[Cyorg]

Test start accomplished. It'a a lovely engine (thanks Molnar), really smooth. Only air in tyres and petrol in tank (not the opposite). It's a very easy starting machine. As an old racer explained it, compression ratio should be where it gives lot of power and is easy to start. In the old days when engine was off when the flag was dropped. Seems the float bowl change worked. Now load everything in the van. Practise on track sunday

Looks very nice. It inspires me to head out to the garage and do something with the shrapnel laying under the bench.
I’m assuming there are modern bits lurking inside that mag. Wonder if they help with the starting, although nothing wrong with a old one in proper working condition (other than price). Good luck at the track. Perhaps a smidgin of R40 just to add to the religious experience.

 

[Mike 40M]

Track test done. On the positive side it's nice handling and fairly comfortable to ride. I am a bit more used to the TTI gearbox but still don't like it. On the negative side it still was ok when warming it up but still power for a couple of seconds and died a couple of seconds. So my guess that it was a float bowl problem was wrong. Luckily a Velocette racing friend appeared. He had time to help me trying to figure out what reason it has to behave as it does. After a while, we found that when I put a finger close to the intake, it got soaked with petrol. Much. Explained the 5 MPG fuel consumption. Our guess is that in the fight between intake sucking in and exhaust blowing out, the silencer won and made the carb work the opposite way.
Some of you probably has a better explanation to it. As carb, engine and exhaust pipe is a proven combination by other racers, the most likely culprit is the silencer.
Next to do will be either to buy or build a new silencer. I think the way to go is a less tapered cone, followed by a revese cone and after that a large diameter stinger. Lots of calculations though to get it right.

 

[jalsteve]

Track test done. On the positive side it's nice handling and fairly comfortable to ride. I am a bit more used to the TTI gearbox but still don't like it. On the negative side it still was ok when warming it up but still power for a couple of seconds and died a couple of seconds. So my guess that it was a float bowl problem was wrong. Luckily a Velocette racing friend appeared. He had time to help me trying to figure out what reason it has to behave as it does. After a while, we found that when I put a finger close to the intake, it got soaked with petrol. Much. Explained the 5 MPG fuel consumption. Our guess is that in the fight between intake sucking in and exhaust blowing out, the silencer won and made the carb work the opposite way.
Some of you probably has a better explanation to it. As carb, engine and exhaust pipe is a proven combination by other racers, the most likely culprit is the silencer.
Next to do will be either to buy or build a new silencer. I think the way to go is a less tapered cone, followed by a revese cone and after that a large diameter stinger. Lots of calculations though to get it right.

Assuming ignition timing and spark is good, you have the float height set up so that fuel floods out of the needle valve at about 1/3 opening (carb vertical) and you have experimented or took advice on the gardener needle to fit - I would take a look at your valve timing and running clearances.

 

[Mike 40M]

Most problems solved this weekend. Met a nice Manxrider from Finland on a race in Norway. He promised me that if I took it to the Anderstorp TT race, he'd like to help me sort it out. As he is the fastest Manx-rider in Scandinavia, racing a 500 Petty Manx, a 570 Petty Manx in the 750 class and an ultra shortstroke 350 which he has built himself, I thankfully brought it there. I took him 5 minutes to get it running quite well. Then he said that it had to be tested on track to fine tune it. He kindly obliged to do the testing for me. Great to have an experienced Manx rider do the testing. It suffered from fuel starvation towards the end of the 800m (halfmile) straight. The brand new Matchbox float chamber had same problem as old gentlemen urinating. Damned AMAL. Replaced it with a Gardner one. Improved but still a bit of fuel starvation. Raised level 3mm. Better but not perfect. No more tracktime so we will try to sort it out next race. Also sorted out the classical problem with primary chain tension. When the bike is warm everything expands and tightens the chain. Now I know how much, so it has a nice slack when warm. Good things are that it handles well, what else could be expected from a featherbed framed Norton. Maybe a bit heavier fork oil. No oil leaks, thanks to Molnar. Only remaining problem so far seems to the lack of power in the end of long straights.

 

[jalsteve]

Most problems solved this weekend. Met a nice Manxrider from Finland on a race in Norway. He promised me that if I took it to the Anderstorp TT race, he'd like to help me sort it out. As he is the fastest Manx-rider in Scandinavia, racing a 500 Petty Manx, a 570 Petty Manx in the 750 class and an ultra shortstroke 350 which he has built himself, I thankfully brought it there. I took him 5 minutes to get it running quite well. Then he said that it had to be tested on track to fine tune it. He kindly obliged to do the testing for me. Great to have an experienced Manx rider do the testing. It suffered from fuel starvation towards the end of the 800m (halfmile) straight. The brand new Matchbox float chamber had same problem as old gentlemen urinating. Damned AMAL. Replaced it with a Gardner one. Improved but still a bit of fuel starvation. Raised level 3mm. Better but not perfect. No more tracktime so we will try to sort it out next race. Also sorted out the classical problem with primary chain tension. When the bike is warm everything expands and tightens the chain. Now I know how much, so it has a nice slack when warm. Good things are that it handles well, what else could be expected from a featherbed framed Norton. Maybe a bit heavier fork oil. No oil leaks, thanks to Molnar. Only remaining problem so far seems to the lack of power in the end of long straights.

