time for a top end?

[m4i2k2e2]

hey, i bought a 1999 cr250r. i asked the guy if the top end was fresh. he said it was recently fresh. he di have to think about it. so, im not sure how fresh it really was. in the last 2 months ive put in about 30 hours. how often should i do it? the bike seems to have alot of power, but ive never ridden another 2 stroke 250.

 

[Brian1c]

I JUST DID MY 99 CR250 AFTER 33 HOURS (AFTER BUYING IT USED). It was ready. You usually can tell when the kick starting gets easy from lack of compression. I am putting a 265cc kit on, but in retrospect, should have stayed with 250cc.

 

[FruDaddy]

Take the jug off and get a look. If you can't tell, find somebody with more experience to take a look for you. Having a piston explode on the track sucks, and can cost you a lot more time and money. The day mine went south, the compression still felt good, and it fired on the first kick. While waiting for parts, I spent a lot of time removing metal particles from the case.

 

[KX250Dad]

To some fresh means simply putting in new rings with a piston... Beings you recently purchased the bike you really need to know what shape the cylinder is in and whether it's in spec... point being, you may get little life out of new std rings and pistion should the cylinder be worn beyond limits. Fru is right, piston slap breaks pistons and the pieces in the wrong place (crank) will cost much more than an inspection now.

Invest a little time and money now and you'll have a lot of fun with little post purchase costs this upcoming season.

 

[whenfoxforks-ruled]

What is the oem recommended hours on a 250 2 stroke?

 

[FruDaddy]

I dunno, my owners manual (04 KX250) says to replace the piston every 5 races (one since the last top end). Of course, I have only participated in 3 or 4 races this year. Knowing the hours wouldn't help me much anyway since I never wear a watch at the track. I have absolutely no idea how much time I actually spend on the bike on any given weekend.

 

[whenfoxforks-ruled]

5 races sure does not seem like much time for a piston Fru, ouch. Course we do not ride like Stuart. But time is still relevant! Good maintenance and staying on top of it should help keep your repair bill down. When I estimate riding I go by how long I ride before my arms get noodly! 20-30 minutes

 

[FruDaddy]

I'm sure Mr. Stewart starts every race day with a new slug.

I pulled a seemingly good piston out of my son's bike after over a year of weekly riding. Not everybody is so lucky.

 

[whenfoxforks-ruled]

Extended use can oval the bore.

 

[xkevenx]

i have been told you should put in a new piston every 30 hours that makes some sence...