New Amal Premier 900 series Carb for Comets
- Thread starter craig
- Start date
Hi, Craig, as I said earlier, I ran a rolling road for 25+years, specialising in classic Jaguars, for all practical purposes you do not need different jetting between leaded or unleaded/ethanol. In fact the "modern" fuels give better power on an e-type because you can now run the full advance without pinking(knock) which the old english 4 star caused. so apart from the drawbacks of corrosion etc I actually like the new fuels. The only bikes I have rolling roaded have been my own-it was my own dyno after all, My race t100 triton and the D M W typhoon (google this one it may be of interest) Regards, Roy.
This info may be of use to some. Having just put my B Rapide engine back together - complete head job and new muffs, thick liners and new standard RAK pistons - I did some test runs at small throttle openings to loosen up. I found that riding a flat road with little wind, 1/8th throttle kept a steady 60mph. 1/4 throttle gave over 70mph and good acceleration up to that. I am talking GPS measured speed not an optimistic speedo.
Now you all know that at such small throttle settings the only bits of the carb that are effectively working are the pilot and slide cutaway. So getting the idle mixture right is critical to combustion chamber health and fuel consumption.
Carbs are original pre-monoblocks, needle in the middle and 190 main jet. Pistons are 7.3:1 with a 1/32" compression plate giving 6.8:1 C/R. It ticks over lovely and at those speeds I am averaging 50mpg.
Later on, 1/2 throttle took me to 85 and rising.
No air cleaners Bob but I wiped a little lime juice around the rim.
Update - One important point I failed to mention was that I had installed new needles and needle jets. The old ones had done 100k miles in my ownership and the replacements made all the difference.
Now you all know that at such small throttle settings the only bits of the carb that are effectively working are the pilot and slide cutaway. So getting the idle mixture right is critical to combustion chamber health and fuel consumption.
Carbs are original pre-monoblocks, needle in the middle and 190 main jet. Pistons are 7.3:1 with a 1/32" compression plate giving 6.8:1 C/R. It ticks over lovely and at those speeds I am averaging 50mpg.
Later on, 1/2 throttle took me to 85 and rising.
No air cleaners Bob but I wiped a little lime juice around the rim.
Update - One important point I failed to mention was that I had installed new needles and needle jets. The old ones had done 100k miles in my ownership and the replacements made all the difference.
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Must be nice to know what you are buying. In the uK if I look on a label in a shop I can even see if a bar of soap contains nuts and the E numbers on a gobstopper but the amount of ethanol in my petrol seems to be a state secret
I fitted a new Premier to my Comet recently. Straight swap for the old Concentric which was on. Bike rides a little crisper than before and has less hesitancy when opening the throttle. Very nice piece of kit. I'm pleased with the result.
I did the same with the Rapide, replaced old worn out Concentrics with the new Premieres, all the same jettings etc. Fuel economy with the worn out carbs had dropped from an average of around 50 mpg solo to around 35 mpg. On fill up, I was providing a lot of entertainment to other Vincent Riders. " Lets go see how much gas Glen used, HAHAHA!"
Lugging power in fourth had also dropped down as the bike was running far too rich at all but full throttle position. This was especially noticeable at high elevation where the thinner air added to the problem.
With the new carbs on there the fuel economy has shot up to 57mpg riding two up, lugging power is back and the idle is smooth ,even when set very low.
Glen
Lugging power in fourth had also dropped down as the bike was running far too rich at all but full throttle position. This was especially noticeable at high elevation where the thinner air added to the problem.
With the new carbs on there the fuel economy has shot up to 57mpg riding two up, lugging power is back and the idle is smooth ,even when set very low.
Glen
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Are Canadian gallons imperial or US?
Fuel is sold by the litre here now, however I grew up with Imperial measure and still tend to use it. The 57 mpg Imperial was calculated over an 800 mile trip, two up plus gear, but on relatively slow roads.
Glen
Glen
You may recall that I had posted the carb setting I used on my new AMAL 900 PREMIER carb. Well it seems that overall I had the settings too lean resulting in overheating and a burned piston.
Once I get things back together I will be searching out a dyno shop that can assist with determining the appropriate setup.
Will report later.
Martyn
Once I get things back together I will be searching out a dyno shop that can assist with determining the appropriate setup.
Will report later.
Martyn