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Starting

Submitted by david_cooper on Sat, 02/01/2021
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Heavy Twins

The Dommie won't go! I'll blame fuel. It's the easy reason...but if it does work with new fuel, what can I do with about 6 litres of rubbish?  My electric lawnmower won't like it.

Submitted by john_holmes on Sat, 02/01/2021

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Stick in a petrol car, the injectors will cope with the loss of volitiles a carb cannot. I add thinners to old fuel each spring and no starting issues.

Submitted by david_cooper on Sun, 03/01/2021

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John...maybe so. This morning I tried a small slave tank with fuel that works in another bike, and it's no better. Fires, runs half a dozen cycles, and stops. Sparks seem fine, swapped plugs, no better and no worse. I think I'll strip the carbs next. Annoying to have to re balance.

I always want to look for changes...what have I done? And in this case I removed the head and cleaned up the valves. Tappet clearances OK. Just might be air leak in carb connections? I thought that affected power delivery and not ease of starting. Maybe pilot circuits blocked? Concentric carbs. I hope it's not RITA.

Submitted by john_holmes on Sun, 03/01/2021

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Blocked pilots shows as needing 1/4 plus throttle to continue to run after starting, the engine will not idle even when warmed. Use a 16 thou drill to clear the pilot. It will start on the excess tickled fuel but not for long. Carb cleaner will not work on the pilot jet, a 16 thou probe will work but risks forcing the crud back into the primary circuit allowing it to come forward and block the pilot shortly after, the drill pulls the dirt out in the flutes of the drill.

Submitted by david_cooper on Sun, 03/01/2021

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Thanks John. I'll give it a try. It's never done this before...and nowadays I'm always careful to drain the carb bowls when it's parked up. It's not done many miles over the past year as I've been playing with a couple of singles. It might just be sulking! They like to be used, it seems.

Submitted by michael_sullivan on Mon, 04/01/2021

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David:

How old is the battery?

It might be self-regenerating enough to get the bike running but is not holding enough in storage to keep it going.

Just a thought.

Mike

Submitted by david_cooper on Mon, 04/01/2021

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Thanks for all your ideas. I tried another battery and still no good. Today I removed the carbs but they seem fine inside. There are 4 surfaces where air might leak...one each side of each of two tunnel spacers, all glued with rather old Blue Hylomar. I replaced the two carb flange o-rings. It was too cold and dark to drag it out of the garage and try again. I might dope the fuel with some solvent fuel I use in my veteran bike! I am beginning to suspect RITA might be past its best, although it sparks fine on plugs outside the engine. I must replace the magneto!

Submitted by philip_hannam1 on Mon, 04/01/2021

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This is a familiar sounding problem and is almost certainly due to the rubbish deposited in the carb jets by the grotty fuel we have to put up with these days. Dumping old fuel inside a car tank is one way of at least using it.

I have a set of those Zinc like balls in a piece of netting dangling inside each of my bike tanks. They certainly seems to stop the fuel going stale in the tanks but not necessarily in the carbs. So I occasionally suffer from Kick-Itus like yourself.

Two things I do which can help.......I have a spray tin of Easy Start which helps get the engines running. Then a few more squirts tends to help keep the motor turning enough for cleaner fuel to flush through the carbs.  Plan B is to get the engine spinning and then place some fingers over the mouth of the carb; acting as an extra choke.

At the risk of teaching you to suck eggs........clean and reset the plugs, check the leads and pick-ups if you have them and finally check the points gap. Also check the filters on both the carb and fuel tap......if they have them.

Submitted by ian_soady on Tue, 05/01/2021

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How do you know those zinc balls do anything at all? My view is that they are snake oil and cannot possibly have any effect.

Submitted by mark_woodward on Wed, 06/01/2021

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I'd be careful if you've put lead-replacement additive in the fuel (Valvemaster etc.) as it's not too kind to catalytic converters.

Submitted by david_cooper on Wed, 06/01/2021

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Thanks again for observations.  I don't expect to be experimenting with starting until the weekend, so I'm hoping that when I removed and checked the carbs I might have dislodged something from one of the jets.  Since it works equally badly with fuel from a bike which does start, I assume the fuel is not to blame.  I'm going to stress test the magneto and maybe replace it.  It let me down when hot even after a condensor change, so I suspect the HT is breaking down when hot, and it probably needs a rewind.  I spent some money on its mechanical refurbishment a few years ago but it was tested and alleged not to need a rewind and I foolishly did not have that done at the time.

 


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