A puzzler - 08 GSA on one cylinder only

[ferguscawley]

Hi All

A buddy of mine asked me to service his 08 GSA with 40k miles on it. It was laid up for a few months on a trickle charger. He still started it occasionally and all was fine. Last time he started it it ran very rough and then wouldn't run at all.

Anyway I have done the following:

• Run it and identfied RH cylinder as the culprit - exhaust stays cold
• Adjusted valve clearances both sides - they were tight.
• Did a compression test - have over 200 psi per cylinder cold
• Replaced all 4 plugs
• Added fresh fuel
• Tested coils and replaced primary coil on RHS
• Removed injectors and cranked over - both injectors spray fuel in a similar fashion

After all that, it still ran like crap.

No fault codes on Gs911
Intake tubes / throttle bodies are well secured with no air leaks

• Removed and bypassed the fuel pump controller - still the same - runs like crap
• Fuel pump and strainer all look good and clean. No crap in tank

The really odd thing about this engine is, when I have it running on one cylinder, and I attached the vacuum guages, only the LHS cylinder is registereing any vacuum. RHS cylinder (while effectively running as an air pump) registers practically zero vacuum, even though piston speed is identical to the working cylinder.

Is there a potential timining issue here ?

How can I have excellent compression but no vacuum ?

@Steptoe - have you any experience with this ?

Many thanks

Fergus

 

[Pukmeister]

You tested coils but do you actually have a spark ?

 

[ferguscawley]

You tested coils but do you actually have a spark ?

Yes I have a spark

 

[Pukmeister]

Is the RH throttle cable seated correctly from throttle grip to cable splitter box and on to both throttle bodies, especially the cable end into the adjuster cup at the throttle body ?

 

[kirby morgan]

As above by Pukmeister.
Had exactly the same on a mates R1150rt yesterday.
Found to be the end of the cable had become detached from the spring loaded cam.
Look underneath the throttle body.
Reconnected and ran sweet.

 

[ferguscawley]

Is the RH throttle cable seated correctly from throttle grip to cable splitter box and on to both throttle bodies, especially the cable end into the adjuster cup at the throttle body ?

Yes. All good. One of the first things I checked. Will check at splitter box end just in case.

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[ferguscawley]

Is the RH throttle cable seated correctly from throttle grip to cable splitter box and on to both throttle bodies, especially the cable end into the adjuster cup at the throttle body ?

Well suck me sideways. Problem was at splitter box. RHS cable not seated properly.

I can only assume that owner went pulling and dragging at the cable and unseated it at the splitter box.

Thanks for the grounding chaps. Was beginning to think all sort of sh1te.

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[Slipperyeel]

This forum is priceless. In two hours, problem identified! Brilliant.

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[Pukmeister]

Does it run smoothly now, or do you need to rebalance throttle bodies?

Sounds like you know your way around a GS so I won’t patronise you with the “how to”.

Glad you got it sorted.

 

[ferguscawley]

Does it run smoothly now, or do you need to rebalance throttle bodies?

Sounds like you know your way around a GS so I won’t patronise you with the “how to”.

Glad you got it sorted.

I synced everything afterwards. She's sweet as a nut now.

I was going down a rabbit hole that was wasting time. Had the blinkers on as they say.

The plus side is I have checked everything on the bike now for him.

Thanks again chaps

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[ferguscawley]

Meant to upload this yesterday but got sidetracked....

Thanks again for forcing me to go back to basics

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[Pukmeister]

Always a joy when you get to help somebody out or save them from hassle.

 

[EVskiy]

This forum is priceless. In two hours, problem identified! Brilliant.

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Two weeks at he the dealership and a few £££ quid later half a bike would’ve been in bits and we need to take the engine apart. Result. Well done all.