98.5 HP Commando motor after 97 races

' switching from gasoline to methanol in the same engine typically adds 8-12% to mid-range torque in un-optimized engines.'

That is an interesting statement. Do you believe my engine is unoptimised ?
What I would point out is that in methanol fuelled engines at 12 to 1 compression, it is common practice to use Amal X and Y needles so that the fuel metering is actually done by the main jets at full throttle. This usually means that from one-third throttle to three quarters throttle, the jetting is too rich to give best performance. Because I am using low comp the jetting is leaner right across the whole range of throttle openings, so I can use petrol needles to give really lean midrange without obstructing the mains at full throttle. The way around the problem if you are using 12 to 1 comp. is to recess the needle jets about 3mm. That way the tip of the needle is still trapped yet the main jets are not obstructed near full throttle and you can use petrol needles to give the necessary lean midrange.

I found it interesting recently when I was in a friend's garage with him and his race bike. The bike is an over-bored 650 Triumph Bonneville on methanol. I was looking at his collection of needle jets and some had already been recessed. I don't know where they came from - recessing the needle jets is not a commonly known dodge. I don't think my friend knows about it, and is still using Amal X and Y needles.

What does "recess the needle jets" mean?

In Phil Irving's book Tuning for Speed it says that if the jetting is rich, methanol will still give good power. That is true, however it is not BEST power. When I started jetting the 850 motor for methanol, from experience I knew where-abouts the jetting should be. In my Mk2 Amals, I started with 0.117 inch needle jets and Mikuni 6D petrol needles but I could not get the motor to cough. So I made two more needle jets at 0.116 inch. Now if I lower the needles one notch from centre, I can induce the cough. The difference between using the two diameter needle jets makes quite a difference in acceleration coming out of corners. Even slightly rich and you can feel the bike is slightly slower. It just doesn't get there as fast.

acotrel said:

Do you believe my engine is unoptimised ?

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I have no idea if your engine is optimized or not. I assume optimized means designed and tuned for maximum performance. A race engine optimized for straight methanol fuel would have as high a compression ratio as possible, up to at least 16:1. For a normal 750 or 850 Commando, the best you could do would probably be 13:1, and that would take a lot of work. It's a little easier with the larger displacement 920s, 1107s, and such. The highest I ever managed was close to 13:1 (on a standard stroke 750). I think you mentioned previously that yours was much lower than that. It would also have the ignition timing and jetting set up for optimum performance. Typically methanol needs more advance than gas, and as has been pointed out multiple times, it needs major changes in carbs to accommodate the larger flow requirements. If it were really optimized to the last little detail, there would also be different porting and maybe some exhaust system changes, but that's getting pretty picky.

Ken

Recessing the needle jets :
When you make your needle jets you drill down about 3mm from the top of the outlet with about a 10 thou inch larger drill. It means that at full throttle the tip of the needle does not obstruct the flow from the main jets. In motors running 12 to 1 comp. the necessary main jet size is very large so the needles used are usually Amal X or Y which have extreme tapers. What it means is that the only way you a can usually lean off at mid-throttle is to cut the slide - an abortionate practice, If you recess the needle jets, the metering occurs a bit lower, however you can use petrol needles to get the mid-throttle jetting leaner. I suggest the taper on the needles is there to account for the lesser vacuum at wider throttle openings. That is why the jetting must be done by the main jets. It is rare to damage a motor by jetting too lean in the midrange unless the mains don't come into operation.
Most guys just forget about leaning off the midrange and concentrate on the main jets. The bike will still go OK. Just won't accelerate as fast.
In doing this stuff, it is wise to try fitting bigger mains then doing a plug chop. If the plugs don't show more colour then the needle might be metering when it shouldn't.

If you use over 12 to 1 comp. ratio, what ignition system do you use unless you have a magneto ?

Ken, I'm wondering about your use of the term 'optimised'. In the end the whole exercise becomes one of balancing variables some of which are not independent.

acotrel said:

It is rare to damage a motor by jetting too lean in the midrange unless the mains don't come into operation.
Most guys just forget about leaning off the midrange and concentrate on the main jets. [/quote}

This makes sense as most time spent should be under WOT conditions and apparently tuning is not as sensitive when using Methanol..

[quote'"acotrel"} If the plugs don't show more colour then the needle might be metering when it shouldn't.

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Thus the need to recess the needle jet so the needle does not obstruct, correct?

Dances with Shrapnel said:

For strict comparison, the analysis should be on a stoichiometric basis in order to compare apples to apples. Another comparison should be done on best power air/fuel ratios.

