Not reaching top speed

[TwoManyXS1Bs]

Might have a fault in one of the sensor/triggers. Or, their wiring.

You can get engine acceleration without spark advance, but you'll get more if it's working...

 

[5twins]

I agree with 2M, the pick-up on your alternator is faulty (or it's wiring). There are two wires running to the pick-up. They are pinned to the alternator with a metal clip. Sometimes that clip cuts into the wires.

 

[Bjorn]

I measure 730 ohms on both wires of the pick up:

Orange-black 730 ohm
Grey-black 726 ohm

 

[Bjorn]

Would unplugging the reg/rec do anything?

 

[funky]

Take the baffles out reduce the rear sporcket 2 to 3 teeth red line before changing gear check plugs for right fueling make sure valve and tesioner and timing is right .. and get the advancer doing its job then report back from looking at the vid
This Question "Not getting top speed " is a tricky idea it depends on many factors firstly lets asume your engine is perfect.
so what would be the speed of a perfect engine say 90 to 120mph OK!
next question where are you testing the so called top speed at sea level or up a mountain is the road level or up hill ,,, these bikes are carborated machines...so fuel is a factor too
Power to Weight is the next issue then tyres ...what about throttle response then gearing or even styling which will effect airflow over the bike what they call AIRO in the race world.
Man has tried to squeeze as much power from and engine as possible to go as fast as they can with that perticular engine.
so the real question is" How fast can i get this engine to go". and to do that everything has to be spot on
Good Luck i have lived and am living in that world it is an expensive endevour
All the best Funky

 

[Bjorn]

Take the baffles out reduce the rear sporcket 2 to 3 teeth red line before changing gear check plugs for right fueling make sure valve and tesioner and timing is right .. and get the advancer doing its job then report back from looking at the vid
This Question "Not getting top speed " is a tricky idea it depends on many factors firstly lets asume your engine is perfect.
so what would be the speed of a perfect engine say 90 to 120mph OK!
next question where are you testing the so called top speed at sea level or up a mountain is the road level or up hill ,,, these bikes are carborated machines...so fuel is a factor too
Power to Weight is the next issue then tyres ...what about throttle response then gearing or even styling which will effect airflow over the bike what they call AIRO in the race world.
Man has tried to squeeze as much power from and engine as possible to go as fast as they can with that perticular engine.
so the real question is" How fast can i get this engine to go". and to do that everything has to be spot on
Good Luck i have lived and am living in that world it is an expensive endevour
All the best Funky

Hi funky, thanks for reading along. I appreciate your recommendations. However Most of them have already been checked in the first 3 pages...

 

[funky]

have you sorted the advance yet is it advancing

 

[Bjorn]

It is not advancing. I plan on getting this sorted first.

What about this theory:

The pick up coil has 2 coils. What if I got the grey and orange wire of the pickup turned around towards the TCI box, due to a wiring error... Would that result in the engine running (which it does) but not advancing since the signals are inverted?

 

[funky]

Bjorn ... Electrics is not my thing you will sort it as when i have electricla issues i speak to Pamcoe pete 5twins and others on this forum and do what they tell me and they are very often on the money.
I changed my 1981special to pamcoe electric ignintion and E advance and all works well. I have fitted reverse cones and mega long exhaust over the years and also fitted a 750 big bore kit.
what i can tell you without a shadow of a doubt is that when you play about with the exhaust it changes the fueling on the engine.so carbs have to be adjusted or re jetted ... If i can help with anything i will just post. You have done a great job so far and with all the issues we have all had they all get sorted out after some reading and money and time
Keep hacking away at the issues
All the best Funky

 

[5twins]

I don't know, maybe. I saw you have new plugs installed where the TCI connects. I was thinking maybe some of the wires may be in the wrong spots. It's not working now so you might as well try switching the pick-up coil wire connections.

 

[funky]

Bjorn
I had a quick look about TCI's my bike did not have that system but it seems they are troublesome and that the PCB suffer from corosion so it my be beneficial try another off a bike that does work if thats possible ...
I sure these chaps will pass on sound advise

 

[Bjorn]

I have had both my TCI boxes inspected and one repaired by an college aka old timer that has been repairing electronics since 40 years. He replaced some elcos but everything was done on "experience" since we didn't have a diagram of the TCI inner workings. Since both start and run my bike I always assumed they were repaired OK.

@ funky after these repairs I fixated all tall components with hot snot and conformally coated the entire pcb to protect it against the elements.

Ill check the wiring details on my bike tomorrow.

I did just find a dutch company (Carlo) that offers a TCI check . They also sell new replacements. For 50 bucks I might just have the TCI checked to rule something out.

 

[funky]

Bjorn I feel for you man It's horrible when you cant find the problem but as you know ist a process of illimnation... wish you all the best mate Great looking bike Also

 

[TwoManyXS1Bs]

I believe that the 2 trigger signal wires go to that clump of 4 diodes at the corner of the TCI board. Do a continuity test of those 2 wires, starting at the wire inputs on the TCI board, back to the sensor connector...

 

[Bjorn]

I just did a test with the reg/rec unplugged. Didn't change anything. Timing stationary ok, no advancing with revs.

Secondly I switched the r/w wire with the g/w coming from the pick up to the TCI. I tried to start it 4 times. First 3 times she kicked like a mule. Fourth attempt she ran 3 cycles and stopped . This can't be it.

 

[Bjorn]

Please don't let the mentioned wire colours confuse you. I see I give them different names. Original was red/white and green/white.

On my bike that's
Orange (red/white)
Grey (green/white)

 

[TwoManyXS1Bs]

Just some TCI stuff for your files.

An '80 TCI board.
The trigger wires enter at the top/right, connecting to the 4 egg shaped diodes, D1-D4.


Member GBGrider's attempt at reverse engineering the TCI circuit.
The trigger inputs are at D1/D2 and D3/D4.

 

[joebgd]

Its got me curious about my ignition. I have a timing light. What's the procedure, one wire on plug wire and one on battery? I haven't looked at the timing light in years. I'm check it out later or tomorrow. I have a 30t rear and in the higher gears it revs right up no problem. If I get on it the clutch will slip but I'm okay with that being I ride for fun and transportation. It is at times my primary transportation.

 

[5twins]

If you have a 1980 then you should have the factory electronic ignition. You can check where it's set but there's really no provision provided to adjust it. It's supposed to be set correctly by the factory and you're not supposed to change it. But you can slightly if you slot the mounting holes on the pick-up and move it a little. Actually, you only need slot the top hole so you can "tilt" the pick-up left or right a little bit.

A timing light usually has a positive and negative lead with alligator clips that you clip to a battery to power the light, then another wire with a pick-up that fits on the plug wire. With the factory electronic ignition, this bike fires both plugs at the same time so it doesn't matter which plug wire you clip the light to usually. But sometimes it does. The spark signal flows out of the coil down one plug wire, across through the motor, then back up the other plug wire to the coil again. This gives one plug wire a positive polarity and the other a negative polarity. Some timing lights prefer one over the other and can give erratic readings if attached to the one they don't like. If that happens, switch it over to the other plug wire.

 

[Wulfbyte]

Also check your pick up magnet on your rotor, they can lose their magnetism and the magnetic field the rotor creates can overpower it causing similar type of problems,unfortunately a number of things can cause same type of problems,that’s why troubleshooting is so much fun! If you do find that this is the case you can j.b. Weld another one on,rare earth magnets from radio shack,new rotors supposedly have better magnets in them!