Author Topic: Engine adjustment fore-aft on 2 3/4hp models  (Read 3227 times)

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Offline Lat Fuller

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Engine adjustment fore-aft on 2 3/4hp models
« on: 26 Aug 2016 at 04:16 »
Can anyone tell me if the front lug on the base of the frame for holding the engine in place should be free - or should it be welded in place ?   I seem to have run out of adjustment between the drive belt and drive chain and wondered if I could move the engine back slightly - but the lug seems to be grafted onto the frame.  (Maybe from years of rusting ?)

Offline Chris

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Re: Engine adjustment fore-aft on 2 3/4hp models
« Reply #1 on: 26 Aug 2016 at 06:00 »
HI Lat
The front engine mounting lug is welded to the frame. Adjustment of the primary chain is by the gearbox mounted in slots in the rear of the frame. Adjustment of the belt is by shortening it as the chain wears and stretches or the belt stretches. Chris.

Offline ian scott

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Re: Engine adjustment fore-aft on 2 3/4hp models
« Reply #2 on: 26 Aug 2016 at 11:40 »
Sometime a half link is required on the primary chain. This worked on my bike.

Offline Lat Fuller

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Re: Engine adjustment fore-aft on 2 3/4hp models
« Reply #3 on: 27 Aug 2016 at 02:26 »
Thanks for the advice..I am battling to get the correct size belt - I fitted a section C78 (closest I could get here).   I may have to purchase a link belt from stationery engine spares.   I also just wondered what the "slot" on the bracket was for .. ?

Offline graeme

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Re: Engine adjustment fore-aft on 2 3/4hp models
« Reply #4 on: 27 Aug 2016 at 23:25 »
You should be able to get C section Opti belts in inch increments, I know I have bought a C77 and C78 and C79 in the past

Offline midman

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Re: Engine adjustment fore-aft on 2 3/4hp models
« Reply #5 on: 28 Aug 2016 at 12:48 »
I recently purchased this Optimat belt though I haven't installed it yet. Should give plenty of adjustment.
 

Offline Chris

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Re: Engine adjustment fore-aft on 2 3/4hp models
« Reply #6 on: 28 Aug 2016 at 15:27 »
Hi Lat and all
You asked what the purpose of the slot was on the rear engine mounting lug. I was informed many years ago that this was to enable the engine to be moved back sufficiently to enable the front cylinder  to be removed without removing the complete engine. The rear cylinder can be removed without removing the engine. However, to move the engine back the exhaust system has to be removed together with petrol pipes manifolds and much more and while you have to remove the front mounting and slacken the rear it is just as easy to remove the engine completely and thereby improve access when re-fitting the front cylinder. On the subject of belting I have used Optimat for many years on several bike and found it to be excellent in terms of wear and little or no stretch. I also use linked belting on some bikes and unless you can find original Brammer belting the wear rate is very poor on the currently available stuff from the Far East and the amount of stretch initially has to be seen to be believed. Chris