Welcome to Netrider ... Connecting Riders!

Interested in talking motorbikes with a terrific community of riders?
Signup (it's quick and free) to join the discussions and access the full suite of tools and information that Netrider has to offer.

Effect on engines of restricted LAMS bikes

Discussion in 'Technical and Troubleshooting Torque' started by ngalbrai, Jul 27, 2011.

  1. Hi, not to start the big debate about how one should run in a new engine, but, technical question occurred to me. If a new bike is restricted to LAMS power to weight ratio with a rev limiter, from new, then was to have the restrictions removed, what, if any, is the effect on the engine of suddenly having a whole new rev and power range? Just wondering from a technical perspective as the debate seems fairly sound on the actual practical implications of derestricting a LAMs 600. I went for a CB400 specifically so i could get used to the entire rev and power range of an albeit smaller engine.

  2. I'm not sure that is how they work, is it?

    As a general rule, I don't think it'd be a big problem. On older engines, like engines in 1950s cars, where the thing has been treated like a hearse from day #1, and you suddenly give it a huge rev - the rods stretch a bit and the rings bash into the wear lip at the top of the stroke, because the piston has never been that far up the bore. That can destroy rings and pistons.

    Having said that, you need to really baby it for a very long time to have that happen, (years - hundreds of thousands of km) but it is one of the reasons why I treat an engine the way I'm going to treat it for its whole life, from very early on.

    You should see the amount of carbon and shit that comes off the top of the pistons when you do, but! Holy Moly!
  3. I'm happy to be corrected, but don't most of the manufacturers do it via intake restrictors? And even if they use rev limits, do they use lower-spec internals to suit?

    If not, I don't figure de-restricting would have that much of a negative effect (if at all). It's not as if the engine gets all fat and lazy as a LAMS bike, and then has a heart attack when you force it to get active (unless, as kneedragon said, you really coddle the motor for a long time).
  4. Some do it by restrictors on the throttle, some do it by different EFI computer chip maps.
  5. Ride it.

    Flog it.

    Love it.

    - boingk

    In all seriousness though, most of these engines are from current production bikes that have been restricted either by throttle/intake or ECU mapping. They are designed for the full power that they are capable of in unrestricted form.

    To break in an engine I really recommend that GP method I used for my Aprilia RS125 - about 15min quarter throttle max, then 15 half throttle max and then another 15 wide open. Make sure to have acceleration to and deceleration from redline in there. This will let your piston rings seal more effectively against the bore before the factory cross-hatching wears off. It won't hurt the bike but I would recommend an oil change after the initial 100km or so as any dags/flecks/chips/micro particles of metal that may have become dilodged will have done so by now... and will subsequently be floating around your engine. Get rid of em.

    Cheers - boingk