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I chose the gas and alcohol A/F ratios of 13:1 and 6:1 because these are real world ratios employed in high performance applications (in my mind the best apples to apples comparison that should be very close to best power). I did not choose the stoichiometric A/F ratios because these are not employed in high performance applications. For curious minds the stoichiometric ratios were inserted in the spreadsheet, shown below, which suggests at the stoichiometric ratios methanol provides an energy increase over gasoline of ~ 18% (1484/1259 = 1.18).


Have a thought to pass along regarding what others have mentioned here about the ability of engines to tolerate very rich mixtures of MeOH and losing very little power as a consequence. Specifically the thought for consideration compares gas and MeOH over the same range of richness. With MeOH, increasing A/F ratio over a relatively wide range, e.g., from 6:1 to 5:1 (a 20% increase in amount of fuel compared to 6:1 or a 28% increase over stoichiometric fuel) results in only minimal loss in power. In contrast, if we richen a gasoline A/F ratio of 13:1 by the same amount (20%), this results in an A/F ratio of 10.8:1, which would be far from optimum and certainly result in a significant power loss.

Another fuel aside that is ever so peripherally related to alcohol, not related at all to Nortons other than 2 wheels are involved, yet might still be of interest to some, is an experience I've had with E-85 (85% ethanol/15% gas). I had been running a small flathead engine on MeOH for quite some time and was quite pleased with the result. For the next year I had the bright idea that if MeOH works so well, yet is a bit challenging for me to obtain, why not switch to E-85, which is dirt cheap, readily available throughout the Midwest, and how could it be that different than MeOH? So proud of myself for this novel idea (duh!) Well I’m here to tell you it is very different.

Drag racers at that time were loving E-85 (cheap, high octane, readily available) and likewise Flex-Fuel passenger vehicles were routinely employing it as well. The thing I didn’t fully appreciate initially is that you need compression to run this fuel, and the flathead at ~ 7:1 just wasn’t going to cut it. Drag racers of course had high compression, and the Flex-Fuel vehicles likely had 10-11:1 static CR with short duration cams, thus all users had plenty of compression.

When I ran my little engine on E-85 for the 1st time of the season, I took it out eager to see how awesome it was going to be on this new "race fuel", gave it some easy miles/time, and when I laid into it essentially nothing happened, i.e., the pipe sounded dead and it just didn’t go at all. Was my ignition timing off? Was the cam mis-timed? Was my A/F ratio way out of whack? I ran through each of these parameters and nothing was amiss. The only thing to do at this juncture was to drain the E-85 fuel, refill with MeOH, rejet and see what happens. I started the bike, headed down the street and as the last of the E-85 in the float bowl was consumed and MeOH filled the carb, the dead sounding pipe came alive and started to crackle, and performance was totally restored. Moral of the story – low compression engines perform admirably with MeOH, but do poorly on high EtOH content E-85 fuel blends.

WZ507 said:

Dances with Shrapnel said:

For strict comparison, the analysis should be on a stoichiometric basis in order to compare apples to apples. Another comparison should be done on best power air/fuel ratios.

Click to expand...

I chose the gas and alcohol A/F ratios of 13:1 and 6:1 because these are real world ratios employed in high performance applications (in my mind the best apples to apples comparison that should be very close to best power). I did not choose the stoichiometric A/F ratios because these are not employed in high performance applications. For curious minds the stoichiometric ratios were inserted in the spreadsheet, shown below, which suggests at the stoichiometric ratios methanol provides an energy increase over gasoline of ~ 18% (1484/1259 = 1.18).

Click to expand...

All good information. In my opinion, the challenge with your approach is that it is a generalization. Are we discussing an air cooled or water cooled engine, two-cycle or four cycle, what compression ratio, drag or endurance, naturally aspirated or boost intake? ...these will all have bearing on the specific AF ratio. If it were a comparison for a single engine and application then yes, spot on. By example, the best power air to fuel ratios for gasoline that I read about are 12.5:1 through 12.8:1 and Methanol has a range as low as 4:1 and as high as about 6:1. I guess one could say a strict stoichiometric comparison would be a generalization and that the various fuels air fuel ratios for a given engine and application would be specifc.

WZ507 said:

Moral of the story – low compression engines perform admirably with MeOH, but do poorly on high EtOH content E-85 fuel blends.

Click to expand...

So what is your take on what happened and why. Any insight on this? ....... relative lackluster intake tract cooling, poor or slower ignition quality (required additional ignition advance), energy flow rate of the fuel? Inquisitive minds want to know.

