Methanol - jetting

Yes I did the same. Double taps and banjo's. And fuel taps like this which are available in a range of internal IDS
Matchbox float chambers hold less fuel. I used one many years ago - they fit in well with twin type 6 or similar Amals and look good. I got rid of the one I had. A big diameter float chamber seems to be better -the fuel level probably rises and falls to give better resilience as you accelerate. But in the end I think the hole at the float needle might be smaller in the matchbox carb.
When I bought my Mk2 Amals from Mick Hemmings, I requested alcohol kitted. When I first used them, the anti vibe rubbers cracked, everything else was good - except the needles, needle jets and main jets. You will always need to correct those whatever carbs you buy. Slides are almost always #3.
 
The Gardner float chamber, though small, works for me. Seen a number of Manxes fitted with big SU float chambers.
Had a friend who fitted a Concentric Mk I to his methanol drinking speedway JAP. Was faster than me so obviously no fuel starvation problem.
When flow is restricted, chamber size don't matter much.
 
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Yes carb is set up for methanol. Unfortunately the second output in the tank is directly over the carb so for the time being I'm stuck with one tap - the single tap id is large so I could run two feeds of the tap to two on the carb.
Acotel, if you're feeding two carbs I should be ok. I'm doing a hill climb in two weeks but am hoping I can get a few runs on a dyne to set up and will get a chance to see if all is running ok.
 
Yes carb is set up for methanol. Unfortunately the second output in the tank is directly over the carb so for the time being I'm stuck with one tap - the single tap id is large so I could run two feeds of the tap to two on the carb.
Acotel, if you're feeding two carbs I should be ok. I'm doing a hill climb in two weeks but am hoping I can get a few runs on a dyne to set up and will get a chance to see if all is running ok.
Good Luck - I hope you are a winner. If the motor misses while you are riding , it could be fuel starvation or just jetted too lean - always check your tank breather, a vacuum in the tank can reduce fuel flow. If the motor does not miss after riding a bit of distance, you should be OK.
 
Finally all done, and got to do some runs down the road to test in advance of the hill climb next weekend. I have a problem on low throttle, just above tick over where it feels like its 8 stroking - difficult feathering the throttle round some bends (more throttle and it comes in a bit too much). If I open the throttle past further it clears and runs fine revving well with good power. At a stand still it's the same 8 stroking unless I rev it more, not helpful trying to warm it up. I tried putting the choke on and it doesn't seem to make any difference.
Started on the bench with a pull on the back wheel, closed throttle but once running not able to tick over.
Back after the first run I turned the pilot screw in half a turn (now 1 turn out) and this seemed to help, however, when I went for another run it was the same.
There is a short v steep hill and turned into it in 1st gear low revs, 8 stroking but cleared with more throttle.
Could this be an issue with the jet bush people say needs drilling out?
I can't make out where the bush is located so don't know if there is one in the carb. Carb is new old stock. Could someone advise please?
There is no pilot jet just a blank jet that can be screwed out - should this have a jet?
Methanol
No 3 slide
120 needle jet
Amal alcohol needle
700 main jet
Thanks for any advice.
 
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Finally all done, and got to do some runs down the road to test in advance of the hill climb next weekend. I have a problem on low throttle, just above tick over where it feels like its 8 stroking - difficult feathering the throttle round some bends (more throttle and it comes in a bit too much). If I open the throttle past further it clears and runs fine revving well with good power. At a stand still it's the same 8 stroking unless I rev it more, not helpful trying to warm it up. I tried putting the choke on and it doesn't seem to make any difference.
Started on the bench with a pull on the back wheel, closed throttle but once running not able to tick over.
Back after the first run I turned the pilot screw in half a turn (now 1 turn out) and this seemed to help, however, when I went for another run it was the same.
There is a short v steep hill and turned into it in 1st gear low revs, 8 stroking but cleared with more throttle.
Could this be an issue with the jet bush people say needs drilling out?
I can't make out where the bush is located so don't know if there is one in the carb. Carb is new old stock. Could someone advise please?
There is no pilot jet just a blank jet that can be screwed out - should this have a jet?
Methanol
No 3 slide
120 needle jet
Amal alcohol needle
700 main jet
Thanks for any advice.
If your motor is on 12 to 1 compression, your set-up might be OK. As a rule, I lean-off the jetting until I create a miss in the motor, then richen it slightly.
My motor is on standard 9 to 1 comp. My jetting:
Methanol
No3 slide
0.1165 inch needle jet
Mikuni 6D needle
670 main jet
The quick taper Amal needle compensates for loss of vacuum in the inlet port. For road racing, the leaner Mikuni needles are better, and feed the throttle on.
If the motor misses while riding the bike, stop and fix it - don't continue riding.
I make my own needle jets out of brass hex, using a mix of metric and number drills.
The main jet does not matter as long as it is too rich.
 
