How many kms should I put on a brand new bike before strapping it to the dyno and doing the full tune??  1000?   3000?   5000?  Not sure how long it takes to "break in" these motors.

The bike will be getting new pipes, intake, cams and a PCV right before getting dialled in on the dyno.

Cheers, berms.

Minimum 5,000k's

Had mine dynoed today at Thunder Tech, only done 34000 after the motor was rebuit didnt want to rush it. Money well spent and fuck they sound great at 6000 rpm as well setting off the car alarm in the car park.

G'day Stinga,  yeah 34000 is definitely not rushing it 

Thanks Scotty, so if I'm reading you right,  its a case of  yes it can be done, but its not exactly the preferred method?  Is that right?

You need to listen to Scotty as he is right.

I run a 5 though ring gap in 2 stroke Kart race engines and run them in on a dyno or on the track in 30 minutes. The critical component is piston clearance and ring bedding in, just need to make sure you are getting a good fuel delivery and no pinging when doing so, running lean will be bad as is running too much fuel as I have seen a few bores washed down when not done properly not allowing the rings to bed. A competent dyno operator will have no problem at all. Once its completed a couple of heat cycles, thats it. I run a 15 minute session on and off the throttle at 7000 revs, then another seesion up to 11 thousand revs, then thats it, full throttle and punishment. Bearings etc are not worth worrying about when the top end has settled, just ensure proper heat cycles throughout the run in proceedure.
Now you may say but thats a 2 stroke but I can tell you I cut my teeth many years ago as an apprentice motorcyle mechanic on a Hartzell Dyno and ran in and tuned many a HD, british and Jap bike without any problems - ever. waiting for 2000 to 6000 k's is just not right/necessary at all.

A good dyno operator will have no issues doing a custom tune with less than 500k's on the motor, I had a gen 3 V8 custom tuned with less which included hitting the rev limiter a few times, all good.
My 2 bobs worth....

Gday Ozroder

The bore size on the air cooled is 50mm 51mm max allowable to rebore
The bore size om the water cooled is 53.97, 98 and 99

Using the air cooled yamaha as an example, we get around 12 hours of use before replacing the ring. 5 thou ring gap has increased to 13-14 thou in that period so basically its worn out, the piston will do double that using a Strike piston becuase of the composition and finishing of the piston, and also the increments available in piston sizes. the yammy piston has a high content of silicon but does not last as long..

I normally like to bore them out to 50.60 and use a 50.7 ring. Filing the ring down acheives the close ring gap as you go up in increments of piston sizes and get close to the 50.7 piston, just use a 50.8 ring and file down to suit. we rev these between 11 - 11.800 revs

The water cooled engine is different, a bit more tolerance is required otherwise you risk cold siezure for obvoius reasons.... Also, the Rotax 125 water cooled has a nikasil bore (super tough, need a diamond tip flexi hone to get a new cross hatch) we get 25 hours out of it before replacing a ring and piston, we rev them to 14,000 revs.

I guess my point is (did not come across well due to halfway through a bottle of wild turkey at the time) is that you can run tight tolerances, and still run in an engine with very low k's. but as mentioned before you need a good switched on operator and lotsa cool air.
 

Just took a pic of one I am doing now which is way past its used by date at 14 thou

 

cheers,
Dave.

Thanks  for the article Scotty, now I know what is involved I can talk to the dyno guys and see what they can do.

Cheers, berms.