Ethanol has a much lower latent heat of vaporisation than methanol so the supercharging effect is less. Depends on how much is there. It also has a lower calorific value than petrol. In a low comp. engine a blend of 65% methanol with a hydrocarbon fuel ( and 10% acetone to help it blend ) is probably better than straight methanol. The freezing effect on the inlet tract is probably not much different in either situation.
Many years ago I tried a blend using ethanol - it did not thrill me too much.
About the stoichiometry - I think you are kidding yourself if you think you can calculate the jetting from the chemical composition of the fuel. All you do is start rich then drill smaller holes in the jets. That is why I set the mains a bit over-rich then make my own needle jets out of brass hex using number and metric drills. I think the thread is 0 BA in a Mk2 Amal. How often do you get the throttle wide open on a race circuit ? I ride my bike like a two stroke - never whack the throttle wide open suddenly - just feed it on nice and steadily with determination, in one swift movement.

Dances, do you try to jet your carburation on a dyno ? With experience when you ride the bike you can tell whether it is jetted correctly (when it goes fastest). The only problem arises when you play with the ignition advance. With 12 to 1 comp. it is normal to use the same advance as for petrol, and jet to suit. The normal needle jet is 0.120 inch, 800 mains and X or Y Amal needles, - then work from that reference point. I don't change the slides from #3 in the MK2 Amals and I have never changed the air jet.
When I bought my Mk2 Amals from Mick Hemmings years ago, I simply asked for alcohol kitted carbs. They arrived just as I described above - too rich for my application, however easy to set to rights. All I changed was to fit smaller main jets and made two pairs of needle jets and scrounged a couple of 6D needles from my brother. It is not rocket science.

acotrel said:

About the stoichiometry - I think you are kidding yourself if you think you can calculate the jetting from the chemical composition of the fuel.

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Understand and not the intent whatsoever. I was not thinking along the lines of jetting.

acotrel said:

Dances, do you try to jet your carburation on a dyno ? With experience when you ride the bike you can tell whether it is jetted correctly (when it goes fastest).

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Initial builds and/or significant changes to the configuration (ex. intake, carbs, exhaust) is usually done on the Dyno with an exhaust gas analyzer with confirmation with plug readings. This is efficient. Usually the more aggressive or specialized an engine build the more sensitive it is.

In the field, say change in altitude, atmospheric conditions or change in track (WOT Daytona versus a smaller, tighter more technical tracks) is with plug chops and feel. Resources for this include previous experience, race notes, what others are doing at that track on that day and relative atmospheric meters, all usually with confirmation by plug reading. Some changes are obvious (clean strong pulling and carburation out of turns) and some you do not notice so much (too lean main jet) and then it is too late. The usual changes in terms of most likely need to change are main jet, needle height and needle jet. At least that is my experience.

acotrel said:

How often do you get the throttle wide open on a race circuit ?

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Honestly, most of the time. There are those tracks such as Daytona or Road America at Elkhart Lake, Wisconsin where there are stretches of WOT time where you can sit back, relax and think about the fellas at work or that conversation you had three Christmas parties ago.

When I mentioned getting the throttle wide open, I meant at maximum revs. When coming out of corners I wind the throttle on, and don't just bang it open. Two thirds of the way down any straight, the throttle is wide open and if the revs are high, there is plenty of vacuum to pull fuel. If you bang it open coming out of corners when revs are low that is when you get detonation if you are jetted lean enough to get best power. If you have your jetting lean enough to get best power, you need to ride your bike like a two stroke - you need to feed the throttle on. When you bang the throttle open, you are immediately on the main jets with a low vacuum situation. In my own racing, I usually only ride on very tight circuits and my bike has less top end than many others, so coming around and out of corners like a rocket is extremely important.
You might notice that the Harley Dynatek ignition system uses two advance curves. Often the lead to the switch is left disconnected so that the more aggressive advance curve is the one being used. The switch used to change the curve operates off vacuum when it is connected - probably not very effective. What would be better would be to use an automatic transmission kick-down switch connected to the throttle so that when it is fully open, the less aggressive advance curve comes into play. Then the carburation could be jetted leaner right across the range. And particularly in the case of methanol more static advance could be used.

I was reading about another Seeley Commando a couple of nights ago. It is owned by a guy in Wagga, however a friend of mine usually races it. The fella from Wagga wanted a Seeley, so he bought one from Minnovation. It cost a big dollar and looks absolutely superb. The article mentioned that it was supplied with an ignition system which has two advance curves. Unfortunately, the system fried itself when a lead came off, so now it has only one curve.

Dances with Shrapnel said:

WZ507 said:

Dances with Shrapnel said:

For strict comparison, the analysis should be on a stoichiometric basis in order to compare apples to apples. Another comparison should be done on best power air/fuel ratios.

Click to expand...

