I tore down the 400 Sport to send cylinder off to HPD for race porting and found that the piston is badly scored on the intake side of the piston. I have only 10-15 hour on the .060 over Wiesco piston. The cylinder on the intake side is also scored. I've noticed a chattering noise on the pull start side of the motor thinking it might be a counter balancer bearing. I now have to bore and install a new piston. I talked with Mike at HPD he guessed that dirt was getting into the chamber. I am a fanatic with oil changes and clean air filters. I have two air filters with one always clean that I put in after the days ride. The airbox has Ritters/Uni foam mods, I'm not blaming the mods but the air filter is very dirt after the days ride. What is the best air filter set up?

Thanks
Jay

 

Are you running premix or using your injector ?

 

I'm premixing 32:1 using Klotz Super Techniplate. The scoring is mainly on the piston skirt about 1" wide and tapers to 1/2" up near the rings. I rotated the crank and did not hear any grinding noises. I looked in crankcase with a flashlight and did not see any filings or major dirt. The way that the piston is scored would account for the chattering I'm hearing. Surdykes told me that Weisco pistons have a tendency to be noisy. Surdykes did not do any work on my machine, just to clear that up.

Thanks
Jay

 

Pud i was just talking to the tech service guys at work yesterday and this sbject came up, They say that it is caused be a improper bore and piston fit. To tight on the cleareance, They actually did tests to figure it out so it may be worth looking into. Also it is that it is somthing to do with the way the piston is made CAM GROUND VS NON CAM GROUND ?

 

scoring a piston on the intake side is caused by not letting the engine come up to temp before getting on it hard. the iron liner expands slower than the alum piston from the heat and you clearance goes away. you should never run a water cooled engine hard till you can feel heat in the cly. i have fixed this problem for many riders who do not let the engine come up to temp.

 

Motorman, you are the second person that advised a cold seize. These Polaris motors are touchy creatures. From hear on, 5-10 min idle warm up will be mandatory. I learned the hard way. Any of you new Polaris/Wiesco piston owners listnen up. If not, it will cost you $150-160 if you do your own work. This Polaris is turning into a major money pit. Crackers are free with the whine.

Sucks to be me, but when I get it right the Sport is gonna scream.
Jay <u>Text</u>

 

Dazed..HPD requires a tolance .045 piston to cylinder tolorance with thier race port. Victory Lane did the top end job and claimed a .035 clearnace. To be honest, break in may have been rushed. To this point, I was a beliver with breaking as you ride it. The EX responded well to this procedure, but it's a 4-stroke.

 

Wiseco pistons are made for &quot;moto-to-moto&quot; only. This is why they are so cheap. Do yourself a favor and use a better quality piston (JE or even stock!). I have had so many problems with Wiseco pistons![img]i/expressions/face-icon-small-disgusted.gif[/img]

 

if the cly has a iron liner this is a big problem. back in 87 my friend bought a new honda 250 R and it had no power. we pulled it down and found the piston seized on the intake side. he never ran the honda hard till it warmed up so it happened at the dealer before he picked it up. nicosil lined cly are not as bad because they expand fast because they are all aluminum.

 

JE does not make a 400L piston . I think JE and Wiseco are owned by the same parent company .