Is running in necessary?

[Pipp]

To make a long story short , my rs200 had a cylinder head overhaul. We did the 1000km run in but after that the thrust washer needed to be replaced.
I'm not mechanical at all so I'm just telling you what the mechanic told me....
They said they need to replace the main and big end bearings whilst doing the thrust washer. I believe they go through the sump to do this.
The crank had to be refurbed and after market bearings used.
I have got the car back again and they have advised I do another 1000km at low rpm and then the relevant oil change.

Is it necessary to do the low rpm run in ?
I have done around 400km at low rpm already but wondering if this style of driving is totally necessary up to 1000km

Any input would be appreciated.

Thanks

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[Dumdum]

There are two schools of thought...

One is yes you do and then the opposite...

From and engineering perspective you should allow the bearings to gently wear any imperfections out and effectively match themselves to the crank, work harden and also allow them to do this very gradually, driving gently and heat cycling the engine allows this to happen in a controlled manner

On the other hand, I can recal an incident of two identical motorbikes which has been bought at the same time from a dealers, one was markedly quicker than the other, dump tests revealed one was 13bhp up on the other... the difference... the pokier one had been thrashed within an inch of its life from day one from the dealers, it had ‘run in’ in a way which meant it was looser and this more able to rev and make power...

Personally I’d rather err on the side of caution and take my time and gently break an engine in, but you also can’t baby it... it’s a lot of hassle to go to getting an engine rebuilt to ‘potentially’ wreck it and then have to shell out again

Have a read down the page

https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/2593270/2

 

[Pipp]

Thanks for the reply

That link was quite interesting too !

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[Dmonk197]

I use to ride a vespa 250CC i had it for 12 years, i use to ride it to the max all the time- the engine would get stronger and stronger every year- 6/7 years into the ownership the new 300CC vespa came out- off the lights i would beat them to and my engine was super strong- could have been lucky with the engine, could be the fact that i thrashed it everywhere- you decide!

 

[Dumdum]

I use to ride a vespa 250CC i had it for 12 years, i use to ride it to the max all the time- the engine would get stronger and stronger every year- 6/7 years into the ownership the new 300CC vespa came out- off the lights i would beat them to and my engine was super strong- could have been lucky with the engine, could be the fact that i thrashed it everywhere- you decide!

Most new engines are dyno tested and therefore run in effectively, just lucky I’d have said...

 

[Dmonk197]

Most new engines are dyno tested and therefore run in effectively, just lucky I’d have said...

not sure what you are trying to say.
my point was that thrashing is not necessarily bad and could make an engine be stronger.

 

[Dumdum]

not sure what you are trying to say.
my point was that thrashing is not necessarily bad and could make an engine be stronger.

Stronger mechanically? Probably not, but in the case of a motorbike it was probably just loosening up (my point with previous post is everything is effectively run in and heat cycled nicely prior to you getting it) and becoming more pokey (guessing that’s the stronger you refer to) with a bit of thrash, this often (not always) comes at the expense of longevity as something has to give eventually though if it keeps loosening up, no disagreement from me on breaking an engine in other than driving like miss daisy it is also why I’d rather have a higher than average mileage car than one that’s done next to no miles and been driven like miss daisy

 

[Foxspeed]

engine bearings run with an oil clearance so in effect no "metal to metal" as there is oil there - worst you can do it give too many revs when first started (oil pressure to build up) thus causing some scuffing of the bearing surfaces...always best to let if warm up then give it death!

most bottom end problems is a lack of oil/oil film clearance - and also poor engine building technique/first run up

 

[Dmonk197]

Stronger mechanically? Probably not, but in the case of a motorbike it was probably just loosening up (my point with previous post is everything is effectively run in and heat cycled nicely prior to you getting it) and becoming more pokey (guessing that’s the stronger you refer to) with a bit of thrash, this often (not always) comes at the expense of longevity as something has to give eventually though if it keeps loosening up, no disagreement from me on breaking an engine in other than driving like miss daisy it is also why I’d rather have a higher than average mileage car than one that’s done next to no miles and been driven like miss daisy

agreed- i use to wear out parts quicker, like exhaust gasket that kept blowing (resulting in me sounding like i am driving a tractor) clutch , breaks tires, was always surprised how quickly i wear them out. but boy was she fun to commute on.

 

[Pipp]

Lots of food for thought here , thanks everybody.
Due to all the hassles with the vehicle and the build warranty being 6 months , I won't keep her after the warranty expires. So I have taken the first 500km fairly easy but will start to open her up now for the remaining 500.

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