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Old 05-14-2015, 04:05 PM   #1
Rockman OP
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Joined: Jan 2007
Location: Inverell, NSW Australia
Oddometer: 331
Starting problem 89 R100GS

Now that the weather has turned a bit cooler in Aus, my 100gs has developed a starting problem first up in the morning. It reluctantly runs on one cylinder for a while (maybe 10- 20 secs), then the other bursts into life and its all good for the rest of the day. Later in the day when the weather is a bit warmer it starts up straight away on both.

A little background. Carbies stripped, new diaphagms, o rings, needle, needle jet etc about 500 km ago,carbies balanced
New plugs around 1000 km ago. Ive tried leaving the fuel taps on overnight, and with them off - no difference. When its running I can turn the choke off after a few hundred metres from cold.

I'm looking for suggestions as to the cause of this.
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Old 05-14-2015, 04:42 PM   #2
Box'a'bits
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Location: Wellington, New Zealand
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Mine had similar issues, resolved when the ICU was replaced. Do you have anyone you can do a swap with to test?
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Old 05-14-2015, 05:55 PM   #3
Mark_S
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Location: Kapiti NZ
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Quote:
Originally Posted by Box'a'bits View Post
Mine had similar issues, resolved when the ICU was replaced. Do you have anyone you can do a swap with to test?
gotta spare you can loan me for testing at some stage?
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Old 05-14-2015, 07:02 PM   #4
Box'a'bits
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Originally Posted by Mark_S View Post
gotta spare you can loan me for testing at some stage?
Yup.
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Old 05-14-2015, 07:51 PM   #5
bmwrench
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There is an improved ICU, developed because of that problem. It is supposed to have a violet dot on it.
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Old 05-15-2015, 02:10 AM   #6
motu
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Location: New Zealand
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Mine does that randomly. There is some drivel about turning the kill switch on and off....doesn't work. I start on half choke, if it does the one cyl thing I push the choke off and it fires up nicely. That makes me think about choke adjustment - then I'm on the road and forget all about chokes and stuff.
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Old 05-15-2015, 06:35 AM   #7
navrat
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Location: Ann Arbor, Michigan
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My 89 R100GS behaved similarly on start up. Replaced the old ICU and problem solved. Incidently, the PO had upgraded to the newer coil which I discovered is not compatible with the stock ICU that was on the bike.
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Old 05-15-2015, 06:45 AM   #8
Biebs
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Pissed Why???

"Ive tried leaving the fuel taps on overnight"

Were you trying to get gas in the crank case?? If you pull the dipstick you can add gas directly to the crankcase. Hope this solves your problem.

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Old 05-15-2015, 07:54 AM   #9
FrankR80GS
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Quote:
Originally Posted by Biebs View Post
"Ive tried leaving the fuel taps on overnight"

Were you trying to get gas in the crank case?? ....

If your bike has a problem with open fuel taps overnight, you should look after the adjustment of the floats or the float valve.
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Old 05-15-2015, 08:01 AM   #10
FrankR80GS
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Quote:
Originally Posted by Rockman View Post
Now that the weather has turned a bit cooler in Aus, my 100gs has developed a starting problem first up in the morning. It reluctantly runs on one cylinder for a while (maybe 10- 20 secs), then the other bursts into life and its all good for the rest of the day. Later in the day when the weather is a bit warmer it starts up straight away on both.
...
If your bike still runs with the factory installed ignition coil, you may want to read this:
http://jhau.maliwi.de/mot/r-elec.html#ignitioncoil

The bad thing about this shitty coil is, that measurements with a multimeter would tell you that it is OK.
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Old 05-15-2015, 09:21 AM   #11
boxerboy81
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Are the starting jets in the corner of each float bowl clear? Is there any water in the bowls?
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Old 05-15-2015, 12:13 PM   #12
CanteenBoy
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I'd recommend that you sync the carbs and check for even tension on the choke cables. If that doesn't fix it, try a different ICU.

Mine did that too until I installed the Motorrad Elektrik ingnition system...this of course is not the most economical fix, but is an excellent upgrade.

CanteenBoy screwed with this post 05-15-2015 at 12:20 PM
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Old 05-17-2015, 04:27 PM   #13
Rockman OP
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Quote:
Originally Posted by Biebs View Post
"Ive tried leaving the fuel taps on overnight"

Were you trying to get gas in the crank case?? If you pull the dipstick you can add gas directly to the crankcase. Hope this solves your problem.

It was just an idle thought that there might be a little leakage past the taps flooding one cylinder. As it is taps dont leak and it doesnt matter if I leave them on or off.
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Old 05-17-2015, 04:31 PM   #14
Rockman OP
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Ok, forget all the stuff about ICU's, balancing carbs, fuel taps etc. I've worked out that it starts up ok with little or no choke,so its running a little rich at idle. Problem solved. Thanks all
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Old 05-17-2015, 06:00 PM   #15
ozmoses
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Quote:
Originally Posted by Rockman View Post
Ok, forget all the stuff about ICU's, balancing carbs, fuel taps etc. I've worked out that it starts up ok with little or no choke,so its running a little rich at idle. Problem solved. Thanks all




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