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If your motor is on 12 to 1 compression, your set-up might be OK. As a rule, I lean-off the jetting until I create a miss in the motor, then richen it slightly.
My motor is on standard 9 to 1 comp. My jetting:
Methanol
No3 slide
0.1165 inch needle jet
Mikuni 6D needle
670 main jet
The quick taper Amal needle compensates for loss of vacuum in the inlet port. For road racing, the leaner Mikuni needles are better, and feed the throttle on.
If the motor misses while riding the bike, stop and fix it - don't continue riding.
I make my own needle jets out of brass hex, using a mix of metric and number drills.
The main jet does not matter as long as it is too rich.
Acotrel thanks for your reply.
11 to 1 compression. Bike flies once above the problem - I guess on the needle and above - I will get a 6D needle as I prefer to feed the throttle on.
While I'm not expecting it to tick over with the hill climbs there's a fair bit of waiting in turn for a run with the engine running - tick over even slightly high is not possible as without reving it will stall. Also warming up needs a fair few revs otherwise it's horrible - almost like megaphonitis but at tick over and upto I'm guess about 2500 revs (will get a rev counter sorted before next weekend).
Riding wise there is a tightening downhill bend and I was trying to feed the throttle on and it was 8 stroking and not pulling well. More throttle and it kicked in, not idea but bad in the wet.
In the late 80's with a Amal TT it would not tick over as such but gentle low revs to warm up.
If it was petrol I would go up a half size on the cutaway but not sure with methanol.
Would the needle affect very small throttle openings?
Should there be a pilot jet?
 
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To set the idle - if the screw controls fuel, I start the motor with the screws out about three turns, then I wind each screw in until the motor gives a cough and back it off until the motor runs smooth. I do the same thing when setting the needle heights - lower the needles until I get the cough then raise them one notch. If you cannot get the cough, your needle jet is too big. Best power is when you just get smooth running without the cough. I usually ride the bike to check jetting, but if the motor is hot, you can do it in your driveway.
The taper on the needles acts at lower throttle openings. If the taper is too rapid the mixture can richen and slow the motor. It acts when the motor is under load - such as accelerating out of corners, and that is where your bike needs to be really fast to be quick enough down the straights. You need to be able to accelerate early out of corners on a lean, without running wide. Take note of what your bike does when you accelerate and you are on a lean. - it will usually either tend to run wide or alternatively tend to tighten it's line. If it runs wide, you have a problem which can be fixed, sometimes by softening the rear shocks. Most guys do the opposite and there is no change.
 
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Your motor should never 8-stroke - that is miles too rich. A cough is the sign of too lean - find that and richen slightly. Main jets are only used for full blast wide open throttle, They need to be slightly too rich. Do not use megaphone exhausts. An unrestrictive 2 into 1 is always better.
 
Your motor should never 8-stroke - that is miles too rich. A cough is the sign of too lean - find that and richen slightly. Main jets are only used for full blast wide open throttle, They need to be slightly too rich. Do not use megaphone exhausts. An unrestrictive 2 into 1 is always better.
Will have a concerted effort tomorrow. Thanks for advice.
 
Check the breather on your fuel tank. A vacuum in the tank can cause fuel starvation on big circuits.
I concur re the breather on the fuel tank. I found that I needed to delete the inline one way valve I had fitted to the breather line to provide maximum fuel delivery at throttle. Consistent with comments by others, Methanol carburettors have different needles/needle jets float bowl needles and seats as well as main jets. Even the supply to the jet blocks differ between petrol and methanol for some carburettor makes.
 
