Off Idle Sputter On My Velocette

Triton Thrasher said:
5 kohm resistance would be one 5 kohm resistor cap and no other resistances in the HT, if it’s wasted spark.

It’s never impossible that they sold you a bad spark plug. One of the last pair of Champions I bought only lasted 200 miles before it started missing under load.
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Absobloodylutely… I try not to say this anymore coz otherwise I say it all the time…

The FIRST thing to do for ANY running issue is to try NEW spark plugs.
 
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Triton Thrasher said:
5 kohm resistance would be one 5 kohm resistor cap and no other resistances in the HT, if it’s wasted spark.

It’s never impossible that they sold you a bad spark plug. One of the last pair of Champions I bought only lasted 200 miles before it started missing under load.
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Wasted spark? On a single cylinder? So firing every 360 deg, not 720 i guess?
 
In my simple mind, an ignition trouble is unlikely given the symptoms described. At small throttle openings, air/fuel mixture pressure is quite low. As we(?) know, voltage needed to make a spark is lower when pressure is low.
You also say that the idle mixture screw don't change anything.
I wonder what workshop manual you refer to regarding jetting. As a MSS was never fitted with a Concentric. from factory. Possibly a Monobloc 376 or maybe a 276. Of course jetting is different for any of these.
I agree with Fast Eddies first reply that a bigger idle jet is the first thing to try. The Concentric Mk I idle jet on my Vincent is drilled a bit bigger. The Venom is happy with a Mikuni.
 
Mike40M said:
In my simple mind, an ignition trouble is unlikely given the symptoms described. At small throttle openings, air/fuel mixture pressure is quite low. As we(?) know, voltage needed to make a spark is lower when pressure is low.
You also say that the idle mixture screw don't change anything.
I wonder what workshop manual you refer to regarding jetting. As a MSS was never fitted with a Concentric. from factory. Possibly a Monobloc 376 or maybe a 276. Of course jetting is different for any of these.
I agree with Fast Eddies first reply that a bigger idle jet is the first thing to try. The Concentric Mk I idle jet on my Vincent is drilled a bit bigger. The Venom is happy with a Mikuni.
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Books i have studied such as the Haynes manual written by Jeff Clew, a Veloce factory man, states late model MSS were fitted wih the 930 concentric. My bike has a 928 Premier.....maybe that is something else to consider, i do have a spare 930 pair from my commando.

But as of yesterday, first longer riding at higher speeds/rpms, I learned issue is more than just off idle rpm....getting misfires at higher throttle opening and rpms.
While i said air control screw did not impact tfe sputtering, it did have effect on idling, engine getting rougher as it is trurned in , richer and increased rpm if it was leaner/turned out. I also tried closing the choke down when sputtering along, no improvment on sputters, but engine got very rough, nearly stalling out. That would indicate sputters are not from overly lean condition i would think.
 
A -54 MSS did not have a Concentric as the Concentric came in -67. The Monobloc came in -54. Forgot that the MSS soldiered on.
As you now know that sputtering occurs at higher throttle openings, idle circuit can be tuned for max rev and then adjust throttle stop to a decent idle rpm.
Did you try a new spark plug?
In my experience of Premiers, they never come with correct fuel level. Could be your problem. Worth a try.
 
Update on this issue....hauled to bike out some 100 km's to a regional Velo guru, ex-racer/designer/seller of a complete e-starter kit for Velo/Owner of 4 excellent velo machines. He fired up my bike and took it for a quick spin. Report back was it is positively an ignition system related misfire, present across most of rev range. Might just be the external "coli" or CDI unit or might be the blackbox or the self-generating components within the BTH mag casing.
Unfortunately trying to get it serviced back in UK is going to be an expensive endeavour. Have heard from other velo owners on the forums that similar experiences as mine were never adequately addressed by the retailer even after much shipping to/from UK cost to owner.

I could just order a new external coil unit to try and hope it is the issue. Unsure what tests if any I can perform on existing one to help determine if faulty. I am thinking to just swap in a regular 6-volt coil from my Commando spares, powering it by the BTH primary leads just to see what happens....bad idea?

Researching other options, original Lucas K1F type mag's do come up on Ebay and the like...in the 200 GBP range but unless fully tested would need to sent to rebuilder for further costs/shipping charges.
The Velo parts supplier Groves Classics, does list a mag EI kit of their own design for 200 GBP, as well as being a reseller of the BTH EI Mag unit for nearly 600 GBP.
I also came across a TriSpark offering for Velocette, complete EI conversion, for around $650 AUD. It appears to use the exact same EI stator we use in our Commandos. Interestingly, I have a compete TriSpark unit for my Commando I have not installed. Wondering if they would sell me just the housing parts to save me some serious $$$? Will see what they say....
 
Tornado said:
Update on this issue....hauled to bike out some 100 km's to a regional Velo guru, ex-racer/designer/seller of a complete e-starter kit for Velo/Owner of 4 excellent velo machines. He fired up my bike and took it for a quick spin. Report back was it is positively an ignition system related misfire, present across most of rev range. Might just be the external "coli" or CDI unit or might be the blackbox or the self-generating components within the BTH mag casing.
Unfortunately trying to get it serviced back in UK is going to be an expensive endeavour. Have heard from other velo owners on the forums that similar experiences as mine were never adequately addressed by the retailer even after much shipping to/from UK cost to owner.

I could just order a new external coil unit to try and hope it is the issue. Unsure what tests if any I can perform on existing one to help determine if faulty. I am thinking to just swap in a regular 6-volt coil from my Commando spares, powering it by the BTH primary leads just to see what happens....bad idea?

