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Hi, does anyone have any general tips on running in my new 375 pistons? How long before i should do the first oil change? The engine has had a complete rebuild with new bearings throughout (including plain main and big end). Thanks.

General tips for air-cooled gasoline engine run-in I have used for aircraft and M/C for a long time....

Use a straight petroleum motor oil of the proper weight for the first 25 hrs (aircraft) or 200/500 miles (motorcycle), then change to the oil you will use from then on.

First startups should last for no more than ten minutes to set carbs, check timing, and looks for leaks of any kind. Let the motor completely cool, and run another 10 minutes varying the throttle from a slow to fast idle then completely let it cool again.

Check the oil for color change and/or signs of very fine "metal particles" floating in the oil... If you see any metal floating in the oil, change it at once and repeat the ten minute fast idle run-in with fresh oil and recheck the oil for metal. If more metal is generated, the motor most likely has a problem.

If the oil is clean and clear, ride the bike at moderate highway speeds (avoid stop and go traffic ) varying rpm and throttle settings as you go. The main thing is to keep lots of cooling airflow moving over the engine.....

Use full throttle burst of acceleration every now and then at the rpm range where the torque peak occurs.... High cylinder pressure is what is needed to get the rings to match to the cylinder bores quickly.

If oil consumption is high after changing to the premium oil you will be using, go back to the straight petroleum oil for another 500 miles.

Good luck and safe riding to you,
Robert in California

Hi Robert, thank you for that, that's exactly the info i needed. Luckily i have a 30km stretch of motorway at the end of my estate which has very little traffic, so can ride up and down that to my hearts content.

Just one question if i may, when you say "Use a straight petroleum motor oil of the proper weight", do you mean a normal straight 40W engine oil? Sorry to ask a stupid question just want to make sure i get it right!

Tony

Yes Tony, a straight 40w motor oil rather than the multi-grades such as 15w-40 and it is not a stupid question.

Here is why, the multi-grades have so many additives included in them that they are too good a lubricant and it keeps the parts from bedding together right away.

A simple straight non-detergent motor oil works best for run-in, and the blokes at the auto supply store should be able to point them out.

(Non-detergent oil is what we Yanks call an oil with little or no additives in it)

If you can't find any, go to the nearest small airport and ask for this oil: http://www.skygeek.com/aeroshell-80-mineral-oil.html

It's the best of the best....

Robert