Completely flumoxed

[Davw]

After a probelm with my engine last meeting (last weekend) I changed engine for the spare today. Normally this is a breeze - put engine in, hook up all the bits and bobs - quick squirt of easy start and off we go. Not today:-

Engine wont start - turns over but just wont catch - not really even sounding linke it is about to catch so

1) Check sparks - OK
2) Check fuel pump - pumping OK
3) Checl carbs - is fuel getting to engine - OK
4) Change over CDI - no difference
5) Try more battery power - jumpt start from car - no go
6) Take all plugs out , clean, check gap, heat in the oven and try again - no go
7) Change fuel pump (to give me something to do while considering options!!!!!)
Drain all fuel and try with fresh - no go
9) Take carbs apart check for crud in bowls / jets- all OK
10) Check the bypass resistor on the loom is still OK - fine 100ohms
11) Check the coils (primary and secondary) OK - try with a new set anyway - no go
11) Wonder if cams are in new engine - check - yep they are there and doing the job thy should be (getting desperate now - thinking Minitwins looks like a good alterantive to this toad!!!)

Still to do :-

New plugs (existing look fine and spark strongly) so dont hold out much hope
End to end check of the loom (ongoing)

I have sparks, I have fuel, I have complresson but this fucker just wont go.

Is it possible to have sparks but at completely the wrong time - could the pickup be completely out but still produce sparks - am off the run a test on the pickup?

Any more ideas totally welcome

[will#224]

I'd be checking the ignition pickup, has someone been tinkering in there?

[Davw]

Checked it-

Rotor (right one for the CDI) is secure on the shaft and the pick up is reading 455ohms between the phases and both phase to infinity against the frame earth. Pick up looks good

Finished checking the loom - looks OK

will give it another go tomorrow

[will#224]

I had a similar problem, i'd only removed the carbs, wouldn't start at all, i removed the carbs, squirted easy start across the inlets and pressed the starter, nothing for ages then it started, i dont know why it wouldn't have it, i put the carbs back on and she was fine.

[Davw]

Hi mate - tried that (amongst other things today) - still no joy. I feel like a total tit - never / ever had a problem like it. The combination of fuel and sparks should give me at least a misfire - but nothing. Engine just turns and turns. Out of desperation I changed the wiring to the coils to see if that would make and difference - ie wired up the wrong coils - didnt make any difference at all telling me that although I am getting sparks and fuel I am a mile away from the engine firing.

Only options now are:-

valve timing completly out (professional refresh of the spare engine - seems very unlikely - besides how far out would it need to be not to get at least a misfire/ backfire)
Lack of compression (for some other reasosn)

Depressed!!!

[Mori Man]

Certainly sounds like you've covered all bases.

Timing can be out by 360' so like you say the fuel and sparks are out of sync so you never get a rumble, however I am sure swapping the coil leads cures this as occasionally I do it on my bike after a re-build and after the 3rd attempt twig that's the problem and swap them over and hey presto off it goes.

My only other experience like yours was with the GPz and the problem was plugs and they were brand new to start ! Nice strong sparks when testing so 3 days later and much missing hair and having gone round in a full circle i put in another new set and 1st touch of button and vroom - can't tell you how sick I was after that one :smt013

Seems under compression the spark were being "blown out" even though they were brand new - this now leaves me to believe that plugs have a shelf life so after that I always bought my plugs from a "high turn over" shop.

In modern day cars you don't get this problem as the ignition system just ramps up the juice until they fire - you can snap the arcing arm of a plug and it will still run as it will just arc to the piston crown / head instead, most likely kill you battery a damn site quicker too.

When it comes to firing up my build I know the plugs that are in were working but I'll have another set sitting and also the ones which are working in the ZRX too.

Good luck on it.

MM!

[Davw]

Inlet cam 4 tooth (possibly 5) retarded - makes me wonder at the rest of the "refresh" - not sure I want to run engine- not confidence inspiring but at least it now makes sense. Was begining to doubt myself and starting to try the same things twice - hoping for a different result. The true definition of madness-- which is just how I feel right now

Not a very happy bunny :smt013

[rmkd177]

I certainly wouldnt run the engine after correcting the valve timing...makes me wonder how they have checked the valve drop and how that will be affected once the timing is somewhere near a reasonable figure.

[Davw]

Roger - After adjusting the inlet 5 teeth the engine fired first time. This engine is the rebuild of the one that failed on new build early in the season. I have been running with the engine I got from Brian up to now and that has worked a treat - until last time out at East Frotune when the inlet cam sprket sheared - hence the messing about with the spare.

After all the dicking about - I have just about rebuilt the electrics, carbs are spotless etc it seems a shame not to run on Sunday (that my heart talking) - my head says - dont.

I thought about "running the engine in" for a couple of hours on Friday/ saturday but not sure that will tell me a lot tbh - as for valve drop and tappets - the tappets cant have been checked on refresh or the timing would have shown up then - unless they were done individually rather than at the tdc timing mark

Thanks for the help

Dave

LESSON - TAKE NOTHING FOR GRANTED - ASSUME NOTHING.

[Robbie]

MMM I wonder who refreshed that engine :wanker Will see you at knockhill if your there mate Anglesey is off for me
Cheers

[Davw]

Robbie - sorry to hear Anglesey is off mate - sounded like a great trip - will see you Sunday but dont think I will be racing - but will be there anyway.