DT125R ARCHIVE

I thinks we needs some heavier modding on subjects like this. It's all well and good having your own opinion but these are peoples bikes and alot of work has obviously gone into rebuilding and if someone is asking these questions then they obviously want genuine advice.

Now it's up to you if you listen to people saying 3 heat and cool cycles and use mineral oil but bear in mind that Engine manafactuars will always say 500miles running in period. It may sound like alot, but the point is to prevent premature wear on the engine by allowing the rings to bed in correctly and create a good seal. The use of a lower grade oil or mineral oil is sometimes reccommended for nikasil plated bores and they also only need 3 heat and cool cycles. This is because the bore surface (nikasil plating) is far far tougher and its only the piston rings that are needing to wear down to create the seal. They also often use single ringed pistons which is naturaly going to reduce the time it takes to run in. I think most people are finding info from offroad 2 strokes that use plated bores and not on road steel bored and honed cylinder bikes.

On steel bores that have been honed and have cross hatching you need alot more of a running in period, hence why road bikes with steel bores all have a reccomended 500 miles run in time. It's also important to realise the difference between initial break in and a long term run in. An initial break in is the first 3-4 runs of the engine after a rebuild which will ofcourse include heat a cool cycles purely because you are starting the bike and then letting it cool down before starting it again. Then you move onto the longer term running in of the engine which is a case of

From my own research, my understanding is that the idea is to gradually increase the amount of time the engine is running for during the start of its life. So 5 minutes, then allow to completely cool. Then 10 minutes, then cool, then 15 minutes then cool.

Things to avoid are prolonged use at a constant rpm. you need to use rev range in a controlled way. Dont get confused with throttle and revs. You can bring the revs up without needing alot of throttle. It's suggested to use no more than 50% throttle for the first 3-4 runs of the engine but bringing the revs up and varying the revs are very important to create a seal. After that, gradually increase the throttle useage.

The reason some people say not to use synthetic oil is to avoid glazing the cylinder but thats more likely to happen by not varying the revs.

Anyway thats my 2 cents on running in.

To be fair Andy that picture i posted came from a Nikasil plated bore. Aprilia rs125 160cc polini kit which is nikasil plates.

as above there are many ways to run in an engine.. Google it if your that concerned. but this thread will not descend into a slanging match!

it always is...