This is running well today.......

Took the KMX200 out for a mooch about the Plains yesterday. My weekly
de-stress session. Did about 60 miles or so offroad over some very mixed
terrain. Sweaty, knackered and happy, I come down off the Plains on to the
Devizes road.
This thing is running really well today. No overheating, plenty of poke. no
nasty noises from the engine at all.
.......best it's run in ages. Only 5 miles to go now, let's give it a bit of
a clear out on the downhill. 60....70......coming up on 9krpm....80..yes!
2seconds later, 60..50..40...screeeeeeeeeeeeep. Skid. Stop.
Bollocks. Seized.
Glad that didn't happen an hour or so back in the middle of the Plains.
Call the SO. Comes out with the Beemer and tow rope. Being towed at 45mph on
a 15' tow rope keeps the mind focussed I can tell you.
Tried to free off the engine this morning. No joy. Piston and barrel bonded
at a molecular level I reckon.
Time for a top end rebuild. About an hours work as it's a nice simple
stroker.

JB

 

Nah. I've got a mandrel type puller specifically for that job. As to why it
seized, now that's the big question. I think it broke a ring and/or lost a
piece of 'land' between the two rings. We'll see tonight anyway.

JB

 

What is the meaning of life? etc...Why do strokers _always_ do this? Who
knows?
I dearly love strokers even all of their little 'foibles'. I'd never be
without one given the choice. Ideally another KX500 and a KR1.
I just wish you got more than a second or two's warning prior to terminal
damage. It felt just for a >tiny< second like it was thinking of going onto
reserve. Silly me for not hitting the kill switch and clutch there and then,
but I was hopeful/stupid!
Engine out tonight. Autopsy at 11.
Spares engine is still up in the barn, so I see a rummage for that later
this week for a possible barrel donation.

JB

 

I could well be taking bollocks - but I'm sure I read somewhere that
running the 'best it ever has' was to do with running lean, therefore
overheating, before blowing.

 

I've heard this. Experienced it on an X7 too so I know it can be based on
reality. Split in the inlet rubber did for the LH piston on that one.
On the KMX I'm not too sure. It was nearly flat out but that's not unusual.
The airfilter is standard but I'll be checking the rubbers as I drop the
engine tonight. It's got an inline filter so shit in the carb shouldn't be
an issue. We'll see.....
JB

 

They all do that sir.
Two strokes sieze due to a lack of lubrication, something is wrong in the
petrol/oil mixing department.
Also check piston clearances, they can pinch up due to expansion when they
get hot if the piston to bore clearance is tight.

 

I was told this too, after I blew up my race-tuned 250LC and
subsequently checked the jet sizes. I bought it pre-tuned and never
thought to check the jet sizes; it ran brilliantly but had a main jet
size of only 150 - the stock size is 190. I really didn't know much
about performance two-strokes at the time, so it was educational as
well as character-building.

 

The time I seized an X7 it was due to a piston cracking. Given
its age and history it wasn't surprising. Practice for a national race at
Oran Park on the Saturday, dropped down a gear at 90-plus at the end of
the straight, turned left and heard this loud screeching. Thought I'd
locked up the back brake, let it off, the bike continued to hang out the
rear, the concrete wall started looming... Just as I realised that the
sound wasn't the tyre but the engine, basic primal instincts went into
action and I blacked out. Next thing I recall I was rolling onto the
grass after the next right-hander. I'd pulled in the clutch and braked to
a halt under autopilot while my brain was saying, "You don't want to
remember this, it may hurt!"

Had a similar period of blackout when I did a 70-mph faceplant in
Vancouver after a novice tried to go under me in a corner, forced me off
the track and into an intimate meeting with a drainage ditch. No memory
from when the front wheel hit the ditch until I picked myself off the
ground. That time I think I fainted again after standing up -- next I knew
I was surrounded by pit personnel who had jumped the wall and ran across the
track to try to help me.

--
Ivan Reid, School of Engineering & Design, _____________ CMS Collaboration,
Brunel University. Ivan.Reid@[brunel.ac.uk|cern.ch] Room 40-1-B12, CERN
GSX600F, RG250WD "You Porsche. Me pass!" DoD #484 JKLO#003, 005
WP7# 3000 LC Unit #2368 (tinlc) UKMC#00009 BOTAFOT#16 UKRMMA#7 (Hon)
KotPT -- "for stupidity above and beyond the call of duty".