ESE's works engine tuner

[adegnes]

The dyno video.

[Michael Moore]

Don't underestimate the effects of foamed fuel.

Gordon Jennings mentioned solving problems at Daytona on several bikes by wrapping lead wire around the carb(s) to change their resonant frequency.

[adegnes]

Gordon Jennings mentioned solving problems at Daytona on several bikes by wrapping lead wire around the carb(s) to change their resonant frequency.

The added weight did seem to help. I'll see if I can find some lead to add even more without the bulk. A brace to the frame could probably solve this, complicated with the moving engine.

[oldjohnno]

The added weight did seem to help. I'll see if I can find some lead to add even more without the bulk. A brace to the frame could probably solve this, complicated with the moving engine.

When I had fuel frothing problems the engine would cut right out at the critical rpms but unlike your bike the fuel bowl never overflowed a drop - there didn't appear to be any problem with maintaining the fuel level in the bowl and this makes me think that we are looking at two different conditions. I assume you use a spring-loaded rubber or viton tipped float needle? I really enjoy your videos BTW, very well done.

[adegnes]

When I had fuel frothing problems the engine would cut right out at the critical rpms but unlike your bike the fuel bowl never overflowed a drop - there didn't appear to be any problem with maintaining the fuel level in the bowl and this makes me think that we are looking at two different conditions. I assume you use a spring-loaded rubber or viton tipped float needle? I really enjoy your videos BTW, very well done.

Thanks!
Yep, spring loaded rubber tip. I think it's time to try a different carb. Maybe my Oko is particularly sensitive to vibration...

[TZ350]

As a matter of interest. I once worked with a TQ midget race car. We found you had to remove the float needle from the carburettor when the midget was being trailered to a race meeting. Leave the float needle in and it would vibrate around and wear out the needle and seat in very quick time.

[adegnes]

As a matter of interest. I once worked with a TQ midget race car. We found you had to remove the float needle from the carburettor when the midget was being trailered to a race meeting. Leave the float needle in and it would vibrate around and wear out the needle and seat in very quick time.

Hmm. Maybe my needle/seat is trash. I can't see anything wrong with it, but then again I need glasses and don't own any.

[husaberg]

Gordon Jennings mentioned solving problems at Daytona on several bikes by wrapping lead wire around the carb(s) to change their resonant frequency.

Kevin Cameron discussed (An itailian ducati tuner I can't think of his name edit later it was Actually Gordon Jennings own Aermacchi 250 ) in TDC 1. He was using lead weights on remote float bowls on Ducatis etc. The fuel was vibrated away and formed foam with air at certain frequencies. The theory was to tune to a complimentary frequency or harmony by trail and error much it like a guitar or piano.
I have seen it done with British bikes with TT and GP carbs as well. These generally have a separate mount to isolate them further. from memory the square matchblock float chambers are worse but they may have a pivoting float rather than a pole slider float valve.
(Note the pommy bikes had solid mounted carbs as did the Jenning Macchi.)
Maybe you inlet rubber is just too hard.

Cameron also mentioned that the first KR3 was near impossible to carburate on account of it severe vibration.

The fuel frothing (i think) does two things first it gives an inconsistant mixture that can be actually be alternating between rich and lean depending on the RPM.
It can also i believe shuts off the fuel supply, as the frothy mixture raises the float level.
The liquid fuel can also be diverted directed away from the mainjet. being replaced by a bubbly air/fuel mix
Some mikunis and Keihins have jet sheilds that might help. Aftermarket FCR bowls have deeper wells and different designs to overcome frothing on whoops and similar conditions.
These below are stock CRF230.


This is the mikuni part

[TZ350]

As a matter of interest. I once worked with a TQ midget race car. We found you had to remove the float needle from the carburettor when the midget was being trailered to a race meeting. Leave the float needle in and it would vibrate around and wear out the needle and seat in very quick time.

Hmm. Maybe my needle/seat is trash. I can't see anything wrong with it, but then again I need glasses and don't own any.

No, probably not. I just posted that as an example of the weird shit that happens and can take a while to figure out.

[Grumph]

As a matter of interest. I once worked with a TQ midget race car. We found you had to remove the float needle from the carburettor when the midget was being trailered to a race meeting. Leave the float needle in and it would vibrate around and wear out the needle and seat in very quick time.

Pretty sure i know which carbs they were, LOL. Never had a problem with the cars I looked after, but back when single cam Hondas were common one guy I knew reckoned the best spot for the carbs when towing was on the rear parcel shelf of the tow car. The brass floats would bend and stuff up the fuel levels if left on the race car. But the carbs were the least of his problems...

[oldjohnno]

The old Amal concentrics had a fine gauze sock over the main jet. At first I thought it was just some sort of strainer but apparently it's to help with frothing. I wonder if some of this stuff would help?

[adegnes]

The old Amal concentrics had a fine gauze sock over the main jet. At first I thought it was just some sort of strainer but apparently it's to help with frothing. I wonder if some of this stuff would help?

Isn't this just how those "stones" on the intake line in chainsaw fuel tanks work?
That fine gauze sock is interesting and worth a try, I'll see if I can find something suitable.

[Flettner]

Sooo, spark plugs, I'm sure it's all been said (I didn't listen) but if in a twostroke detonation is a limit to ultimate power and it seems careful attention to the spark plug surroundings (cooling water) helps, would a smaller spark plug offer less 'hot area' to light up detonation? I have 8mm plugs in 9 heat range, a lot less metal and spark plug. A lot more water cavity. ???

[Michael Moore]

We found you had to remove the float needle from the carburettor when the midget was being trailered to a race meeting. Leave the float needle in and it would vibrate around and wear out the needle and seat in very quick time.

This was found to be a problem in the USA with new automobiles transported by rail from the factory. They were getting "false Brinelling" on the wheel bearings from the vibration with the otherwise stationary bearings. The bearings would fail soon after leaving the dealer's lot.

https://en.wikipedia.org/wiki/False_brinelling

[adegnes]

Was granted some dyno time later today by girlfriend.
Gameplan:

1. Go over and tighten mounts as much as possible without restricting movement, shim out where/if necessary.

2. Rubber hose extension on intake to make it softer, will be hopelessly long but for testing purposes it'll be fine.

3. "sock" over jet block, material from fuel filter or something.

4. Better jet "shield".

4. Different carb, my neighbor maybe had one lying around.