KR-1S.co.uk Forum

two days ago on a freeway runnin' 160 kmh in 6th constantly (just about under for kips to open) for bout an hour..
met a friend and overtook him with kips open and bloody thing seized...clutch applied for a few seconds and engaged again, engine started, both cylinders working, power slightly decreased, no strange noises. I was so pissed that I continued to run 140-150 kmh
On a paytoll engine stopped, on right cylinder no compression at all, over 3000 rpm both cylinders working, trip continued as I was in a hurry for a ferry.
At home found as on a title, earth electrode worn, rings completely seized by melted aluminium but not broken, on a crown part of a piston melted/erroded just under the plug, and piston melted over top ring on exhaust side..cylinder head without any carbon
left piston in perfect condition together with cylinder head, both with any carbon deposit

any diagnostics?
seems to me plug was giving spark to a piston

Sounds like the right hand cylinder was too hot. Pictures would be useful and an explanation of why you were running it in. i.e. what work had been done and why?

The overheating could be caused by jetting being too lean, but if it's severely on one side, I'm thinking a complete carb in-balance and an issue with your right carb suffering fuel starvation.

As I say, pics and a few more details would help us determine exactly what's gone wrong here.

pics cannot send because mobile is too bad,I'm not at home for few days and comrades over here are not equipped as well..
spark plug was BR10ES
oil is total two stroke racing full synt.
part on a crown which was erroded is about 0.5 mm deep and 15mm in diameter approx.
if fuel starvation, would say that fuel filter was partly clogged or line from tank till carburetor, but few days ago made same trip with other piston and only top rings changed on both sides.
before bike was able to do 225 kmh, with cast iron sleeves, so I wouldn't be suspicious about jetting
what I'm suspicious about is electrical part, cables, CDI(but assume with CDI would have problem on both cylinders), spark plug...

It may have gone lean due to an air leak on the intake for the r/h cylinder.

Hi
I have exactly the same problem yesterday . Did you found what was the problem. In my case, for now I found voltage regulator is not working and I have almost 18 volt on net, but I am not sure is this the problem.