Hello, I´m rebuilding a 1948 international from
parts for use on street.
What would be the best carburettor for this purpose.
From my experience of using a TT carb, a racing DellortoSSi and a pre -monoblock 289 on the road I would suggest one with a tickover!. The 289 or similar would be my choice as I looks the part. I would still carry a small fire extinguisher though and protect the mag from drips.
Agree with Robert that a TT carb can be a bit tricky to set up for road use. My 16H has it's old 276. The ES2 has a Monobloc. The Comet has a Concentric. The Venom a Mikuni VM. All runs well for road use. As you intend to use the Inter, it doesn't need to be exactly original. A Monobloc is not a bad choice, almost period. Try to figure out what is easiest to fit to the engine. If you are familiar with setting up an AMAL, go for one. The Mikuni VM is quite easy to set up too, only thing is that there could be a problem finding the right needle. If you have a friend who is better on setting up a carb than you are, choose one he is familiar with. An old worn instrument with worn throttle and jets + clogged drillings can give you extra problems.
Good luck, Mike
Hi, I have a '37 Alloy Inter motor in a post war Manx plunger frame which is used on the road
the TT carb was well worn, so ordered up a new AMAL 930 Concentric from Surrey Cycles who jetted it accordingly. Worked perfect straight out of the box, it starts easy and even ticksover. I added a long intake trumpet as well. So wouldn't hesitate to use one of these plus they are relatively inexpensive.
All the best Simon
I also agree with Robert as I used a 289 on my Inter many years ago and it is possible to bore them out to 1+5/32" which is the Inter size. 15 degree float chambers are available and if you use a Monobloc 375 long type bell-mouth it all looks very convincing. If you use a Monobloc carb check the plastic float as these could deteriorate with age and modern fuels.
The TT.carb gets some bad comments, but you can get a tick-over, you have to adjust the cable so the slide hangs on the cable. When you turn the handlebars it might make the engine speed up a little, but it's not really a problem. Starting is just a matter of practice, so try different settings until you find the best set-up for cold and hot starting which will not be the same, it seems the amount you flood them that is the tricky bit !
I have a 500cc clubman inter from 1952 which has a TT carb and it causes me trouble when hot, or pulling off from cold.
Anyone know what the settings are, especially the throttle cutaway. Mine has a 7 cutaway on inspection which I think is too large and causing problems with overheating (weak mixture?)
A friend lent me a 930 concentric set up for his inter and that has a 5 cutaway but on opening the throttle 1/4 plus it knocks out black smoke and misfires - rich mixture, (although works perfectly on his standard inter) ..any ideas anyone
The type of silencer or exhaust will affect your carburation, especially regarding the slide cut-away. If you have the borrowed 930 fitted you will probably need the same silencer as your friend. Also if you have Manx cams, this might affect the pick-up, depending on how they have been timed.
Thank You all for the information.
I've just started riding a prewar Inter. It has a brass TT carb refurbished by PO. As far as I'm concerned it just does its job. Maybe a different one might do it differently. Tick over is dealt with rather crudely by hanging the slide from the cable, with a big knurled lock nut to help. That must be locked or unexpected things may occur.
The TT looks decorative, which surely is much of the point in riding such a noisy and oily beast!
Mark...I'll look up the notes on cutaway etc. when I get home from work. Mine is prewar but notoriously they scarcely changed! At about £50 per slide there is a limit to how much you can afford to experiment.
David / John
thanks for the replies and your help.
I have a straight through (although its silencer shaped) and I was told it had race cams.
The Amal carb co also lists a 7 cutaway as standard on its website but any manual I have seen its a 5 or 6
Any help or advice appreciated
Check this out:
now that is interesting - shows a 7 cutaway for the m30 inter
For what it's worth these are the details of mine according to the notes in my possession.
Flange marking 34/041 10TT 34
Needle 10, middle notch of 7
Needle jet 109
Main jet 320
Bore 1 + 5/32"
Throttle slide 6 (cut away 3/8")
quite an assortment of answers with different settings. I actually dug out the memoirs of the man who raced my Inter in 1952 at the TT. He doesn't mention cutaway sizes but states he was on a 420 main jet - although he says it was spluttering over 106mph. (Pool petrol)
Looks like I'm gong to have to experiment but I bought a 5 cutaway from Surrey cycles (only size they had) which is an oversize diameter and it fitted fine into the carb. Maybe too much air was bypassing a worn slide???
Thanks all for your help
It may be possible to arrange an idle stop on a TT carburettor by drilling and tapping the top of the slide for a grub screw, to press on the top of the choke tube. I haven't tried it, but intend to experiment.
In the '50s, my father ran his International with a 289, largely for the benefit of an idle stop.
Some say they drill a small hole (but how small?) through the bottom edge of the slide. Or file a little notch. Neither strikes me as being reversible..
Informacion Amal 274,275,276,229,289.