When running the bike and stationary I noticed that there was methanol dropping quite fast from where the exhaust slips on to the spigot at the head (modified for ease of maintenance). I’d put 2 gallons in the tank and did a maximum 14 miles and there seems to be under a gallon left so huge fuel consumption even for a 350.
First job was to pull the carb away from the inlet, keep at same angle and turn the fuel on see if leaking. Result dry even if I tilted it and shook it.

I’d read that the choke sealing could be a problem and stripping the carb and testing with WD it was leaking so I swapped it for one from another carb leaving the mechanism off so that the spring could seal at the base unimpeded. Squirting WD through none was getting past the seal. Started bike and the 8 stroking was only just off of closed throttle and cleared with just a little more throttle- much better than before. Experimented with pilot screw and there was marginal difference. However, methanol was still dripping out of the exhaust joint quite fast.

There is no popping symptomatic of an air leak in the exhaust. I can seal the head joint but then the excess methanol will get into the silencer and kill the fibre material.

I swapped all the ‘upgrade’ methanol bits from the 32mm carb to a 30mm Mk2 and ran the bike. The 8 stroking was slightly worse but the methanol dripping from the exhaust was a little less but still not good.

Somehow this seems to be two problems. The choke plunger sealing made a big difference and it was possible to warm the bike up at low ish revs. However the dripping fuel is a problem, and odd that it still drips with the smaller carb but not so much.

Looking in the oil tank the oil (caster) has diluted, methanol washing down the bore as well as out of the exhaust joint.

Any suggestion please - Hill climb only a few days away.
 
Problem solved and I'm a plonker.
Initially I found that the choke was not seating (Chap at Amal suggested this). Sorted and ran for a few moments. Better but still fuel pouring out.
Thinking that the over fueling might be something to do with the float bowl I thought I would put a std one on just to start up. Looking at the std one I noticed the starter jet and that the methanol bowl did not have one! Transferred it, started up and runs fine.
Only issue is while I was testing on the road and not realising the high methanol usage it was diluting the oil. Drained the oil tank and the oil has diluted around 50%. All I can do is hope that somehow the caster oil did its job and the cams haven't worn and big end etc. Cross fingers.
Thanks for all your help.
 
You should not have methanol dripping anywhere - let alone out of an exhaust joint. If your jetting is right, all that comes out of the exhaust should be gas. You might have a sinking float. If you immerse the float in very hot water, if they leak, you will see air bubbles escaping. Also before tuning, check your float heights.
 
Follow on, I discovered that with a down draft inlet the pilot jet should be in the body not the float bowl. Running at the hill climb today the needle is totally wrong needing a fist full and no subtle roll on. Will order a
Mikuni needle as suggested Acotrel.
I do have one problem with the anodised slide hanging at 2000 rpm when heating in the line to go off. Amal said to use these slides as the chrome one flake with methanol.
I’m riding again tomorrow (Sunday). Can anyone suggest a temporary solution just to get me through the day. I tried spraying the slide with WD40 with little effect?
 
If the slide hangs-up, that might give you 2000 revs, but it also might hang-up when it is at full throttle. You should be able to wind the throttle open fully when the motor is not running, and it should drop to the bottom freely when you let go of the twist grip. If it hangs-up while you are riding the bike, it can mean a quick trip into the bush.
I suggest a lot of guys probably believe that using more fuel means more power. Methanol is as easy or difficult to tune with as petrol, but with petrol, the errors are twice as significant. With either fuel, you need the mixture to be just slightly on the rich side of doing damage to the engine.
 
There must be a reason the slide hangs-up - you need to find it. It might be the cable or a dag on the slide, or a bit of gunk inside the body of the carb. Do not stuff around - be slow and systematic. Do you have a quick-action twist grip ? The throttle should be totally free.
If the chromed slide works properly, I would use it. The chrome flaking is probably a more long-term effect, and there is no chemical reason for it to happen more with methanol. Chrome is not very resistant to impact. The flaking probably occurs when the slide is loose enough to rattle.
 
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I would not listen too much to the kids behind the counter in the motorcycle shop.
 
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