(ex) V65 Florida no start after changing headgaskets

[motortouring]

If the heads are off, the sparkplug caps are off. You probably pull on the cable to the coil when mounting. This could be a bit loose on the end of the coil. Enough to give a spark in the open but too little under compression. Just some thoughts.

But I agree; it sounds like almost everything has been checked already. Are you sure you turned the crankshaft in the right direction? Using the rear wheel to push it forward, for example?

[80CX100]

I then changed the head gaskets (both were the cheap version & wheeping) and since then, I cannot get her started anymore. I have not touched any of the wiring in the process.
The bike is equipped with Carmo Electronics electrical ignition and "wants to run" (plopping in the exhaust). Sometimes during starting the starter suddenly stops as if she tries to fire whilst on it's way up on the compression stroke.

Checked/adjusted:
- Spark (good strong on both sides)
- Spark timing (created mark on flywheel as flywheel appears to not be installed in the correct orientation) for RHS TDC - +/- 7deg, checked with strobe OK
- Went back to jet size 128, 115 and eventually 105 (original)
- Changed spark plugs for new
- Compression both sides 13.5bar
- Switched spark plug leads left/right (no "trying to run" anymore when switched)
- Adjusted mixture screw anywhere between 1/2 turn and 4 turns (manual states 1,5 turns out)
- Adjusted idle screw up/down
- Emptied float bowls & tried to start her with brake cleaner, same result (only popping, no running)
- Removed air filters, no change

 

 

Before you get too far into it,just for shits & giggles, hold a decent sized wire up to the battery positive terminal & the contact on the solenoid at the starter, hopefully that will eliminate the ignition switch as a potential source of grief.

KiwiRoy once admonished me that my 35 yr old ignition switch would cause me grief;naturally he was later proved correct 

This is all waayyy above my pay grade,but I'll throw some thoughts out there jic,fwiw.

TLDR is the main ground one of those funky hidden under the battery tray ones & is it good?

TLDR when you were doing the mods to your bike, any paint/powder coat work that might be ground issues,wherever? 

Do you have installation instructions for the electronic ignition & what & how it's set up at a known baseline to operate from?

Are you certain you can provide that baseline for it to operate from?

With all the confusion about the flywheel, you might consider printing off a degree wheel;learn how to use it on a guzzi engine & mark your flywheel more accurately?

My strobe light(cheap) always worked flakey for me; I had much better luck using an analog multi meter hooked up to the appropriate ignition spots, set up beside the valves as I worked through TDC, showed me exactly what my ignition was doing & when.Then you can relate that to your flywheel marks; it'll help tighten up your baselines more accurately.

I like to work on the left side first,then switch my multi meter probes for the right side & it's a shorter roll to check right TDC,fwiw ymmv.  

Someone else already mentioned it; When you marked the flywheel,were you certain of the direction?

I know there's been times I've gotten twisted around those flywheel marks as I roll the engine through different cycles,backwards to what I was expecting to see. 

All I got for now

 

 

 

[MartyNZ]

Just for an experiment, can you try reducing your spark plug gaps?

I have seen healthy fat blue sparks on removed plugs, but no fire when fitted. Compression pressure can be high enough to prevent a spark jumping the gap. The higher the air pressure at the plug, and the larger the plug gap, the higher the voltage needed to spark.

Maybe the new gaskets have raised the compression pressure?

I've seen a 1909 Fairbanks Morse engine run with a plug gap of 0.15mm (0.006"), but not with 0.63mm (0.025"). The weak spark from the magneto sparked a 0.6mm plug gap fine when removed.

A V11 runs well with a spark plug gap of 0.7mm (0.028"), with 9.8:1 CR, because the factory electronic ignition delivers high voltage with high energy to each plug.

Nippon Denso has some basic information on plug gap and compression pressure:

 Conditions that affect the discharge voltage | Spark and Ignition | Basic Knowledge | SPARK PLUG | Automotive Service Parts and Accessories | DENSO Global Website

[audiomick]

16 hours ago, MartyNZ said:

... your spark plug gaps?

