Odd No Start VFR700F - Has spark, has fuel, zero fire

Have a no start issue that is driving me insane. PO stated that the bike ran until he took the carbs (and most of everything else sans the engine itself) off to clean them a year ago.

Finally have this thing mostly back together - 1986 vfr700f Calif (sans cali emissions).

Bike cranks but does not fire. Starter engages and sounds normal. Charged Ballistic Lithium-Ion Battery on charger.
Spark plugs all throwing spark (during testing anyway)
Have fuel - even tried using a few squirts of starter fluid (which I hate doing-last resort)


Absolutely no fire - no pop, nothing. Not even sure how that's possible when there is spark and starter fluid. I would think that the starter fluid would remove the carbs from being a possible cause.

Some fuel/ignition related changes that have been made (but should be irrelevant since bypassing it while trying to get any fire). New fuel pump (generic pump - bought a used oem one too but it was getting extremely hot so wired in a generic one temporarily and bypassed the fuel cutoff relay). Carbs removed and cleaned. new plugs. new air filter, cleaned fuel tank. new fuel filter. new starter solenoid.

Spark seems is blue and strong on cylinder 2, remainder seem to be orange when using tester. Notice that when engaging the start button multiple times it will stop firing the starter for a minute or two (lights will dim when button depressed so looks like start button itself is working) but starter will not fire. Then a few minutes later while battery still on charger (not sure if that is why) the starter will engage again. Starter always engages if jump starter solenoid.

I've read through the million posts on here re no start condition but haven't found one that matches my same conditions (I may have missed it).

Checking compression tonight, had to pickup a new gauge. But i wouldn't think I would get zero fire (unless all 4 cylinders had bad compression?)

Any suggestions would be greatly appreciated. Thanks in advance

 

Does the engine turn over at a normal speed on the starter?

Can you smell fuel out of the exhaust pipe?

Are you sure you are getting fuel?

 

when you remove the plugs are they wet?

 

is the choke working ??

 

If you have fuel, spark, compression and the timing isn't wrong it will run.

 

Ok Previous owner said it was running OK so it sounds like something in your rebuild is preventing the bike running. The first step is to focus down on what is causing the problem - so if the bike turns over nomally on the starter - I would first try and determine if its not starting due to lack of fuel or lack of spark.

Perhaps remove the easiest to get at spark plug then rest it on top of the engine so you can see the plug gap. Connect the ignition, make sure it is out of gear, check the kill switch is at run and briefly the try the starter. If you see sparks - chances are it is a fuelling problem but if no sparks then its electrical - so focus on any/all ignition inhibit features - did the bike have an immobiliser/alarm? Check the kill switch for corrosion (firmly flip it open shut several times as that may clear corrosion without dismantling, raise the side stand, and pull in the clutch lever and try to start again - are you getting sparks now? ... be methodical and you will get it going.

Good luck Let us know how you get on.


SkiMad

 

Thanks everyone for your posts. trying to keep my frustration from pushing this thing off a cliff. Going through each reply and starting over from square one re getting this bike started.
Well now when i test the spark i am getting zero spark from any coil. I'm seriously thinking about pulling the entire harness and just starting over from scratch, and go step by step. As i look at the wiring more closely I see multiple sketchy splices throughout. And i probably should make 100% sure the electrical system is at least correct before going forward.

 

less work than wrestling with a wire harness, just replace the cdi.

test that cdi is supplied with 12 volts when key and run switch are on.

 

yes - choke operates correctly

 

Starter turns over at normal speed.
No fuel smell out of exhaust (don't think it is flooded - plugs not wet)
Fuel getting to carbs - ran pump until fuel exiting the overflow ports slightly

 

no - doesn't seem to be flooded - plugs are new and are not wet.

 

true - that's what is driving me insane. I need to confirm timing though. But PO indicated that was running prior to him dismantling and pulling carbs - so timing should be as was when running.

 

wait a minute, Bunky !! no, none, never should fuel be dripping from those tubes.

if carb float needles need cleaning or replacement and aren't controlling fuel flow it could account for starting probs. (despite saying plugs look dry. )

 

Thanks squirrelman. I will attempt that first. I did a complete wiring harness on my 77 xs750 project and that was a huge pita and was not looking forward to doing a similar job on this bike.

 

ahh - i ran the pump to prime. oops. But wouldn't starter fluid at least give me something? regardless of the carbs?

 

sure, IF you have sparks

for easiest starting, carbs need to have idle speed set about 1- 2 turns IN on the speed adjustment screw from the point where it's not contacting the throttle wheel as you back it out.

opening the throttle during starting attempts should be avoided. as it leans the fuel mixture too much and only helps with flooding probs.

maybe taKe a closer look at idle jets or blocked mixture screw passages.

plug wires in front can't easily be switched, but the rear cylinders wires could be incorrectly placed.

• 

IF you have consistent, blue sparks !

 

ok i have to get a base line. Think i'm changing too many things at once.

1) Checki

ok. Think I just need to start over and get a base line and go from there. I'm all over the place i think.

1) Pulling plugs. testing spark again. replacing with new plugs. - this will 100% rule out wet plugs.
2) Then will replace the cdi
Then will move on from there.

Thanks again for your help

 

I just did this on another bike forum: i'm offering to TEST and report on your cdi box as it performs on my super well-tuned similar bike. free and quick, how's that ? you pay return shipping.

 

That is a perfect looking vfr. Sweet Job. I was playing with leaving the lowers off (if/when i get this running), I like how it looks. And thank you very much for the offer. I may very well take you up on that. But before i waste more of your time, let me get these plugs sorted and make sure i didn't do anything completely moronic (other than flooding the carbs) and see what happens. As i was busy throwing tools around - just had to order a new valve cover breather as apparently the factory didn't take into account a wayward wrench slamming down on it allegedly in frustration. Cracked like an egg, huh, who would have thought.

Also, looking at the various issues - spark then no spark, starter turning then no starter. Possible bad kill switch? I also see the boot for #2 cylinder plug is torn. Not sure if it was always torn or my repeated pulling and installing ripped it. Another variable. So i better square away things i know for sure are not working, go through the bike with a multimeter and see what is what.

Thanks again.

 

Correct me if I am wrong but the plugs should have some gas on them....they should not be totally dry. Do they at least smell like gas?