Installing Carby's

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I seem to have air leaks when i install the amal carby's.

What is the correct order of assembly?
I have been assembling the manifold with o-ring to the carby then attaching them (with cap heads) to the head with spacer.
Would it be better to attach the manifold & spacer to the head first. and then carby's on to the manifold afterwards?

Those o-rings look a little skinny I would think a slightly thicker ring could do a better job what is your experience with this?
 
Fiddly work - I don't think it matters on the order, as long as you get them on!

Not sure on your o-ring measurement - perhaps someone out there has a spec you can double check.
 
i'm not sure of the thickness, but with the nuts finger tight, there should be space between the carb and the intake. that way when you tighten it, it squishes the o ring and it seals.
 
You cannot fit the carbs to the manifolds after they are on the head.It is impossible to tighten the nuts.Assemble the manifold to the carb first then fit to the head with the allen screws.
 
And don't tighten the nuts too much or you'll warp the carb bodies. You want them just barely more than finger tight, with some loctite to keep them from coming loose. Green loctite works great here.

Have you checked the flanges on a glass plate? If they're warped that could be your air leak.

Some people prefer to discard the o-ring and use yamabond or a gasket instead, to prevent the flange warpage. I have not tried that myself though.

Debby
 
Thanks for your replies.
It seems I am using the correct proceedure. I will check the flanges for warpage and use some new o rings.
I have just installed a trispark ignition. The engine feels a lot stronger and more positive(hard to describe) It idles better than ever but there is a hesitation and rough running from idle to 1500 rpm when taking off, definately a carb problem! :?:
 
A friend here in Michigan has done some work with a single Mic on an 850 with a new Tri spark.
After the install if this ignition the carb needed some leaning adjustments, no longer needs a choke at all. Also the Iso mark 3 spring type added when the Dave Taylor got put on needed tightening as the vibration spot changed.
 
Probably everyone has a method here but since I no longer have angle capable allen wrenchs I found a flat screw driver that just fits to allow me to spin the allen screws on quickly. You need to resort to your cut off allen wrench to finish up but this makes the job of installing those quite fast.
 
Maybe because I don't know any better, but I always connect the Carbs to the manifold, which are already mounted to the cylinders...
All you need is a cut-off Allan wrench and some patience. Never tried to mount the carbs on manifold and then install the suckers. Next time I have the opportunity, I will attempt that approach...
Keep them riding until the roads wear out ....
 
You can do it that way but it is tough. I think I did that once before I figured out the other way. I was turning the nuts with the edge of a screwdriver.
 
OK...slight hi-jack, but how do you get the intake manifolds off the head? I am pulling the jugs and am currentltrying to use a punch and hammer to get the inside nuts off!!
 
but how do you get the intake manifolds off the head? I am pulling the jugs and am currentltrying to use a punch and hammer to get the inside nuts off!!

If you are looking at a nut, you must be looking at the carb to manifold fastener. The manifolds should be fastened to the head with socket head cap screws. To remove the inside screws you need to shorten an allen wrench to about 3/8 inch in length. It is a pain as you can only do short strokes, but once loose you can spin it out with your fingers. Remove the carb from one side and the other will be much easier.
 
Ah the beauty of a "re-built" bike.

When I bought my bike the guy had "re-built" it...

He had put the allen head bolts on the inside carb to manifold.

I can only assume he has nuts to studs on the inside manifold to head and I can't even figure out how the hell he would've even got the nuts tightended.
 
That could be a real pain to get off. Once you do you can put it back correctly and it will be far easier.
 
can only assume he has nuts to studs on the inside manifold to head and I can't even figure out how the hell he would've even got the nuts tightended.

Ugh!! Maybe a 1/4" drive socket with a universal and long extension?? :?
 
Well couldn't get anything int there...tried grinding down a halh inch wrench to a knub as well as cutting a socket.

In the end had to use the old hammer and punch to work the nut off. One one side was off the other was easy enough. I will be backing the studs out and replacing with teh allen heads for sure!!

Got the jugs off her now. Everything looks good although the one piston is definetly sootier than the other and both are 0.040 over on the stamp. Funny enough the one marked R was in the left cylinder (atleast I think it is the left one....it is left when I sit on the bike).
 
Funny enough the one marked R was in the left cylinder (atleast I think it is the left one....it is left when I sit on the bike).

If you have a 750 that's a real problem. There are valve reliefs in the pistons. Swapping side to side invites valve to piston collision. 850's have no valve reliefs (unless the head has been milled). I can't remember if the 850 pistons are usually marked L and R. I don't believe they are, but I'm not near the shop to take a look.

It sounds like the guy who put the engine together wasn't very observant. I think I'd tear the whole thing down to find what else he f@$ked up.
 
I have a set of mismarked 750 piston. R and L swapped. They are Taiwanese repos. In order for the large relief cut to center under the intake valve, the pistons must be swapped. This is with a Combat head. There are probably more out there.
 
Mine were indeed mis-stamped as the valve cut-outs woudl only be in the correct position to make it work.

I had originally posted the start of my probs under "Clueless" but I am slowly becoming more enlightened...

With the head off it is clear my left piston (the one that had been acting up and that had the carb fall off while on the highway) is scored/scratched up as is the jug which it came out of. Am now getting it bored out to 0.060 with new pistons and getting the head looked over.

The subject of valve guides came up with my local Brit bike specialist and he indicated that he out sources the valve guides to get done as they are such a pain and are a precision gig. He also siad that the valves need to be set-up at the same time as the valves themselves.

Do many people do their own valve guides?
 
I did my own many years ago but I was trained in an airplane shop and had a full machine shop available. These days I'd send it out.
 
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