2006 250 - Engine Knocking When Warmed Up...

[waynerobshaw]

Hi All,

I've been to see a 2006 250 this evening. It looked just the ticket, started well and ticked over just has you'd expect. Took it for a quick blast, but once i'd come back (2 mins), the engine was making a knocking noise just as it returns to idle. At high revs it sounds fine, just when it returns to idle does the knocking appear.

Now, I'm thinking main bearing, what does anyone else think?

So, the basics are, sound fine when cold, knocky when warm and dropping back to idle.

Any wisdom guys?

Cheers,

Wayne.

[baldilocks]

Sounds like piston slap. The watercooled barrel expands more than the piston. To be fair most used bikes more than a couple of years old will have this unless they have been reconditioned, its basically wear on the piston / bore. Check splatshop for piston prices. Re coating cylinder is about £120.

Performance is affected but not to a great extent.

[sectionone]

I think it's normal for an average use trials bike ridden by an average rider to not need a new top end for up to 10 years or more because of the low rpms involved. MX and enduro bikes need new top ends as part of regular maintenance, but a well maintained trials bike won't need it for many years. I would look for another bike to buy as this one was probably not well taken care of.

[baldilocks]

Its 8 years old.

I have rechromed bikes after two years before.

[lineaway]

Are you chopping the throttle? Or just as it slows down. If chopping, it`s just lean on the low end.

[copemech]

lots of bikes get a bit rattly! God forbid anyone recall what many old air cooled bikes sounded like! We are now spoiled!

So take the cost of the used bike and divide it into the cost of a new one! Multiply by thickness of wallet and somewhere in there you may find what you like! Add for your aptitude and deduct for parts! Problem solved!