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Discussion Starter · #1 ·
1974 T120V.
A quick story.
Last year stripped the engine and fitted new camshafts.
Set the cam timing on the marks after faffing about with keyways, etc.
Had trouble starting the engine and called in a mate to give it a good kick-over.
Ignition timing retarded a few degrees [static], but still kicked-back and seemed to be firing out of the carbs...no air filters.
Played with the valve timing again to no avail.
All back together and still rough...wont start.

Tuesday morning 4am woke, thinking, `I wonder if somehow the valves have been timed 360* out?`.
Checked valve timing at the running gaps.
Left inlet opens at 44* BTDC...0.002 gap.
Left exhaust closes at 40* ATC...0.004 gap.
Right inlet opens at 47* BTDC...0.002 gap.
Right exhaust closes at 45* ATC...0.004 gap.
Seems reasonable given that the gaps should be 0.020".
All back together again, still horrible, no start...nasty bitch, sore feet.
Barking up the wrong tree :rolleyes:

So I think I`ll go for weak mixture.
*No air filters!
Pilot jets cleared.
Needle jet .106 x drilled.
Main jet .190
#3 slides and needle in centre slots.

Possible remedies:: raise floats first.
Bottom needle slot, second.
Air screw in. (1 1/2 turns out now)
Larger jets.

After having the head done, I was advised to fit #3 1/2 sliders, 0.105 needle jet, and larger main jet.
Warnings about petrol-wash.
I`ve put it back as standard-ish, but it wont go.
BTW my mate (above..Harley man) got very upset when I revealed there`s no choke.
Apologies for the long post!
Good plan? This has not been run-in.
 

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What kind of ignition are you running? My Sparx did the exact same thing until I switched the leads from the pickup. If there are two of you, you can have one guy cover the inlets with his hands while the other kicks. Or stuff rags into the inlet and kick it over a few times with ignition off to flood it then pull the rags out to start.
 

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Discussion Starter · #3 ·
What kind of ignition are you running? My Sparx did the exact same thing until I switched the leads from the pickup. If there are two of you, you can have one guy cover the inlets with his hands while the other kicks. Or stuff rags into the inlet and kick it over a few times with ignition off to flood it then pull the rags out to start.
I dont think anyone is brave enough to cover the inlets with hands, Jimmy.
However, I`ll try switching the wires on the Sparx stator.
I did try kicking it with the ignition off first.
Maybe the smoke and hot gas emitting from the carbs is more evident with no air filters, and I should ignore it. :confused:
 

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If the float levels are right,don't change them.Even if they're out by 1/8",it should still start and run.
Changing the needle position won't change the mixture at 1/4 throttle or less.
Main jets won't have any effect below 3/4 throttle.
1/2 turn richer on the mixture screws might help.

Any air leaks on the manifold balance tube?
Fat Triumph O-rings on carb flanges,or standard thin AMAL O-rings?
Any air leak at float bowl gaskets?
How strong is the battery?
If all else fails,try different plugs.What's your plug gap?

Later,when it runs properly,you might get away with .105 needle jets.I doubt if you could use 3-1/2 slides at the same time.
 

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Discussion Starter · #5 ·
Thanks for your replies...I`ll fiddle and get back with the results.
I did try the fat O-rings earlier but they were larger than the groove and got pinched.
BTW is weak mixture a reasonable diagnosis?
If it starts I can look for air leaks.
Battery is tip-top.
The carb set-up at present, and the flanges were flattened.
the heat shield gasket seemed like a good idea, thin rings with grease:
 

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Hi Dave,

What a hassle for you! We're getting too old to do much kicking these days.

You will remember on the old Austin of something, if she ran out of petrol, we'd pull the air cleaner, slosh a liberal amount of petrol down the carby throat. Then, with the throttle wide open, she soon fire up.

Try that here. Spray some fuel into each carby throat, then with WOT, get into her!!

Disclaimer: Without an air cleaner, I have known Amals to light up the odd bike by a lick a flame. Just be on your guard.

Let's hope you find signs of life soon. RR
 

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Discussion Starter · #7 ·
Well, swapped the Sparx stator leads and set the mixture screw at one turn out.
Seems to be a lot kinder, only one kick-back in about ten kicks and no carb smoke. :D
I think it will run if I can get someone with a strong kick.
My kicks are very weak due to disability.
Rod, I thought about removing the plugs and shoving a bit of fuel in.
WOT eh?
Thats a point, perhaps the throttle needs opening half when kicking.:eek:
 

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Jimmy Bush....I'd like to revisit this a bit...I have Sparx and a bear of time starting...you switched the pick up leads...same effect as swapping plug wires ? I spray 1 second of starter fluid and she fires right off. Iridium plugs are a nice grey-tan color. Your thoughts ?
 

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David, swapping pickup leads on a Sparx is not the same as switching plug leads. If it runs ok after you get it fired up, it probably isn't the EI unless there is a week battery involved. Didn't you put some different carbs on yours? I suspect too lean at start up.
 

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thanks...I have a new battery...13.75 volts as it charges, and I put on the new JRC 30mm carbs...I was super careful with flanges, sealing O-rings, etc. Unfortunately I am finding that JRC does not like to address individual items, but refers to your dealer. My carbs were supposed to come with a range of main and idle jets, but I only received the ones in the carb. I am giving the seller a try to see if he will step up. Idles at 800 smooth, and after start is seems fully OK. Even when I use the choke, no go unless a shot of SF. Frustrating!
 

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FINALLY!!!!! I kept pecking at the web site until I got a dialogue and quizzed the JRC Engineering folks on my hard to start PWK carbs ( Amal replacements). I found out that they start WITH THE THROTTLE CLOSED. Unbelievable...I went from kicking my intestines out with full throttle to a little baby 1/2 kick and it purrs like a kitten! rode about 10 miles and runs like a deer!!!! don't be afraid to ask and it pays off.
 

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FINALLY!!!!! I kept pecking at the web site until I got a dialogue and quizzed the JRC Engineering folks on my hard to start PWK carbs ( Amal replacements). I found out that they start WITH THE THROTTLE CLOSED. Unbelievable...I went from kicking my intestines out with full throttle to a little baby 1/2 kick and it purrs like a kitten! rode about 10 miles and runs like a deer!!!! don't be afraid to ask and it pays off.
So simple David!!

It's a reminder to all, Amal fitted engines as well. Cold starts are always lots of fuel, little air. RR
 
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