Posted by Tiago on June 16, 2011, 1:57 pm
Hi!
I have a friend who have a XR400 (actually, the brazilian street
version with electric start and plush suspension and a few other
diffs). He have a Wiseco 440 forged piston on it. He rode less than 6
hours on it and the bike is smoking like hell. He thinks that being an
overbore and forged piston, the machine shop should have give the
piston more clearance on the bore, they used the factory spec for the
OEM ~400cc piston and bike started smoking after he raced an enduro -
full throttle for extended period. He did the break in as advised, he
went trail riding before the race and all was ok.
What you guys think? Should he get the machine shop to re-do the bore
with slightly more clearance or should he just have it honed and
replace rings if needed and be done with it?
Thanks for any insight!
-- Tiago
Posted by Wudsracer on June 18, 2011, 6:20 pm
Factory clearance is fine on the overbore. Properly warming the engine
is very important.
Disassembly, inspection, and then probably just rings and a bore.
Break it in (seat the rings) with non=synthetic oil; and as soon as
the engine warms up run the piss out of it. High compression pressure
will better seat the rings quickly.
Check the valves for leaking while the head is off. (pour gasoline in
the inverted head and see if it leaks through)
Good Wrenching!
Jim
*******************************************************
wrote:
>Hi!
> I have a friend who have a XR400 (actually, the brazilian street
>version with electric start and plush suspension and a few other
>diffs). He have a Wiseco 440 forged piston on it. He rode less than 6
>hours on it and the bike is smoking like hell. He thinks that being an
>overbore and forged piston, the machine shop should have give the
>piston more clearance on the bore, they used the factory spec for the
>OEM ~400cc piston and bike started smoking after he raced an enduro -
>full throttle for extended period. He did the break in as advised, he
>went trail riding before the race and all was ok.
> What you guys think? Should he get the machine shop to re-do the bore
>with slightly more clearance or should he just have it honed and
>replace rings if needed and be done with it?
>Thanks for any insight!
>-- Tiago
XML Sitemap
> I have a friend who have a XR400 (actually, the brazilian street
>version with electric start and plush suspension and a few other
>diffs). He have a Wiseco 440 forged piston on it. He rode less than 6
>hours on it and the bike is smoking like hell. He thinks that being an
>overbore and forged piston, the machine shop should have give the
>piston more clearance on the bore, they used the factory spec for the
>OEM ~400cc piston and bike started smoking after he raced an enduro -
>full throttle for extended period. He did the break in as advised, he
>went trail riding before the race and all was ok.
> What you guys think? Should he get the machine shop to re-do the bore
>with slightly more clearance or should he just have it honed and
>replace rings if needed and be done with it?
>Thanks for any insight!
>-- Tiago