Author Topic: gear ratio change kickstart queerie  (Read 1494 times)

Online bsa-bill

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gear ratio change kickstart queerie
« on: 20.12. 2009 14:04 »
If and when I get back to my project ( can get nowt done for doing stuff for others ) I have a slight problem to investigate.

It is extremely difficult to kick the engine over, there are a number of factors involved however

1. I have altered the gearing. engine sprocket now 22 tooth gearbox now  reduction in gearing18
      this to give a very slight reduction in gearing - would rather have a bit more get up and go than top speed these days.
2. engine rebuilt with spitfire cam and 9.5:1 pistons, rebore and bottom end made good.
3. the bike is on a low bench

All this is with the plugs out by the way
The problem is not with the kickstart or gearbox as it spins fine with the clutch released, also the engine can be turned with a socket/breaker bar on the end of the crank.
I think it might pay me to wait until I get the bike on the ground and see how it feels then.
So I'm wondering can that small difference in gearing make a difference to the load on the kickstart, or could it be the higher cams, or just the fact the bike is not planted on the ground.
The reason I want to turn the engine is to get oil through all the important bits.
Anybody had this experience before, I can't recall this happening with my previous rebuild but then I did not have any of the above three conditions applying.

All the best - bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline chaterlea25

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Re: gear ratio change kickstart queerie
« Reply #1 on: 20.12. 2009 22:15 »
Hi Bill,
You are not making sense here !!!!!!,

"I have altered the gearing. engine sprocket now 22 tooth gearbox now  reduction in gearing18 "

Bigger engine sprocket will make the engine easier to kick over/ smaller harder

If you have only asembled the engine etc it will be quite stiff until you have several hundred miles on it

I have used a jacked up front wheel drive car, steering locked over running  in to drive the back wheel of a bike (on its stand) pushed up against the car wheel  to circulate the oil!!!!!

HTH
John
1961 Super Rocket
1963 RGS (ongoing)

Offline LJ.

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Re: gear ratio change kickstart queerie
« Reply #2 on: 20.12. 2009 22:24 »
Bill I've noticed a big difference in my bikes starting when... 1/ On bench lift and 2/ When on the ground. But John... That sounds a brilliant way to circulate the oil before first firing up of engine. Must remember that one.
Ride Safely Lads! LJ.
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1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
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Offline MG

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Re: gear ratio change kickstart queerie
« Reply #3 on: 21.12. 2009 09:32 »
John - great idea with the jacked up car  *idea*. I usually tow the bikes around the village behind a car to circulate the oil through the rebuilt engine for several minutes.
Got to be pretty careful there and people around usually feel like: "Well, that's it. Now he's finally out to lunch!"  *eek*
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Online muskrat

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Re: gear ratio change kickstart queerie
« Reply #4 on: 21.12. 2009 11:48 »
Ah, the poor mans starting rollers. I once saw a poor soul try to start his race bike (Tri) like that. It did start and then jumped off the stand and headed straight towards another competitors bike. Not nice.
Bigger engine sprocket easier kick as it spins less revs per boot.
If you are liberal with the oil on assembly and before you put the oil pump on rotate crank to bottom of stroke and use oil can to fill the crank. It will start to circulate a lot quicker.
Cheers
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Online bsa-bill

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Re: gear ratio change kickstart queerie
« Reply #5 on: 21.12. 2009 12:12 »
AH sorry folks John is quite right as the engine sprocket is 22 replacing a 21.
 and the line should have read - I have altered the gearing. engine sprocket now 22 tooth and gearbox now18.

Those senior moments!!!, they kind of shake your confidence at times too resulting in me doing some jobs over again as I can't recall every nut and washer that I replaced, so far I haven't found anything I've missed, also it's taking so long ( five years so far ) I forget what's been done and bought ( got a few extra spares for sale soon )
A pencil and paper has to be the answer I suppose.

Glad to hear it's not unusual for the engine to be so tight, once I get it off the lift I'll give it a good turning over and get oil returning.
Bit difficult to get car and bike close at the minute John as our drive is too soft to trust a bike stand on, we do have a garage that the car fits into but you would have to crawl out through the boot to get out of it. 
Could tow it around the farm of course  - the cows would turn a blind eye.

Many thanks for your replies chaps

All the best - bill
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Offline MikeN

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Re: gear ratio change kickstart queerie
« Reply #6 on: 21.12. 2009 20:22 »
When Ive rebuilt engines.I take out the spark plugs .Put the bike in gear and just take it for a short walk up and down the road. Quick and easy.
Mike

Offline chaterlea25

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Re: gear ratio change kickstart queerie
« Reply #7 on: 21.12. 2009 20:40 »
HI Bill and MG,
Towing a bike with whatever means available is fraught with DANGER!!!!
Imagine dropping the fruits of your 5 years labour labour *eek* *eek* *eek*

A friend of mine finished building a 4 cylinder Henderson some time ago, it has all plain bearings on the crank and bigends
It was quite stiff to turn over so he went of to the scrapyard and found a couple of rollers, He made some mountings from 4in. angle iron. Then welded a gear to one end of a roller and mated this to a starter from a truck!
He fitted the rig between the rear wheel and the bike bench and strapped the bike down, Starting rollers for Nought!!

Another funny incident with this bike was when he went to get an oil filter to fit the aftermarket kit available for the Henderson (this is a proper pressure fed kit with oil pressure gauge and all!)
He went to the local factors and asked if they had a"black" filter so it would not be too noticable
The Guy said no, but I have some "blue" ones! It turned out they are a near perfect match for the colour the bike is painted!!!!


Cheers
John
1961 Super Rocket
1963 RGS (ongoing)