Decades ago my R65LS exhibited similar behaviour. I carried out the
following test. At night, in a practically darkened garage I fired up the
bike and looked at the petrol tank/hi- tension leads. The right lead clearly
was sparking against the metal tank, meaning a 'leak', the spark was being
diverted. At higher revs the spark was overcoming the 'detour' and continued
towards the spark plug. Replacement of the leads eliminated the problem.
Frank
Down Under
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-----Original Message-----
From:
[email protected] [mailto:
[email protected]] On Behalf Of
Richard Chawes2
Sent: Thursday, 30 July 2020 4:50 AM
To:
[email protected]Subject: Re: [R90SWORLDNET] Bad Stumble below 3000 RPM after Brief Stop
Maybe take your float bowls off and see if any water or particles floating
around. Since it ran so good first time I doubt it is ignition related,
sounds like fuel
Richard Chawes
On Jul 29, 2020, at 11:39 AM, Joe Dille <joe@...>
wrote:
Scott,
I can't say about your ignition or charging system. However, one
thing that would be helpful would be to know is the if bike is running
on 1 or 2 cylinders. The best way is to use an IR temperature gun.
Measure on the bare aluminum, perhaps the exhaust nuts in the same
place. Plan B would be to just feel how hot the valve covers are.
If it is running on 1 cylinder then the Dyna III is the culprit.
Let us know how you make out.
Joe
This is a new to me 74 R90S with a DYNA III Electronic Ignition and,
I believe, the upgraded 450 Watt charging system. Again, this bike is
new to me, but I have attached photos so maybe the trained eye can
confirm.
As was mentioned in my previous thread, the bike had been sitting for
a very long time on a dealership floor as a show piece. I drained all
the fluids, added a bit of oil to the cylinders (thanks Richard),
grounded the plugs and cranked it until the oil pressure light went
out. Put the plugs back in, drained the old fuel, replaced it with 5
litres of Chevron Ultra 94, started it and ran it until the smoke
cleared. Took the bike for a quick 2 mile drive and was impressed
with how tight the bike felt - WOW was all I could say when I got home.
This morning I took the bike out for a 4 or so mile run and it ran
perfectly. Idled perfectly at stop lights and ran incredibly smooth.
I stopped at a Chevron to fill the fuel tank, again Ultra 94. The
bike started without the enrichener but didn't want to idle. The
charge light seemed to stay on until I brought the RPM above 2000. I
pulled away and it seemed to stumble a little bit and the Volt meter
showed a discharge until I brought the RPM above 3000. As I continued
to drive the stumble got worse. I engaged the enrichener to see if
for some reason it opened, even though I hadn't touched it at the gas
station, but it made the stumble worse. As I drove more it got worse
and I needed to keep the RPM above
2500 for the bike to stay running. This reminded me of when the coil
on my R69S was packing it in, but in that instance it totally died
after a mile or so. I was able to limp the bike all the way home but
it died in the driveway as soon as I rolled the throttle off. As I'm
at the office, I haven't tried to start it again, so I can't say if
it's a heat soak issue, or now a constant low RPM stumble. I can check
that when I get home.
Any ideas on where to start?
Thanks,
Scott.
--
Joe Dille
Telford PA
What happens on earth stays on earth
Frank ---Down Under