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Summer's passing by and I thought I'd have one more go at trying to figure out why Signor Falco won't run - if I can't then it's time to let him go.

Recap: low mileage RSV engine from a running bike shipped over from NI - all looked good. Not fitted for about 7 months but it went in well enough but has never run on the rear cylinder. I was moving flat and had nowhere to keep the old knackered engine, nobody wanted it, so I ditched it - thinking whatever was up would be a quick fix.

Sparks ok, fuelling ok, runs on front cyinder (difficult to tell how well), pops and flames on the over run from unburnt fuel.

Timing SEEMS to be right (this was a allegedly a running engine). Dumping quickstart into the rear makes no difference. I replaced the ECU - made no difference - I switched to my original Falco throttle bodies - no difference.

Cam sensor is ok. Compression on rear cylinder enough to nearly strip the skin off of my finger with it over a plug hole.

I shipped it off to Tamworth for a few hours but I was in danger of spending my rent money on a lot of searching - there was nothing obvious coming up and the suggestion was the flywheel had spun on the crank.

So I shipped it back, and have subsequently found the flywheel to be in the right position although some bodger has been in there for a sprag replacement and mashed up heads and left out the washer from the M16 hex holding the flywheel on. Indeed it was pointed out that my pristene 10k big valve RSV engine was running small valve heads and it looks like the same bodger rebuilt the thing, having lost a cam hex bolt and put in an ordinary bolt in its place. Something bad happened to this top dollar engine in the past.

So I'm wondering what to do now... since the heads and the crankcase is off I can verify that the cam chain isn't a tooth off - but that's unlikely to be it unless the cam fairies nobbled this engine while it was holed up in a friends garage for seven months.

I moved the coils around - so it can't be them and as I said there are definitely sparks to all the plugs.

This thing has never once tried to fire on the rear - it's very consistently not running which indicates some very solid cause rather than fuel starvation etc...

Any thoughts would be most appreciated.

Ian

Forgive me if this is an idiotic suggestion but if you're sure it is getting fuel and a spark. That only leaves oxygen missing.

Have you checked fuel lines to injectors and sensor wire condition and connections?

Plug caps and leads as I've known sparks to be seen out of the motor but for them not to be good enough to ignite the mixture under compression.

This is probably something idiotic -

I put an LED across the rear injector terminals - flash flash flash...

I ran the engine one of the rear plugs out - petrol scented mist jetted out (plus bangs and flames on the over-run indicates plenty of unburnt fuel)

Without a cap on one of the rear leads, spark was jumping 15mm to the frame.

This was literally - running engine out - new engine in - so the coils/leads/caps were unmoved so not possible for them to break down in the few days during the swap!

I'll have another play tonight and check the cams are where they should be as I'm at the point of questioning everything I was told about the state of this engine.

Hi Hisnibbs! You tipped me off about Ridersite a good few years ago on Knighton Road in Leicester!

Are both of the plugs definitely sparking? One on its own is not likely going to provide enough of a spark.

Also, have the actual plug caps disintegrated? I have broken my fair share of plug caps by breaking the graphite inside the plug cap. If so, spares can be found cheap on ebay - search for VD05EMH and VD05EM. One of them is the internal plug the other is the external plug. Only I forget which.

Also sounds like a good idea to check the cam position.

..... and if you do have both fuel, spark and the timing is right, do you have decent compression?

When mine recently dropped to one cylinder it was due to lack of compression as a plug had come a little loose. Not saying it's a loose plug - there are several potential causes of a drop in compression.

This has been a long running drama ( no pun intended ).
A while ago I wondered if it may be a holed piston but you say you have the heads off so you would have seen that.
Did Griff do a comp test ?
The lump has seen some awful bodgery so maybe the rear barrell and piston were robbed for another project and your rear cylinder is so shagged it is incapable of running or the wrong heads dont work with this lump
Odd that it would not run even with a dose of vehicle Viagra (Easystart).
Im thinking compression issue as you seem have all the other needs

I've not had the heads off - just the valve covers. But my finger was nearly sucked down a plug hole when turning the engine over. Not an exhaustive test I grant you, but ugh... do I have to spend another £25 just for 1 second of use to confirm it's OK? Last resort maybe - if only I knew some local mechanics and could borrow one for that one second!

Not sure if Griff did a comp test - just that they couldn't see anything obvious wrong with it and it was pointing to a spun flywheel. I do know my saddle and fairing panels are stranded there as they didn't return with the bike so if I do get it running I'll be riding on a cushion for a while.

Why would your fingers be sucked down a plug hole? Which hole was that?
Should be blowing out through the plug hole...

Good point... there was indeed much blowing. It felt like my fingertip was in jeopardy but of course it isn't unless the inlet valves aren't opening - which they are