R1100GS CO level and low rev hesitation

[beaky bike]

After what seems to be a successful balance and synch of the throttle bodies on my 1996 R1100GS all seems ok when I ride the bike and certianly better than it was last week but 2 problems remain. I cannot get my CO level below 4% when adjusting the POT (spent an hour on it this morning), and the bike hesitates when you go to pull away from a standstill. As you blip the throttle the revs drop slightly - almost like it wants to stall (and did once). Once you are moving all is good. Ideas, suggestions please.

 

[Timolgra]

After what seems to be a successful balance and synch of the throttle bodies on my 1996 R1100GS all seems ok when I ride the bike and certianly better than it was last week but 2 problems remain. I cannot get my CO level below 4% when adjusting the POT (spent an hour on it this morning), and the bike hesitates when you go to pull away from a standstill. As you blip the throttle the revs drop slightly - almost like it wants to stall (and did once). Once you are moving all is good. Ideas, suggestions please.

Try it with the yellow 'cat code' plug removed

 

[uncle dick]

Is oil change due? Could be fuel dilution.

What was TPS voltage after you balanced it? Check the CO as you slowly increase throttle. Adjusting TPS will greatly vary how the mixture changes at low throttle openings.

If the bike's done any reasonable mileage, getting the throttle bodies overhauled by Scriminger will make a big difference to low speed running

 

[uncle dick]

Just noticed it's a '96 bike. If you still have single cable then ditching it is a good mod.

 

[Timolgra]

If the bike's done any reasonable mileage, getting the throttle bodies overhauled by Scriminger will make a big difference to low speed running

Long way from New Zealand

 

[ahutcheon]

Long way from New Zealand

Yep, but what are the alternatives? My throttle bodies are getting progressively noisier (44k miles), wondering whether one winter soon I'm going to have to post them to Mr S and stick a kiwi in each inlet 'till they come back.

 

[beaky bike]

Is oil change due? Could be fuel dilution.

What was TPS voltage after you balanced it? Check the CO as you slowly increase throttle. Adjusting TPS will greatly vary how the mixture changes at low throttle openings.

If the bike's done any reasonable mileage, getting the throttle bodies overhauled by Scriminger will make a big difference to low speed running

Oil change last done 3000kms ago. What is the 'fuel dilution' you mention? Have not checked the TPS voltage yet - bit shy of going near it to be honest but will have a go.

CO increases slowly as throttle is opened.

Was looking at getting the throttle body bushing overhaul kit from Dan and doing these myself this winter.

Can the throttle cable be retrofitted on a '96' bike to the later style from '97' onwards?

Bike only completed 25000kms, I have had it for 12 months.

 

[MattW]

Yep, but what are the alternatives? My throttle bodies are getting progressively noisier (44k miles), wondering whether one winter soon I'm going to have to post them to Mr S and stick a kiwi in each inlet 'till they come back.

There has to be a machine shop in NZ that could rebush your throttle bodies. I've read on ADV from people who've done this themselves so it must be possible. If I was as far from Scriminger as you are, I'd have a go myself with my lathe.

I'm fairly sure there must be some NZ laws against using Kiwi's as throttle bodies. When we were there I got the feeling they'd have locked us up for looking sidways at a Kiwi

 

[beaky bike]

Just checked the TPS voltage and it was 0.289 volts so somewhat different to what is stated in some of the discussions I have seen on this forum. Have now reset this reading by rotaing the TPS to 0.390 volts and rebalanced and synchronised the throttle bodies. Will take it for a ride tomorrow and see if I have succeeded in solving the problem or made it worse.

 

[ahutcheon]

There has to be a machine shop in NZ that could rebush your throttle bodies. I've read on ADV from people who've done this themselves so it must be possible. If I was as far from Scriminger as you are, I'd have a go myself with my lathe.

I'm fairly sure there must be some NZ laws against using Kiwi's as throttle bodies. When we were there I got the feeling they'd have locked us up for looking sidways at a Kiwi

Is it just a re-bush of the pivot points? Given the things that can be made out of no. 8 wire, I should probably start by trying a few local engineering shops.

As for kiwi misuse, Wildlife Act 1953 would get me for a start. Stoats, possums and rabbits are all unwelcome here, maybe one of those would work?

 

[Shep]

If you have left the bike standing for a few months then started it up on the old unleaded fuel, you may have messed up the spark plugs, classic symptoms IME is a hesitation on in initial throttle openings.

No idea why it happens, its always tempting to start the bike on old fuel after a layup, it will start ok but starts to run rough after a few miles on the old fuel. The only remedy IME is fresh fuel then new plugs.

HTH

Shep

 

[MattW]

Is it just a re-bush of the pivot points? Given the things that can be made out of no. 8 wire, I should probably start by trying a few local engineering shops.

As for kiwi misuse, Wildlife Act 1953 would get me for a start. Stoats, possums and rabbits are all unwelcome here, maybe one of those would work?

You can actually buy a rebuild kit from Bing - with these it's pretty much a diy job (or straightforward for a good bike mechanic / engineer). You'll probably find that the shafts are worn too so you'll need to change them. By all accounts, the hardest bit is removing the old bushings - most people screw a tap into the old bushing and use it as an extractor (this is what Scriminger did with mine - you could tell as he included all the old stuff he'd changed out when he sent back my TB's).

