hi there chaps,

I had a problem tonight. Just replaced my engine (same type, but this one has lots of go-faster bits, big valves, slightly bigger bore, etc.) and went for the first start-up. Just to clarify, I am running MS1 with the hi-res extra code (10G I think it is called). Also I am running wasted spark with dyna coils and a 12-1 trigger wheel. I have decent maps from the previous engine, but this engine has different valves, cams, compression and cylinder volume.

After the usual problems (fuel injectors multiplug disconnected, flat battery) it fired up and ran. Eventually with a bit of throttle it got going. There was a bit of vibration, but I kept it going in the hope that things would settle down, and up the rev range it ran quite smoothly. More thottle than I expected, and not the normal lightening response to throttle.

RPM's were high (3k) it was stable. So, I slowly reduced the throttle, but at low RPM it was a bit nasty sounding with loads of vibration.

I stopped the engine (it had got to maybe 70deg C), and had an investigate. I took out a couple of plugs and it was clear that 1 and 4 were sooty, but 2 and 3 were wet. So, 2 and 3 (it is wasted spark) were not functioning. Also at this point I got a complaint from my dear lady wife concerning the fuel in the kitchen.


Upon diagnosis everything was fine at the engine end, but the LED on the front of the MS (spark B) was not doing anything interesting (remaining black). I opened up the MS and the chip was a bit loose. So I put it back in and tried to start again. The LED was playing ball again, so I tried to start, but then the LED wasn't flashing. Some nasty intermittent nonsense (was my guess).

The trigger logger was good at the beginning (nice and even), so I assume this is still good (but this is a possible problem and one that I should have another check of).


Is it right to assume that the poor seating of the MS chip has somehow upset it? ANyway I guessed that might be the problem, so, I reflashed the chip (eventually, as I had to find the old laptop, as my nice new one only has a USB-serial cable that doesn't work so well for flashing), and reinstalled the right tune.

It is too late now to try starting the engine again, but I wondered what you guys thought. I think I will check to see if the low tension side of the circuit is functioning, it may be the coil driver was damaged by all this (I have a spare so it isn't a big deal). Probably with check the tooth logging again (maybe with plugs out).

I am struggling to start this engine. With higher compression should I be reducing the amount of advance at cranking?

Any thoughts appreciated.


Thanks,

Matt

Reduce cranking advance to 2deg BTDC which will really help the cranking.

Sounds like a bad connection somewhere on the ignition driver circuit either inside or out if its intermittently working.

If the chips been corrupted by coming loose then a reflash usually fixes it and you may find the problem fixed when you try again later today.

I am in the process of having my MS2 tested and checked out if you fancy an upgrade?

David,

Thanks for your words of wisdom very reassuring in these troubled times (especially after a late night of annoying the neighbours).

Good tip on the cranking advance. It was at 10deg so that can't have helped.

I'll have a think about MS2. Do you know if it is better at sensing the trigger wheel than MS1 with LM1815 circuit? I have crank speed fluctuations that I worry about (bike engine so low moment of inertia, and feeble battery).

Thanks,

Matt

Output transistor blown.

I can't blame MS though. The piston walloped the sparkplug such that it was completely closed. Not so clever. I think I need some spacer washers under the plugs.

I guess I will be seeking out BP Ultimate 102 once I get this thing running as the compression is a bit out of control!

Matt

Ahh glad you found it

The big advantage of MS2 over MS1 is 16x16 fuelling/ignition and a lot more processing power for things like enhanced accel enrichment etc.

A couple of 10mm i.d. copper sealing washers under each plug and it started first time. I should probably advance the ignition a little as the plugs are now a bit hidden.

Ran up to temperature and then dumped the coolant as I hadn't tightened up one of the hoses. Fortunately it was just water (been here before), so I have now popped some antifreeze in.

Idle has to be kept reasonably high or otherwise is a bit rough, but my guess of increasing the req fuel from 8 to 9 seems to be about right (at idle).

Hopefully my next posting will be asking for larger injectors!

Matt