Start/Idle problem 1150gs

Outbacksidecar

Guest
When I first start it up it coughs and farts, runs on one cylinder and goes on until its warm. Then it will idle properly, and run properly, although it is still a little rough just off idle.

I'll recheck the throttle body balance, but I dont think so. Sounds more like an ignition problem to me - plug or coil etc not firing properly until it is warm.

Any suggestions
Phil
 
sproggy said:
Coil pack if it's a twin-spark?
Click to expand...

Yes its a twin spark (2003, 67000 km). I read through various threads on the coils - mainly happens when the bike is warm it seems. My problem is when its cold, or even when first starting up after sitting for 1/2 hour or so. If I give it a bit of a rev when I start it up it seems to clear the problem.

What about spark plugs?? Could be originals as Ive never changed them since Ive had it (10,000 km). Any comments on the iridium plugs? Worth the money or not?


cheers, Phil
 
I replaced the plugs with BRISK and this eliminated minor surging at 4000 rpm.

From your symptoms, however, I would examine the entire length of the throttle cable on both sides. It may be hung up or a small stone trapped between the cable and wheel.

Maybe the throttle cable is too tight or loose? Does the "choke" make a difference?
 
Steptoe said:
Happens any time hot or cold.
Click to expand...

OK - so what are the symptoms? It seems strange to me that is should run ok once it is past the initial startup. I would have thought coils would have continued to give problems - but I'm open to correction.

Is there an easy way to check the coils? Nearest dealer is about 350 km away so I cant just drop in.

cheers, Phil
 
On many occasions that I have seen odd idle problems its usually an air leak. If it had been a Jap bike particularly a Yamaha I would have pointed you straight to carb rubbers but being new to BM's I don't know if this happens to them. Its a quick test either way if a bit messy so crab a can of WD40 and spray round the carbs/throttle bodies and if the idle changes you have an air leak.
 
Outbacksidecar said:
OK - so what are the symptoms? It seems strange to me that is should run ok once it is past the initial startup. I would have thought coils would have continued to give problems - but I'm open to correction.
Click to expand...

If the coilpack has gone on one side the secondary spark probably wouldn't be enough to ignite the mixture in a cold cylinder at startup so the engine would be trying to start on one cylinder. When the engine (and therefore inlet charge) is hotter the secondary spark might be enough to ignite the mixture. It still wouldn't run evenly, but it'd run better than when cold.

Try pulling the plug lead off one cylinder and see what difference that makes - if very little then it's faulty. Now re-fit it and try pulling the other one off - if there's a change in how the engine runs then that one's probably OK. Of course if you unplug the good one first the engine may just stop dead so you know it's the other side causing the problem.

All of the above assumes it's a coilpack problem, of course, but it's fairly common on twin-sparks.
 
Outbacksidecar said:
Is there an easy way to check the coils? Nearest dealer is about 350 km away so I cant just drop in.

cheers, Phil
Click to expand...

Simples.

Pull off the lower/secondary plug caps and see if it runs on just the two main caps.
If it runs on one side only reconnect the lower on the side not running and it should then run on both.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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