Stock Head Studs Constantly Loosening

L.A.B. said:

Setting Fuel Level on Amal Mark 1 Concentric Carburetters | AMAL Carburetters

Guidelines for achieving optimal fuel level in Amal Mark 1 Concentric carburetters. Covers fuel level measurement techniques, & more.
amalcarb.co.uk amalcarb.co.uk
Route the tubing in a vertical position alongside the float chamber, then open the petrol tap and fill the float chamber with fuel. If the fuel level is in the correct range, the fuel will rise in the tube to a point between 0.170" and 0.240" , below the top edge of the float bowl.
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Although AMAL doesn't state it, I believe the measurement with tube should be with the tube 1/2 way fore and aft of the bowl. I believe their instructions are meant for the top of the bowl to be level which it isn't on a Commando. In other words, the fuel height will be closer to the top of the bowl on the head end and farther away on the air cleaner end but correct in the middle.

The pilot circuit starts at the bottom rear of the carb. The lower the fuel level the harder it is to suck fuel through the pilot circuit. If you measure the fuel level at the front (head end) of the carb it may be too low at the rear for consistent idle and starting.
 
marshg246 said:
Although AMAL doesn't state it, I believe the measurement with tube should be with the tube 1/2 way fore and aft of the bowl. I believe their instructions are meant for the top of the bowl to be level which it isn't on a Commando. In other words, the fuel height will be closer to the top of the bowl on the head end and farther away on the air cleaner end but correct in the middle.
Click to expand...

Yes, although the carbs or just the float bowls can be set "on the bench" (old type floats shown) often useful as adjustments can be mad if necessary.
Stock Head Studs Constantly Loosening
 
I do have the Amals on the workbench. The Wassels took some time to set up. They currently work well. I assume the Amals will be the same. I need to check float levels, and make sure all orifices are clear. They came with 260 main jets, and the Wassels are 240 mains. I ordered a pair of 240s. One thing I noticed with the Amals was that the ticklers are so tight or misaligned that they would not depress. I had to tap them after removing the bowl to free them. Twice.
I may have had a minor air leak. They are beautiful looking. I will use them eventually. Not cheap at $600 a pair.
I really appreciate the wealth of knowledge you folks have imparted. Thanks.
 
robertv said:
I do have the Amals on the workbench. The Wassels took some time to set up. They currently work well. I assume the Amals will be the same. I need to check float levels, and make sure all orifices are clear. They came with 260 main jets, and the Wassels are 240 mains. I ordered a pair of 240s. One thing I noticed with the Amals was that the ticklers are so tight or misaligned that they would not depress. I had to tap them after removing the bowl to free them. Twice.
I may have had a minor air leak. They are beautiful looking. I will use them eventually. Not cheap at $600 a pair.
I really appreciate the wealth of knowledge you folks have imparted. Thanks.
Click to expand...
A 74 850 MK2 is supposed to have 260 main jets. If it's a MK2A then 220 or 230 depending on where you look. The main jets are only used from 3/4 to full throttle. With E10 gas, going up one size is often good for WOT operation. Normally, most riding is 1/4-3/4 throttle and that's about the needle position (106 is the right needle jet).

Most like #19 pilot jets. #17 work but the idle is not as nice and starting is a little harder. If you bought the correct AMAL carbs, they came with #19.

So, what air cleaner/mufflers do you have? Do you have cross-over pipes? What are the numbers on the sides of the AMAL carbs (especially the sub numbers)?
 
robertv said:
Last retorque, the center front stud was down to 4 lbs.The rear nut was pretty good. the two front upper nuts were down to 10lbs. The two front lower up through cylinder bolts were quite loose also. Bolts (4) through head to cylinder always loosen. So everything really, loosens. No oil or compression leak between head and cylinder
I have not exceeded 55mph.
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Centre front is a bolt!

You have:
4 off long 3/8" bolts (2 each side around the spark plug location)
1 off short 3/8" bolt (front centre location)
2 off 5/16" studs and nuts (front location)
3 off 3/8" studs into the head, 2 with sleeve nuts (front outer location) and 1 with an ordinary nut (rear centre location)

You don't mention what type of gasket you are using.

Has there been any skimming of head or barrel surfaces?

Is it possible that the bolts are bottoming in the thread holes in the barrels which makes you think you have set the torque, but prevents you from getting the seal you want on the gasket?
 
jseng1 said:
Use solid copper gaskets with pliobond sealer and waisted triangular studs with thread inserts - end of problem.
Stock Head Studs Constantly Loosening
Click to expand...
But investigate the state of the 3/8" head stud threads first, or you could end up putting in inserts, and buying a second set of studs!
 

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