One cylinder working ...

[Bert fegg]

Sorry should have said filter off and slide up throttle open, also plugs swapped out for new, leads also changed over, she fired up on both cylinders straight away but this has been whats happening on both sets leads plugs etc, then it will start on only rear cylinder firing up.

[wedge]

You are only at about 35' above sea level in London if my search was correct, so I am thinking that you should be around 200# static compression and it should pump up fast, which it did do. 145 sounds very low, however; since it is same in both I wouldn't expect to see the problem you are having.

[IXL2Relax]

Originally Posted by wedge

You are only at about 35' above sea level in London if my search was correct, so I am thinking that you should be around 200# static compression and it should pump up fast, which it did do. 145 sounds very low, however; since it is same in both I wouldn't expect to see the problem you are having.

According to our research for the SP, the 2004+ 1200 engines should have a minimum of 180psi - While the earlier 1200 models should have a minimum of 150psi.

This is why I suggested a shot of starting fluid down the throat when it is missing on the front cylinder, to see if the increased combustibility would fire off in that missing cylinder.

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[Bert fegg]

The compression tester I use is not the best so didnt want to screw in overtight otherwise might crush the orings, I shall do another comp test tomorrow .

[Bert fegg]

Just done a compression test (warm) with a decent tester, slide up throttle fully open the readings are
Rear 152
front 150

she started on the button on both cyl but after a minute decided to want to only fire on rear for about 5 sec then back to 2 cyl

leads swapped and replaced
plugs replaced
coil replaced
ign module replaced with oem used but assured was a good working one which i obtained from a seller (ebay USA) I was also unaware that these oem modules were no longer in production so purchased this thinking I was lucky to find one (lesson learnt)

valves and springs all good (assumed) from visual inspection & compression readings

to summarize bike decides to fire on both cylinders one day and only one cyl on another day.

I am hoping at the end of the day it is a wonky ign module but it is an expense I don't need if its not.

[IXL2Relax]

Originally Posted by Bert fegg

ign module replaced with oem used

Well - You replaced all the typical suspects...

You might try opening the nosecone and cleaning the Cam Position Sensor on the backside of the module. If you spray any electrical cleaner in there, be sure to blow out any excess liquid or dirt, etc, when done.

While there, double-check that the rotor cup is not loose or damaged in any way.

Put everything back where it belongs and set the static timing with the LED on the module.

I have my doubt whether this will affect the problem, but short of replacing it with a known good, new, aftermarket module, this is about all you can do with the existing module.

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