Throttle/fuelling issue?!

Bayram

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Cumbria, England
2004 GS. Nice fresh oil and filter and a new air filter (just to remove these as possible culprits). In neutral it revs up absolutely fine and in fact if I use less than about 1/3 throttle it'll rev all the way too (bit weird to rev a bike so high under small throttle!). But at around 3-4k revs if I open the throttle more than about 1/3 the bike stutters and lurches and doesn't really accelerate at all. Backing off the throttle but allowing the revs to rise again and it seems fine (or slipping the clutch), it is only when in gear and with larger throttle openings.

Any ideas on something I can easily check myself before I have to succumb to paying a garage?! Thanks very much.
 
Possibly throttle cables have frayed and causing sticking renew both and and all will probably be resolved. Had the same prob and this was the cure.
 
My money would be on primary coils breaking down.

I agree with the above comment. Primary coil.it'll run ok at small throttle opening to a certain amount of revs then with a wider opening it'll stall and splutter. Been there done that.
 
I agree with the above comment. Primary coil.it'll run ok at small throttle opening to a certain amount of revs then with a wider opening it'll stall and splutter. Been there done that.

Agreed, first place I would go. Plenty of threads on here where to by replacements rather than the ridiculously expensive BMW ones.
 
Thanks very much for the advice folks. Can anybody suggest how to test the ignition coils? I have a multimeter. Would be good to work out which one rather than replacing them all, as they seem crazy expensive! Cheers
 
Thanks very much for the advice folks. Can anybody suggest how to test the ignition coils? I have a multimeter. Would be good to work out which one rather than replacing them all, as they seem crazy expensive! Cheers

I replaced both of mine when one was packing up. Just thought that at near 100.000 miles the other one was likely to go soon as well. I have both of my old ones still in the garage somewhere. I think you're a bit far away to swap one over to see which is failing. There are cheaper options but I just bought from BMW, the originals lasted well tbh and I couldn't see the point in trying to save 40 quid to have them not last as long again.
 
Thanks very much for the advice folks. Can anybody suggest how to test the ignition coils? I have a multimeter. Would be good to work out which one rather than replacing them all, as they seem crazy expensive! Cheers

You could try disconnecting the secondary coils then start the bike. It should then be obvious which one is failing.
 
If the op decides not to buy OEM, I can safely say it's way more than 40 quid you'll be saving...

More like 120 quid saving if you buy two... Sorry Gazza

And that's with the very same OEM items, not copies. Beru coils.

Sent from my SM-G975F using Tapatalk
 
If the op decides not to buy OEM, I can safely say it's way more than 40 quid you'll be saving...

More like 120 quid saving if you buy two... Sorry Gazza

And that's with the very same OEM items, not copies. Beru coils.

Sent from my SM-G975F using Tapatalk

Okey, so you can buy a new primary coil for just £20.00 each. My BMW ones were just £80.00 each from Wollaston's.
The cheapest I could find back then we're about £50.00 each. Good saving then.
 
Okey, so you can buy a new primary coil for just £20.00 each. My BMW ones were just £80.00 each from Wollaston's.
The cheapest I could find back then we're about £50.00 each. Good saving then.
Thanks to someone in here, I went to sparkplugs.co.uk....

And thanks to Ian in here, he gave all the corresponding codes between Beru/NGK/Champion. The letter being Beru units with a champion sticker over it!

I'll try and find the post

Here you go: https://r.tapatalk.com/shareLink/to...&share_fid=19781&share_type=t&link_source=app

20200930_112928.jpg

Sent from my SM-G975F using Tapatalk
 
It was Waggy who have the tip to use sparkplugs.co.uk

Thank you Waggy! Superb tip!

Sent from my SM-G975F using Tapatalk
 
Thanks very much. I tried a new secondary coil as the plug was so filthy (did all the plugs as well) but that hasn't cured it. Will try changing the rest of the coils!

On a slightly different note, once I've got this misfire sorted what do you guys think the bike is worth? It's cosmetically quite tatty and the left hand panels are held on with cable ties (!) after the wind took them back and broke the fixings (NOT dropped). I'm not sure I have the time to ride so much these days sadly.

Cheers
 
Quick update: changed all the coil packs with Champion ones (thank you Slipperyeel you saved me a load!) and it’s back on form. Thanks very much for all the advice on here. Very useful!

Now, must be time to ride again soon...?
 


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