How often do you rebuild your 2 stroke?

[InfernalVortex]

Im kinda new to this sport, but I've pretty much fallen in love with riding. I think I've been out practicing on the bike at least 5 days a week the last two weeks since I got my bike running. As you can imagine the hours are clocking up on that rebuild pretty quickly. Eric Gorr says the 125 two strokes need new bottom ends every 80 hours. I think I'll go through 80 hours within the next year or two!

But I can deal with that, whatever.

But my service manual says i need to replace the piston every 7.5 hours. Do you guys really replace these things taht often? I will stretch that out to a few months probably just because Im learning to ride and I just dont have the guts to hold on and ride the pipe very often so it probably doesnt get beaten as much as some of the race bikes do, but still.

So I wonder... how often are you guys rebuilding your top ends?

Im curious about the bottom ends too. I dont think I'll just split the case at 80 hours and replace the crank, but its kind of sobering to think the week I spent learning to rebuild the bottom end may only be good for a year or two.

Just wondering what the real world intervals are... for us regular guys.

[farfromhome63]

you need a hour meter to accurately guage your riding time. I have a 250 2stroke and I religously keep the air filter clean and keep good oil and fuel. I make sure my jetting is right . I go without getting nervous 40-60 hours on a piston. 80 hours is pushin it.. now rods I usually check when I do the piston. the manual should state the range or tolerance.
In my case it lasted 10 years before blowing the lower bearing up! thats a long time. now if your not riding hard I say go 6 mo before piston replacement. and as long as the rod is inspected every time you change the piston I dont see what could keep you from using it for 2-5 years. air cleaner maint is the biggest culprit then jetting next is what causes failures. the piston skirt usually breaks and that takes the rest of the engine with it.. good luck have fun and be safe!

[KKXR400R]

The wife's CR gets a piston after 80-90 hours and a re-ring around 40-50 hours. The KTM seems to last a little longer. I pushed 114 hours and 21 races on a stock piston/rings. When I pulled the top end apart the rings, piston and cylinder were still in spec and cross hatches were still visible. I tear the low ends apart every other season. Just to make things easier I have adopted the same schedule as the CR.

Buy yourself a compression tester and an hour meter. These are great indicators of the life of your top end. Keep records/dates of the numbers your getting, the maintenance you do to the bikes (bearings, cable cleaning etc) and settings (suspension, jetting etc).

Hope this helps.

-Kevin-

[Dan Surett]

i usually wait till it looses power or makes noises to replace major engine parts. But it also depends on how you ride, my father has a 78 rm 100 all original except for the clutch and its still being ridden and starts up 2nd kick

[BigRedWood]

I do rings at every 15-20 and a new topend about every 50-60.
I kind of over do it personally. I like that fresh topend feel.
Otherwise, I have probably 100 hours on the bottom . . . I just change the oil every other ride and filter every ride. Not a fan of splitting cases. Crap I have been sitting on a new crank for two years . . . no real play / vibes from the crank
I get in the habit of getting extra base gaskets. You can always take a look at the piston / ring / cylinder for 4-5 bucks. Rings are reasonable also.

[rodogg]

i just ride my bikes till they stop, in my opinion theres no point replacing something unless it has to be done, or its just a waste of money

[MegaDeTH]

hundreds on my ktm, 80-100 on my japanese mx bikes

[alecks]

i keep the air filters and make sure the mixtures always correct to keep the top end in its best condition. then i just run it till its outta compression.

ive gotten over 100 hours on my cr, then it needed a new ring job

[skos]

Originally Posted by rodogg

i just ride my bikes till they stop, in my opinion theres no point replacing something unless it has to be done, or its just a waste of money

Agreed. My 98 YZ I bought for 1200 bucks 5 years ago. Rode it hard about 20 times a year sometime for 6hr at a time. I take real good care of it. When something breaks, I completly fix it (if I have the money).

[ossagp]

The kind of bike owners I won't ride with if we are getting out of sight of the pickup, just responded lol

[BOSARACING]

Have just purchased a used bike for the next season, it have 125 hours on the hourmeter, do it need rebuild of the bottom end ?

[ossagp]

skos thinks you should wait for it to break.