They're good for many surfaces Eric, including aluminium, you just need to set them up for the correct emissivity of the surface.
ET: Engine (Twin) Front cylinder cooler
- Thread starter Chris Harrison
- Start date
Thanks for the input guys. I picked up a pair of Throttle and Pilot Screw Kits today from Burlen. I bought full kits because on inspection the heads of the pilot screws were visually different, may not affect performance but having spotted it I would be looking at them for ever more. The bad news is the reason the throttle screw dropped out is the thread in the carb is stripped. I'll be ringing Burlen tomorrow to see if it's possible to helicoil the hole, 2BA I think? With luck they'll be able to do it while I'm there. If they're not interested has anyone any experience in trying to helicoil a carb before I invest in a 2BA helicoil kit? Confirmation that the thread is 2BA would be handy if anyone knows for sure.
Is it die-cast zinc alloy or the brass body ? enough meat around to tap 1 BA ? Not at home so can't nip into w/s to check.
Whoa, steady-on Chris. I am almost certain that both the stop-screw and mixture screw are 1BA. Given that you have new Burlen ones to hand you can confirm that by measuring the OD at the thread with a mic or vernier. The nominal OD of a 1BA screw is 0,208". If you have a set of thread gauges to hand the thread pitch of 1BA is 28.2 tpi, so a 28tpi gauge should almost fit.
By comparison, 2BA is about o.185" dia (close to 3/16ths) and a finer pitch - about 31.35.
So my advice would be to get hold of a 1BA tap and check the sloppiness of it, or otherwise, in your carb body - before helicoiling unnecessarily.
Peter B
By comparison, 2BA is about o.185" dia (close to 3/16ths) and a finer pitch - about 31.35.
So my advice would be to get hold of a 1BA tap and check the sloppiness of it, or otherwise, in your carb body - before helicoiling unnecessarily.
Peter B
Hi Peter & Marcus,
The carb is the zinc-alloy variety.
I wasn't sure of the thread size however the new throttle screw is the same size as the old one removed from the rear carb. The thread in the front carb has been stripped to the extent that the new screw barely engages with the threads at all. I checked the the OD of the new screw is 0.204" which as you rightly say is 1BA.
A 1BA helicoil uses a 5.5mm tapping drill which is only marginally bigger than the existing hole at 5.2mm, there's 9.8mm of 'meat' which is reassuring!
I spoke to Burlen who wouldn't be interested in carrying out the repair although the guy said there would be plenty of meat to support a helicoil. I enquired about a new carb out of interest, one available at, I think he said, £250+vat.
I think a helicoil is the way to go.
Thanks for the input,
Chris.
The carb is the zinc-alloy variety.
I wasn't sure of the thread size however the new throttle screw is the same size as the old one removed from the rear carb. The thread in the front carb has been stripped to the extent that the new screw barely engages with the threads at all. I checked the the OD of the new screw is 0.204" which as you rightly say is 1BA.
A 1BA helicoil uses a 5.5mm tapping drill which is only marginally bigger than the existing hole at 5.2mm, there's 9.8mm of 'meat' which is reassuring!
I spoke to Burlen who wouldn't be interested in carrying out the repair although the guy said there would be plenty of meat to support a helicoil. I enquired about a new carb out of interest, one available at, I think he said, £250+vat.
I think a helicoil is the way to go.
Thanks for the input,
Chris.
Blimey! £250 + vat! you could get a jetted set of Mikuni VM28 carbs for that and never worry again....
Amen to that. It worked for me.
Yes 250 pounds seems a lot I suppose............Easy to tune, fuel lines and cables all fit neatly just as the factory made them, they work fine..........Oh and they happen to LOOK THE BEST..........BEST 250 pounds you could spend............Let the "Hot Rodders" play around for ever trying to get their after market carb's sorted...............Do you get the impression I like the originals the best............ Bit like a standard Vincent clutch really.
I'm with you on the looks of the carbs but my lovely Honda clutch is hidden 
)
I think my Rapide clutch is lighter than the one I had on my Garelli Tiger Cross, mind you that was a long, long time ago. Stadium helmet (with full face visor), Parka, Gauntlets, I was sooooooo cool (or thought I was...)
) I think my Rapide clutch is lighter than the one I had on my Garelli Tiger Cross, mind you that was a long, long time ago. Stadium helmet (with full face visor), Parka, Gauntlets, I was sooooooo cool (or thought I was...)
Hi Erik,
I find that my IR thermometer works fine on aluminum as long as it isn't highly polished. Here in the U.S. most people who have English cars have one as there seems to be quite a bit of poor quality engine temperature sending units on the market. Consequently best practice has become to warm up the motor and take a few readings particularly at the thermostat housing. On my M.G. I run an aluminum head, sump, and radiator. The readings from the head are consistently in the 190F range. When I had a standard radiator it was only a few degrees cooler, as expected. When pointing at the aluminum rad after a run the IR says it's room temp. My highly calibrated right index finger disagrees. I put the in accuracy down to the highly polished nature of the rad, as the head is as cast.
Steven