ok so i have a 99 polaris spor 400 2 stroke. when i bought it i was told the head gasket needed to be replaced so i went ahead and replaced the head gasket, the intake gasket, the exhaust gasket, and the lower gasket(sorry cant remember name).

Well now when i ride the bike overheats. i get smoke out of the radiator and the exhaust. I also have alot of pressure building up in the radiator, when i start the bike it bubbles out. I checked everything. there is no water in the head. there are no cracks in the head or the jug. im lost. can someone please give me some ideas.

 

Welcome to the forum! If you didn't crack open the 10 mm bleed bolt on the rear of the cylinder head to purge any trapped air when you installed the new head gasket, then it's possible you may have overheated the engine. Just open the bolt and for about a minute or so until nothing but coolant flows out (NO air bubbles) Don't know if you did this or not,but I've had a lot of people that didn't and ended up with warped heads/cylinders and some ruined pistons. Plus it could have already been that way when you bought it? Plus is the fan kicking on and off? OPT

 

The fan stays on at all times. And I did not bleed it so I will do that today.

 

If the fan stays on constantly it's probably the thermal fan sensor mounted at the top back of the radiator(two wires to it) They usually short out when coolant level gets below this sensor and they get too hot. You can take it out and match it up at most auto stores. Hopefully you wont have to tear the engine down. If coolant still spews out after you've bled the system ,take the head and I would also take the cylinder to a machine shop to check it out. If you have a really flat hard surface you could work on (marble slab,etc) you can take 600 grit wet/dry sand paper and do figure 8's while turning the head around a little as you do this. Then clean the surface up and while holding flat you shouldn't be able to slip in a .001 feeler gauge anywhere under the head. Same on the cylinder. If this doesn't help then best to let a machine shop take care of it. OPT

 

Forgot also to mention you can use a straight edge along the cylinder at different angles and check it out with a feeler gauge along with the head also. If in doubt let a machine shop look at em. OPT

 

Alright. I'll check it out. The bike runs like a champ it just overheats quickly. Starts on first pull and runs strong and hard.

 

Then just try bleeding the head and replace the fan sensor and see if it still over heats. Plus not a bad idea to replace the 13 psi radiator cap (only about 6 bucks at the auto stores where you can find the sensor too) OPT