ESE's works engine tuner

[husaberg]

Now for the trick with the restricted flow to the float bowl. Driving WOT would cause a gradual drop in float bowl fuel level and an accompanying leaning of the mixture.
In the twisty parts of the track WOT would never take more than two seconds, but on the straight it would start making a difference.
Like I said, it was a risky business, and putting a hand over the carb would not do much good if the fuel level in the bowl was too low.

What good would an extra volume of fuel do if it is too low in the bowl?

One of the ways i used to establish it was too lean was to wind off the throttle a smidge whilst maxed out to see if it gained revs. If it did go richer
it must have momentarily enrichened it or just went to a less lean state. not sure which, but it used to work for me at least. But was never on the ragged edge.

[jato]

Attachment 353205

Up sized the fuel line and tap plus the float valve. Followed F5 Dave's suggestion for seating the float needle. Worked Ok.

Even with the bigger fuel line there were no apparent improvement to fuel flow, it still ran like a bag of Poooo with the hiccups. I will have to explore F5 Dave's suggestion about drilling out the cross drilling in the carb itself and get one of those float valves Wob suggested.

Otherwise I might have to look at Larry's idea of a fuel pump.

Also I found the cylinder base nuts had worked loose again! It had been reliable before I pulled it down for re balancing. I am surprised to be having this problem again. Are NordLock lock washers single use?

Excluding safety, putting 3 or 4 psi of air pressure into the tank will encourage the fuel to head for the float bowl. it might help establish where the problem lies. wear goggles and overalls incase the tank doesn't like the idea...

[DoldGuy]

Attachment 353205

Up sized the fuel line and tap plus the float valve. Followed F5 Dave's suggestion for seating the float needle. Worked Ok.

Even with the bigger fuel line there were no apparent improvement to fuel flow, it still ran like a bag of Poooo with the hiccups. I will have to explore F5 Dave's suggestion about drilling out the cross drilling in the carb itself and get one of those float valves Wob suggested.

Otherwise I might have to look at Larry's idea of a fuel pump.

Also I found the cylinder base nuts had worked loose again! It had been reliable before I pulled it down for re balancing. I am surprised to be having this problem again. Are NordLock lock washers single use?

TZ, why not use a Bigger Suitcase?
(Hopefully the pictures attached)

[F5 Dave]

That will only slow the problem down. The level will still always lower if the float needle cant let enough past to keep up with horrific consumption.

[pete376403]

You need an Amal GP with dual float bowls. Of all the problems possible, running out of fuel in the carb wont be one of them

[lodgernz]

Also I found the cylinder base nuts had worked loose again! It had been reliable before I pulled it down for re balancing. I am surprised to be having this problem again. Are NordLock lock washers single use?

https://www.theboltholder.co.nz/view...ck-nut-zp-cl10

[jato]

If you do go with those nuts from the boltholder you'll need to check the nut seat is true to the thread as every nut bolt and stud i've used from them in recent years has been miles out - aircraft quality is what's needed...

[wobbly]

TeeZee , the only reason the base nuts loosen off is due to gasket crush , created by detonation shock.
Maybe not enough to eat a piston but certainly enough to eventually kill bearing cages.

[flyonly]

Attachment 353205

Up sized the fuel line and tap plus the float valve. Followed F5 Dave's suggestion for seating the float needle. Worked Ok.

Even with the bigger fuel line there were no apparent improvement to fuel flow, it still ran like a bag of Poooo with the hiccups. I will have to explore F5 Dave's suggestion about drilling out the cross drilling in the carb itself and get one of those float valves Wob suggested.

Otherwise I might have to look at Grumph's and Larry's idea of a fuel pump.

Also I found the cylinder base nuts had worked loose again! It had been reliable before I pulled it down for re balancing. I am surprised to be having this problem again. Are NordLock lock washers single use?

