Running in after rebore and new piston

Mtoliva said:
So apologies for my mistake, Moto Corsa didn’t work on the head, but I have ask why, during a major engine overhaul didn’t they make some simple investigations.
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A situation like that wouldn't necessarily show up in the running of the bike. I have had bikes come in with broken rings without any symptoms or bore damage. Good on you for your apology.
 
aside from the large amounts of white smoke ,the bike pulled really well, plenty of power, so I must agree with your comment.
 
Laverdalothar said:
Oh man... that's really a pitty... Hope the bike comes back together soon and you can appreciated it again! Tough time to bed-in the engines though after a serious overhaul, have two engines which need to complete their first 1.000km... :rolleyes: hard to keep patience, especially on the 1000 SFC that runs best beyon 3.000 rpm...
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We have quite a different process in Australia… take a zero off, seems to work for us
 
all the engines I build I tell the owners to not baby them, ride them normal, 8,000 rpm is fine but not all the time but whatever you do, do not lug the fuck out of them with an imposed limit of 3,000 rpm
Dam engine will never be happy doing that
We take brand new engines straight to the Dyno shop or the race track and give them shit, works every time
 
Hi Red,

pretty sure you have torqued the head down then at least twice before you give it back to the owner? Have seen some engines blowing oil when going high revs to early (before the head gasket has bedded in).
 
Laverdalothar said:
Hi Red,

pretty sure you have torqued the head down then at least twice before you give it back to the owner? Have seen some engines blowing oil when going high revs to early (before the head gasket has bedded in).
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I tell the owners first service at 200 klms, no restrictions on revs, but you are correct, I run the engines through a ring seating sequence that involves 10 starts going from 10 seconds for first start to 4 min for the last start, after which I do check shim clearance and torque the head down again before I hand the bike over to the owner

Then at 200 klms, change oil, shim check, torque head, etc, after that next service at 1,000 klms, check shims, torque head, etc
once that is done I do not expect to see them again, all they need to do is change oil and check shims at 10,000 klms

some folk specify restricted running in periods, I have no restrictions on running in my engines, if you want to give them shit, all the better
they will work far better that way, only thing you are trying to run in is the ring seal, roller bearings need no running in, they are what they are
 
OK, that sounds like a different way of making sure the head is torqued down well. I know that Piet mounts the engine with the head torqued down, leaves it over night, torques it again before he puts it into the frame and then starts the engine, goes for a test ride and afterwards re-torques the head again and checks the valve clearance. That normally should do it also for the first 500km even, but I prefered to do a check after 300km again... then 500, 1000 and then again at 5.000.

My understanding was that the bedding in of the piston rings/oil rings takes a while and needs to be done gently. But you might be right with the quick way - at least for race-engines, that get overhauled every season anyway (if not more often). So far, I had no oil consumption related to piston rings (just due to a worn valve seal on the inlet). I just experienced on a two-stroke engine a lot of piston sizing (even until it blocked the engine...) when doing a too harsh bedding in.
 
when running in piston ring seal there is no difference between a race engine and a street engine as far as I am concerned
is far better to load them up as opposed to giving them a gentle run in, glazed bores help no one

that is my take on the engine deal, others may differ as I am sure they will in droves, but as far as I am concerned, sooner you give the engine a hard time the better it will run
 
redax5 said:
when running in piston ring seal there is no difference between a race engine and a street engine as far as I am concerned
is far better to load them up as opposed to giving them a gentle run in, glazed bores help no one

that is my take on the engine deal, others may differ as I am sure they will in droves, but as far as I am concerned, sooner you give the engine a hard time the better it will run
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That is exactly how aero engines are run-in. Pretty much two full throttle runs without lugging (very slow throttle input but all the way to maz) all the way up to 10,000 feet and then slowly ease the throttle off to descend. Then change the oil (and filter the oil with a paint filter to look for metal) and then Bob's your cousin and you are on your way.
I doubt that the liability involved with aircraft would allow this if there was any problem with the process.

Jim
 
Every engine builder has his way of seeing things. Keith Nairn recommended revving the engine normally, oil change at 100 miles and again at 2-300 with a torque of the head. I checked the valve clearances at 3500 km. They needed doing but new valves and seats in there.

As a road rider, what imports for me is the longevity of the engine, not it's performance.

Paul
 
Point taken, Red & Jim, even though aero engines might not 100% be comparable (different intensity and frequency of inspections, different rev-range - at least for ultra light plane engines, which I think only rev up to 3.000rpm).
On the other side: the tolerances are so much reduced today that bedding in might really just be a question of the rings seating and not the piston tempering etc. Not an engineer at all though, just trying to learn ;-)
 
Old style running in was for big running clearance, high expansion of pistons, thick rings and things like side valves heating up unevenly. Most modern bike manufacturers recommend a running in period with rpm limits basically to stop people revving the tits off them from cold/ new - had an Iranian customer (Mr Safwat) start a brand new GPZ600 and Rev limit it in front of his friends whilst I was explaining how the lights work🙄.
Have had BMW & Triumph burn oil through being too gentle, we used to put them back on mineral oil and give them ” a good birching” as per Triumphs head of tech suggested.
Dynoing doesn’t put a great deal of load on an engine so runs them in nicely.
My advice is warm The engine up by riding it ( not idling) then ride it normally, obviously nor redlining it but make it do a bit of work. Change oil at 500 mile then bingo job done.
 
More home truths from the bench and road, one well known RGS rider, barrels removed, reassemble engine, no addressing of piston rings ( reused original high kms ), barrel bores not dressed, assembled, road test engine, smoke machine that would have covered a major outdoor festival.... i did the engine that way, was a long time ago. Went on for weeks the constant smoking while riding, on domestic local roads. Cut to the NSW Laverda Snowy GP as we called it.... after day one of high spirited upper RPM engagement, less smoke, end of day two, no smoke and nice easy motor to ride and idle...

Last motor i did, ball hone the bores, to give some surface bite for the rings, have a great problem with the notion of "glaze" effect in a bore, without insisting upon it being an anomalous term, my perspective is that it is more aligned to a "case hardening" effect than actual "glass/glaze/polish" effect, being high carbon content liners, it is my less than expert knowledge of metallurgy, a limited working knowledge at best. The more qualified than myself may expand on this perhaps. j. *** oh and that motor was perfect, not even a wisp of white smoke, just the first minute or so after rebuild and oil used in the reassembly clearing.
 
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It was a surprise to me at the time, having grown up in the 'progressive throttle opening school' of running-in, but when I visited the Porsche Factory, the engines go straight from initial build to the dyno. There, they are run to full power to make sure they're up to spec.
 
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