Unpleasant in traffic.

Twosheds

Twosheds

Junior member
Location
Surrey. England
Hello people. Someone here will know the answer to this. My 76 Jota starts fine, accelerates well right up to and beyond the red line, even ticks over but on a neutral throttle, neither accelerating nor slowing, it's horrible. It only seems to want to accelerate. The more beans I give it the better it is. On a race track you'd say it was great but trying to ride at a steady speed, say 30 or 40mph in traffic is really lumpy and unpleasant. Is there a fix for this or is that just what they're like?
 
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Are you running on original Bosch ignition and are the coils and leads new ish or original
If so I would upgrade to one of several replacement ignition systems and put on new coils and leads at the same time.
Given you say it ticks over fine and revs up cleanly above 2000 rpm 30 mph in top carbs are probably okay.
Bob
 
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Replacing the ignition was the best thing I did to mine. The original has one advance setting (full) and switches in and out at about 3-4000, roughly the speed you’re talking about. The main brands seem to be Ignitec, Witt and Sachse. I don’t know which is best, I’ve only used Sachse so far and I don’t want to start another “oil thread” 😉
 
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FWIW, my RGS displayed similar performance issues until I discovered the previous owner had replaced the stock slides with ones that drew a richer mixture. Can't remember the slide numbers right now, but returning to stock transformed performance. Near as I can tell, the previous owner thought that big jets and fat slides would make it go faster. It just made it run shittier.
 
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The single step from 5dbtdc to 32dbtdc, at what rpm, is governed by the TEAG ( Total Effective Air Gap ) for the oem Bosch variable reluctor pup's, to impulse cam lobe. You will have the 65 pilot jet to overcoming pinking in hot weather, maybe. You will have 12kms per litre horrible fuel consumption with BTZ.

Reducing the TEAG, has the 32degree step sooner, mostly at 1800 to 2200 for the correct type BTZ module. Balance the carbs at cruise rpm, not at idle ( useless, you do not ride around on idle ), balanced all customers and mine at 3300 for lowest vibs... unwanted vibs that is.... the 4c on the cam is another vib all together, a smile here. HTH j.
 
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too much techy going on here especially from the highly respected (by me) John Wilson.

it does sound like the stock igition is your problem, I spent many years commuting from suburbs to central Londin with BTZ equiped 1200.

the BTZ ignition has no advance curve, it has an RPM sensitive switch from TDC to 32 degress BTDC at around 1800 to 2300 RPM depeneding on the air gap at the triggers, so you get "lurching" as you cross the RPM for your individaul bike when the switch from TDC firing to 32 BTDC fring happens, I have lived with this system for 43 years and still do. My trigger gaps give me a switching speed of 1800 RPM, never a problem on rising revs, and in traffic on decending revs, I just pull the clutch in, and use the brakes.

Any afternarket ignition will have a progressive advance, that is to say at the switching speed, advance increases just a tad as the engine gets faster it increases more, until at a certain RPM full advance is achieved, the gentle curve removes the "lurching" that you wuld seem to be putting up with. Which is made much worse if the trigger gaps are not identical, one trigger controls the outer two plugs, the other the inner one, so synchronisation is important. (for 180's) and all three for all three (on 120's).

There are a few choices, but I would go with Red's (Redax Australia) ignition, which is availabale from Keith Nairn at Laverda Scozia Glasgow. or direct from Red. I dont know if it is true currently, but a while ago Keith was making some of the turned parts for the conversion which also gives a significant charging boost for your battery.
CLEM
 
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Indeed Clem, of the posting here, run the gamut of simple to complex, as actors we have our part to play, doffs me retired Arai to the more than famous Upstart Crow, of a world in plays moment, we play our part.. a smile, well... more of a wide grin...

The 180 series tolerated the BTZ "better" in some regard over the much burdened by BTZ, 120 series. A Corsa of well known Laverda man out here was available to me over protracted periods. Going up a moderately steep mountain and tight curves, being a CR head, torque was very good, the BTZ would cause severe anxiety with the top heavy 120 type bikes, jerking just as you laid into the tight bend, nearly dropped the immaculate Corsa.. no skill in recovery, i was just plain fortunate and quick clutch pull in, rev it and reengage the clutch quickly...as you do/had done i note, Clem

As a side comment, the HKZ burdened with same one step, was rider friendly, for the most part, awaiting the arrival of first on the block Uwe Witt DMC, though Silent Hektik were around similar time, as the more knowledgeable may clarify... The Phil Todd custom Boyer was also early in the history ( been covered previous the real Todd/Boyer against the fakes that appeared ). Regards to all, j
 
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iis_iis said:
Indeed Clem, of the posting here, run the gamut of simple to complex, as actors we have our part to play, doffs me retired Arai to the more than famous Upstart Crow, of a world in plays moment, we play our part.. a smile, well... more of a wide grin...

The Phil Todd custom Boyer was also early in the history ( been covered previous the real Todd/Boyer against the fakes that appeared ). Regards to all, j
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Nice nod to the Bard, Jon.
I have one of Phil's Boyer systems in mine and found it a big improvement on the OEM. It ticks over slow and steady at an indicated 500 RPM. I do a lot of riding in Town (London) and have no problems.
To be fair, I commuted into W1, on a daily basis for years, on the OEM CDI system and didn't have any issues, apart from the erratic tickover. The original ignition became rain/bike wash sensitive and that forced the change.
 
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Andy said:
Replacing the ignition was the best thing I did to mine. The original has one advance setting (full) and switches in and out at about 3-4000, roughly the speed you’re talking about. The main brands seem to be Ignitec, Witt and Sachse. I don’t know which is best, I’ve only used Sachse so far and I don’t want to start another “oil thread” 😉
Click to expand...

I don’t think it’ll be the oil.
 
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Andy said:
Replacing the ignition was the best thing I did to mine. The original has one advance setting (full) and switches in and out at about 3-4000, roughly the speed you’re talking about. The main brands seem to be Ignitec, Witt and Sachse. I don’t know which is best, I’ve only used Sachse so far and I don’t want to start another “oil thread” 😉
Click to expand...
Sachse do not make a system for the Series 1 triples anymore after Volker died as I was supplying him with the systems
Choice now for Series 1 triples is DMC Witt or my Redax system with the upgraded 250 watt 3 phase charging system
 
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very difficult choice as Uwe witt is still a relatively young and fit bloke (and a blindingly nice geezer) plus, his after sales service, even for 30 year old systems is second to no one, if only because Red hasnt been making his systems foir 30 years, but after sales service is still very good and might get the long service award in the end, personally I would go for the Redax system, better charging rate by a country mile, very modern and variable advance curves with many more options than the Witt, akthough the Witt is simply swutchable the redax requires some techy skills to set.
CLEM
 
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