Do a flow test with the bowl off but with something limiting the drop of the float. This way you can check the flow of the system from the tap to the bowl. There is a guide on how much fuel you need to flow per minute per hp for petrol. I found with the bowl off it could flow enough but bowl on, the needle could not fully open


Sent from my iPhone using Tapatalk

[wobbly]

Yes Fly I agree , I had to lift the fluel level very high in the bowl , so the the floats would drop alot , pulling the needle well of the seat before bottoming on the floor.
TeeZee I do have a brand new Dellorto 4.2 Methanol float valve assembly you can have - the 55 Hp 125MX TM multi Championship 1 plate winner ,needed a 4.5 so yours should be fine with a 4.2.
I also have a screw adjustable powerjet that worked perfectly when its flow was equal to 25% of the main when set to 1/4 turns , and easy to access by hand on the fly to keep a consistent egt
with small adjustments in and out compensating for the changing weather RAD.

[husaberg]

You need an Amal GP with dual float bowls. Of all the problems possible, running out of fuel in the carb wont be one of them

This was due to downdraft angle. mk2 concentric's with matchbox gp floats for the quantal Norton Cosworth twin prior to it being converted to fuel injection
Surtess was the manager or something so i guess he had used or offered what he had or was familiar with.

it also used a couple of 60's F1 Ferrari radiators or oil coolers it miht have been Ferrari oil collers as radiators
Grumph will remember

But pretty sure this guy was the mechanic.
The best rider you have likely never heard of.
Son of the famous Bultaco importer Bert..


for you Greg

Cam profiles were originally lifted straight from the Cosworth DVA engine, with valve lifts and durations being equal, exhaust and intake, and set at 102 degrees maximum lift both. Maximum valve lifts were 10.4 mm, and at 1mm lift, durations were 274 degrees. Later Gary Flood changed these settings to give intake full lift at 98 degrees ATDC, but despite this early opening, no problem was ever found with valve to piston clearance. Later the intake cam was changed to one developed by John Judd when working with the Williams F1 team, which gave 1.5mm more peak lift.
Squish was set cold to 0,024 thou. but was found to shrink dynamically to 0.006 thou.

Duration looks to be the same as the CB700sc nighthawk at 1mm

The CB700SC was incredibility
276 deg at 1mm lift 120 lobe center for intake 118 for ex.
they must have put a hot can to make up for the 50cc lost due to US making to protect Harleys.

[Flettner]

Blah, floats, needles, jets.

[Grumph]

Blah, floats, needles, jets.

And of course, cams valves etc etc...

[pete376403]

This was due to downdraft angle. mk2 concentric's with matchbox gp floats for the quantal Norton Cosworth twin prior to it being converted to fuel injection

Aboout the time I started speedway the standard two valve Jawas carb was a DellOrto SS1. The hot setup was two remotely mounted bowls (even bigger than the pic of the Amal GP bowls I posted. I couldn't be bothered withthe continual adjustments so put on a 36 (38?) Mikuni and the thing would even idle.
However none of this is helpful wrt to TZ350s problem

[husaberg]

Aboout the time I started speedway the standard two valve Jawas carb was a DellOrto SS1. The hot setup was two remotely mounted bowls (even bigger than the pic of the Amal GP bowls I posted. I couldn't be bothered withthe continual adjustments so put on a 36 (38?) Mikuni and the thing would even idle.
However none of this is helpful wrt to TZ350s problem

i have two of those ss1's .......
if tz added a su float bowl it would have to be able to flow enough for half or a third of a jag 4.2
You should be able to mount it under the main jet?


bellow is an HS4

Another view austin maxi these are rubber hose jointed and can be mounted anywhere at any angle of carb

Said it earlier when this problem came up - use Cone lock nuts. Do try it.....

Example - A sidecar outfit rear brake disc was continually coming loose with Nylocks on the retaining screws.

Cone locks fixed it.

Are cone locks like the axel nuts on modern bikes?