KH500 Crankshaft Oil Seal / Engine Shock Absorber

[Alan.Haynes]

How does the oil seal that goes on the crankshaft before the engine shock absorber sleeve actually fit? It's diameter is much larger than the crank. I assume the spring on the outside is supposed to hold it some how but what does it hold the seal to?

Apologies for what may seem a simple question. I have no prior knowledge of the KH engine. I bet the answer is blindingly obvious.

Thanks

Alan

[brenton.roy]

Hi Alan, you may have worked this out, but there's a sleeve.
it's pictured here http://www.draganfly.co.uk/shop/pi11816 ... egoryId=79
I love the "blindingly obvious" questions - they make me feel better for when I ask them.
Brenton

[Alan.Haynes]

Hi Brenton,

Thanks for the information. I now know how the oil seal should fit..........only it doesn't!. The engine sprocket I bought from Draganfly has a flat back and having had the project inspected by the club to get an age-related number, I have been advised that the sprocket should have a recess to accommodate the seal. I took a trip to the National Motorcycle Museum on Friday and they have a sectioned KH engine (1956 so slightly different from mine - it has the extra spacer fitted from 1956 on). I now understand how it should fit.

I can't understand why Draganfly sell a sprocket that is clearly not a proper copy of the original. It does confuse the first time restorer. Looks like I'll have to source the correct engine sprocket.

Alan

[brenton.roy]

Bugger, I'm sorry about the statement in my post. Not so blinding after all..
I don't have a KH sprocket where I can easily get at it to check / measure for you. Perhaps some one else does.
There is a note on the Draganfly page though ... "Check the chain alignment and that there is space for the oil seal when fitting the above sprockets to KH models. Usually a 1180-26/64 shim will do the trick." Do you have this shim? it might be all you need. If not, perhaps someone with a lathe could sort this out for you.
What year is your KH Alan?
regards, Brenton

[Alan.Haynes]

Hi Brenton,

I'm not sure about the Draganfly comments about adding a shim. It seems that this would have to go between the crankshaft bearing and the engine shock absorber sleeve. I am concerned that if I get enough clearance for the oil seal to fit with the current sprocket that the chain alignment would be out and then I'd have to try and space the clutch chainwheel out to regain chain alignment. I fear that that way lies madness.....

I don't know if the Draganfly sprocket could be modified. Shouldn't it be hardened?

What would be the effect of leaving the oil seal out completely?

The KH is a 1955 frame and engine - although not matching numbers. The rebuild has gone remarkably smoothly up to this point...

Regards

Alan

[nevhunter]

Ive had a look at two new sprockets for the KH.. They are hard as and the face is flush with the inner sprocket face. There is only a small area to purchase on the splined sleeve so I wouldn't be altering anything there. The splined sleeve has no shoulder to come up against. What I have here is (I presume) for the earlier model. Does it have a seal?
The "K" models have a good oil pump that circulates a lot of oil, but I would think that if the early models got away without a seal , the later ones COULD also provided the fit of the hole in the crankcase is good. Don't alter the chain alignment, (as you rightly state.) There's no room to do much there without an unsightly spacer, and other problems... Nev

[brenton.roy]

Hi Nev, Alan,
I have the KH motors stored elsewhere, which doesn't help much, I'm not sure if they have the seal or not.
The sprockets are extremely hard, but they can be ground with a high speed, hard tool. I have a sprocket that has been rebanded, so it must be possible.
I was talking with a mechanical fitter mate today and he suggested either a ceramic tool bit on a lathe or something like a dremel fixed to the post. This setup (the dremel) has also been suggested as a way to repair oval big end outer shells (after pressing into the rod). I'm assuming we're talking about grinding for clearance for the seal. The centre of the sprocket could stay untouched. It would just be a matter of grinding a "ring" into the rear of the sprocket.
Apparently this youtube video (suggested by said fitter) will make toolies go weak at the knees. It certainly worked for him... http://www.youtube.com/watch?v=BU14tfjUfQU
Brenton