polaris Sportsman 700 Service Manual PDF Download

 

I think I need a new crank shaft. One of the piston rod has a lot of play in it at the crank shadt end. Do you think that could be the issue.

 

Rod should have no up and down play,if it does crankshaft has to be replaced.

 

Okay thank you. It's pretty clear that this is what is causing my knocking issue. I have been able to find a crank for $660. Do you know anywhere I would be able to find a used crankshaft?

 

Last thing I'd trust is a used crank shaft on 700 or 800 twin! If the atv is worth repairing,that is everything else is in decent shape,I'd repair it right. I will warn you though there is a lot of posts on Ducati ignitions failing eventually on this model also. Just search ignition problems on 2002 to early 2004 Sportsman 600 and 700 models on this or other forums or just do a Google search. If it does fail,it's another $500 for the kit,on top of the engine repair.