Rolling Road recommendations

[Laverda Dave]

Not SOHC related but does anyone know of or can recommend a company with a rolling road/Dyno?
Reason I am asking is because I cannot get my Triton running correctly and I guess this is the problem with building a special! I cannot get the engine to tick over with any regularity and it's running rich. I would like to go to a company with experience of tuning old British parallel twins if possible. I think the carbs and timing will need setting up as the standard settings are nowhere near optimal considering the 650 engine is now a short stroke 750. I live in Middlesex, north west London and would like somewhere reasonably close.
Any suggestions welcome

[McCabe-Thiele (Ted)]

Any Norton  owners clubs that might help sort your bike out?

[SteveD CB500K0]

PDQ Motorcycle Developments in Taplow (Maidenhead) sorted out my Triumph Sprint.

Not sure if they have old bike expertise. Best to ask.


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[Orcade-Ian]

Dave,
Are you running Monoblocs or Concentrics?  Are they worn?  I would try the guys at Dresda who took over from Dave Degens - they might have ideas about jet sizes to start from.  Also Les at Norvil might be able to advise before you throw rolling road money at it. Is it on electronic ignition or a mag or something else?  What camshafts do you have - perhaps E3134's?  A steady tick-over can be elusive with lumpy cams but you ought to be able to get the mixture pretty close.

Ian

[Bryanj]

When i morgo'd a t110 i had to drop a size on mains from the 650, running concentric carbs, also if mag check timing side to side, my slip ring was 20 deg different L to R, only found out when i timed it on the oposite side by mistake, 6 hourscwith a small whetstone sorted it

[ComfySofa]

Not that near you but can recommnend CjS racing (your side of Bristol) - take all of my bikes there.!

[Rozabikes Tim]

I used TTS but fair way for you in Towcester...

[Laverda Dave]

Dave,
Are you running Monoblocs or Concentrics?  Are they worn?  I would try the guys at Dresda who took over from Dave Degens - they might have ideas about jet sizes to start from.  Also Les at Norvil might be able to advise before you throw rolling road money at it. Is it on electronic ignition or a mag or something else?  What camshafts do you have - perhaps E3134's?  A steady tick-over can be elusive with lumpy cams but you ought to be able to get the mixture pretty close.

Ian

Thank you all for the recommendations. I will give them a call in the next few days. Most of them appear to require the bike having an ECU which of course the Triton pre-dates but I'll see who may be best, nice to see the one in Northampton has 40 years of experience though. Alan has also given me a good tip.

Ian, the carbs are concentrics marked as R300/930, so I guess they are 30mm choke size. I built the bike originally at Dave Degans workshop in 2000. Dave told me the size of carbs to purchase as he built the engine and undertook all the mods so knew the carbs to fit and jet sizes. He lightened rockers, valves, short stroke 750 conversion using Morgo barrels (with the top fin cut off to suit the short stroke), modified hepolite pistons, building up the combustion chambers to make them 'egg' shaped, fitting 3134 cams for inlet and exhaust and converting the single carb head to twin carb but not splaying the head but making it parallel intakes. He set the jetting up on his basic rolling road. Ignition is a Lucas Rita and it's working 100%. TBH the bike never ran properly from day one, it ran very rich, very hot, used oil and leaked it over the garage floor! It was totally unreliable to the point where I took two sets of keys into the garage when I went out, one set for the Triton and one for the VFR to use when the Triton wouldn't start or played up. I lost all interest in it after it nipped up and this was taking it easy whilst running it in .
It sat unused under a cover for 18 years, I stripped the whole thing down just as we went into lockdown to rebuild it properly and started from scratch. A lot of reverse engineering went into the rebuild as Dave Degans does not like to reveal exactly what he does to his motors! I fitted new barrels (modified properly by Miles, the owner of Morgo), new pistons, rings, Morgo oil pump etc. Ferret made a complete wiring loom.
So, I'm starting from scratch in terms of settings. I have set the ignition as for a 750 Bonnie and not the 650 Saint the motor began life as, I think these are the settings Degans used but he couldn't tell me when I asked! The jets remain the same as Degans installed so these are my starting points. I could spend days chopping and changing jets and ignition timings and I don't think I will get there hence getting the bike onto a rolling road where I can see what is happening. I guess I'll have to take it there and leave it as I think it may be a long process to get it running correctly.
Dave Degans has now fully retired. Dave sold all his bikes at the recent Stafford Show, I think he must be in his 80’s now?

[Bryanj]

He was an awkward sod back in the 70's when the shop i worked for dealt with him and Paul Dunstall, as i remember it opposite end of block did Sunbeam bike sares,
Not sure why the short stroke and not just the 750 morgo conversion(a65+20 pistons from memory) but i would think the 50 standard ignition timing would be about right, no idea on jetting though

[K2-K6]

Could it be worth an educated guess start point Dave ?

