precision float level adjustment.

Status
Not open for further replies.
Triton Thrasher said:
Do you not close the throttle at some points, during a lap?
Click to expand...

Of course I do, but rarely completely shut, in fact I think I was really just illustrating that much less of a lap of any race circuit is actually run at full throttle....

So a good race bike needs to be tuned for something other than full throttle......of course other riders may use more throttle more of the time, but not I suspect, another 6 litres in 20 minutes!
 
SteveA said:
Of course I do, but rarely completely shut, in fact I think I was really just illustrating that much less of a lap of any race circuit is actually run at full throttle....

So a good race bike needs to be tuned for something other than full throttle......of course other riders may use more throttle more of the time, but not I suspect, another 6 litres in 20 minutes!
Click to expand...

You need enough fuel flow to feed the engine when it is flat out: full throttle at maximum rpm.

The total fuel used during twenty-minute sessions of accelerating, braking and cornering is not relevant to the flow of fuel required at max power.
 
I installed a cheap plastic inline fuel filter one time, a hardware store item meant for lawn mowers. The 850 would not get over 55 mph on the highway until I removed it. They do need fuel flow.
 
When you shut the fuel tap, there are still two fuel lines full of petrol. If one does not empty into it's bowl . . ?
The height of the fuel does not matter much as long as it is the same in each bowl, because you rarely jet the carbs independently of each other. In any case, most guys with road bikes probably jet too rich anyway. If you don't jet rich, the performance of the motor can become more weather dependent. The step between a 0.106 inch and a 0.107 inch needle jet is huge if you are using petrol, and how many guys try different taper needles ?
 
Last edited:
Saw this Royal Enfield today with a pair of Mononlocs. One had no float, just a blank off plate while the other one, left side, did have a float and bowl which fed both carbs.

Made me think of this thread. No need to balance the two float levels.
 

Attachments

  • precision float level adjustment.
    80409024-29C2-472B-A728-415B37D7F81F.jpeg
    218.1 KB · Views: 212
  • precision float level adjustment.
    3BCB1519-1B8E-4E00-9D0B-47DB158F8C39.jpeg
    205.1 KB · Views: 200
Triton Thrasher said:
You need enough fuel flow to feed the engine when it is flat out: full throttle at maximum rpm.

The total fuel used during twenty-minute sessions of accelerating, braking and cornering is not relevant to the flow of fuel required at max power.
Click to expand...

I didn't say it was!

I was musing around if I needed to try harder :rolleyes:!
 
xbacksideslider said:
Saw this Royal Enfield today with a pair of Mononlocs. One had no float, just a blank off plate while the other one, left side, did have a float and bowl which fed both carbs.

Made me think of this thread. No need to balance the two float levels.
Click to expand...

Only one float to mess with, but dependent on mounting at same physical height, fairly easy to confirm in the close proximity demanded in these applications!

If they weren't done like this they would not fit. Assume basically that the motor in question was originally designed as a single carb application.

I have a pair of these monoblocs somewhere, with a home fabricated steel manifold to fit a 5TA.

As inferred earlier in the thread, the concentric design eliminated the need for these 'solutions'.
 
MexicoMike said:
Hmmm...surprised nobody has tried a Holley 650 double pumper with an electric fuel pump just to be sure there's enough fuel/air for this 50HP engine. ;)
Click to expand...

The Monocoque Commando racer had a fuel pump.

I’m sure Dell’Orto and other carbs with accelerator pumps have been tried.
 
maylar said:
I think a Weber might adapt more easily...

precision float level adjustment.
Click to expand...

Tongue in cheek right?
I thinkTT is referiong to the MC dellorto not the car dellorto (DCOE weber type)

custom manifoldneeded, bore to bore, much wider than NHT head/ports.
Would need to fit under frame web...Ask Jim C

I own a 67 elan S3 coupe(2X40DCOE weber ) since 1985. New dcoe = $400 ea or more

I'm going to try a single 38mm Keihin throttle plate big bore w/accelerator pump (mid 70's sportster) You can find them used for around $50 or a little more. Fully tuneable... And quite short...only 1/4" longer than mikuni
 
xbacksideslider said:
Saw this Royal Enfield today with a pair of Mononlocs. One had no float, just a blank off plate while the other one, left side, did have a float and bowl which fed both carbs.

Made me think of this thread. No need to balance the two float levels.
Click to expand...
Assume you posted this with tongue in cheek. Set up illustrated probably adequate for that bike/application as it is rather agrarian. It’s really a non issue in long coordinated turns.

Run that Enfield as a side hack in a long sweeping right hand turn and the right hand carb will run leaner.

There is a reason to set float levels reasonable level (indexed) to their respective carb body index points and there are reasons most if not all later model motorcycle carbs went with a concentric design.
 
dynodave said:
Tongue in cheek right?
I thinkTT is referiong to the MC dellorto not the car dellorto (DCOE weber type)

custom manifoldneeded, bore to bore, much wider than NHT head/ports.
Would need to fit under frame web...Ask Jim C

I own a 67 elan S3 coupe(2X40DCOE weber ) since 1985. New dcoe = $400 ea or more

I'm going to try a single 38mm Keihin throttle plate big bore w/accelerator pump (mid 70's sportster) You can find them used for around $50 or a little more. Fully tuneable... And quite short...only 1/4" longer than mikuni
Click to expand...

There’s a bit in Tuning for Speed about fitting a Weber to a twin cylinder bike.
 
A few years ago I saw a commando chopper with a side draft Weber fitted
It certainly ran well the way he took off up the road!!
 
FWIW, A Norton Commando, assuming it really made 60 HP as per the ads (!) would need around 134 CFM of air flow to produce that power at 7000 RPM. :)
 
No doubt the DCOE can use 28-30-32-34 or more choke diameter. Even as my lotus is only 1558cc and uses two DCOE double of a norton . Size wise it is fine . It's just to wide to be practical. But of course anything can be done if you work at it hard enough. Biggest drawback is they are somewhat intolarant of vibration...UH a commando isolastic? vibrations for rider . NAAHH engine YES!
 
MexicoMike said:
FWIW, A Norton Commando, assuming it really made 60 HP as per the ads (!) would need around 134 CFM of air flow to produce that power at 7000 RPM. :)
Click to expand...

"Amal 30mm concentric w/offset velocity stack------175.9 CFM

Amal 32mm concentric w/offset velocity stack------188.8 CFM

The Amals loose 15% of flow without the velocity stack. " - Jim Comstock
 
Status
Not open for further replies.
Back
Top