Boxerworks.com

I have new rings, stem seals and a carb kit in my ST.
How do I run them in ? Gently, gently ? Moderately and up to 4000 rpm ? Suggestions and recommendations please .
and when to retension the heads ? 500 km ?

People refer to this website for insights on breaking a new top end in:

http://www.mototuneusa.com/break_in_secrets.htm

My thoughts are that the first 60 seconds after engine start are the most critical. You get the maximum wear on the rings before the oil begins to glaze on the cylinder walls. Beyond that, vary RPMs and accel/decell often to get pressure on the rings both directions...avoid excessive idling. Keep the top RPMs down to maybe 80% of normal usage for the first 500-1000 miles. I changed oil fairly quickly after the first couple of heat cycles. Probably good to recheck the torque after a couple of heat cycles and then several times out to say 1000 miles.

YMMV...Kurt in S.A.

Generally you want to "cycle" the new parts with a lot of heat up and cool down cycles. Ride a bit and shut the bike off to allow it to "cool" for a bit. Avoid lugging the engine, and also avoid a continuous rpm on the highway. You want to VARY the rpms and not put too much of a load, so avoid extra luggage, trailers..........check your oil level frequently.

Thanks Rebel, thanks Kurt. It sounds like I'm doing it right, staying under 4000 with the odd blip up, cycling up and down . I'll do a retension at 500 km and an oil change then too.

Kurt's suggestion is more in line with my understanding. Rebel's is more what I follow for a new or rebuilt engine, but for just rings, a fast break-in is usually suggested. The rest of the parts are already all adjusted to each other.

There are those who make the fast break-in argument for new engines as well, citing racers as using that technique to get full power out of the engine as quickly as possible. Personally, I think they are idiots, and that's a fine suggestion if you want your engine to also last as long as a race engine. That doesn't change the fact that it does have its proponents, regardless of the confused rational.

are those nikasil cylinders?

The next post will be someone suggesting to run them in dry, at start up. Oops.

STs were '83-'84 models in the States, so, yes, they'd be Nikasil.

khittner1 wrote:STs were '83-'84 models in the States, so, yes, they'd be Nikasil.

Yep, Nikasil.

She feels a LOT better, more power and the carbs are leaner now too. Happy , happy.

Sibbo wrote:Happy , happy.

Joy joy.