Stubby v Standard can

[Steve B]

As I'm not too mechanically minded and know my limits on what I can and cannot do on my 1150, I recently took the bike to a independant mechanic for some work. After collecting the bike the mechanic, who has many years working on airhead BMWs, said he thought my bike was running lean due to the stubbie. He'd not seen a stubby on a BM before. My question is; do 1150s run leaner with a stubby as apposed to a standard can? I'd like to keep the stubby, if only to save some weight. Thanks for any opinions.

 

[alanbmwgs]

Have you checked the colour of the plugs after a good run ?

 

[jefformston]

I’ve had a stubby fitted to my R1150GS since 2005. Bike had done around 40k at that point, it’s now at 113k and runs fine. Plugs are always a healthy colour. So as far as I can tell it make little or no difference to the fueling.

 

[DrFarkoff]

As I'm not too mechanically minded and know my limits on what I can and cannot do on my 1150, I recently took the bike to a independant mechanic for some work. After collecting the bike the mechanic, who has many years working on airhead BMWs, said he thought my bike was running lean due to the stubbie. He'd not seen a stubby on a BM before. My question is; do 1150s run leaner with a stubby as apposed to a standard can? I'd like to keep the stubby, if only to save some weight. Thanks for any opinions.

You r mech has been exposed to years of carburation and Rich mixtures

1150 Mixture is controlled by the lamda and the Throttle position sensor

Is your TPS set correctly ? about 0.38 Volts measured between the rearmost red and white wire and ground with the ignition on

If you have your original Catalytic convertor the can is just really for decoration rather than noise reduction as the cat suppresses a fair bit of noise

 

[Udders]

If you want to save weight remove the mega heavy cat, put a Y piece in and put the standard end can back on and bin the stubby.

 

[Mzokk]

If you want to save weight remove the mega heavy cat, put a Y piece in and put the standard end can back on and bin the stubby.

Funny, I went the other way with mine at the start I had a Y piece and a standard can then went back to the Cat and a stubby about 40,000 miles ago. Mainly for the ability to fit a full size pannier on the left. I had no bother with either set up and no difference as far as i could tell in performance The bike has 82K on it now and when I change the plugs they are the same colour as they have always been. 2002 Single spark. BTW.

 

[Steve B]

Many, many thanks for all the detailed replies. Much appreciated. Think I just needed the reassurance primarily.
The mechanic did the valves and TBs (the main reason for him doing the work was having braided brake lines fitted. As I said, I'd prefer leaving it to someone who knows what they are doing) but he did say that he couldn't find the info on-line for the TPS baseline reading (Ohms/Volts ). Thanks for the info on this Dr Farkoff. I'll pass it on.
I'd fitted 1200 injectors and post-service, a John Gemi chip. I did have new plugs, but damned if I didn't leave them on the bench in the garage after leaving to take the bike in for the work, so don't know what my old plugs look like.

Can I ask what would be the reasons for the 1150 to run lean?
The bike only has 15k on it so not yet run in

Many thanks again for the collective information

 

[Mzokk]

I think from the factory the bikes were set up to run at 14.7 to 1 Air Fuel Ratio which is on the lean side and this is controlled by the Lambda sensor feeding info to the Motronic unit on a feedback loop. The chip you are fitting is likely to enrich the mixture slightly to 13.5 to 1 or there about. The good Dr would know more than I on that. It will run lean if there is a airleak on the stub connecting the throttle bodies to the heads but that will likely manifest itself as other rough running and an inability to balance the TB's and or pinking. I'd say if its running well there is not too much to worry about. As i say the Dr will know more than me.

 

[Paul Young]

It will run lean if there is a airleak on the stub connecting the throttle bodies to the heads but that will likely manifest itself as other rough running and an inability to balance the TB's and or pinking.

I was having some frustrating issues with this just recently and found that both o-rings had broken inside the inlet tubes from the airbox. The air leaks were slightly different on each side so the clue was that the adjustments needed were way out of sync.

 

[Steve B]

You r mech has been exposed to years of carburation and Rich mixtures

1150 Mixture is controlled by the lamda and the Throttle position sensor

Is your TPS set correctly ? about 0.38 Volts measured between the rearmost red and white wire and ground with the ignition on

If you have your original Catalytic convertor the can is just really for decoration rather than noise reduction as the cat suppresses a fair bit of noise

I do have the cat in place and I didn't think the bike, with the stubby, sounded loud at all.
Thank you for the TPS measurements. I'll pass them on to the mechanic (for future reference).

 

[Steve B]

You r mech has been exposed to years of carburation and Rich mixtures

1150 Mixture is controlled by the lamda and the Throttle position sensor

Is your TPS set correctly ? about 0.38 Volts measured between the rearmost red and white wire and ground with the ignition on

If you have your original Catalytic convertor the can is just really for decoration rather than noise reduction as the cat suppresses a fair bit of noise

I spoke with the said mechanic and discussed your comments giving him the volts measurement asking him if he could check the TPS. His only related comment was 'how can you measure volts if you disconnect the TPS'? I did say I hadn't a clue as...well, I hadn't a clue
He thought the measurement should be in Ohms. I decided to leave it alone because if he didn't know how to do it, I certainly don't.
Thanks again for your advice and information.

 

[DrFarkoff]

I spoke with the said mechanic and discussed your comments giving him the volts measurement asking him if he could check the TPS. His only related comment was 'how can you measure volts if you disconnect the TPS'? I did say I hadn't a clue as...well, I hadn't a clue
He thought the measurement should be in Ohms. I decided to leave it alone because if he didn't know how to do it, I certainly don't.
Thanks again for your advice and information.

I would be looking for a new mechanic!!!! Plug remains connected BUT You peel the rubber boot on the plug down off teh connector at its wider end this showing you the wires on the lower side

Then poke a long pin or a back probe up the rearmost wire from the bottom of the plug through to the TPS

you switch on the Ignition and take measurements ??

 

[theoneandonly]

I would be looking for a new mechanic!!!!

depends how old the mechanic is , i've worked with some who didn't know what points were.

 

[Steve B]

I would be looking for a new mechanic!!!! Plug remains connected BUT You peel the rubber boot on the plug down off teh connector at its wider end this showing you the wires on the lower side

Then poke a long pin or a back probe up the rearmost wire from the bottom of the plug through to the TPS

you switch on the Ignition and take measurements ??

 

[Steve B]

depends how old the mechanic is , i've worked with some who didn't know what points were.