That'll be Jarkko...…

Matchbox floats work well and the least problematic of their products.

if the engine is getting too hot at the end of the straight you'll loose power, turn the Gardiner needle up a turn or two. If the engine is a new build it'll loose a few degrees of advance when it settles so worth checking it against Andy's figure. Hopefully you're running a mag not electronic for the longer duration spark they give.

If your forks are old its worth fitting new damper rods and damper tube caps, more that 2 or 3 thou clearance and they don't work well. Also replace the piston for an "A" spec item with is a tighter fit in the tube. Failing that 30 grade oil 180cc to 195cc per leg.

 

[Mike 40M]

Nope, Ari Tiainen.
Not this Matchbox, Flow is about one pint in five minutes. A friend tested one of his yesterday at approx. 6 seconds per decilitre.
Thanks for your suggestions on the forks.

 

[jalsteve]

Nope, Ari Tiainen.
Not this Matchbox, Flow is about one pint in five minutes. A friend tested one of his yesterday at approx. 6 seconds per decilitre.
Thanks for your suggestions on the forks.

Seriously the matchbox should flow as much as the Gardiner float, you need to check the fuel level in the chamber as the valve maybe shutting too soon keep the fuel level too low. Given all your fueling problems there must be something else going on. If the valve timing is good, ignition too, setting the carb up, especially a Gardiner is 5mins and 2 or 3 x 5mins track visits. My Petty 92bore uses a Gardiner 42mm (bored) took a couple of mins to setup with a matchbox float. Usually you need a big bore fuel tap will a Gardner, also check the needle number (taper) and length sometimes owners take a file to them.

My Petty below, about 110kgs dry and 59/60hp at the back

 

[Mike 40M]

My Velocette friend (7 Velos including KTT Mk III and Thruxton) examined the Matchbox, after some drilling and level adjustment got it better. Obviously Burlen who makes AMAL carbs and parts is keeping the British tradition of sometimes producing crap. So I'll continue to use the Gardner float chamber.
Off topic. How do you manage to keep focus on a track day when temperature is more than 86F (30C)? And then get the leathers off?

 

[jalsteve]

Don’t do that producing crap thing - or perhaps your mate should sell his velocettes and you your manx. All British produced and still around 60 years on!

With respect I work with this stuff all the time and never have a problem with reproduction stuff.

But then.......

 

[Mike 40M]

On an extremely hot day, maybe it's too easy to use a not adequate word like "crap". But on a decent morning with temperature around 20C, maybe saying that it was foolish of me to expect that fitting a brand new matchbox without checking flow rate and level was optimistic. Yes, most reproduction parts made in the UK are good, if bought from renowned suppliers, but not all. I have a number of nonfitting parts in the shelves. And a number of parts that needed milling, turning or bending to fit. No, I have no intent to get rid of my six British bikes simply because I enjoy riding them.

 

[jalsteve]

For the sake of production and cost efficiency Burlen make some parts differently eg floats form plastic and not copper soldered up. This makes the newer floats more buoyant add viton tipped float valves and you get better seat to valve sealing and reduced flooding but you can get stiction in valve or the valve not opening quick enough or just not enough! I run brit bikes wet at low RPM and racing brits even wetter.

You also need to look at the size of the bore of the float valve there come in different sizes (the hole against which the float valve seats).

Float chamber - I buy used and rebuild, I never new.

 

[Mike 40M]

Just returned from my first race on the Norton. As the engine is new, I only rode it parade class, in order to give it a bit of break in. Six times a quarter of an hour in the saddle. I found the most difficult thing was to navigate through the pits to get out on the track. I had to keep it at least at 4000 rpm and play with the clutch to be able to go slow. When we got green flag and went out on the track it felt much better. Though I'm quite familiar with that track (raced the Honda there a couple of times) it took some time sorting out which gears and gear changing points. Started very slow to get a feeling of handling. Quickly found that it behaved as a featherbed Norton should. No problems there. Then found that I shall never go under 5000 rpm, which meant that I had to go a bit faster in the bends. Though it prefers anything over 6000 rpm to be happy. Any problems? Yes the gear lever doesn't suit me at all. Downshifting no problems, but I had trouble upshifting. I hope making a new lever will sort that out. Otherwise scrap the TTI gearbox and find something better. Another small problem was that on the last time on the track, after a couple of laps with good feeling, the screw holding the clutch lever disappeared. Called it a day, went into the pits. Where the guy who raced it in the sixties said: What! Going out just for a nonworking clutch lever. You should have kept on without it.
Funny thing, most of my bikes are it or she, but the Manx is definitely a he. With firm opinions on how to be ridden. Fast.
In -68, I looked at this machine and wondered how it would feel to ride a real racer. Now I know, FUN.
Still a lot to learn but very happy.

