How to start a Single Cylinder Q ?

speirmoor · May 20, 2024

Here's a Q for the knowledgeable and experienced among us.
How do you know when you are at the correct time to Kick?
I've been told to ease past compression, reset the kicker and then go for it.
How does one know they're on the right stroke and not the exhaust stroke for a single cylinder engine ?

batrider · May 20, 2024

Does it have a compression release?

concours · May 20, 2024

speirmoor said:
Here's a Q for the knowledgeable and experienced among us.
How do you know when you are at the correct time to Kick?
I've been told to ease past compression, reset the kicker and then go for it.
How does one know they're on the right stroke and not the exhaust stroke for a single cylinder engine ?

Well, you will know, because there is NO compression on the exhaust stroke.

baz · May 20, 2024

It does depend to an extent what bike it is
If it's a BSA b50 you have to get it past tdc until the exhaust valve starts to open
The kickstart must be returned to the top
Ignition on no throttle and usually will start on the first kick
I believe velocettes are best started this way too

speirmoor · May 20, 2024

batrider said:
Does it have a compression release?

yes

speirmoor · May 20, 2024

concours said:
Well, you will know, because there is NO compression on the exhaust stroke.

baz said:
It does depend to an extent what bike it is
If it's a BSA b50 you have to get it past tdc until the exhaust valve starts to open
The kickstart must be returned to the top
Ignition on no throttle and usually will start on the first kick
I believe velocettes are best started this way too

Yes its a Velo

speirmoor · May 20, 2024

concours said:
Well, you will know, because there is NO compression on the exhaust stroke.

Its still feels like its tight though when your cycling the kickstart ?

Tornado · May 20, 2024

A search on YouTube for Velocette finds you many velo starting videos, with complete details on what is being done. Im no expert, but from what I have gleaned, method is to get it to compression, pull the valve lifter, get it past tdc, return kkcker to top, then slowly push it fully to bottom (this gets it through power and exhaust strokes). Now return kicker to top, valve lifter released, and give it a full hard kick. If no joy, repeat the whole process.

concours · May 20, 2024

speirmoor said:
Its still feels like its tight though when your cycling the kickstart ?

Negative.
Not on a four stroke single.

S
S
B
B

Nortoniggy · May 20, 2024

Some Velocettes, particularly Venoms, have a reputation for being difficult to start. The kickstart is rather short and the way it's geared means it doesn't turn the engine over much.

baz · May 20, 2024

Nortoniggy said:
Some Velocettes, particularly Venoms, have a reputation for being difficult to start. The kickstart is rather short and the way it's geared means it doesn't turn the engine over much.

The kickstart gearing is part of the problem with a b50
Compounded by an extremely light crankshaft and 10 -1 compression
The crank doesn't have the weight to carry the piston through compression and can just bounce off
Open the throttle at your peril !
Once that motor has a big gulp of air and fuel it can hurt the uninitiated

Tornado · May 20, 2024

Nortoniggy said:
Some Velocettes, particularly Venoms, have a reputation for being difficult to start. The kickstart is rather short and the way it's geared means it doesn't turn the engine over much.

Ues the gearing on kicker is a big contributor. Also got to find where to place the manual timing lever to get reliable fire ups. Mine is auto EI mag, so i should not need to worry aboit that aspect, assuming basic timing is correct.
Current problem it has is the kicker itself jammed up when trying to restart after a brief clutch adjustment test. No amount of force or changing gears, rolling bike around could free kicker. Turned out the mechanism was missing a crucial washer/spacer called "the wedding ring" on the layshaft where the kicker toothed gear engages with layshaft first gear teeth. Some DPO messed that up.

Richard Tool · May 20, 2024

Retard spark if manual advance .For engines with magneto ignition bring it to TDC compression stroke , pull compression release and ease it just past TDC. Let off compression release ( restoring compression) and then a long swinging kick . Magnetos make better spark when they spin
faster .This is the reason for bring it past TDC .
Coil / points ignition bring it to TDC on compression stroke then kick . REMEMBER to RETARD SPARK .

speirmoor · May 21, 2024

Thanks for all the tips everyone. Luckily I've been able to start the Velo now somewhat regularly even tho there's no Choke fitted or Advance/Retard capability
I miscalculated thinking it was getting tight twice during the cycle when it was really once all the time as Concours pointed out. I'm glad I asked now because I'm not guessing any more

ilikevelos · May 21, 2024

To clarify one thing about velos, the kickstarter should be used to accelerate the flywheel mass in a smooth stroke. It is the mass of the flywheel that takes the engine through the compression stroke. The kickstart does not need to be long because you are accelerating the flywheel before the compression stroke and using the momentum to carry it through the compression stroke.

One thing that screwed me up when I bought my thruxton. Because of the cam overlap you should not kill the engine with the valve lifter since it fills the inlet tract with spent charge and it takes forever kicking it over to replace this with fresh charge.

I find a big single easier to start than a commando, for example, since there is time to gain momentum without the second cylinder's compression stroke getting in the way.
M

Tornado · May 21, 2024

ilikevelos said:
To clarify one thing about velos, the kickstarter should be used to accelerate the flywheel mass in a smooth stroke. It is the mass of the flywheel that takes the engine through the compression stroke. The kickstart does not need to be long because you are accelerating the flywheel before the compression stroke and using the momentum to carry it through the compression stroke.

One thing that screwed me up when I bought my thruxton. Because of the cam overlap you should not kill the engine with the valve lifter since it fills the inlet tract with spent charge and it takes forever kicking it over to replace this with fresh charge.

I find a big single easier to start than a commando, for example, since there is time to gain momentum without the second cylinder's compression stroke getting in the way.
M

So if killing with lifter is a no no, what is correct way to shut it down? Braking while in gear with no clutch so it stalls?

Tornado · May 22, 2024

Tornado said:
So if killing with lifter is a no no, what is correct way to shut it down? Braking while in gear with no clutch so it stalls?

Thinking more on this, can't see it taking more than one 4 stroke cycle to clear any residual exhaust gases from the chamber. None issue?

baz · May 22, 2024

Tornado said:
Thinking more on this, can't see it taking more than one 4 stroke cycle to clear any residual exhaust gases from the chamber. None issue?

Does your magneto not have a cut out?

Tornado · May 22, 2024

baz said:
Does your magneto not have a cut out?

Yes it does, but the velos never implemented a cutout switch of any sort from factory. Only the valve lifter was used as per owners guides that came with the bikes.
I have a friend with a '57 MAC velo that wet sumped pretty rapidly. He took great interest kn my homemade anti wet sump tap with ign defeat switch on my Commando. He bought the tap from Feked with switch for grounding out the mag on the MAC. Wet sumping solved and he uses the tap to actually shut off the engine!! I shudder and close my eyes when he does that!

Richard Tool · May 22, 2024

I’ve been shutting down my Garden Gate ES 2 for years by
using the valve lifter with no apparent problems . It is my understanding that there is some valve overlap with this motor.

How to start a Single Cylinder Q ?

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