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Discussion Starter #1 (Edited)
Hi all,

Hope someone can help, because I'm just not sure what is wrong.

I've got a 1996 Tiger 900. Its done 17.5K, with a full Triumph service
history. As a bit of history it has been stored for a few years, but
done properly, with the fuel system drained, battery removed, air
intake covered up, exhausts covered up, fresh oil, a dash of oil in
each cylinder, protective grease to protect the finishes etc, you get
the picture.

I recently took the bike out of storage, cleaned the bike up, removed
the plugs and turned the engine over by hand, checked it over, put
fresh fuel in the tank, primed the carbs, new battery and it went
first press of the button with a dash of choke, and settle down into a
nice health fast tick over (1500rpm). As she warmed up, reduced the
choke to hold the revs, and within a few minutes was happily idling
with no choke.

As an aside I replaced the hydraulic fluid (clutch and brakes), fitted
new brake pads all round. Took the bike for a test ride to check it
all out and was absolutely spot on. So very happy indeed!

About a week later tried to start her up and well its bag of spanners
for some reason. The symptoms are it will only idle with at least half
choke, at which point its idling 1500-2000RPM, any less choke and it
just stalls. Touch the throttle, the engine just stalls. It will only
run if you apply nearly full choke, so its revving at 3000rpm, open
the throttle full, and then shut the choke off, at which point it
starts hunting at 3500RPM, then revs fairly cleanly heading to the red
line. To keep it running on the throttle you have to have more than
3000RPM, and at least 2/3 to full open , anything less and it just
stalls. It sounds a bit like its running on two cylinders possibly
between idle and 3000RPM, but as I say its hunting. On the choke it
can by carefully adjusting obtain a steady 1500 RPM, but its not that
sweet. The exhaust is smokey, on the garage wall there is lot of soot and carbon dust coming out of the exhaust, which worries me, all because its running so richly.

So I don't know where to start! Could it be the carbs? or its it
ignition (weak spark)? I replaced the plugs and checked the leads from the coiled
are seated correctly, but no change.

Has anyone got any ideas? How can it go from running perfectly to
being such a dog???
 

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With those symptoms, I'd start by looking for an air leak in the induction side. Maybe split or displaced carb rubbers or similar.
 

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Any chance it could be that the idle jets are in need of a clean?
 

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Any chance it could be that the idle jets are in need of a clean?
I thought that too but the part about the bike running perfectly the day he got it running throws me off. It's like it was running perfect, shut it off, then the next day it wouldn't run right. Strange scenario.
 

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Discussion Starter #7
Thanks for the responses :)

I drained the float bowls on each carb, plus drain the tanks, disconnected the fuel pipe to the carbs from the tank, and placed a bung in the end to prevent foreign debris getting in.

You can now understand why I really don't know where to go with this! I've had quite a few bikes, single, 500 twins, etc and never one which worked prefectly well, then next time doesn't work.

I have started to wonder if there has been some residue in the tank, which fresh petrol has loosened up, contaminanted the fuel, and this has been drawn into the carbs. I've bought a small inline fuel filter and some carb clean spray, but not looking forward to stripping the carbs out.
 

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Discussion Starter #8
Yesterday I check over the ignition system. The coils are made by PVL.

No1 Coil Low Tension 0.07Ω High Tension 13.38KΩ
No2 Coil Low Tension 0.07Ω High Tension 13.21KΩ
No3 Coil Low Tension 0.07Ω High Tension 13.15KΩ

The spark on each plug wasn't yellow and quite bright. Only observation was No 1 cylinder plug looked a light white and hence lean, the No 2 and No 3 where more black.

I fitted an in-line fuel filter (too late now), but as a prevention. I flushed the carbs with a 50/50 mix of petrol and redex, then flushed the carbs with petrol. Had a go at starting it up and well no different, other than when initially from cold on choke, as you'd normally expect), the exhaust was clean. It was only as a engine temp rose, the choke was reduced, and well it started to go sooty again, particularly from the right exhaust.

So today going remove the carbs and air box, and clean the carbs. Having looked at the cost of parts, while its removed I'm going to replace the carb to cylinder head rubbers (£6 each from World of Triumph), and fit a new airfilter - any thoughts here, a genuine Triumph one or replace the filter in the box with a K&N?
 

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Yesterday I check over the ignition system. The coils are made by PVL.

No1 Coil Low Tension 0.07Ω High Tension 13.38KΩ
No2 Coil Low Tension 0.07Ω High Tension 13.21KΩ
No3 Coil Low Tension 0.07Ω High Tension 13.15KΩ

The spark on each plug wasn't yellow and quite bright. Only observation was No 1 cylinder plug looked a light white and hence lean, the No 2 and No 3 where more black.

I fitted an in-line fuel filter (too late now), but as a prevention. I flushed the carbs with a 50/50 mix of petrol and redex, then flushed the carbs with petrol. Had a go at starting it up and well no different, other than when initially from cold on choke, as you'd normally expect), the exhaust was clean. It was only as a engine temp rose, the choke was reduced, and well it started to go sooty again, particularly from the right exhaust.

So today going remove the carbs and air box, and clean the carbs. Having looked at the cost of parts, while its removed I'm going to replace the carb to cylinder head rubbers (£6 each from World of Triumph), and fit a new airfilter - any thoughts here, a genuine Triumph one or replace the filter in the box with a K&N?
Mine is doing same thing, same year, same Bike. I completely blocked off clutch side air intake and the throttle side is capped because I’m at sea level. I’m able to get it to Not Stall when I give it throttle and everything is normal beside the fact that I have both air intakes blocked off almost completely and to get an idle I have to have the choke on just a little bit (1/10).
I'm getting a good idle right at about 1400rpm. At least I won’t have to push it up into the Truck to take to the Shop 😎.
Anyone think it’s anything besides a crack somewhere in air box area??
Did you ever figure out your issue or did you just light the bike on Fire then call it a Day??
 

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He hasn't logged back in since 2013 so I'm thinking you won't get a response from him. Maybe someone else will help though.
 

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If it's been stored, there's a chance the carb rubbers have split. Maybe that one run you did flexed them enough to do damage
 

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Could be crap in the float bowls. I'd take them off & have a look, at the same time you can check the slow running jets.
Or.. (and I hate to admit this) but I recently put diesel in my tank. Mixed with the existing petrol, surprisingly it ran ( but really badly) on full choke only. Took me ages and 2 carb strip downs to realise what I'd done !
 
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