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Running in opinions?

Discussion in 'General Classic Motorcycle Discussion' started by Tigernut, Jan 25, 2014.

  1. Tigernut


    Jan 1, 2013
    What do people reckon on best approach to running in an engine with newly honed bores and new rings? I'm thinking of an air cooled 360 degree parallel twin such as Norton, Triumph or BSA here, and built using factory clearances (or slightly over, eg: 5 thou skirt clearance).

    Modern thinking seems to be to give the engine plenty of work right from first startup, but I was brought up thinking it was best to be gentle for the first few hundred miles and gradually increase the workload.

    Who does what on here?
  2. Triton Thrasher

    Triton Thrasher

    Feb 10, 2009

    Ok, so what bike are you actually running in?

    Or are you just trying to get the usual suspects to argue?
  3. ashman


    Jul 11, 2010
    Rings don't take long to bed in, just ride it nomal but don't over do it and don't labour it, but a full rebuild the first 500 miles you must take it easy, when I rebuilt my motor I kicked it over with a dry bore to pump the oil up before I started it, when it fired up the first time it didn't even blow any smoke and that was over 4 years ago now and my mortor still feels tight and have never had any probems with the rings.

    I have done this with all my motor rebuilds and have never had any problems at all.

  4. X-file


    May 4, 2013
    I believe in the "dry" assembly.No oil on the rings or ring grooves,VERY lightly oiled cylinders (wipe of as much oil as possible with a rag,what remains is enough),and one drop of oil smeared on each side of the piston skirt.

    From the second I start up,I'm in gear and loading the engine.Avoid all idling;just go.Load is your friend,but heat is your enemy.I get around that by loading the engine hard for about 3 seconds,then fully closing the throttle for about the same time to cool off.Keep doing that until it's run in.Most of it will be right within 50 miles.Avoid idling and running at light-to-medium load,keep it on or fully off.

    Motoman has a similar opinion,but he believes in a little warm up time at the first start up.I dont',because I think it's more important at that time to get things seated,rather than to avoid a very small amount of wear from a one-time start up.Well seated rings will run well for the life of the engine.http://www.mototuneusa.com/break_in_secrets.htm

    Don't be afraid to go beyond 1/2 revs.It's better to be running at 4000 than it is to be running at 3000.Lug the engine at low rpm and you can have detonation problems.It's not uncommon for people to melt a piston by not using enough rpm during running in.High rpm is not really a problem.Keeping the throttle fully open at high rpm will eventually cause too much heat,when the engine is new.A few seconds won't hurt,if you give it a chance to cool off afterward.
    High rpm at light throttle (like going downhill),will never hurt.
  5. Tigernut


    Jan 1, 2013
    Thanks Ashman and X-File, this is exactly the kind of detail I was hoping for. Plenty of people say vague things like "thrash it from the start" but that is clearly bad advice without qualification. I think your caution about heat has given the qualification needed, and I get it now.

    People also say not to let an engine with new cams and followers run below 2000rpm or so for at least a certain length of time on first startup - could anyone please give any more detail on this aspect of running in?

    To Triton Thrasher, no, I was not trying to start an argument. I was deliberately as non specific as possible about the engine because the principle must be similar whether an A65, a Commando or a Triumph, and I didn't want to limit responses by mentioning a make.
  6. nickguzzi


    Dec 25, 2013
    Cams have their own regime. This can cause some conflicts with some of the above suggestions.
    The only problems I have ever had on any engine I have built has been cam/follower related. Pretty much all terminal wear I have seen on 100's (if not 1000's) of engines not obviously down to lack of maintenance has been in a similar area.
    I religiously follow cam maker directions on running in now. This usually requires copious specialist cam lube and running in at circa 2000rpm for twenty minutes.
    Assembly lube on plain bearings should be up to its job of protection until the engine can take care of itself. A purge of oilways before allowing firing up won't go amiss.
    Over lubing bores can result in glazing, requiring another spanner session to rectify. It was/is quite popular to use a spray of light lube on the bores, wiping off as much as possible with a lint free rag. I suspect this is more to give a final clean - which is a good thing - than provide lubrication.
    The blipping throttles at race tracks wasn't just done for fun, it was done to help rings bed in more quickly, so a bit of a thrash but no heavy loading or extreme revs or heat should speed the process.
    Modern bore honing and rings should bed in very quickly. Pistons are splash lubricated normally, so will soon be covered under running conditions.
    Once built, I would try to start the engine asap. Lube drain, condensation, rust from finger prints if you don't wear gloves, settled dust from storage getting in when unmasking, and probably a few more are all things to avoid.
  7. Tigernut


    Jan 1, 2013
    Thanks. Just to be really clear on new cams & followers, do you mean a steady 2000rpm for 20 minutes, or a minimum of 2000rpm for 20 minutes?

    The former would clash with the ring bedding procedure but the latter wouldn't clash at all.

    I have been liberal with cam lube and very sparing with lube on the bores, and I will prime the crank and other oilways thoroughly before I start up. I just need to know whether to sit there for 20min or take off down the road immediately.
  8. X-file


    May 4, 2013
    Any new cam should have re-ground tappets.
    Any used cam should have all tappets,that were previously used on that cam,fitted in their original position and direction.If that can't be done,at least re-grind the tappets and be prepared to bed them in again.

    Keeping the rpm ABOVE 2000 rpm will be fine.Some even say above 2500 rpm.The highest load on the nose of the cam lobe happens when you're turning the engine slowly by hand.Once you have the rockers in place,avoid turning the engine slowly and wiping off the cam-lube.Only turn it when you plan to start it,and go straight up to 2000 rpm.

    It's OK to stop the engine completely,and then re-start it.It's not OK to be running it at less than 2000 rpm,during the first 20 minutes with a new cam or re-ground tappets.

    Just start it up and ride it at 2000 or more.
  9. Rohan


    Aug 26, 2010
    Whatever, 20 minutes is too long to be parked with the engine half revving.
    They say that 10 minutes will produce overheating.
    Unless its VERY cold, or you have a good fan...
  10. Tigernut


    Jan 1, 2013
    OK, thanks, I think I know where I am now. Just to confirm, this is new followers and cams. If I am going to set the valve timing using a dial guage and degree disc, I will need to do some turning by hand, that's inescapable. Just have to hope enough of that cam lube grease stays where its doing some good.
  11. domiracer66


    Jun 4, 2009
    If we are talking Hepolite rings here there are very specific instructions for run-in..


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