Starts cold, then dies warm

[Rocinante]

Rocinante´s got a new pick up coil today, and I hoped that would be the end of the problems, but no. It solved the sudden death syndrom but I still have the problem of stalling when warm, which it did before the cylinder head replacement as well. Symptoms are:

Dead cold it fires as a rocket and runs very smooth.
As it warms up the idle starts to go down and up but most down, until I have to rev it to keep it running.
It gets worse until it starts coughing and finally dies. This takes about 10-15 minutes (fan´s running towards the end).
Sometimes it makes huge bangs.
It doesn´t smoke at all.
Plugs become dead black.
It happened 1,5 year ago as well a few times. I replaced the plugs and that seemed to solve it - though I didn´t feel confident. Tried that now to no avail.

What I have done:
Did the water on exhaust pipes test. Centre cylinder slightly colder indicating it was the one who died first, though not solid enough proof.
Measured primary and secondary resistance all HT coils, all in spec.
Replaced the centre coil with a spare I have lying around, no difference.
Cleaned plug wires and coil connections.
Replaced spark plugs.
Drained and refilled with clean fuel.
Drained the carbs.

Will leave for a three week trip to Mexico on Friday. Hoped to have the bike ready in the garage for when I come back (not traveling on a bike, obviously). I only have tomorrow left to fix this.

Any suggestions are welcome!

[Mustang]

even though you tested the coils , I have a set of gills here that test fine also but 20 minutes after start up 1 of them goes tits up .
So even though they test good cold , they suck when they get hot .

Not saying thats your problem but ..mine had the same backfiring and piss poor running before I said screw it and bought Nology coils .

Do you have some new plug leads you could try , they might be the culprit here too ......there was a thread on the trophy mailing list not to long ago that the OP had problems like you are describing and it turned out to be the plug leads .

[Rocinante]

I replaced the plug wires as well 1,5 years ago. It hasn´t out of old age started to eat plug wires I hope...

I still have the Gills and they´ve been on the bike since new, with one exception. It didn´t fail but the mechanic broke it by mistake.

I´ll do one more test tomorrow since you say the coils might die when warm; start up the bike and when it dies, check for missing spark and measure resistance on the coils again. And also try the spare coil on all cylinders, not only the centre.

[rybes]

check ya ignitor pick up too. had similar problem on mine and it turned out to be that

[Mustang]

Rocinante´s got a new pick up coil today,

Ummmm I believe he has ...............
now I assume that you set the gap correctly.....???

[JetdocX]

Rocinante´s got a new pick up coil today,

Ummmm I believe he has ...............
now I assume that you set the gap correctly.....???

Good catch.  If set too wide, heat induced expansion could possibly cause it to get out of range. :shock:

[rybes]

Rocinante´s got a new pick up coil today,

Ummmm I believe he has ...............
now I assume that you set the gap correctly.....???

hmmmmmmm missed that one  :oops:

[Rocinante]

Pick up gap was set to exactly 0.7mm (should be between 0.6 and 0.8 according to Haynes).

[nightrunner]

They have you covered above.  I can only add that when my coils went, they were also OK cold and then misfired when warm.  I went with the tt600 stick coil swap though so no worries on plug wires either.  They work great.

[Rocinante]

I went with the tt600 stick coil swap though so no worries on plug wires either.  They work great.

Ah ehm, que? :icon_scratch

[BruKen]

Is just me who thinks it has all the hallmark symptoms of running rich?

[Rocinante]

I didn´t have the time to do more on this issue, so the hunt will continue in the beginning of May.

Vamos a Mexico.

[Rocinante]

The saga continues.

Rocinante´s still not running ok. What I´ve done since last post is this:

Started the engine fine and let it run on choke and then on idle for 15 minutes until the fan started to run. Then it started to run badly and when it didn´t want to run anymore, about five minutes later, I plugged in three spare plugs, lay them against the engine block and hit the starter to check sparks. All three seemed fine, curiously enough.

I got another Gill coil and had five in all (one spare that´s been lying around for ages).

Next I pulled the three plugs in the engine and found that cyl 2 and 3 were dead black while 1 seemed fine. So I replaced coils 2 and 3 with the two spares and fired it up again. Or tried to. It was still warm and didn´t start. So much for the coil theory.

But here´s another thing I did. I replaced the plugs and let it cool down, and then started it up again. The gas tank was lying over the seat, so the coils were in the open. Now it ran evenly for 25 minutes, then I put the tank back in it´s position while the bike was running, and five minutes later it started to run badly again. The coils would then heat up a lot more than when in the open because the tank is like a lid over them.

Earlier to this I also checked for water in the gas, drained all the carbs, and checked tank vent (also ran it with the tank lid open).

I don´t know what else to check. Maybe just replace the coils with Nology (I can get all three on the net for the price of one Gill in Norway, including plug wires).

Any other suggestions are welcome.

[Mustang]

I , much like you , kept chasing my tail with vents and carbs etc etc  trying to get my 98 to run right and finally bought the nology's .
Imagine the delight on my face when it ran like the tiger I first brought home  all those years ago ....................... :D

also if you dont have the plastic pcs on the frame covering the valve cover , ............well lets just say they do work in keeping the heat down under the tank

[Rocinante]

I , much like you , kept chasing my tail with vents and carbs etc etc  trying to get my 98 to run right and finally bought the nology's .
Imagine the delight on my face when it ran like the tiger I first brought home  all those years ago ....................... :D

also if you dont have the plastic pcs on the frame covering the valve cover , ............well lets just say they do work in keeping the heat down under the tank

That´s true, the plastic´s not been there during testing, so the coils get quite hot.

Ok, the order has been placed, fingers are crossed for a fast transport and for it being the solution, even though I don´t believe it before I see it (that´s just a defense mechanism to avoid great disappointment, and not to be regarded as distrust in the forum oracle:)).

Dag