E: Engine Blind jetting

[Robert Watson]

We were having trouble jetting a street Comet with a 34 mm Mikuni VM34. I rigged up an exhaust sniffer and after a few quick trips around the block (which is a mile X 1/4 mile) we had it pretty much dialed in. I have tried to use it on the TTR with a long 1 3/4 pipe but could not get a reading and surmised there was too much turbulence, hence the pipe in post #5, which made it come alive. I will try again one day and see if it reads better, but just been too busy to play with it and as there is really nowhere to twist the throttle around here on an unlicensed street bike so it hasn't made it to the priority list.

 

[Bill Thomas]

Martyn have you got the slot in the float chamber, To allow more petrol half way up the needle valve, Well worth doing, Mk1 s don't pass enough petrol. Cheers Bill.

 

[davidd]

Tim,

Make sure you snug up the air lever. I had mine slipping with the vibration and it would not stay in one position. Better a little tight than loose.

David

 

[nkt267]

You could use something like this to hold delicate parts. https://www.belmontmetals.com/product/117-f-47-c-low-melting-alloy/ or you could just fill the inside of the slide and use your current method

I use Woods metal when I'm bending oval tube to stop it collapsing, it melts in boiling water.

 

[Martyn Goodwin]

Martyn have you got the slot in the float chamber, To allow more petrol half way up the needle valve, Well worth doing, Mk1 s don't pass enough petrol. Cheers Bill.

Sure did! That 'mod' is fully described in OVR #25, April 2006.

Martyn

 

[vibrac]

Well I fitted a 5 slide I would have fitted a 4 but only when I went to fit it its for a opposite side TT (rear pot for Vincents) I have a 3 as backup, time presses.

 

[Bill Thomas]

Well I fitted a 5 slide I would have fitted a 4 but only when I went to fit it its for a opposite side TT (rear pot for Vincents) I have a 3 as backup, time presses.

Unless I am going round the twist !, A 5 will be richer ?, You said you had a 6,1/2, And when you gave choke it was worse. Cheers Bill.

 

[Bill Thomas]

I think for the day, Just Pin ! It, As you say it goes well when you give it one.
I did it outside my house the other day !!, I had took too much off my slides, It went from woolly to a bad misfire, Strange these Mk2 s, But I had an onlooker, So went back to my Sprinting Days !.
Good Luck, Bill.

 

[davidd]

A No. 7 slide for a TT is just a little leaner than a No. 3.5 slide for a concentric. The unit of measurement for the TT throttle valve, actually, GP and earlier throttle valves, is 1/32". After the GP Amal changed it to 1/16". At least, that is what Amal says. It is easy to confuse the two.

David

 

[Bill Thomas]

Just a thought, I have sorted my Mk2 weak slide, With the pilot screw !!, Now 1 turn out.
Next time they are in bits, I will take a nat's off the bottom, But for now they are fine once it has been run for a very short time.
Yours is a T.T. ?, With your Pilot screw, IN is weaker, They also cover a bigger range than standard type carb's.
Cheers Bill.