Running In

[moyo64]

Hi
Ive just had a new piston and rings and the barrel honed,
Could someone advise how many miles this should be run in for please,
The scoot is fitted with a DR180 kit
The local dealer reckons 50 miles ?
Thanks

[kru251]

Sounds like your dealer wants to see you back again; soon. Well scooter work drops off a bit in the winter eh?
You will always hear variations from "thrash it from the start" thru to "run it in for 500 miles" etc. I'd not be wanting to pay out again so would go at least double that suggested mileage starting gently and at the 100 miles start giving it little bursts etc to build up the speeds/load. I mean with a bore hone you're basically back to a new cylinder wall & what with new piston & new rings it all new metal-to-metal to bed-in. Up to you really. Await a lot of other variations to follow. We all have our own methods.
I have had a honed cylinder, new rings and piston just nip up at 300 miles without a long sustained hill to load it. Just on the level at about 45/50mph on a 200 so am now a bit careful/over careful perhaps.

[pxguru]

Just as KRU251 says there will be a whole load of ideas on this subject. On a track bike they run in for two heat cycles. Warm it up to full temperature then stone cold, twice and its run in but they don't expect them to run for 20,000 miles!

I say, whatever you are running in will need far richer jetting until it is run in. Be really sure to up jet the main until you are confident it's running rich then back down one jet. If you have a carb with a needle the clip needs to be a notch over where you would normally put it as well. A dash more oil won't hurt for the first tank full either.

[marco]

on my new px 150 the book says dont use over 80 precent throttle, (whatever that is), but my dealer told me not to be too gentle and use the full rev range , but dont thrash it , official running in time is 1000km (piaggio). Mine is defo running rich at the moment, hopefully it will be sorted at its 1st service.

[sbwnik]

On a complete engine rebuildI'm always very cautious - 1000 miles run in, slowly working up from tickover (I do a half hour static session before the clutch is even pulled in!). Completely OTT, I know, but it's what I do.

Rings are different though. Gap them properly to just inside the minimum gap and then 50 miles at no more than half revs and another 50 miles at no more than 3/4 revs, then the next 100 miles at "backing off the throttle every few minutes on fast runs".

PXGuru - I don't understand why you'd want more oil in? We're not talking about a new bore here, we're only on new rings, ditto running rich? I understand that second one for a new built engine as it stops you thrashing it from the off, but on a new set of rings... Really?

But as commented above, you'll get a dozen different answers if you ask a dozen different people. None of them are right, and one reputable Vespa engine builder I know laughs at the idea of running in, as long as the bottom end is solid and the rings are gapped. His logic? If the bore is already run in, the work is done.
He gets a lot of business, so I'm guessing that he knows something I don't.....

[pxguru]

If you have changed something in the engine, running in with the jetting obviously rich is the important point here. It's the one thing that will keep it running cooler and prevent making your shiny piston all battle scarred.
Once you're happy you have run in long enough (round the block or Scotland and back, your choice), then jet it in properly.

Almost all running in heat seizing is caused by high Exhaust Gas Temperature (EGT) burning the oil off the piston. The jetting controls the EGT