Forum

[NicoV]

I installed a new (alloy) cylinder and a new European-made piston plus rings (6.5:1 compression ratio) on my Bullet 500. How long is the break-in distance ?
The first 400 km I never did more than 65 km/h. I now have done nearly 700 and do not exceed a speed of 70 km/h.
My trips are anywhere between 20 and 90 km on windy country roads in Norway, slopes all of the time, but never really steep. The oil temperature in the oil tank nearly never exceeds 70 degrees Celsius.

[Gwilly]

Thats only 434 miles in english money so not really enough to smooth out honing pattern.

Having said that just keep doing what your doing, give the motor some more work to do and keep the revs up, do not lug in high gear..

Change the oil if you haven't already and again at 1000 miles/1600 kms inspect for shiny deposits, that should be enough for just piston/ barrel change.

The biggest killer is motorway running at prolonged speed and throttle opening, heat will increase with risk of seizure..

Gentle up and downhills with gear changing is perfect for standard non racer which should not need a rebuild again for years.

[Leon Novello]

A bit of reading for the weekend, might be useful.
http://mototuneusa.com/break_in_secrets.htm

[Alan R]

PHEW !!!---Interesting reading but as it says at the beginning}---- Controversial stuff indeed !!........Just 2 observations from myself}--- First) His method seems to be based mainly on loading gained from engine RPM.. Our long-stroke Bullet engines will have a higher average piston linear speed than say an equivalent 500cc short-stroke one.....Second) He used the phrase}--" Thousands of psi" acting on the piston rings.....To be fair this is a difficult one to accurately measure but diesels typically show around 1,000 psi after combustion ( injection ) gained from a Compression Ratio approx. 15 : 1......Again, our Bullets have 6.5 : 1 as standard so cyl. pressure after combustion will be proportionally lower...NicoV states that he has fitted a new ALLOY cylinder...This in itself would require different ring gapping AND different piston/barrel clearance during machining compared to the Iron one............BULLET WHISPERER, what's your racing experience "take" on this one ??

[Bullet Whisperer]

Hi Alan, I was going to stay out of this one, but since you ask, most of my stuff gets pretty rough treatment almost straight away - certainly the racers, as there is no way you can realistically put hundreds of miles on them to loosen them up [especially @ 7 mpg on methanol], so I start a rebuilt engine, warm it right up with no load, until it is VERY hot. Next, I will ride up and down the lane a few times, before it goes into the back of the van to be taken to a top secret location for, perhaps 10 - 15 miles of testing. If all is well, it is brought home, allowed to cool right down, then all the head nuts etc are checked and tightened if required, oils checked and so on. The next time the engine is run might be on a dyno, where I might not exceed about 6,000 rpm to begin with, but if all seems well, once an engine is fully warmed up, I will push them just past peak power rpm - if anything goes wrong here, I didn't do my job well enough and will have more work to do, but usually everything is fine and the next outing might be a track day, but more often the next run will be in a practice session at a race meeting. Road bikes? - well here is my first ride of a totally rebuilt Continental GT 250. Regards, Paul. ... https://youtu.be/lHLjtipUh-0