Hii, I have a Jawa 250cc In India, I recently replaced the Engine with a new Cylinder kit & New Standard piston set I have Run the Bike for 2500 Kms, but still the engine seems to seize when run for speeds inn Excess of 60kmph for more time like 5 minutes.
What should I do to stop this siezure from happening?
What do people do to Run in a new bike for Racing is there a posibility, to follow any rules so I can do it on my bike?
Regards Abhi India
Hello Abhi
It seems you have got lost in the newsgroup section somwhere !
You have anded up in the Aircool Volkswagen section.
Good look finding the right place and with your bike.
Rich
Sounds like you are running lean, try larger main-jet in your carb(s). Also try a higer grade(Quality) of oil if it is available.
Is the 250 a Two cylinder engine? Is it a injector oil system or pre-mix? If pre-mix, increase oil amount slightly, try 2,5 - 3% of high quality TT-Oil.
If it has an oilpump and injector system, you can increase oil-mix by adjusting the oilpump. Normaly this is done by turning the cable adjuster outwards, try two full turns.
One problem now after it has seized several times is the Aluminium smear on the piston, make sure the piston rings are free and not sticking.
If no other factor was changed after installing cylinder and piston kit, the seizing is caused by a to narrow piston to cylinder tolerance(gap).
If this is a performance(tuning) cylinder, you will be turning higher revs. and need a richer fuel to air mix. As above, you need a larger main-jet with slightly increased oil mixture. If the cylinder and exhaust allows for high rpm, you need a full synthetic high quality two-stroke oil.
Hope this helps.
J.
Ps. Did you alter the ignition point when you replaced the cylinder? To late and it will run very hot, to early and it will ping..(melting a hole in your piston).
When I worked at a motorcycle shop in NY the only Jawa's we saw were flat track bikes that were only meant to run 5 min, at full speed. No brakes even in fact they just ran the oil thru the frame. It was popular weekend racing in that area.
Mario oh wrong news group
When I worked at a motorcycle shop in NY the only Jawa's we saw were flat track bikes that were only meant to run 5 min, at full speed. No brakes even in fact they just ran the oil thru the frame. It was popular weekend racing in that area.
Mario oh wrong news group
-- Arrie
Performance Bikes: The Navigator eats corners and spits out rocks afterwards
Back in the 1970's the USA Jawa distributor folded and 125 and 250cc Jawa tw0 stroke singles were dumped on the market dirt cheap. I considered getting one just for the oddity of it but I figured getting replacement parts would be unobtainable.
Good service info was already provided so all I will ad is; before any failed two stroke engine is rebuilt from a top end failure, the reason for the failure needs to be addressed before rebuilding the engine or you will end up doing it all over again....
Tony
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