Shaving down neutral switch O-ring

[the-chauffeur]

Folks

I've finally gotten the K2 engine to the point where the cases, barrels and top end are oil tight.  It'd be fair to say it's fought me every step of the way, and even though it now runs really nicely, it isn't prepared not to let some oil go from out of somewhere on the lower left hand side.

I know the gaskets in that area can be a pig, and I've already had to replace the generator gasket for one made from thicker material; before I put the side covers back on, I made sure the mating faces were completely uniform by wet 'n' drying them on a very flat surface. Turns out I might have removed fractionally too much from the generator cover (or the gasket I used was crap) 'cos one of the generator assembly faces met with one of the coil faces.  Thicker gasket cured that, and I'm going to replace the shifter assembly cover gasket to match.

Anyways, I think the oil is probably coming from around the neutral switch.  When I originally relocated the switch, I found that a brand new 3mm Honda o-ring (specific part) didn't compress and/or allow the switch assembly to sit deep enough in the recess for the switch itself to work - in other words, the bike could be in gear, but the neutral light would still be on.  I swapped the o-ring for one out of a generic metric kit which is 2.5mm thick, and that cured the light operation problem, but it looks like it's the cause of my leak.

So what are my options?  I guess I need an o-ring with a 3mm thickness left to right, but with a smaller thickness top to bottom.  My instinctive response is that there must be a way of shaving down a standard o-ring, but that's a pretty imprecise science.  I've also had a look to see if I can find something else that would replace the original, but so far I haven't turned up anything suitable.  

Ideas/suggestions/pointers gratefully received - and help me put this issue to bed once and for all . . .

Thanks

[UK Pete]

My F2 has a small weep of oil fromt the neutral switch, which i cant seem to solve so i will also be interested in the answer
Pete

[K2-K6]

You could try this:-

Clean the switch and degrease properly then glue the 2.5mm O-ring in place with "puncture repair patch glue" and allow it to dry and cure completely before re-fitting it.

[Bryanj]

Just checked my very old parts book and it definately sez 18 x 3 for the "O" ring, is the casing groove super clean?

[Spitfire]

Check that the clip holding the switch is in the right way, mine had a definate angle to it, put in upside down it does not seat the switch correctly.

Cheers

Den

[Hinomaru]

Try this:

If you put the o-ring on the switch first it may not seat correctly. Notice how the boss on the neutral switch is tapered? Put the o-ring into the engine case first. Use a bit of grease to hold it in place, then insert the neutral switch up into its normal position.

   

[the-chauffeur]

Thanks chaps.

Bryan - cases are clean as a whistle after vapour blasting.  I think the problem is more to do with wear on the face of the shift drum that the switch bearing runs on.  I've got three or four shift drums and all show some degree of wear; the bast one I've got is in the engine now, but the neutral light stays on in second.

Don - yeah - I noticed the clip is sided.  It's the right way up.

Hino and K2 - I'll try them ideas . . . and so much for the switches not being rebuildable - check out the posts halfway down this thread.

[UKROBK7]

good to know they ARE rebuildable!

[the-chauffeur]

Yeah -  I should have added a caveat to that . . .

 . . . they may be rebuildable, but I still can't get my spare one apart.  The plug on the underside seems to be held in by a thin ring of what I'm guessing is molten plastic (looks not unlike a wax seal).  That's easy enough to pick off, but getting the plug to turn is not proving so straightforward.  I've busted a couple of tools on it and I've backed off until I've worked out how to free the threads.

Might try some very gentle heat, but other than that I guess I'm going to have to look at fabbing some kind of four pronged device that I can lock in a vice.

[K2-K6]

I guess it should be safe in the oven to about 80-90 deg as the motor will usually reach that anyway.

There's enough talk of cooking various parts of engines on the site to get a recipe book together!

You would feel if it had any more "give" in it at that temp to make it worth chasing.

[Phil k]

Sorry - not been on the site for some time so just picked up on this thread.

Have you sorted your problem or are you still after a 'square' o-ring?

If so let me know the size that you are looking for and I'll see what I can do

Phil