kmx 125 top end rebuild

[indo247]

I just rebuit my top end, new piston rings and the like.. in the haynes manual it says 500 mile break in at 4,000 rpm 500 - 1000 miles at 6,000 rpm.. seems like a long time to me. what do you reckon?

[stevo as b4]

Yeah it's Kawasaki's reccommended running in schedule. I personally think that running in a 2stroke engine should not take more than 300-400miles really. 1k takes some of the lifespan away of the top end on a high performance 2 stroke.

It's important to not load it up too much to start with, and also not baby it for too long. I Personally think that 120miles or 2 tanks of fuel at under 5k rpm is plenty, but use the gears and don't let it labour even slightly. Rev the engine freely up to 5-6k but with no more than 1/2-2/3 throttle for a while and use the gears more when slowing down too. Try to vary the road speed so that the bike cruises at 5, 5.5. 6k and occasionally take it to 7k max just in acceleration briefly, not for crusing. The Kmx won't pull 4k in top without labouring the engine too much, so keep it at 5k and above.

After 3-4tanks of fuel you should be freely revving it up to the power band, and occasionally going into it and revving it closer to 8-9k and then occassionally to the redline. Always vary the cruise speed and sometimes sit in 5th and 6th at different revs. Once you have done around 400-500miles, then the bike should be pretty well as good as it gets. Just remember not to load it up or use full throttle for more than a few seconds until 500miles+ and then gradually work up to using more full throttle use and putting it under more load over say the next 100miles.

[indo247]

thanks for the reply, very helpfull i thought 1000 miles seemed a bit much. I took it out today for the first time and did 50 miles keeping the revs around 5, 5.5 which gave me a max speed of 45 -48 mph.. the miles clock up slow at the speed!! all seems ok it runs better than it did before might be becasue i threw in some hi-tech reeds as well.. the old ones were looking a bit warped..
only problem seems to be the exhaust is not sealed properly at the manifold i'm getting alot of oil on the barrell, tried to reseal it again, but it's still the same i'm a bit worried about cranking the exhaust bolts up too tight in case i strip the buggers.. put a new gasket in there as well??