bike will not start

GrantAndrew

Well Known and Active Forum User
Non-VOC Member
i have been working on my dads vincent rapide for a while in the hope of getting it up and running.
it was bought in 1971 as a kit from roger slater and has to my knowledge only been running once.
we have changed the oil, stripped and rebuilt the carbs added fresh fuel and checked the spark.
the bike still does not want to start.
the plugs do look like they are getting a small amount of fuel but never get really wet.
The bike does spark but maybe not as much as i would have imagined it would.
it is very hard to kick over to start with but gets easier the more you do it.
we have ordered a spanner to check valve operation is ok.
my dad insists he has started it years ago so could the timing be out?
what could it be?
any ideas appreciated.
Grant.
 

wparr2

VOC Hon. Technical Officer
VOC Member
VOC Forum Administrator
VOC Forum Moderator
After all these years it is highly likely that the magneto has
deteriorated leading to a weak (or no) spark under compression forces.

Also recheck the carburettor passages (ie idle settings) to make sure they are clear.

Thirdly, check the valve operation, as you may have a valve stuck (unlikely).


Bill Parr
Technical Officer VOC
 

GrantAndrew

Well Known and Active Forum User
Non-VOC Member
we have not checked the magneto so may be as well to strip and check.
what would you recommend inside the magneto to get it sparking as it should?
thanks, grant.
 

Tnecniv Edipar

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Non-VOC Member
The comment that it is very hard to kick over is interesting. Do you mean it is stiff or not turning freely ?
Once over compressions it should turn without too much effort. Try removing the plugs and see if it turns over easily.
 

CometHRD

New Forum User
Non-VOC Member
Re: Bike will not start.

Grant, As you live in north somerset it may be quicker for you to take your magneto to APL Magnetos in Shaftesbury. His telephone number is 01747852136. Fifteen months ago he rebuilt my comet magneto within three days, and it has worked fine ever since. Regards, Tony.
 

GrantAndrew

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Non-VOC Member
Thanks for the ideas we will take a look at the magneto and maybe send it off if needed.
As far as kicking the bike over it does turn over freely after compression stage all be it a little tight. Not too concerned though as its a fresh engine.
 

Tom Gaynor

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VOC Member
Hard to kick over

I had this problem. It was because the timed breather wasn't. Timed, that is. Somehow, possibly while faffing with the magneto pinion, it had gone out 90 degrees. (You can check with a timing disc and simply blowing down the breather (stop the motor first...) to find out where it opens and where it closes. Numbers in KTB.
An ineffective breather (too long, too small a bore) will do the same. The pistons are having to fight compression at TDC and BDC. I changed to a breather on the front exhaust valve cap, much shorter, with a PCV valve in it, and for the first time could start the bike "on its wheels" instead of on its stand with all my weight behind it.
Look also to the oil you're using. Vincents run so cool (read cold) that SAE 20 is enough. Particularly with a new, tight, motor.
My mags go to Dave Lindsley. Excellent service, and so far, quick turnround.

Tom

Thanks for the ideas we will take a look at the magneto and maybe send it off if needed.
As far as kicking the bike over it does turn over freely after compression stage all be it a little tight. Not too concerned though as its a fresh engine.
 

Albervin

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VOC Member
There was an article recently here in Australia about the first Slater bike to arrive in Australia. The owner was so disappointed with it he sold it very quickly. The new owner spent a not inconsiderable amount on rebuilding the engine then parked it in the shed where it has remained for close to 30 years..... I wish you you better luck & hope you persevere long enough to enjoy the machine.
 

Bill Thomas

Well Known and Active Forum User
VOC Member
Hello Grant,
Hope I'm not too late.
We must get this bike going. Have you got the plug leads on the wrong way round ? It's been done many times !!. If it's a standard mag' is the earth brush and slip ring clean, "It screws in the top of the mag at the drive end ".Get at least 4 new plugs, Gap them at no more than 18 thou'.
Put the plugs you have been useing in the Bin !! Even if they don't look wet they can short out deep inside the plug.
Just had a thought I wonder if the old oil has filled up the Crankcase,
You can drain it by taking out the drain plug close to the primarychain adjuster, Some Vins do this after a Winter lay off ! Put the drain plug back in.
With the plugs out and the petrol off spin the engine over a few times to clear the rubbish out.
New plugs in, Petrol on, Don't use the choke, May be flood the carbs a little ,Try to start the bike with thick boots, Not shoes.
If it does not start, Open the throttles up and squirt a few squirts of W D 40 down the holes and try again," It acts like easy start".
Good Luck . Bill
 
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