Researching other options, original Lucas K1F type mag's do come up on Ebay and the like...in the 200 GBP range but unless fully tested would need to sent to rebuilder for further costs/shipping charges.
The Velo parts supplier Groves Classics, does list a mag EI kit of their own design for 200 GBP, as well as being a reseller of the BTH EI Mag unit for nearly 600 GBP.
I also came across a TriSpark offering for Velocette, complete EI conversion, for around $650 AUD. It appears to use the exact same EI stator we use in our Commandos. Interestingly, I have a compete TriSpark unit for my Commando I have not installed. Wondering if they would sell me just the housing parts to save me some serious $$$? Will see what they say....
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Probably no use to you at all
But I saw this on eBay
I guess these are ok if you have a reliable 12 v supply?
 
Tornado said:
Yes, I have seen that one as well. I do have 12v conversion, negative earth on the bike. But this unit is of unknown function and so would be a gamble, likely needing restoration for more $$$.
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I've seen these electronic mag conversions before on a k2f using a Boyer ignition
 
On a single I’d suggest that a good magneto should be probably the best ignition option ?

Have you thought about contacting Joe Hunt to see if they have an offering ?
 
Fast Eddie said:
On a single I’d suggest that a good magneto should be probably the best ignition option ?

Have you thought about contacting Joe Hunt to see if they have an offering ?
Click to expand...
Velocette mags not listed on their site. The Velo's use a flange mounted mag, three bolt holes. Lucas K1FR or equivalent BTH version fitted OEM. Seen a couple on Ebay but of unknown function at around 200-300 GBP in UK. So looking at easily double that if rebuild needed plus shipping.
 
Tornado said:
I am thinking to just swap in a regular 6-volt coil from my Commando spares, powering it by the BTH primary leads just to see what happens....bad idea?
Click to expand...
I think the BT-h electronic magneto is CDI type, which means you need a CDI coil, which has lower impedance than a “regular” coil.

A new coil is worth a try though.
 
Fast Eddie said:
On a single I’d suggest that a good magneto should be probably the best ignition option ?

Have you thought about contacting Joe Hunt to see if they have an offering ?
Click to expand...
I agree
The best thing I did with my A10 was buying a rebuilt mag and recon aar unit
 
Tornado said:
Update on this issue....hauled to bike out some 100 km's to a regional Velo guru, ex-racer/designer/seller of a complete e-starter kit for Velo/Owner of 4 excellent velo machines. He fired up my bike and took it for a quick spin. Report back was it is positively an ignition system related misfire, present across most of rev range. Might just be the external "coli" or CDI unit or might be the blackbox or the self-generating components within the BTH mag casing.
Unfortunately trying to get it serviced back in UK is going to be an expensive endeavour. Have heard from other velo owners on the forums that similar experiences as mine were never adequately addressed by the retailer even after much shipping to/from UK cost to owner.

I could just order a new external coil unit to try and hope it is the issue. Unsure what tests if any I can perform on existing one to help determine if faulty. I am thinking to just swap in a regular 6-volt coil from my Commando spares, powering it by the BTH primary leads just to see what happens....bad idea?

Researching other options, original Lucas K1F type mag's do come up on Ebay and the like...in the 200 GBP range but unless fully tested would need to sent to rebuilder for further costs/shipping charges.
The Velo parts supplier Groves Classics, does list a mag EI kit of their own design for 200 GBP, as well as being a reseller of the BTH EI Mag unit for nearly 600 GBP.
I also came across a TriSpark offering for Velocette, complete EI conversion, for around $650 AUD. It appears to use the exact same EI stator we use in our Commandos. Interestingly, I have a compete TriSpark unit for my Commando I have not installed. Wondering if they would sell me just the housing parts to save me some serious $$$? Will see what they say....
Click to expand...
I would give them a try for housing only.
 
Found a place in Austria supplying fully rebuilt mags, having the Lucas K1FR for velo singles in stock for 430 GBP, 5 yr warranty. Does not include manual or auto advance unit. So add another 50 or 200 GBP for one of those. Plus shipping/taxes, I'd be looking at more than $1k CAD.

The TriSpark unit comes with the newer stator which works for either CW or CCW bikes. My Commando TriSpark stator is the older type, with CCW indicated on the plate. Unfortunately the Velo setup is CW. Mr. Marsh has offered me a CW type trispark plate from his older stock at a very reasonable rate. Waiting to hear back from TriSpark as to what the charge would be for their kit minus the stator/rotor unit....
 
I suggest there is a need to eliminate any doubt about the ignition system. A rotating magnet magneto was used on Manx Nortons, and I have used Lucas SR magnetos. They might be the most reliable system. Sometimes it is almost impossible to distinguish between an ignition problem and a mixture problem. If you fix the ignition, jetting the carb is easy and systematic. If adjusting the mixture alone was going to fix the problem, you should have had it fixed by now.
 
acotrel said:
I suggest there is a need to eliminate any doubt about the ignition system. A rotating magnet magneto was used on Manx Nortons, and I have used Lucas SR magnetos. They might be the most reliable system. Sometimes it is almost impossible to distinguish between an ignition problem and a mixture problem. If you fix the ignition, jetting the carb is easy and systematic. If adjusting the mixture alone was going to fix the problem, you should have had it fixed by now.
Click to expand...
Yes, I feel carb concerns fully exhausted.
Trispark for velocette singles on order.
 

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