G12csr rev counter?

alan humphrey · Post by **alan humphrey** » Mon Feb 02, 2009 10:35 pm

hello there lads and lasses.i wonder if anyone can help me, were any of the g12csr`s fitted with rev counters as i think mine has had one at some time in its life.I am at present stripping my engine for a rebuild (will be my first),and at one end of the front camshaft there is a blanking plate, behinde the plate there seems to be a rubber drive of some sort i have taken photos of it but i am unable to get them on here.I will email them to anyone who will help.I cannot get to the camshaft yet as i am waiting for the camshaft puller to arrive the bike is a 1961 and it was a factory bike for the first part of its life.

arsey30 · Post by **arsey30** » Mon Feb 02, 2009 11:40 pm

Yes, I bought a new G12CSR with factory fitted speed kit in 1963 and it was fitted with a rev counter.
I think there was an aluminium adapter to mount the r/c gearbox on the crankcase, drive was from the camshaft.

Dave.

Don Madden · Post by **Don Madden** » Tue Feb 03, 2009 2:13 am

You don't need a puller for the cam gears if the cases are already split. Just light taps with a hide or plastic mallet will drive them through. Do NOT place any puller with tapered extractor bolt directly on the end of the camshafts or they may break. A properly shaped button is best but a thick washer of the right size can be placed on the shaft.

Cheers, Don.

alan humphrey · Post by **alan humphrey** » Tue Feb 03, 2009 3:14 pm

hello don and dave,thanks for your interest.
first of all don, i have not split the crankcases yet as i am waiting for the puller plus a load of other stuff to arrive from jampot spares i will not attempt it without the correct puller especialy as i am only a learner.
Dave i am now wondering weather i can get the parts to fit the speed kit as the bike probably had this when it was used for testing and as a marshals bike by the factory,does enyone no if thease parts are availible anywhere? thanks for all your help.
regards alan

arsey30 · Post by **arsey30** » Tue Feb 03, 2009 3:29 pm

The kit was available from 1963, but I dont think many were sold, mainly for production racing I suppose, but the Bonneville and Norton were most competitive by then.

The kit consisted of twin carbs [1 chopped off monobloc] cams, 10.5 pistons, optional twin pipes and rev counter with fly screen like G50.
I found that the carbs were starved of fuel, so fitted a remote rubber mounted GP carb float chamber, but i did rev it until if would go ne more, not something i would do today.
Dave.

alan humphrey · Post by **alan humphrey** » Tue Feb 03, 2009 3:59 pm

Dave as my bike is a 1961 it would not have had that racing kit fitted when it was new or would it? Iam trying to get my bike back to as near as orriginal as i can (within reson) cost being my main obstical having already spent just under £2000 and certainly more to come.
regards alan

arsey30 · Post by **arsey30** » Wed Feb 04, 2009 9:26 am

Alan,
It will be difficult to say what your bike was like as original, unless you find that owner, will you restore it to marshall or standard trim?

Most restore to factory original unless they know the history, but if yours was a factory/marshalls bike then it may well have been non standard to start with, maybe like those raced in the Thruxton 500.
You need to find some old TT issue magazines.

Good luck,

Dave.

Rick.Edwards · Post by **Rick.Edwards** » Wed Feb 04, 2009 1:36 pm

The race kit came with seriously leary cams they are monstrous i have a new old stock pair,but lack the courage to fit em.

arsey30 · Post by **arsey30** » Wed Feb 04, 2009 4:06 pm

I found the engine on my '63 bike with full speed kit [10.5 pistons, twin carbs, cams, hand controlled mag] was not much less flexible than my standard '61 bike.
The factory told me the power increase was only about 48bhp to the standard 46.
Acceleration was better but top speed about 5mph extra [110 against 105]

Held on the stop, it would show 100mph in 3rd at 7000rpm [max power at 6,400, safe to 6,800rpm I think the factory said]
They advised me not to do that too often, but I covered 20,000m on it with little trouble [punctured float, cracked mag pick up holder, and oil drilling missing in crankcase]

Happy days.

Dave.

Rick.Edwards · Post by **Rick.Edwards** » Wed Feb 04, 2009 4:14 pm

Hmmm sounds like my kinda 650,may fit them cams,there was some years ago an article in classic bike written about Bob Doughty he had a Thruxton CSR it apparently did 126mph if i recall.