Supposed to be 0,6 mm according to the workshop book.

Page 9 here:

https://guzzitek.org/gb/ma_us_uk/V35V50V65_041983_Atelier(GB).pdf

 

Is that what you had them set to?

[Tinus89]

On 2/28/2024 at 1:15 AM, audiomick said:

Supposed to be 0,6 mm according to the workshop book.

Page 9 here:

https://guzzitek.org/gb/ma_us_uk/V35V50V65_041983_Atelier(GB).pdf

 

Is that what you had them set to?

Yes, it is.

 

I have been fiddling with the ignition for a while now. Somehow, the spark seems a bit weak now (not before) and the left side is not always sparking.

I am currently away from home for work, but when I get back, I will investigate further.
So far it seems like the problem is most present on the left cilinder.
When changing the ignition CDIs, coils (plus leads/caps) and even the pickup, the problem remains on the left side the most.
I will have to re-investigate the ignition parts & wiring from the start when I get back.

[gstallons]

To make yourself an ignition system for one cylinder of this bike. Remove the wiring from the - side of an ignition coil .

 Take a push button switch and jumper a 0.25mfd capacitor across the pushbutton switch.  

Install about 2' of wire onto each side of this switch. Run one lead to a GOOD known ground and the other lead to the - side of the ignition coil . 

Remove the spark plug wire and plug it on a good known spark plug touching a good known ground . You can use a spark tester from a tool truck or mower shop. 

 W/the ign. key on , look for 12v on the + side of the coil. If this is good, then take the pushbutton and push it and release it . This will be your substitute ignition system. 

 You get spark and you have a good coil and (almost) a good ignition system. This means your problem is with the bikes ignition system .

 Try this out and report your findings. Meanwhile I will be thinking.

[Tinus89]

Lovely (potential) ladies and gentlemen. White smoke. The issue has been found!

Long story short, I have been changing components left/right so many times now, I lost the baseline. During this process, I had an intermittend spark, which in turn was intermittend again. I got frustrated, cursed, wanted to push the bike into a canal.

Decided to start over. Begin at the base I was left off with (which was with the signal wires of the pickup crossed).

Put some fuel in her, had a huge backfire (remember the crossed wires?) But hey, the size of the backfire was new. Switched the wires back and BOOM. Started up "like a dream" But why?

 

And then there was it. I had already abused one lithium battery to failure. In the process of getting the fueling so that she would start quick, I jumpered the battery of my V11 onto her. I only used the engine ground (and not the central ground point cable I also engineered into it) and she ran fine (before the head gaskets).
The only thing that changed between the last no-run-with-fuel and yesterday's baseline attempt, was I added a central ground wire. I never looked into that because she ran fine without it earlier.
Started the bike, removed the ground cable and she died. Repeated 4 times without failure.
So yeah, the luck of the bike running without that main ground, turned into a big search later.

 

The real story? I sold my Caponord 1000 two months ago to a friend. 
Yesterday I received my Aprilia Tuareg 660 AND found out the above. Moral of the story? I just needed a new bike

Thanks everyone for thinking along!

[gstallons]

99.99999% of all sensors are polarity sensitive .  Trust me . You will get frustrated  learning this but you will be a better man knowing this . 

 We found out things like this when HEI came out on GM vehicles in 1975 .  You would install a distributor pick-up coil in the distributor of a Chevrolet w/a part # from an Olds or vice versa and get similar results. WHY ? The Chevy dist. rotation was clockwise and the Olds was CCW.  Also wheel speed sensors , crank sensors , all kinds of sensors are polarity sensitive . I watch DiagnoseDan videos and he encountered something like this with a sensor (cheap part) wired backward at the connector .  

 I love the education , I HATE the @$&%%&*&%$!@)(&%$ tuition !