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SSD will not run past about 4000 rpm
Posted: Fri Jan 19, 2018 1:38 am
by OZHoppo
Gurus,
I have an SSD with 40mm carbies.
Engine idles beautifully and blips very crisply but when taking it for a ride it accelerates normally from standstil up to about 60kmh but when throttling up to speed in a 100kmh zone the bike will not pull. It struggles to get to 4000rpm and then stops accelerating. There is a vibration that feels like the cylinders are out of whack or it is not advancing.
Float heights checked, carbies cleaned a dozen times, balanced using the BH method, no apparant air leaks using carby cleaner spray, pumpers delivering 5ml after 20 pumps.
Am i looking at the wrong things; could it be electrical - something like pickup gap, faulty ignition module or coil, etc.
Steve (Australia)
Re: SSD will not run past about 4000 rpm
Posted: Sun Jan 21, 2018 6:35 am
by Gardner
Have you replaced the wires that run from the pickups inside the left engine cover and up to the
Bosch ignition boxes under the fuel tank?
Re: SSD will not run past about 4000 rpm
Posted: Sun Jan 21, 2018 1:20 pm
by wdietz186
The pickup wires are probably deteriorated and shorting due the insulation falling apart. Harmonic vibration can cause intermittent shorting/misfire. But! I have had 3 bad Bosch ignition boxes fail in the past few years and the symptoms were what you describe. Ok running until the ignition goes to full advance and 1 of the boxes dies or doesn't advance fully,around 4k rpm. It can be checked if you have/or have access to the stroboscopic timing tool,you will see the difference when the revs approach 4k
Re: SSD will not run past about 4000 rpm
Posted: Sun Jan 21, 2018 5:59 pm
by OZHoppo
The pickup wires have been replaced and I swapped out the ignition boxes while I was under the tank
Taking the tank off (again) to check connections I discovered that I had crossed connected the ballast resistors so they were out of circuit. A quck change of connections and away she went. Will now pull evenly and up beyond 5000pm.... still running it in, so I did not take it above that.
Now just have to sort out the popping when it gets to around 4000rpm and on the overrun and I should be all good to go. I suspect that is just a case of sealing the cross-over pipe.
Thanks for the input.
Re: SSD will not run past about 4000 rpm
Posted: Tue Jan 23, 2018 1:33 am
by Craig in France
OZHoppo wrote: ↑Sun Jan 21, 2018 5:59 pm
<snip> I discovered that I had crossed connected the ballast resistors so they were out of circuit. A quick change of connections and away she went.
Thanks for reporting back. That's one I haven't heard of before ...
Re: SSD will not run past about 4000 rpm
Posted: Wed Jan 24, 2018 2:37 am
by OZHoppo
Having a really good look around under the tank at the wiring showed up a number of issues including partially broken wires to the coils at the connections and a bunch of other issues.
I am chasing my tail with this and decided to go down a different path. I have ordered an Ignitech unit to go with new GT40 coils and high quality plug leads and resistor caps.
That way I can dispense with the Bosch coils and ignition units.
I will keep you posted on how the Ignitech unit performs.
Re: SSD will not run past about 4000 rpm
Posted: Mon Jan 29, 2018 3:15 am
by OZHoppo
Ignitech installed with Bosch GT40T coils.
After a bit of hassles with wiring connections the bike is running superbly. Idles at 1000rpm like a champ and pulls cleanly to 5000rpm (running in new engine).
The unit is plug and play and has resolved all the issues I was experiencing.