Difference between late KH and FH chaincases

[pete.collings]

I have an inner chaincase suitable for a 1956-59 twin with the fully enclosed rear chainguard (FERC), which I believe is from a Huntmaster. However, on checking part numbers, there is a difference between the KH and FH numbers. The case has a casting number of K400, whether this will enable the case to be identified I am not sure.
Visually it looks like a FH inner case (having owned a FH), but as I have not owned a KH, I cannot be sure what if any the differences are between the two models. If anyone on the forum has/does own both models in the 56-59 range, I would be most appreciative of any feedback.
I understand the KH was dropped from production in 1957, so presumably there would be fewer primary cases around, but one cannot count on this!!

[Alan.Haynes]

Hi Pete,

Having built a 1958 Huntmaster earlier this year and now being in the process of building up a 1955 Fieldmaster, I have been told by experts that despite different part numbers that there are only 2 versions of the chaincase, one for singles and the other for twins. There was a change in 1956 when the rear of the primary chaincase was altered for the FERC. Others may know more / differently but I believe the K400 casting number is correct.

Regards

Alan

[Simon.Gardiner]

Where's my anorak gone.....
'56 part nos for chaincase inner, 5711-56(singles), 5712-56(FH), 5713-56(KH)
However I have run a bike where the 650 engine was swapped for a 500 single, the chaincase wasn't changed, I cut a spacer from a piece of alloy sheet and used it between the chaincase inner and the crankcase; along with thick gaskets my point here isthat it wasn't a particularly good piece of engineering but when everything was tightened up (albeit just ebough to make everything 'firm' as opposed to 'rock solid) all the gaps closed and nothing broke, so I suspect it's possible to interchange the KH and FH inners with a bit of care.

[Simon.Gardiner]

PS - casting number on that chaincase inner is also K400

[pete.collings]

Thanks for the info, from what has been said the chaincase is from an Huntmaster.
I am also selling it on behalf of a branch member, and have posted details in the Buy a Bit/Sell a Bit section in the members area.