View Full Version : 66' Triumph 1 cylinder not firing

07-03-2012, 1:20 PM
66' Bonneville left side not firing. there is spark.
what would be the next step to test?

Also, I recently bought this bike. it has a fresh rebuilt engine.


07-03-2012, 1:24 PM
Is the left side getting any fuel? Is the slide adjusted up a couple mm with the idle screw?

How far turned out is the fuel screw?

07-03-2012, 1:44 PM
I am 2 turns out..
all this happened after adjusting the float.
maybe i will open up the carb to make sure everything is in place.

07-03-2012, 1:47 PM
Something small but could be a fouled plug...

07-03-2012, 1:51 PM
2 turns out on the fuel screw
5 turns out on the idle screw it is open about 3.5 mm

the plug look good, but i will try swapping it out

07-03-2012, 1:52 PM
Maybe go into 1 turn out on the fuel.

When you tickle it, it gets fuel, right?

And you have 3.5mm on the front of the slide or rear?

07-03-2012, 2:25 PM
i have mikuni carbs so no tickler.
it is getting fuel.

i just started it and both cylinders were firing then i went for a ride around the block and the left cylinder died on me.

07-03-2012, 2:42 PM
3.5ish on the filter side

07-03-2012, 3:03 PM
Not to be a dick. Seriously though.

Throw those carbs in the trash. New amals are so easy and there are no tuning headaches.

After you buy your first new Amal, you'll wonder why you ever messed with those bullshit carbs.

07-03-2012, 3:11 PM
i have amals on my other triumph. yes they are simple and work with no frills.
Mikunis came on this bike so i would like to get them dialed in, everyone says they have better performance once they are set correctly.

07-03-2012, 3:29 PM
I think Lord Cornwallis once said, "it's better your Triumph run well with Amals, than not at all with shady Asian carbs."

07-03-2012, 5:16 PM
i got new spark plugs. quick cleaning and inspection of carb. tried adjusting the screw in and out.
it fires up and both cylinders are working. the idle is a little high but that is the least of my concerns.

i go for a ride. it is running strong /good enough will need a better tune up.
then a 1/2 a mile away i loose the left cylinder again.

does this seam like an intermittent electrical issue?

i am back to checking the plugs, wires, connections at coils, gonna check the tappets while i have the take off.

any thoughts?

07-04-2012, 7:03 AM
go with AMALS...,,, check out elec system ,,try a donor set of amals on it ,, if your running points how are they looking ?or maybe you got a short going on somewhere

07-04-2012, 8:40 AM
Mikuni is the Japanese term for "leaking gas with plugged jets"