hello all ive just has mt 199B rebored with new piston 2nd 1 how should i run the new piston in? the bike is not back together yet as am waiting for other parts.

Edited December 30, 201312 yr by bondy

Its the rings and bore surface that need running in - not the piston. A lot of heat is generated by the friction of rings on a fresh bore so the main thing is to only run the motor until the cylinder gets hot, then let it cool down. If you get it too hot, the rings and bore can be damaged. On the first run it might only take 1 minute to get hot. With each successive run, the time it takes to get hot will be longer. I judge that the cylinder is hot when I wipe a wet finger on a fin and the water/saliva sizzles. If you have an infra red thermometer, 110 degrees C is about right.

Use a fuel mix that has a lot of oil in it to reduce the risk of damaging the rings or bore. I use 20:1 semi-synthetic for the initial runs. If you use full synthetic oil it will take more running time to bed the rings in.

After the first few runs, the heatup rate will be slow enough that you can ride it gently for a short while before it gets to water sizzle temperature.

When you notice that it is taking a normal time duration to warm up the motor, the rings will have been run in. I find that new rings on a fresh bore usually takes 5 to 8 runs to bed in.

One lesson I learned the hard way and it was a shame as It spoiled what must have been a perfect bore/piston, was taking a new bike out of a very cold environment and starting it up keeping it at tickover for 30 secs. The piston expanded first and nipped up solid. Be careful or at least not cautious (?) at the same time!!!!!????

running a trials bike is very hard to get right,if it was a road bike its easy run around for 500 miles without over revving or labouring it.so same rules apply.but 500 miles off roading would take years.i would ride around no big hills for a bit,dont let it get too hot,and use up to half revs for a day.

good addvice guys manny thanks. i dont ant to ruin a good piston and bore eigther so i will follow your addvice cheers.

hello all got the cylinder head bolted down today forks and exhaust to to back on yet should be a few weeks before its all done

Hi Bondy, what is the black finish you have used to spray/paint? the Bulto engine with please, it looks very well.

hi i havant sprayed it mate it was like that when i bought it. the clutch covers the same ive trye quit a few over the last few years the 1 off inmotion is good jve donn my 198A barrel in it looks nice. i first warmed the barrel up with an heat gun then gave it 7 thin coats heating inbetween coats on the final coat i sick it in the oven for 1 and a half houres on 170-180 then let it cool down. you can buy the pj 1 satin flat black again now i bought 5 cans not cheap at £14 each but its the best ive used i will do both exhausts and the 198A bottom end in it in summer tho cant spray in cold weather its got to be warmer as i do all my spraying out side. so i will have to wait my 198B was done in pj 1 satin flat black looks the same as the 199b

Edited January 4, 201412 yr by bondy