ESE's works engine tuner

[oldjohnno]

So. . If you made a float drain plug that had a pipe that sealed with a rubber tube to the pilot jet. . . Pause for Thinking. . And that lead to a secondary Float bowl because you don't want to flood it or starve it. . . You could have another carb bottom fed petrol. If that was mounted on a slide mount you could adjust the level to something that works ok.

And if you are really careful won't be a fire risk when crashing.

Given that most slide-type carbs have a float bowl that is barely adequate at best for alky - except for quite small engines - I'd go the other way. The stock bowl and float valve would handle the idle and off-idle duties easily while a more competent external bowl could handle the alky for the main circuit. I don't use any float bowls (butterfly style carb) - the lo speed circuit pulls directly from the small tank below the carb while the main circuit is fed directly from the top main tank via a barrel valve linked to the throttle and a pill.

I haven't tried it yet but I think the petrol-part-throttle setup would work very well with nitro. I've only played very briefly with it but it's a bit like methanol in that it needs heat, pressure and a load to burn properly, only much more so than methanol. It hates a light load and less than W/O throttle, and besides it make no sense to be burning expensive nitro when it isn't necessary.

[Pursang]

Given that most slide-type carbs have a float bowl that is barely adequate at best for alky - except for quite small engines - I'd go the other way. The stock bowl and float valve would handle the idle and off-idle duties easily while a more competent external bowl could handle the alky for the main circuit.

I think that's very clever!

[SwePatrick]

To add to methanoldiscussion:

I don´t see the problem as discussed, but it may very well be.
I see it another way though.

When reaching a certain engine temprature you start to vaporize the fuel better, before this the engine runs bad and seems rich.
This due to the combustion isn´t good, actually not good at all.
A methanol engine the first seconds after startup is very dull and tired.

64.7c is methanols boiling point.
Petrol has a boilingpoint of 30-190c depending on pressure(i guess)
This is in direct relation in how easy it is to start an petrol engine versus an methanol engine.

[Pagi]

Once again Frits is on the money.
My empirically derived idea of exhaust duct exit reduction to 75% of the effective Exhaust Port area works very well as a guide to the size to be looking for.
Frits has always maintained the exit area should be tied to the Blowdown capability.
Here we have a case of the Blowdown , that is optimized to achieve a relatively modest 13 Bar bmep , achieves Mach 0.8 at the pinch point with a 71% area reduction.
Smaller looses power as does a larger exit diameter.
It seems the only way to optimize this factor is by tracking the Mach number to achieve 0.8.

Wobbly,

does this Mach number (0.8), is a value that must be taken into account for a single exhaust duct ? ( around 90% area reduction, if i remenber correctly)

[wobbly]

The 90% area for a single Ex is a pointer , but the whole idea was developed in the scenario where you have a huge amount of 3 port Blowdown area initially dumping into an oversized duct volume.
With all that Blowdown the BMEP is high obviously , and thus the bulk gas flow at peak power is also very high.
But in a single Ex port we are never going to get close to those Blowdown numbers , nor the BMEP , and thus the power delivered.
From memory I havnt seen a single Ex project where it was possible to achieve 0.8Mach before power was lost due to the exit getting too small.
All you can do is start at 90% and move down in area until you loose power - then go back a step.

Re the Methanol burning engine problems , all I can say is that we ran a 60 Hp 150cc bored out TM-MX engine for years in open class with a 41mm Dellorto carb using the 4.2 float valve and a diaphragm pump
set with a return line jet to give 18" of pressure head above the carb bowl ( as a tank would give on a bike ).
We never had any tuning issues with dropout or any weirdness of any sort , except having needle ends dropping off from being spun down too thin.
This was solved with the adjustable powerjet that replaced 25% of the main jet flow ( 1mm dia powerjet with a 2mm main ) and thus the needle didnt need to be thinned so radically.
Later we went to a 250cc MX engine using the same carb , and just had to redrill all the jets slightly bigger and use a 4,5 float jet to keep the bowl full.

[Niels Abildgaard]

Some serious austrians are working to design and dominate the market for EV range extender .

https://www.fvt.at/ka/en/references/...er-engine.html

It is a two stroke with side exhaust valves and no charge through crankcase.
They claim it is a must for three-way catalyst after treatment.
I do not understand and will love to.
A gentleman here was working with the Orbital and they must have seen the problem.
What is his entry name here?

[Frits Overmars]

Some serious austrians are working to design and dominate the market for EV range extender .
https://www.fvt.at/ka/en/references/...er-engine.html
It is a two stroke with side exhaust valves and no charge through crankcase. They claim it is a must for three-way catalyst after treatment. I do not understand and will love to. A gentleman here was working with the Orbital and they must have seen the problem.
What is his entry name here?

The same as his name in real life: Ken Seeber.

[Niels Abildgaard]

The same as his name in real life: Ken Seeber.

Hello Nightraven
Thank You and I will ask him tomorrow.
Sleep well

[wobbly]

Whaaaaat Frits , you mean there is a " real life ".

[TZ350]

The stock bowl and float valve would handle the idle and off-idle duties easily while a more competent external bowl could handle the alky for the main circuit.

I have had a good look at one of my Mikuni carb's and it looks like the petrol through the original float bowl for choke and pilot jet duties. And an external methanol float bowl feeding through Mikuni's float bowl nut to the Mikuni's main jet would be easiest way to go.



This Mikuni has a brass shield around the main jet. I guess it's purpose was to reduce fuel surging away from the jet when moto crossing over Jumps and rough ground. Anyway it looks like it will be helpful in retaining some sort of sealing arrangement between the fuel bowl nut and the main jet. Looks easy.

Does anyone have a matchbox or other remote float bowl they would sell?

[F5 Dave]

Is there room for a second carb off to the side? Cut the top off and seal drillings, bar of course a dirty big breather hose up out of the way.

Um, like that Delorto.

[Grumph]

Does anyone have a matchbox or other remote float bowl they would sell?

I've used matchbox float chambers and while the size is convenient, I'd doubt if capacity or flow rate would work. They're also very sensitive to vibration.

Bite the bullet and find an old SU chamber. If i can find it post move I may even have one here.

[oldjohnno]

Re: SU bowls - float bowls from an Amal concentric or Mk2 would also be a good choice - the float valve is part of the bowl so they'd only need a flat cover plate that could also incorporate a mount. But if you really need a lot of fuel you can't beat a Holley bowl. They'll handle 7 psi of pump pressure no problems but they're a little bulky.

[TZ350]

Bite the bullet and find an old SU chamber.

Ok, I have found a SU float chamber. Certainly looks like it can be made to do the job.

[Grumph]

Ok, I have found a SU float chamber. Certainly looks like it can be made to do the job.

Can i suggest a swill pot on the opposite side of the carb to the float chamber. IE - chamber in front of the carb (front of the bike) and a small swill pot behind.
Doesn't need to be very big at all - make it from something like a piece of 3/4in stainless tube.
Ensures the mainjet is not affected by braking and acceleration.