rs 125 top end rebuild problem

[john0207]

hi
ive just rebuilt the top end (new piston, piston rings and gaskets)
and it ran fine for a couple of days, but i had only done a couple of miles to test it

now it wont start i think because i couldn't tighten up the bolts fully to the bottom end.

there was water coming out(only a little) between the top and bottom end where the bolts tighten up on it

question

should i have used some sort of thread glue

and any tips for getting the bolts tight enough would be handy as there just doesn't seem to be enough room for conventional spanners (7/16ths is the size i think)

thanks a lot guys

regards
john
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Most motorcycle problems are caused by the nut that connects the handlebars to the saddle

[Kickstart]

Hi

The RS is all metric. Forget any imperial sockets. Cannot remember what size it is, but either 11, 12 or 13. Mildly fiddly to do, but not that bad.

Those nuts holding the barrel to the bottom end do not need to be that tight and do not need thread lock. You do need to use a new gasket and you do need to clean the remains of the old gasket away thoroughly (and being careful not to scratch the mating surfaces).

Suspect that you might have had the cooling system drain into the crankcases. How old a model of RS is it?

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[john0207]

its 1998 rs125 extrema , rotax 123 engine

it worked fine yesterday

and now wont start

i thought the loose bolts were the problem

cheers
john
____________________
Most motorcycle problems are caused by the nut that connects the handlebars to the saddle

[Kickstart]

Hi

Highly unlikely the loose bolts are all the problem. They might allow water to leak out or air to leak in, but neither on there own would be a major problem. However water leaking into the crankcases and filling them up would be a problem.

Right, 123 engine. That makes things easy.

Take off the fairing on the right. Look under the engine, just in front of the starter motor. You should find an allen key bolt. This is to cover a hole used for setting the ignition timing, but is useful to drain the crankcases. Undo this and see if you get a load of water coming out.

Put the bolt back in before attempting to start the engine.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[john0207]

[Kickstart]

Hi

You really need to know why it is no longer running. However a water leak from the gasket would only really cause a problem by draining into the engine (assuming the last time it was running it did not run out of water and nip up).

Check the water first (easy check). Then check things, such as whether you have a spark.

Those nuts holding the barrel on should be done up to 30Nm.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[john0207]

it has compression as far as i can tell

the bolts are loose , and i can turn them with my fingers.

i will re-tighten them and drain any water out of the bottom end

it ran well ticking over with no coolant in at all when i ran the engine for the first time in the garage for only a minute or two

it seems to have gone wrong when i introduced the coolant

and like you say has flooded the barrel with coolant, hence no spark (?)

this is turning into a labour of love rapidly

thanks for you help keith

regards
john
____________________
Most motorcycle problems are caused by the nut that connects the handlebars to the saddle

[Kickstart]

Hi

A decent quality ring spanner will fit on the nuts easily (but make sure it is the right metric size). They need to be far tighter than finger tight.

Don't run it for any length of time without any coolant.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[ZRX61]