Mid-range jetting.

I had an interesting conversation with a friend a few days ago. He has a 750cc Triton and also uses methanol fuel, as I do. He said that when he adjusts the needles and needle jets in his carbs, he increases the jetting until the motor 8-strokes when he rides the bike, then lowers the needles one notch. I do the opposite - I decrease the jetting until the motor coughs when I ride the bike, then I raise the needles one notch. In Phil Irving's book Tuning For Speed, it says 'if you run methanol rich you still get good power', however I believe that you get BEST power when you run methanol so lean that you almost get destruction of valves and pistons. The slightest bit rich and the motor will be sluggish. With petrol as fuel the situation is even worse because there is less margin for error.

Ten - four , good info , although no source of methanol here ... have been getting 114 oct. racing fuel with lead , mix it about 25%-75% racing to pump high test .... we have no ethanol added here .... with this mixture my plugs are staying good longer and feels like I’m making better power .... while expensive the 25L can is lasting longer than expected ....

Just curious, and a bit off topic.

I understand that methanol is quite corrosive to the metals. What do you do with your fuel systems to prevent damage?

With either methanol or petrol, the method of tuning is the same, however with methanol it is easier because you have twice the margin for error. The jets need to flow double the amount of fuel, so the hole in the needle jet is usually about 1.6 times the size you would use for petrol. A half thou of an inch wear or error in that, has much less effect. Also with methanol, if you end up slightly too rich, the bike still performs better than with petrol.
I once built a T250 Suzuki two-stroke which I ran on methanol. With a two-stroke, getting the needle jet size right was the most critical thing. If it is wrong, the motor won't even start. I had the bike performing well enough to blow-off a new TZ350G in a road race at Ballarat Airstrip. However I usually rode it at Calder Raceway. On one occasion, I took the bike home after practising and forgot to drain the fuel from the carb bowls. The white crap formed inside and the next time I rode the bike, it leaned right off while I was flying down the back straight at Calder. The bike turned into an absolute blur - it absolutely flew, until it seized. Taught me a lesson about methanol - running it rich is bullshit. Getting it right is just as critical as it is with petrol. With Mikuni carbs, you will find the screws in the bottom of the bowls are already drilled, so to drain the bowls you simply slacken them. With my Mk2 Amals, I usually take the jet caps off and put them on a shelf and let the bike stand. So I never get the white crap inside the carbs.
I don't know where most of the guys on this forum live, but all speedway Jawas use methanol - so those guys must be able to source it.
If you are going to use it in a Commando, the start size for the needle jets is 0.117 thou of an inch and the mains should be 670 Amal. I make my own needle jets from brass hex and use a 0BA die nut and a mix of metric and number drills. The needles are Mikuni 6D, the slides are still number threes. If you buy alcohol kitted Amals, the bits inside will be the right materials, otherwise you will need to check, also the seat for the float needle needs a bigger hole.
Commando engines love methanol. If you use it, the motor will always perform better, but you need to recognise when you have got it too lean. The main jets always need to be too rich, but the needle jet size is critical - if it coughs, raise the needles and if you cannot stop the cough, drill the holes bigger. If you are going to tune your bike, always try to do it on a cold day. Because if you do it on a hot day, when the weather cools-off, the jetting will be too lean. I always use sparkplugs with a heat range of NGK 8. And my ignition timing is advanced 4 degrees ahead of standard, because my comp. ratio is 9 to 1.