A couple of threads to get you going:

http://www.bmwmoa.org/forum/showthread.php?t=54960
http://www.advrider.com/forums/showthread.php?t=248583
http://largiader.com/tech/tb/

A stoat would probably be a good fit in a GS inlet. We had a pair have a fight right in front of our towels on the beach when we were on South Island! We reported them to the local ranger (also our campsite owner). We only saw a Kiwi in a sanctuary when we were over there, although we heard them at night when we were staying in a remote cabin in Abel Tasman. My other half picked up some nice possum gloves.

 

[beaky bike]

Best thing you can do with a Possum is to turn it in to gloves, jumpers or socks. Always a bit messy though trying to get your foot up it's arse !

 

[Trullion]

You can tell if the bushes/spindles in the injector bodies are worn by starting the engine and then pressing against the cable pulley. If the noise goes there's some wear. Another (probably slim) possibility is that the pot itself is b*ggered. This happened to my 850GS. A crude test is to remove it then test the resistance with a multimeter as the screw is slowly turned. The value (in milliamps) should change. Unfortunately I have no info on what the values should be, but assuming it works you could try setting it to whichever value you can get that produces the lowest CO output. (Offhand I can't remember whether you turn the screw clockwise or anticlockwise to weaken the mixture - I thinK the latter, but could be wrong). In my case the range produced was nowhere near that of a second-hand one Motorworks kindly sold me on a trial basis, which cured the rich running at low throttle openings. Mine never had a cat code plug of any colour from new.

Hope this helps.

 

[Trullion]

Sorry, I meant ohms, not milliamps.........

 

[Stewart H]

After months of messing around with a not very good CO meter I found a gem here in the archives of a chap who gives some values for setting the CO pot using a multimeter set for resistance, I set up my spare pot to 873 ohms and the bike runs well, it may help as a starting point if nothing else.

 

[uncle dick]

You can actually buy a rebuild kit from Bing - with these it's pretty much a diy job (or straightforward for a good bike mechanic / engineer). You'll probably find that the shafts are worn too so you'll need to change them. By all accounts, the hardest bit is removing the old bushings - most people screw a tap into the old bushing and use it as an extractor (this is what Scriminger did with mine - you could tell as he included all the old stuff he'd changed out when he sent back my TB's).

A couple of threads to get you going:

http://www.bmwmoa.org/forum/showthread.php?t=54960
http://www.advrider.com/forums/showthread.php?t=248583
http://largiader.com/tech/tb/

A stoat would probably be a good fit in a GS inlet. We had a pair have a fight right in front of our towels on the beach when we were on South Island! We reported them to the local ranger (also our campsite owner). We only saw a Kiwi in a sanctuary when we were over there, although we heard them at night when we were staying in a remote cabin in Abel Tasman. My other half picked up some nice possum gloves.

I tried to get the Bing kits for mine but no-one in the UK could supply. May be different elsewhere...

 

[uncle dick]

Oil change last done 3000kms ago. What is the 'fuel dilution' you mention? Have not checked the TPS voltage yet - bit shy of going near it to be honest but will have a go.

If your bike (or car) is doing a fair bit of low speed running - especially with suspect fuelling - the unburnt fuel will find its way past the rings and into the sump. Sounds like bollox but it's true. The vapour from this will get sucked back into the engine via the breather system meaning that you have to weaken the mixture right off to get your exhaust CO right. When emissions testing first came in for car mot's it was a common fix to change the oil rather than adjust anything.

CO increases slowly as throttle is opened.

Try adjusting the TPS so it stays as constant as possible. Fiddly, but time well spent.

Was looking at getting the throttle body bushing overhaul kit from Dan and doing these myself this winter.

Your choice but I'd happily go back to Scriminger.

Can the throttle cable be retrofitted on a '96' bike to the later style from '97' onwards?

Yes, buy the later cables and splitter box - which sits under the ABS unit. The left hand handlebar control needs a slight mod to fit the later 'choke' cable and you might need a very small spacer on the RH throttle body (cut 2mm from the end of the old cable) just to get the adjustment right.

This is an excellent mod - less than 2 hours and transforms the bike.

Bike only completed 25000kms, I have had it for 12 months.

Others here have suggested how to check the spindles for wear and TBH yours should probably be ok at this mileage. Did mine at 93000m.

Dick

Sorry, just realised I messed up the 'quote' function but I guess you'll work it out

 

[Smug]

After what seems to be a successful balance and synch of the throttle bodies on my 1996 R1100GS all seems ok when I ride the bike and certianly better than it was last week but 2 problems remain. I cannot get my CO level below 4% when adjusting the POT (spent an hour on it this morning), and the bike hesitates when you go to pull away from a standstill. As you blip the throttle the revs drop slightly - almost like it wants to stall (and did once). Once you are moving all is good. Ideas, suggestions please.

If you let the bike idle for too long it will run much hotter than when you are travelling and give you a false Co reading. Tricky to set up an aircooled engine without cooling fans.

 

[beaky bike]

After months of messing around with a not very good CO meter I found a gem here in the archives of a chap who gives some values for setting the CO pot using a multimeter set for resistance, I set up my spare pot to 873 ohms and the bike runs well, it may help as a starting point if nothing else.

Just checked the resistance of the CO POT and this goes from 0 ohms to 1k ohms over about 14 turms so I would say that is is working ok. Have set it up for 875 ohms as you have mentioned. Seems to run fine so now just need to take it to my friendly garage this week to get it on the CO analyser. Last time I had a go at setting the CO value I found that even the slightest adjustment of the POT made quite a bit difference. ie
1/16th turn would take it from 4% to 9% CO.

Thanks for the help.