Ticks over smooth, but doesn't Rev clean - Pops and Bangs 2004 Model GS1200

bluebossa

bluebossa

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Just bought this 2004 GS 1200 unseen and am trying to get ahead of a Diagnosis process for Fuelling...
It's had a new Oil/Filter and air filter, but not plugs fitted, also new Battery, starts on the button.
It also has a non OEM Exhaust bolt on called a LASER Duo Tech

Here's what the Seller says:

BAD POINTS FIRST:
STARTS INSTANTLY AND TICKS OVER SMOOTH BUT DOESN’T REV CLEAN. POPPING AND BANGING ETC. LIKE FUEL STARVATION BUT SEEMS BETTER WITH GENTLE THROTTLE

My Question: What process, where would you start to diagnose?

Does anyone know this Bike or it's history... couple of pics attached... I quite like the wrap...
 

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I'd start by checking everything is hooked up correctly. No loose connections on the fuel, air intake and exhaust.

If it doesn't smell like its overfuelling, then i'd say it's probably an air leak (air leaking in, after the MAF) causing the pops/bangs
 
Stick coils and or plugs

pull them and sniff them and see if you get bakelite smell off the coils ??

coils usually give bother under load but its an easy look at it
 
A very common problem are the main coils. Very very easy to check. Disconnect the connectors on both lower secondary coils on each side, leaving only the main coils connected. Start bike and see if it runs on both sides. Give it a couple of revs to see if they break down. If not firing on one side reconnect the secondary coil of that side and see if it now fires on that side..
 
DJ123 said:
I'd start by checking everything is hooked up correctly. No loose connections on the fuel, air intake and exhaust.

If it doesn't smell like its overfuelling, then i'd say it's probably an air leak (air leaking in, after the MAF) causing the pops/bangs
Click to expand...
Great thanks good checks...
 
DrFarkoff said:
Stick coils and or plugs

pull them and sniff them and see if you get bakelite smell off the coils ??

coils usually give bother under load but its an easy look at it
Click to expand...
Great thanks... can the coils be tested with a Multi Meter?
Will take em off and give em a sniff!
 
Steptoe said:
A very common problem are the main coils. Very very easy to check. Disconnect the connectors on both lower secondary coils on each side, leaving only the main coils connected. Start bike and see if it runs on both sides. Give it a couple of revs to see if they break down. If not firing on one side reconnect the secondary coil of that side and see if it now fires on that side..
Click to expand...
Thanks - great tip for troubleshooting, will do and report back...
 
Been a few threads about it or mentioned a few times at least. I'd go with the other suggestions first as they are a lot easier to do and it's good to know things are working properly anyway.

 
MWH said:
Been a few threads about it or mentioned a few times at least. I'd go with the other suggestions first as they are a lot easier to do and it's good to know things are working properly anyway.

Click to expand...
Thanks MWH - Bike arrives today so will be walking down each suggestion to try and chase down... Will be posting back here as I go for others in the future.
 
bluebossa said:
Great thanks good checks...
Click to expand...
So - update, fiddling with the Bike all afternoon today...

First thing I noticed was that the left hand throttle body wasn't seated in fully and was leaking air... the hose clip wasn't holding it so I replaced with another 60mm traditional clip and tightened up.
Seemed to run a lot better with this, though a brief ride showed that it is still Backfiring and running rough... Pics attached.

All other Rubber and Air components seem in good condition and intact.
The non standard exhaust is noisy and seems to offer very little back pressure, so my first thought is to go back to an OEM silence - they seem to cost circa £50 from Motorworks or eBay...

Next on my mind is the Coil check, not yet disconnected them and the bottom plugs.
I spent time though instead taking the GIVI box and Rack off the back.... will list for sale.

As well as removing the Engine Bull Bars - 3 out of 4 Bolts came out but one ******* sheared! So that's another job that will need an Engineering shop to take out the stud and refit somehow.
 

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Steptoe said:
A very common problem are the main coils. Very very easy to check. Disconnect the connectors on both lower secondary coils on each side, leaving only the main coils connected. Start bike and see if it runs on both sides. Give it a couple of revs to see if they break down. If not firing on one side reconnect the secondary coil of that side and see if it now fires on that side..
Click to expand...
Hi Steptoe, so as suggested I just disconnected the lower secondary coils on both side, via the connector plugs and tried to start the Bike, it wouldn't run or start at all without these connected.
I re-connected one secondary back up - it fired up on that side, same on the other side... ran on that side... with both secondary coils connected Bike fired up fine.

Does that indicate that both Main coils are shot?
Meaning I will need replacement Main coils.... x2
I disconnected the Main Coils via the plugs and the Engine runs on Secondarys and re-plugging them in doesn't seem to make any difference!

By Main coils, I'm assuming you mean the ones that go into the Cylinder head from the outside Centre Side of each bike? (see diagram attached)
The lower ones being the Secondary ones? ( which I can now get at due to the Bull Bar removal )

Thanks again .....
 

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MWH said:
Been a few threads about it or mentioned a few times at least. I'd go with the other suggestions first as they are a lot easier to do and it's good to know things are working properly anyway.

Click to expand...


ummm... I guess not secret but it does seem none of us know about it and never talked about on forums

just discovered the same set up on a Toyota Corrola... the massive white housing everything clips too is actually the fuel filter.... £40 quid for the Toyota part (that's twice the size)
 
Mistacat said:
Autodoc are a good price on Beru coils https://moto.autodoc.co.uk/beru/8348495
Click to expand...
Yep got them from there I think... though it was a badged website... £55 each, I also ordered a couple of Spark Plugs just in case it's them...
Seems odd that they are both dead and that the Bike still runs! I am wondering if its more the wiring loom rather than the Coils, but if its a common item then let's see if it sorts it and it fires on the Mains when replaced...

Did just take a little video of unplugging one while running... no change in tone at all.

 
botus said:
ummm... I guess not secret but it does seem none of us know about it and never talked about on forums

just discovered the same set up on a Toyota Corrola... the massive white housing everything clips too is actually the fuel filter.... £40 quid for the Toyota part (that's twice the size)
Click to expand...
I read about it on here, several times. That's how i knew about it.
 
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