#1 no spark coil to sparkplug

[DiverRay]

As a "rule of thumb", 10% is the max between the high and the low number. You do need to hold the throttle wid open when doing the test. IF you didn't, try once again.
You may also want to buy 4 new spark plugs, BP6ES NGK's, before the next start-up attempt. Plugs have been known to be bad. Whith #1 not firing, and #4 the lowest pressure, I would try checking the gap on all plugs. Set #1 to .028, #2&3 to .030, and #4 to .032. This should make up for the difference between 1 and 4, and may give you fire on all 4 IF the carbs are good.
Ray

[mason79]

i again thank you all for your help, i was getting a little discouraged

the book did not tell me to open the throttle, but will do.

yes i pulled the plug from #1 wiped it down and put a lighter to it and rested on the head, there was a weak spark,

i'm not impressed with the spark rather anemic, thanks again.

[LoserShoes]

Swap the plug from the cylinder that doesn't fire into a cylinder that does and see if the problem follows the plug or stays with the cylinder. Bet you have a fouled plug.

Steve

[mason79]

as above stays with the cylinder

i forgot to mention, #3 exhaust pipe has a rather large crimp from hitting something at speed so does #2 to a lessor degree,will this cause the high compression on 2 and 3?

i will redo the test later with open throttle

[mason79]

okay i did the compression check with the throttle wide open, book says arould 140 psi but i got


#1 190
#2 179
#3 190
#4 185

at least i don't need rings and valves for now,

i put in new plugs, gaped at .032,

i paid $3.05 did i get ripped off? no matte, they are so much cleaner than the ones in them already, the old one were not worn just, for lack of better words fouled looking, dirty and sooty


#1 seems to get warm now but when i pull the plug cap away it does not stumble like the other clylinders, verdict:

no firing, i pulled the carbs now i am a carb puller expert, such a useless designation...

i hear a little something in the floats like i did last time, but i gave it a gentle squezze and i pop back i am still under the impression it is tight, and even if leaking has not filled up enough to vary the content of gas much from the others.

how should i check for leaks, boil them as per tech tips, i don't think thats it though,

any comment from anyone may topcat or diverray, you guys are real technicians, thanks again for the help

[TopCatGr58]

You'll be boiling mad when you confirm the float leak!

Hey Mason,

Thanks for the compliment, but I'm just a shadetree survivalist.
DiverRay, Prom, and many others here are the real techs!

Now, what's interesting is your compression values! Yes, Stock is rated around 140psi at sea level. After I did my big bore kit, I then got values like yours around 185, so I wonder if you got a hold of a bike that's had one put in it!?

As for the carb float, yes, if it makes noise, it's leaking, and placing in already almost boiling water will reveal the leak. You've probably got the metal floats, and so you could try to seal it with solder, but you will need to let it sit out in the sun or slow bake it to evaporate the small amount of fluid=gas out from in it. With possibility of unwanted fire, heat it in well ventilated place, perhaps run a blow dryer or heat gun on it for a while!

IF that float is sinking, the carb is flooding which will definitely cause poor performance. Fix the float, and it should then behave.
T.C.

[mason79]

mr topcat,

small leak but the side its coming from is not the side with the noise, regardless, the unit seems sufficiently corroded(green stuff) for me to not attemp a patch,

i don't want to spring another, i hope this is it,

did i see the term triple clean somewhere, or did they mean 3 times a charm?

thanks again topcat

[skids]

As long as air flows easily at that low rpm from the starter, there should be no affect to the compression. It could affect the operation of the bike while running, as could a squashed and now leaking header pipe gasket(s).

Originally posted by mason79
as above stays with the cylinder

i forgot to mention, #3 exhaust pipe has a rather large crimp from hitting something at speed so does #2 to a lessor degree,will this cause the high compression on 2 and 3?

i will redo the test later with open throttle

[LoserShoes]

From all the above, seems to me you have a bad coil. These things work by firing across the two plugs at the same time. Bout the only way to have one fire good and the other bad is to have an internal short on one end of the primary in the coil or a short in the plug wire to the chassis somewhere.

Might try swapping the coils to see what happens.

Steve

[mason79]

po spent 130.00 for 1 and 4 coil with reciept, as per topcat i swapped 1 to 4 and the problem followed the cylinder, still thinks its the coil?

i found a tiny leak on the float for that cylinder, i don't think i was sinking the float,though,

coming from yamaha tue, and i'll put it back together, we'll see...

would like to take it out more that around the block, and see why people love this bike, so far it's the looks, specs and heavy petting, while in the hospital, but i want to comsummate the deal...

[turbopete]

Compression is fine. 10% variation across the board is the rule of thumb but it wouldn't stop the cylinder working if it were 20% or even more. Your later figures are good.

If the problem jumped from cylinder 1 to 4 with the spark plug then the plug is bad, so fit new plugs. If the problem persists you have a fault on the leads/caps or a weak coil. If you have a weak coil the bike will run with the gaps closed up almost touching to take the load off the high-tension side and diagnose the problem.
Running the bike with a bad plug can knock the coil out as I found out recently when I ran mine with the cap loose.

I have a set of four plastic floats. If you want them send me your address. I don't know what model they are off but others might. It'll take a few days to get them from me in the UK.

[mason79]

thanks turbopete for the float offers, i'll keep them in mind, i think they came about in 81 from my reading in this site.

i paid 27 bucks for a new brass float from yamaha,coming tuesday
in the meantime i've been polishing this sculpted statute of a trophy...


the problem follows the cylinder, when i put a known good plug and give it spark via #4 secondary wire, in other words, i got compression, and known good spark, i got fuel, but i think the air fuel ratio is off...

what i'm afraid of, is the float in question never really took on too much gasoline, but topcat says, it needs to behave, so hopefully our carburation woes are from very sensitive and finicky technolgy and just a little rebalance would tip the battle in my favor.

[turbopete]

If it helps one of my cylinders doesn't run on idle (happens to be No4 too). I gave up worrying about it, the spark is there it just don't go bang

I have been thinking about the idea someone had of fitting the XJR carbs on my bike, but I really don't want to spend the money on what is my work hack.

[mason79]

turbopete,

i don't even think it fires beyond idle, but could have , the pipe just does not get hot to the touch, absolutely no sizzle...

so could this be an underrich enrichment circuit or non existant pilot circuit?

i smell and see wet plugs though, do you? or you didn't bother ?and the irony is insofar as "taking it in" my po fought with a yamaha dealer for weeks to get it running and i've; thanks to the
coaching from here has gotten further.

guys here are specialist and everywhere else are generalist, meaning an excercise in futility...

[turbopete]

No my bike picks up the cylinder off-idle and runs fine.