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You stated the alu float needles gave you issues....that is very unusual....just about everything I've read/heard is the alum ones are a significant improvement over the heavier brass. Also, you've gone with the old non-Stay-Up floats. Why do this on brand new premiers?
 
seattle##gs said:
I will not rule out the Boyer as a potential problem though my experience is that the work or don't work. They are tough little units and last years.
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Not my experience. I had an intermittent misfire on acceleration that I was convinced was carb related !
 
I had a Micro Digital (red box) on my Tiger 750 & it would just cut out occasionally whilst riding. Chucked it in the bin & fitted a Trispark before I ended up in an accident.
 
I had the owner try the Norton with my Mikuni installed and though he liked the results he really wanted the dual Amals. He knew someone who was good at tuning Amals and drove it over to him to see if he could solve the idle problem. I got the Mikuni kit back, he was happy with his Amals. Haven't seen him.
 
Did you go back to your Premiers after switching the the Mik last year?

I just fitted new Premiers and have had similar issues you reported here, namely periodic dips in idle rpm from 1k set down to 800-400 range at stop lights or just coasting with clutch in. Seems to clear up after few blips but does return later.

Bike also has just had head re-built.
 
generally, the idle is in the 1200 range. With the dual premiers, at idle, the motor had a strong exhaust on the left, a pow-pow-pow whereas the right side would only give me a puff-puff-puff no matter what I did. Possibly I am too persnickety but I want both sides the same. I do not recall if his friend solved the problem.
 
My JC ported FA head uses completely different setups with my then new Premiers. The right side needs bigger mains and different needle heights, and a slightly higher slide height at idle to give an even response and plug color.

Some of this is due to the Maney style exhaust running hotter on the right side, but those tendencies were there with dual peashooters.
 
Very few people would be able to tune the carbs like you did. How did you arrive at the mismatched jetting?
 
Trial and error. Started out the same setup, went for hands and ears behind exhausts for "feel" for.balance.

Then plug chops, pulling bowls to check float heights (which were uneven), fixing a float hanging up on bowl gasket, more plug chops at different throttle positions. Round and round for a while.
 
seattle##gs said:
generally, the idle is in the 1200 range. With the dual premiers, at idle, the motor had a strong exhaust on the left, a pow-pow-pow whereas the right side would only give me a puff-puff-puff no matter what I did. Possibly I am too persnickety but I want both sides the same. I do not recall if his friend solved the problem.
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Ah I see! Didn't catch the bike described in this thread was not yours.
Mine also had poor right side exhaust pressure. seemed to resolve that with using silicone sealant at silencer joint, it was leaking there.
 
Tornado said:
Ah I see! Didn't catch the bike described in this thread was not yours.
Mine also had poor right side exhaust pressure. seemed to resolve that with using silicone sealant at silencer joint, it was leaking there.
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His problems are never his bike. I would guess that is why they are problems.
 
I deal with a lot of brit bikes, mostly Norton. My own Atlas was running beautifully and all of a sudden began to darken the plugs. Head was built less than a year ago. Turns out the the valve guide seals had "perished"
 
Did you hang out with Phil at MSI ever?

My first house was 21st and Barton. Lived there all of the 90s.

I am better with my Amals now.
 
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I met Phil a couple of times but he was a chronic smoker and I couldn't breath in his shop. His glasses must have been 1/2" thick.
You want problems? A friend brought over a brand new frame, brand new cradle. I installed the isolastics and something is seriously catywampus. Something is not lining up, I had to really load the rubber on the front iso to connect all the bolts and found the rear right was way out of line like a bent frame would produce. Everything is new, straight from Andover Norton. I have to make a jig to measure the front iso hole to the rear iso hole then see if both sides are the same. It means pulling the motor out again. Simple job becomes a long job.
 
Yeah, but a six pack of Henry Weinhards would get you access to his shop all night. He was a great motor guy and would sell parts for the sticker price from the 70s if all was good.

Bugger. Complain to AN. With pics. I know the man here in NZ to fix that...
 
Couple of things from my experience:

A poorly adjusted cam chain can lead to poor idle qualities, as both ignition and cam timing will vary erratically.

I never was able to get decent consistent idling with a Boyer - tried with both the Mk3 and the Mk4. After experiencing the the superb idle quality of a friend's bike fitted with a Tri-Spark, I made the switch - beautiful consistent idle now. Carbs are the original stock Amals, sleeved about 20 years ago.
 
Derek Wilson said:
Couple of things from my experience:

A poorly adjusted cam chain can lead to poor idle qualities, as both ignition and cam timing will vary erratically.

I never was able to get decent consistent idling with a Boyer - tried with both the Mk3 and the Mk4. After experiencing the the superb idle quality of a friend's bike fitted with a Tri-Spark, I made the switch - beautiful consistent idle now. Carbs are the original stock Amals, sleeved about 20 years ago.
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Thx.
I replaced timing chain just last season. Have not gone back in to recheck tension. Is that normally needed?
 
Tornado said:
Thx.
I replaced timing chain just last season. Have not gone back in to recheck tension. Is that normally needed?
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The conservative side of me says that a new chain probably should be checked after a few hundred miles, as it will take a bit of a break-in set, and could stretch a bit initially (similar to a drive chain, primary chain, etc.) - could be worth a check.

I checked mine recently, and although it was not crazy loose, it was enough to add about 8-9 degrees of timing "slop". Note the cam turns at half engine speed, so 1 degree on the cam is 2 degrees on the crank.
 
I guess the difficult part to explain is that the dips in rpm are not constantly bouncing from 500-1000. Its more like fine when setting idle at stand still, then fine for next number of minutes riding around. Thne at next throttle roll off with clutch in or at a stop light, I'll see 800-500...where it stays until after a few repeated blips. If it were a loose chain giving play in timing, then I'd think it should change with each change in crank speed....a constantly wavering idle rpm.
 
If you are still running the stock mechanical automatic advance unit, that can be a problem for idle when it occasionally sticks in the advanced position, for instance when you roll up to a stop light.
 
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