Hitchcocks Forum

I have a 1995 Bullet 612 with a MK 2 concentric with the methonal kit and dont know how to get the right mixture by looking at plug colour , the engine is new and has not been started yet and Australia has now given the option of E85 fuel from Caltex , I have the Meth needle at mid point and Meth jets etc , ignition timing at 28 degrees and my comp ratio is 10 :1 and the oil is Speedway 50 that mixes with Meth and Ethonal . How many turns out on the mixture screw out as a starting point , dont want to get it wrong , it's so clean burning that tan on the plug wont happen , any ideas ?

would a colourtune work ?

I think alcohol burns with a colourless flame so I can't see the colourtune being much use.

I think I'd email Hitchcocks direct on this one, their knowledge of Amal carbs and set up is probably better than anyone on the Board! If you are talking about the pilot/idle/tickover screw the standard setting is 1.25 to 1.75 turns out from fully closed. I would think that would be your best starting point as the jetting should have been set up to make the idle mixture range sit within that adjustment.
REgards, Mark

To be fair this question is a bit like ‘how long is a piece of string’! The first question I’d say is ‘what is the bike to be used for?’ Carburation always relates to a particular type of use as well as a particular type of fuel, air filter, altitude, temperature, etc. We can only guess that this is for some form of competition use. Why else would anyone run on methanol? The second question is ‘why would anyone running on methanol be too concerned about the pilot air screw position? As the tickover setting would normally be of little if any concern. And in any case the setting of the pilot air screw will have very little effect on the plug colour (and/or mixture strength) in normal running – the main and needle jets having much greater influence. Maybe with a bit more info it’ll be possible to give a bit more help.

The USA is going for M85 and Australia is going for E85 with a pump 10 mins from my flat all from sugar cane so supplies will never run out . This bike is for road use and is vertualy full race from our hosts parts , both fuels are for the future of a post oil world , I am now using Jawa speedway manuals for the mix set up and a wet plug is the best place to start , as usual fuel consumption will be way up with this fuel, you should see the size of my jets !

The Hitchcocks scrambler, 612cc, 10:1, twin spark head, etc. ran 890 main jet 125 needle, 45 pilot.

All this was on 38mm smoothbore carb.

Only spec change from the parts in the Hitchcocks catalogue was a skwish piston

In my view the air screw will have very little effect on the running this fuel in a highly tuned engine.

You will not get a good idea of the carb and timing setup by looking at the plug, probably wont show any colour at all if your are running only methanol.

However ..... I strongly suggest that you book some time on a dyno, this is probably the only way you are going to get optimum carb and ignition setup

R1 at Hitchcocks

I was thinking about getting a smooth bore carb but I wanted some tick over , I one day will get a Big head with the 1 1/2" inlet port but with that you can kiss goodbye to tick over , I'm only running a 32mm on my head at a loss of 5 BHP so I will see how this engine spec will cope with traffic use , if all is OK I will save up for a big head with a GP 38mm Amal carb that will take a while to save up for.
The Meth kit cost 70 pounds so I think 45 BHP will be a cool starting point .
Jawa boasts near 70 BHP on their latest engines but you have keep striping it down after every races for inspection.

Here is a 500 Fury, with Big Head and 1 1/2" GP carb ticking over [for a little while anyway]. Cheers, Paul.
https://www.facebook.com/jayne.henshaw. ... =3&theater

I’m interested that you’ve fuelled your bike with fuels for a ‘post-oil world’. I guess your bike will be growing moss on the piston and grass out of the carb before that day arrives!