compression relief valves, to allow easier kicking?

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jimbo

jimbo

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Has anyone installed compression relief valves, to allow for easier kicking on a pre MKIII? I'd rather not spend $2300 on an estart. I would have to pull the head and have someone machine the head to accept them. Then again where would they put the holes? Nowhere to put them :shock:

http://www.ebay.com/itm/COMPRESSION-REL ... hi&vxp=mtr
 

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there are other types that install with the spark plug
 

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When you get it well tuned, so that it starts first kick,
you'll wonder why you even considered this !
 
Rohan said:
When you get it well tuned, so that it starts first kick,
you'll wonder why you even considered this !
Click to expand...
a lighter,less strong person will still have a problem.
 
Not if its well tuned and starts 1st kick !

Unless you are 7 stone after a big breakfast ?

Heck, I've seen folks start a well tuned bike, once warm, using just their hand on the kickstarter.
I've not tried this myself, if it did kick back it could be messy..
 
I have kick started a methanol-fuelled 1000cc Vincent which was on 13 to 1 compression. If you don't kick ANY bike over the correct way, you can get bitten. Perhaps somebody should set up a school to teach young motorcyclists how to kick-start their old bikes ?
 
Triton Thrasher said:
I'm not sure it would do much good on a twin.
Click to expand...
The early Yamaha xs650s had a valve lifter fitted to one side,they were later deleted so may not have been successful, I had always thought that maybe you used it differently on the yam IE start it as a 325cc single then let the lifter and the other cylinder chimes in?
 
jimbo said:
there are other types that install with the spark plug
Click to expand...
Thanks for posting this I have not seen the type that incorporates the spark plug , anything that can keep you kicking the bike over into old age is good cheers
 
I have a well tuned Norton 850, had one in the 70's 80's and 90's, no problem with kick start.
Nearing 60 years old with a knee that is needing replacement, it has now become more difficult.
Can still start it but am concerned my knee will give way, sometimes that makes you tentative, especially on a bad knee day, which is not ideal.
Don't want a decompressor, cannot afford electric start conversion.
Will carry on for as long as I can.
 
peter12 said:
I have a well tuned Norton 850, had one in the 70's 80's and 90's, no problem with kick start.
Nearing 60 years old with a knee that is needing replacement, it has now become more difficult.
Can still start it but am concerned my knee will give way, sometimes that makes you tentative, especially on a bad knee day, which is not ideal.
Don't want a decompressor, cannot afford electric start conversion.
Will carry on for as long as I can.
Click to expand...
I'm in similar position! bad right knee and planta faccittis in my foot , so an electric start would be great
 
The compression release works for a single cylinder where there is compression every other rotation - you get some flywheel inertia. With a twin you have compression on one side every rotation.

It's the method not so much the weight. The old adage is if you can start it you can ride it. My 26 year old son that weighs maybe 130lbs fired up my combat 750 in one kick. No, I didn't let him ride off.
 
illf8ed said:
The compression release works for a single cylinder where there is compression every other rotation - you get some flywheel inertia. With a twin you have compression on one side every rotation.

It's the method not so much the weight. The old adage is if you can start it you can ride it. My 26 year old son that weighs maybe 130lbs fired up my combat 750 in one kick. No, I didn't let him ride off.
Click to expand...
good for him,(youth!) :D however couldn't you install one on each side?
 
jimbo said:
Has anyone installed compression relief valves, to allow for easier kicking on a pre MKIII? I'd rather not spend $2300 on an estart. I would have to pull the head and have someone machine the head to accept them. Then again where would they put the holes? Nowhere to put them :shock:

Jimbo, about 6 years ago I installed a set of compression relief valves on a new build Commando for a customer who never owned a classic bike before (only modern bikes with electric starter). Although the Commando MK3 did have an upgraded electric starter my customer was eager to kickstart his Commando as well so I machined two valves in the head to make an easier first kick. Result was indeed an easier first kick (the valves close at first compression stroke) but you still had to make a powerfull swing with the kickstarter to actually get the bike started. So don't expect the valves will turn your Commando into a Triumph twin kick starter.

Good luck,
Constant Trossèl
http://www.hollandnortonworks.eu

compression relief valves, to allow easier kicking?


compression relief valves, to allow easier kicking?
Click to expand...
 