I chose the gas and alcohol A/F ratios of 13:1 and 6:1 because these are real world ratios employed in high performance applications (in my mind the best apples to apples comparison that should be very close to best power). I did not choose the stoichiometric A/F ratios because these are not employed in high performance applications. For curious minds the stoichiometric ratios were inserted in the spreadsheet, shown below, which suggests at the stoichiometric ratios methanol provides an energy increase over gasoline of ~ 18% (1484/1259 = 1.18).

Click to expand...

All good information. In my opinion, the challenge with your approach is that it is a generalization. Are we discussing an air cooled or water cooled engine, two-cycle or four cycle, what compression ratio, drag or endurance, naturally aspirated or boost intake? ...these will all have bearing on the specific AF ratio. If it were a comparison for a single engine and application then yes, spot on. By example, the best power air to fuel ratios for gasoline that I read about are 12.5:1 through 12.8:1 and Methanol has a range as low as 4:1 and as high as about 6:1. I guess one could say a strict stoichiometric comparison would be a generalization and that the various fuels air fuel ratios for a given engine and application would be specifc.

Click to expand...

At this juncture I think we’ve pretty well danced around the subject, through it, atop it and nearly exhausted it. You are correct about my approach being a generalization, because the sole purpose in offering it initially was to dispel the misinformation you offered (60% power increase on MeOH), and reign the troops back to the reality that in a given configuration of our dinosaur (not a water cooled, two-cycle, boosted, 15:1 engine), one should be looking for a power increase with MeOH on the order of 10% (+?), not 60%. End of story.

Dances with Shrapnel said:

WZ507 said:

Moral of the story – low compression engines perform admirably with MeOH, but do poorly on high EtOH content E-85 fuel blends.

Click to expand...

So what is your take on what happened and why. Any insight on this? ....... relative lackluster intake tract cooling, poor or slower ignition quality (required additional ignition advance), energy flow rate of the fuel? Inquisitive minds want to know.

Click to expand...

Regarding my take on the E-85 episode? I don’t really know but suspect the difference lies in the physical property differences between EtOH and MeOH. EtOH is a larger molecule, has higher mass, has a higher boiling point, a lower vapor pressure and lower flammability than MeOH. The 15% “gasoline light ends” present in E-85 are present to enhance flammability.

In light of the foregoing, it is my opinion that the combustibility/flame speed or whatever other terminology describes efficient combustion of an air/fuel mixture in an engine were absent in this engine. The most telling anecdote of the endeavor to me was the sound of the pipe – you’ve never heard a sadder more pathetic sound in your life – just absolutely dead to the point that an old “hit- N-miss” engine would sound crisp in comparison. As noted previously, no variation in ignition timing or A/F ratio could alter the performance to any measurable extent. If you heard it run you’d assume it had 3:1 compression ratio with ignition timing set at 0 deg. And as pathetic a condition as the E-85 rendered the situation, doing nothing more than draining the fuel and replacing with MeOH resulted in 100% restoration of the pipe sound and performance. It was really magical to head down the road after the fuel change and over the distance of a block or two hear the pipe come alive and feel the difference in performance. You’d have to experience it to really believe it.

WZ507 said:

The most telling anecdote of the endeavor to me was the sound of the pipe – you’ve never heard a sadder more pathetic sound in your life – just absolutely dead to the point that an old “hit- N-miss” engine would sound crisp in comparison.

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Too funny.

Yet Flexfuel vehicles seem to manage with the E85. I've never tried E85 in a Flexfuel vehicle but based on your description above I think it would fall flat on it's face in the market and I have not heard that. What are the things a Flexfuel vehicle can change:
Ignition timing - yes
Metering - yes
Compression ratio - not likely
Tuned lengths - not likely


Any chance there is something you missed on the E85 set up? Perhaps compression ratio (or lack of) is the issue.

Dances with Shrapnel said:

WZ507 said:

The most telling anecdote of the endeavor to me was the sound of the pipe – you’ve never heard a sadder more pathetic sound in your life – just absolutely dead to the point that an old “hit- N-miss” engine would sound crisp in comparison.

Click to expand...

Too funny.

Yet Flexfuel vehicles seem to manage with the E85. I've never tried E85 in a Flexfuel vehicle but based on your description above I think it would fall flat on it's face in the market and I have not heard that. What are the things a Flexfuel vehicle can change:
Ignition timing - yes
Metering - yes
Compression ratio - not likely
Tuned lengths - not likely


Any chance there is something you missed on the E85 set up? Perhaps compression ratio (or lack of) is the issue.

Click to expand...

It is very likely that flexifuel vehicles do have switchable intake runner lengths as well as well as some sort of VTEC system which could be used to alter the effective compression ratio between the two fuels, that and they are probably already running much higher compression ratios than the old Norton anyway.... maybe