2 stroke running in

Iv got an aprilia rs125r just blown my top end (predictable LOL) doing top end rebuild. Any info on running in, some people say 100 miles others 600.

Dont want to do either of these extremes, any suggestions. I was thinking 300miles then every +100miles i add 1000rpm

In general, from what I've read about running in two-strokes, the idea is to not alow the revs to stay constant (i.e. always vary them, dont just sit at say 6000 rpm), and to allow the bike to get up to correct operating tempurature each time until the running-in period is done. In between runs, let the engine cool (the expansion / contraction of materials will help enable a goo seal between the piston and bore)

I'm not certain how long you should give it though...

[Red Herring]

That's topical having just posted on the other running in thread. If it's a track bike warm it up in the pits, switch off and let it cool down (ideally abut an hour of you've got time between engine start time and first practice) then when you first go out do a couple of laps at 1/2 to 2/3 speed, then nail it.

If it's a road bike do a few miles just to make sure the engine is properly up to temperature and the piston hasn't got any tight spots then ride is at it was intended....enjoy.

[Doinitmyway]

Well when I had my old 350LC we were told to run them in for 750 miles, never to run them hard from cold and gradually increase revs from 500 miles. Dont use fully synthetic oil *to run it in on* as good oils stop them bedding in so quick. This was for road engines.

The two strokes needed a longer running in as they have got the exhaust ports in the barrells. The rings were supposed to be stronger to compensate - yeah right Never heard of a set that lasted 10000miles.

Top ends dont normally blow for no reason though, if you've put a spannie on it then up the main jet a bit.

[Bibio]

biggest killer of strokers is to much fekin 2 stroke oil... dont have the thing smoking like a chimney on fire the 2 stroke oil is only there to lubricate the bore and ends. too much in the fuel will kill a piston in no time... check your pump to see if its still on 'run in' mode.

also if the bike has a good few miles on it them the gearbox will be well and truly run in, bores only take a couple hundred miles. and as said above dont hold the throttle in one position. town driving is as good as it gets to run a stroker in.

Originally Posted by Bibio

biggest killer of strokers is to much fekin 2 stroke oil...

Yes, if it is leaning the mixtures to dangerous levels (a pre-mix problem), otherwise lack of oil or break down of the lubrication film are the biggest two stroke killers.

As far as break-in goes, it comes down to what is done in the first hour on the road. 100mi is plenty if it is done right. There are all sorts of theories out there, but I find a quiet piece of road and work it up and down through a moderate but increasing load/rpm range for an hour or so.

Cheers

This is what i do to my 350LC

Warm up in the morning, You can never warm her up to much. I spend up to 5 mins reving and letting her idle. Even then she will stil cough and choke when reving her! Then Ride off Gently.

As its a RS125 go REALLY steady, she will go again if you rant it....! Dont be scared to go into the power ban a few times on your trip but for 90% of you time ride bellow it. I would say after a few tanks start going up into the band more often and often.

Check your power valve is adjusted too I would be checking this weekly after a rebuild then not bother...

Now its running right Buy another head as its going to go again, you can never have too many pistons and heads when owning a RS125...

One final, Use the BEST two stoke oil. This stuff is good

http://jestersmotorcycles.com/accessories/maint/P1%20TTS_2T.jpg

Two stokes are awesome!

[yorkie_chris]

I can understand an over-rich premix ratio killing pistons, but surely an injector pump one will not make any difference to the mixture?

Ever heard of 2 stroke being run on 4 stroke oil?

I know it sounds weird, but aparantly one of the mechanics I know, used to do this when he raced them..

[Bibio]

Originally Posted by yorkie_chris

I can understand an over-rich premix ratio killing pistons, but surely an injector pump one will not make any difference to the mixture?

it will if it's not set up properly, there is usually a 'run in' mark on them and if not set to 'normal' it lets far to much 2stroke oil in the system. they are usually set at the first service but a lot of mechanics forget.

best to check just in case.