If so, I'd err on caution with base level ignition advance (if too much it may have contributed to nipping the pistons) based on shorter stroke.

Burn time would stay the same for an equivalent combustion chamber and mix, but the piston linear approach would be slower at any given rpm. The combustion time constant vs shift in timing angle measured in degrees doesnt show the full picture.

Effectively I'd see it as a shorter stroke needs less advance (in degrees) to match the combustion time of mixture burnt to prevent the whole event going off too far before tdc and trying to go backwards against forward inertia of crank etc.
The start point would be sensible at the lowest degrees specification to allow safer margin.
Jetting, some hold the view that excess fuel should be used to "cool" the combustion and compensate for other compromise in design spec, unless quantified its hard to support this.
Worthwhile taking 10% off (from existing Degens spec) main jet size, running conservstive advance (perhaps- 2 from lowest listed conventional spec)  and run on equivalent of NGK 7 heat range plugs to see what it'll give you.

Note:- you'd not use a 7 grade plug on a dyno as it's likely to overheat the ti0 and give you problems.

Getting hot under light load suggests static advance is too high as there's not much other input to it without wide open big load running conditions.  Promotes erratic tickover too.

Also, if the main jets are much above a decent range for that carb it starts to loose the fine metering effect in comparison to the needle taper, making it difficult to resolve apparent errors.

[K2-K6]

My spell check changed "Degens" to "DeGeneres" and now edited in previous post 

Hollywood obsessive spell checking overlord......what's the world coming to ?

[Laverda Dave]

Could it be worth an educated guess start point Dave ?

If so, I'd err on caution with base level ignition advance (if too much it may have contributed to nipping the pistons) based on shorter stroke.

Burn time would stay the same for an equivalent combustion chamber and mix, but the piston linear approach would be slower at any given rpm. The combustion time constant vs shift in timing angle measured in degrees doesnt show the full picture.

Effectively I'd see it as a shorter stroke needs less advance (in degrees) to match the combustion time of mixture burnt to prevent the whole event going off too far before tdc and trying to go backwards against forward inertia of crank etc.
The start point would be sensible at the lowest degrees specification to allow safer margin.
Jetting, some hold the view that excess fuel should be used to "cool" the combustion and compensate for other compromise in design spec, unless quantified its hard to support this.
Worthwhile taking 10% off (from existing Degens spec) main jet size, running conservstive advance (perhaps- 2 from lowest listed conventional spec)  and run on equivalent of NGK 7 heat range plugs to see what it'll give you.

Note:- you'd not use a 7 grade plug on a dyno as it's likely to overheat the ti0 and give you problems.

Getting hot under light load suggests static advance is too high as there's not much other input to it without wide open big load running conditions.  Promotes erratic tickover too.

Also, if the main jets are much above a decent range for that carb it starts to loose the fine metering effect in comparison to the needle taper, making it difficult to resolve apparent errors.

Thank for the advice Nigel. Your suggestions do sound like a good starting point. I am at Kempton Park on Saturday collecting some TEC shocks for a 400/4 so I will visit the Amal guy and get some additional jets. I'll knock back the timing to put it between the 650 & 750 setting as a base point. I'll get some plugs as well. I have no idea what CR is but I think it is high considering the hepolite pistons had to be machined to clear the squish band in the combustion chamber as built up by Degens. It really does take some kicking over however, if I take it over compression and turn the ignition off I get a very loud blowback through the carbs and I certainly wouldn't like to suffer a kickback on it, I'd have a broken ankle !
Do you do house calls

[K2-K6]

I'd be fine with coming to look at it with you, a couple of heads together to consider a few things further. Let me know if you want to arrange something Dave.

He was an alternative thinker, Mr Degens, with some interesting angles on things that others may have dismissed.

Short stroke, bigger bore, high squish combustion geometry could be described as not that far from the current F1 engines in terms of what they are doing.
I know they are light years apart, but of very close axis in my view.
The current F1 is around 18:1 compression with single point injection to a chamber enclosure around the spark plug, this on first ignition sends out a flame shockwave to periphery of bore which serms to the burn back towards the centre, a little like squish but more advanced in concept. That's loosely speaking.
It's all fascinating stuff to see how others have set about solving some issues.

[Sesman]

It may be worth measuring the CR as anything above say 9:1 on these old motors with modern fuels can be a real problem. I may have missed what jet sizes you are currently using, but I’ve been recommended 190s and I’m running twin premier 30’s on a splayed head. Might also be worth checking the valve timing; if DD believed you were performance oriented, he may have got radical?

[Sesman]

Incidentally, are you sure both carbs are marked ‘R’? It’s just that they come as handed pairs ‘R’ and ‘L’? You’ll have a devil of a job accessing the idle screw adjustment on a parallel head arrangement. Also make sure the idle jet airways are scrupulously clean. Concentrics are very prone to clogging in this airway and Amal modified the 930 ‘modern’ concentrics to aid cleaning. Good luck and let’s us know how you get on.