My MK3 does not rev beyond 4500rpm

johnm said:
I always forget to ask that. After 50 years of pulling Amal Concentrics to pieces you tend to assume everyone knows how the choke works.

Cable tight. Choke off. Opposite to many bikes and cars.
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Yes, they are counterintuitive where the handle needs or be perpendicular or more to the bars, not inline. Also, the screw needs to be tight or the handle relaxes and the choke slides fall. Every other manuel choke you have to pull to close, push to open.
Amals are the opposite.
 
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Yesterday I made the following tests:
I interchanged the Spark plugs caps (they are both NGK LD05F-R RED SPARK PLUG CAP resistor type and they both read 4.8 KOhms)
I interchanged the Spark plugs (they are both Champion N7YC)
I replaced the faulty cylinder spark plug cap with another similar NGK.
I replaced both spark plugs with new Iridium.

On every test I fired up the engine and read both cylinders with the strobe light with the same frustrating result: the Right cylinder strobe light lights up erratically and does not light at all beyond 2000rpm.

According to Boyer troubleshooting you are right the only possible origin must be the coils because both the Control Box and the captor rotors do produce spark correctly on the Left cylinder.
The only option I have is to order new coils and hope for the best!
 
javifoto70 said:
On every test I fired up the engine and read both cylinders with the strobe light with the same frustrating result: the Right cylinder strobe light lights up erratically and does not light at all beyond 2000rpm.
Click to expand...

As it's a dual coil have you tried swapping the HT leads over to the other cylinders (not remove them from the coil as theyr'e fixed) but just swap them onto the other plugs (assuming they will reach, if not turn the coil around) to see if the fault transfers to the other cylinder or not.
 
Oh yes I also swapped the HT Leads, what I did was just swap the HT leads+ spark plug cap from left to right and the only result was that the faulty spark was the Right cylinder instead of the Left one. This means to me that the problem must be on the Left coil and cable.
 
The coil is definitely suspect but you should not be using resistor plugs with resistor plug caps. You only need one resistor in either the plug or the cap, as NGK Iridium plugs are now 100% resistor type then you need to get non resistor caps.
 
The plugs on the bike are Champion N7YC (as far as I know they are non resistor) and the caps are NGKLD05F-R RED SPARK PLUG CAP (Resistor Type). Then the configuration should be ok.
 
I replaced both spark plugs with new Iridium.

If you have gone back to the N7YC then yes they are non resistor, but if you try the Iridium again then you need non resistor plug caps/
 
javifoto70 said:
Yesterday I made the following tests:
I interchanged the Spark plugs caps (they are both NGK LD05F-R RED SPARK PLUG CAP resistor type and they both read 4.8 KOhms)
I interchanged the Spark plugs (they are both Champion N7YC)
I replaced the faulty cylinder spark plug cap with another similar NGK.
I replaced both spark plugs with new Iridium.

On every test I fired up the engine and read both cylinders with the strobe light with the same frustrating result: the Right cylinder strobe light lights up erratically and does not light at all beyond 2000rpm.

According to Boyer troubleshooting you are right the only possible origin must be the coils because both the Control Box and the captor rotors do produce spark correctly on the Left cylinder.
The only option I have is to order new coils and hope for the best!
Click to expand...
I have a Pazon system with a Pazon dual output coil
When setting up the timing with my Snap on strobe, i also experienced intermittent flashing of the strobe, this is irrespective when using either HT lead.
As the coil was new i suspected the strobe which was 8 years old, but after checking it on several bikes & cars it performed correctly.
A friend has a Tiger 100 also fitted with a Pazon system & coil, and when checking this the strobe also flashes intermittently.
I contacted Snap on over the issue who advised me there was nothing wrong with the strobe & that it was never designed for use on a wasted spark ignition system
 
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javifoto70 said:
Yesterday I made the following tests:
I interchanged the Spark plugs caps (they are both NGK LD05F-R RED SPARK PLUG CAP resistor type and they both read 4.8 KOhms)
I interchanged the Spark plugs (they are both Champion N7YC)
I replaced the faulty cylinder spark plug cap with another similar NGK.
I replaced both spark plugs with new Iridium.

On every test I fired up the engine and read both cylinders with the strobe light with the same frustrating result: the Right cylinder strobe light lights up erratically and does not light at all beyond 2000rpm.

According to Boyer troubleshooting you are right the only possible origin must be the coils because both the Control Box and the captor rotors do produce spark correctly on the Left cylinder.
The only option I have is to order new coils and hope for the best!
Click to expand...
Has your new ngk cap got a resistor, you can unscrew the brass bit and fit a short piece of brass 4mm x 17mm .cheers
 
htown16 said:
How are you powering the strobe light? You need to use an independent battery, not the bike battery. I have used jumpers off my car battery.
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Never thought of this...i have alwsys used the machine being tested battery. I Will certainly try it next time.
 
Tornado said:
At the very bottom of this thread, the "Similar Threads" list shows one entry from 2010...a 750 Commando that does not rev above 4000 rpm....found to be a carb needle had come un-clipped.
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I had something similar last year - the spray tube on one carb had become loose and had dropped down onto the jet holder!
It's amazing how you can look at a part and not notice something as blindingly apparent as this :-)
 
johnm said:
When all else fails follow the instructions of the ignition manufacturer.

I have a Pazon on my bike. I use the 6 volt coils sold by Andover Norton and NGK BP7ES plugs. I use a NGK resister cap and solid copper HT leads. If you buy cheap plugs off the internet they may be fakes. You tube videos and the NGK site will tell you how to spot fakes. You need to follow the ignition manufacturers instructions regarding the requirements for any resistor plugs or caps. Different systems have different requirements.

Andover Norton - IGNITION COIL (6V) PVL 45222A, 55.1153, 06.2092 1.5/8" (40mm) diameter - 99.0576 https://share.google/6l1F8shBScEoeabny
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My setup exactly! Works great. My coils, though, are the original s that came with the bike. 50 years on, still sparking fine.
 
Initially my strobe light is OK, I use it on my other classic bikes and it works. I always use a dedicated separated battery to power it.

I am in touch with the guys from Holland Norton and they assest that they had bad experiences with dual output coils (some last many miles, some go bad after a short time of use) so they stopped using and offering dual output coils. Now they only use and sell the new Lucas 6V oil filled ignition coil. I have just ordered two new coils together with two high tension spark plug lead & cap assemblies.

My carbs are Amal brand new so initially I do not suspect them... although after the bad experience with the also brand new Boyer dual coils I starting to loose my confidence on the spare parts manufacturers.
 
javifoto70 said:
Initially my strobe light is OK, I use it on my other classic bikes and it works. I always use a dedicated separated battery to power it.

I am in touch with the guys from Holland Norton and they assest that they had bad experiences with dual output coils (some last many miles, some go bad after a short time of use) so they stopped using and offering dual output coils. Now they only use and sell the new Lucas 6V oil filled ignition coil. I have just ordered two new coils together with two high tension spark plug lead & cap assemblies.

My carbs are Amal brand new so initially I do not suspect them... although after the bad experience with the also brand new Boyer dual coils I starting to loose my confidence on the spare parts manufacturers.
Click to expand...
SOME of the brand new Burlen Amal carbs have been found with manufacturing debris in them. Others have pointed out rare failures easily fixed. Might be time to pull them off and have a proper VERY CLOSE look...
 

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