 

[Mike 40M]

Another weekend on the racetrack. The Norton started easily as usual ( after I found I had forgotten to remove the plug in the intake ). The new gear lever Mk IIIB, worked well. They had made some changes to the course since last time I raced there, so it took a couple of laps to find the new lines. Luckily the Manx is very forgiving and sorted out my wrong racelines without complaining. In the end of the first practice I was really enjoying riding it. Still I played safe and braked way to early, not knowing how good the brakes are. Back in the pits noticed a wet point in the rear left part of the tank. A maybe fifty year old plastic repair had started to leak. Removed it and found a 2"+ crack in the weld. Instead of making a quick fix, I called it a day and took out the Honda instead. More of that in my Honda thread. Will talk to my favourite alloy welder.
Still some questions needs answers. What oil temperature I shall try to get? Seems 3 litres is too much oil as temperature is only 55 degrees C, when back in the pits. What grease to use in the cluch roller bearing and how much? How long to warm up the engine?

 

[Mike 40M]

Met an experienced Manx mechanic from Scotland in the pits at Goodwood. He answered to the question I asked in #8 in the thread. The tabs close to the steering head was fitted on 59 and 60 frames. Why no one knows. They were never used for anything. He kindly answered a lot of other questions ( and offered me a beer to).

 

[XB33BSA]

For the sake of production and cost efficiency Burlen make some parts differently eg floats form plastic and not copper soldered up. This makes the newer floats more buoyant add viton tipped float valves and you get better seat to valve sealing and reduced flooding but you can get stiction in valve or the valve not opening quick enough or just not enough! I run brit bikes wet at low RPM and racing brits even wetter.

You also need to look at the size of the bore of the float valve there come in different sizes (the hole against which the float valve seats).

Float chamber - I buy used and rebuild, I never new.

i have never seen copper floats ,brass is what you meant i am sure,
copper is red, brass is yellow ,that is an easy way for us to distinguish the diff
re sticking viton tips this is why the japs and others have a simple dangler hook at the spring loaded stem end
it serves to mechanically pull the valve open upon a bit of float drop
the hole size in the seat has 2 distincr effects
a larger hole offers more flow at any given float drop/opening but also needs more float pressure to shut the valve

spring loaded stem tips are very desirable

 

[Cyorg]

i have never seen copper floats ,brass is what you meant i am sure,
copper is red, brass is yellow ,that is an easy way for us to distinguish the diff
re sticking viton tips this is why the japs and others have a simple dangler hook at the spring loaded stem end
it serves to mechanically pull the valve open upon a bit of float drop
the hole size in the seat has 2 distincr effects
a larger hole offers more flow at any given float drop/opening but also needs more float pressure to shut the valve

spring loaded stem tips are very desirable

......

 

[XB33BSA]

......
View attachment 99123

yep those are all brass my color ref was regarding clean metal the brass turns brownish-red
i have in front of me now a dozen del's from early 60's on and even the remote bowl ss1 ss2 have brass floats
copper is too ,weak and would need be heavier than brass by a considerable amount to not be as fragile as a dry popcorn fart

 

[XB33BSA]

Another weekend on the racetrack. The Norton started easily as usual ( after I found I had forgotten to remove the plug in the intake ). The new gear lever Mk IIIB, worked well. They had made some changes to the course since last time I raced there, so it took a couple of laps to find the new lines. Luckily the Manx is very forgiving and sorted out my wrong racelines without complaining. In the end of the first practice I was really enjoying riding it. Still I played safe and braked way to early, not knowing how good the brakes are. Back in the pits noticed a wet point in the rear left part of the tank. A maybe fifty year old plastic repair had started to leak. Removed it and found a 2"+ crack in the weld. Instead of making a quick fix, I called it a day and took out the Honda instead. More of that in my Honda thread. Will talk to my favourite alloy welder.
Still some questions needs answers. What oil temperature I shall try to get? Seems 3 litres is too much oil as temperature is only 55 degrees C, when back in the pits. What grease to use in the cluch roller bearing and how much? How long to warm up the engine?

131f is def chilly when i worked in the natural gas production field we had lots of diesels converted with a mag to run nat gas
every day on rotatyion shifts one of us would vist the 30 some compressors and manually observe and write down temps presures etc
the oil temps were of course higher than the water but in the 200- 220f+ range was good
high enough to boil of water low enough to help cool valve springs and whatnot
keep in mind that too much grease or oil in high speed rolling element bearings is very much a bad thing they can catch fire in the worst case
the main reason for the lube is to lube the cage and its sliding type contact with the rolling element be it ball or roller

 

[Cyorg]

yep those are all brass my color ref was regarding clean metal the brass turns brownish-red
i have in front of me now a dozen del's from early 60's on and even the remote bowl ss1 ss2 have brass floats
copper is too ,weak and would need be heavier than brass by a considerable amount to not be as fragile as a dry popcorn fart

......

 

[Mike 40M]

Learned a bit more about the Matchbox float chambers, which I had problems with earlier. On the about a dozen Manxes at Goodwood, most had Gardner float chambers, some had SU, no one used a Matchbox.
Learned that in the old days, riders was paid by AMAL for using their carbs. Had to use their float chambers too. So they got half a dozen float chambers, tested flow and used the best one.
Obviously a new made AMAL Matchbox is a close reproduction of the old one. Not usable on tracks with long straights.