Running in

[Yanker]

A couple of miles up and down the box and using engine braking a lot,

Chris

Interesting approach, but surely a 2T needs fuel and oil at any given rpm and not a lack of both (especially when running in)?

Engine braking (breaking?) will deffo push the boundaries and if the top-end survives that treatment it will bed it in quicker. I'd only advocate this with known clearances and on a cheaper/smaller bore and not on a big/tuned/kit cylinder until the user is happy about ignition and carburation.

Will be 'running-in' newly built overbored 72mm iron cylinder for the first time tomorrow am's commute (temporary set-up while the Rapido is re-bored) ...not sure the bore is not somewhat distorted (it is) so deffo no engine braking on this one.

[mick1]

I wonder how many of know why we should "run it in" ? I think there's several reasons but my favourite is you're hardening the barrel walls. An ideal cylinder should have very hard walls to help make them smooth and less likely to sieze. The best way to do this is to case harden (or anneal....not sure which is the correct term ) This is done by heating the walls of the cylinder then allowing to cool (running-in). The more this is done the better the result. If the walls are over-heated or kept to long at a high temp' the process will be less efficient.

Well that's my thoughts but i'm open to different opinions

[shocky]

I wonder how many of know why we should "run it in" ? I think there's several reasons but my favourite is you're hardening the barrel walls. An ideal cylinder should have very hard walls to help make them smooth and less likely to sieze. The best way to do this is to case harden (or anneal....not sure which is the correct term ) This is done by heating the walls of the cylinder then allowing to cool (running-in). The more this is done the better the result. If the walls are over-heated or kept to long at a high temp' the process will be less efficient.

Well that's my thoughts but i'm open to different opinions

The wall wont want to be to smooth or there will be nowere to trap the oil that lubes the bore , its not annealing as that soffens metal copper gaskets being a good example and to case harden well lookhere you need to physically melt the surface and induce some other element http://en.m.wikipedia.org/wiki/Case_hardening
The repeated heating and cooling will to an extent normalize the cylinder but that can soften as well as harden metals so can be a double edged sword ( yes a play on words there ) theres also work hardening and tbh its been to long for me since I last did all this stuff to explain it well (wiki is your friend )

[ducksta]

so mick was wrong then?

[shocky]

Any anneling ive done has heated the metal to orange red and any case hardening was with chrome alloys such as H13 and duplex die steels for extrusion press dies , backers and bolsters( http://www.intoco.co.uk/special-steels/) which are stress relieved or machine worked to get hard , the h13 if not pre heated or coolex corrdctly is like glass and can only be ground as machine tool tips wont touch it , there maybe some truth in what he has said but id say it was negligible the friction from the rings going up and down might be enough to "work " some hardness into the cylinder material but as ive not really used cast irons much its hard to tell, I do know that cast iron contains graphite which is a lubricant but cast irons can have any number or things added them there are literally thousands of combinations which is whyit can be hard to weld like I said its been 10 yrs since I worked in any industry that ive need to make use of any facts

[mick1]

Some fair points made by Shocky and quite informative......but the question remains "why do we run them in ?". bearing in mind Nicasil/ceramic doesn't need running in, only the rings.

[dapper]

Ron Moss recommends on his Avanti nicasil lined kit that you let the scooter tick over for a minute to let it warm up as the cylinder and piston expand at different rates. He the goes on to detail running in periods and mentions cold seizes

Alloy Nickel Silicone Carbide cylinders have been used for many years and you may well have owned one. However this kit is different and you MUST follow these instructions to the letter! If you think you can just bed the rings in for 50 miles or so and go for a blast then you had better think again. Please be patient follow the instructions, if you do not, I will know.
Whilst the TT3 will be more forgiving to heat seizures than other kits, ignition timing and jetting of the carburettor is still critical at any time but more so during the initial set up and running in period. At ¼ throttle you are running on the pilot jet, if this is weak you can still seize an engine even at 35 mph.
IF IN DOUBT ASK.
Cold piston seizures
This is a condition where a piston expands quicker than the cylinder in certain conditions, causing a piston to seize.
Because this engine runs cooler than any other Lambretta air cooled kit you MUST WARM THE ENGINE BEFORE moving off for about a minute even after running in. Keep engine RPM down to about 3,000 rpm for the first mile.
In Cold Conditions make sure you allow more time to warm the engine up.
This Kit also has a central exhaust port and care must be taken whilst running in.
Always use good quality synthetic oil, whilst running in use at 4% for the first 500 miles, thereafter this may be dropped to 3%. Use an NGK B8ES spark plug or equivalent whilst running in then maybe changed if necessary to a B9ES
Running in
First 200 miles stay below 45 mph and vary the speed (RPM)
Next 200 miles stay below 55 mph and vary the speed (RPM)
Next 100 miles stay below 65 mph and vary the speed (RPM)
For the next 250 miles keep varying the speed whilst gradually increasing the speed, do not hold at maximum speed for any length of time. Do not hold at maximum speed until you have done at least 750 miles.
Extra care must be taken whilst running in if you are running into a head wind or going up hill, slow down and use a lower gear if necessary, the engine must not labour in any conditions.

He knows his stuf!!