Holland Norton Works said:
jimbo said:
Has anyone installed compression relief valves, to allow for easier kicking on a pre MKIII? I'd rather not spend $2300 on an estart. I would have to pull the head and have someone machine the head to accept them. Then again where would they put the holes? Nowhere to put them :shock:

Jimbo, about 6 years ago I installed a set of compression relief valves on a new build Commando for a customer who never owned a classic bike before (only modern bikes with electric starter). Although the Commando MK3 did have an upgraded electric starter my customer was eager to kickstart his Commando as well so I machined two valves in the head to make an easier first kick. Result was indeed an easier first kick (the valves close at first compression stroke) but you still had to make a powerfull swing with the kickstarter to actually get the bike started. So don't expect the valves will turn your Commando into a Triumph twin kick starter.

Good luck,
Constant Trossèl
http://www.hollandnortonworks.eu
Click to expand...
Click to expand...

Good to know. I never thought about them closing after one kick. That would be a pain, as you would have to reach down and open them after every swing, if you didn't get the bike to start on one.
 
Can you share some pictures of these compression release valves installed on the combustion chamber side?


Holland Norton Works said:
jimbo said:
Has anyone installed compression relief valves, to allow for easier kicking on a pre MKIII? I'd rather not spend $2300 on an estart. I would have to pull the head and have someone machine the head to accept them. Then again where would they put the holes? Nowhere to put them :shock:

Jimbo, about 6 years ago I installed a set of compression relief valves on a new build Commando for a customer who never owned a classic bike before (only modern bikes with electric starter). Although the Commando MK3 did have an upgraded electric starter my customer was eager to kickstart his Commando as well so I machined two valves in the head to make an easier first kick. Result was indeed an easier first kick (the valves close at first compression stroke) but you still had to make a powerfull swing with the kickstarter to actually get the bike started. So don't expect the valves will turn your Commando into a Triumph twin kick starter.

Good luck,
Constant Trossèl
http://www.hollandnortonworks.eu

compression relief valves, to allow easier kicking?


compression relief valves, to allow easier kicking?
Click to expand...
Click to expand...
 
When I first got my Commando it was hard for me to start, then I developed an educated leg. Than and a well sorted bike makes for easier starting, granted I don't have and knee issues either.

John in Texas
 
Interesting topic - I saw recently that in the Harley world the performance company S&S developed a cam that senses when the motor is off and at that state a little 'nub' protrudes from the cam and pushes the valve rod just a little higher (raising the exhaust valve a smidge, releasing compression) to make starting easier - then when the engine turns over, the 'nub' is retracted by the centrifugal force back into the shaft (until needed again). Really ingenious engineering -

Here's a pic I found online - I think they call it an 'easy cam'

http://www.bikernet.com/docs/stories/86 ... 0037sm.jpg


-kjo
 
In the past on several different makes (and in the present) ,there were/are cable operated systems that kept the exhaust valve open with a mechanical stop acting upon the spring collar. However that's a big engineering hill to climb for our bikes.
 
jimbo said:
In the past on several different makes (and in the present) ,there were/are cable operated systems that kept the exhaust valve open with a mechanical stop acting upon the spring collar.
Click to expand...

The valve lifter, and its associated lever on the handlebars, was pretty much a standard feature on ALL motorcycles from about 1890 until well into the 1960s on all big single cylinder and most v-twin motorcycles.
Its well nigh impossible to start them from cold without it.
I'd can show a few examples to show, if anyone is seriously interested - not very relevant to Commandos though.

Its a bit of a rigamarole to ease the piston over compression using the valve lifter, and THEN deliver that famous long-swinging-kick, using all your bodyweight. The idea is to build enough momentum in the flywheels so the piston will go over the next compression tdc and thus start - rather than hit tdc and bounce back...

The big sales feature of parallel twins was how easy they were to kick over - and thus start.
You can just kick them from where-ever the engine happens to stop, and be assured you'll get one cylinder over compression - and a well tuned example should just start.

My old dommie, Nortons first parallel twin, with only a low compression (6.5:1) 500cc twin is dead easy to start - you just prod the kickstarter and its running.
The 850 needs a bit more muscle, but if its in good tune it should start on the 1st compression it comes to.
If it needs more kicking than that, its not in good tune...
Bearing in mind you HAVE to tickle the Amal(s) if its a cold start...

Those compression releases below the plugs look very promising.
Shouldn't be too difficult to install there either ?
 
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