low idle and gas tank vacuum

[SCOOTRP125X]

My 04 R1150RT has 24,000 miles on it. I had the dealer do a valve adjustment and TB sync back in March at 21,000 miles. I have done the valves and TB sync myself in the past so I know the idle is supposed to be around 1100 plus/minus 100.

The past few weeks while sitting at stop lights I have noticed the idle being slightly low, around 1000 but sometimes it is normal at 1100.

I just returned from a 500 mile round trip today and on the way home I filled up the tank and noticed a vacuum sound when I opened the gas cap. I thought it could just be the gasket sticking to the tank but it happened again when I stopped for a second fill up. I also noticed my idle was around 900 and the engine sounded like it might die a couple of times at stop lights. It was very warm today with temps in the high 80's.

I was thinking about adjusting the idle with the BBS on the right hand side of the bike. I assume that is why there is a hole in the fairing on the right side and not the left side. The gas cap vacuum sound makes me wonder if there is some other problem causing my low idling. I replaced my air filter last week but I have not done anything else to the bike since last March.

Thanks in advance for any suggestions anyone can come up with.

Mark

 

[1aretea]

Check your charcoal canister and the three hoses coming off, I had the same problem with the vacum in the tank. I had little bits of charcoal pluging the lines. I did what is refered is "canisterectomy" basically you remove the can, the 2 hoses going to the throttle bodies and replace with a bolt in the old hose. For the vent from the gas tank, just route behind your right foot peg. Only down fall is you will smell the gas vapors some times.

 

[flars]

vacuum

Yep. Canister is clogged. You can either get a used one from Beemerboneyard, or a new one, or do a canisterectomy. If you replace the canister, you will have to blow air through all the lines, because the charcoal migrates up the hoses.

 

[SCOOTRP125X]

Thanks for the tips. Is the charcoal cannister the black tube on the right rear side of the bike? Are they easily replaceable? I would like to keep the bike stock.

 

[DrPaul]

To canisterectomize or not!

Are they easily replaceable? I would like to keep the bike stock.

Everywhere else in the world, "stock" BMWs have no charcoal canister. Lose the canister and prevent the same problem down the road. However, if you must replace it, let me know. I have three out in the shop.

 

[SCOOTRP125X]

Everywhere else in the world, "stock" BMWs have no charcoal canister. Lose the canister and prevent the same problem down the road. However, if you must replace it, let me know. I have three out in the shop.

Boy thats a tough decision. I like the idea of not having to deal with the canister ever again. I'll read up on it and think about it for a day or two. I can't work on the bike today since I have to be at work in a couple of hours. I think I have seen a canisterectomy on the ADV forum.

 

[kgadley01]

get rid of the canaster!!! when your done with which ever you decide to do and your idle is still low. you can adjust it by putting a screwdriver threw the hole on the right side and turning the BBS slightly to the left...

 

[pauls1150]

Be advised that if you adjust just the right-side Big Brass air screw, your throttle body sync is now mis-adjusted. Get a differential gauge (like the Twin-Max) and adjust both of them so you have a balanced vaccuum. You can verify the cable sync at ~2500 rpm while you're at it.
An erratic idle may also be caused by junky buildup in the idle air tube(s) restricting the flow. Pull the brass air screws out and examine their tips, and shine a flashlight down the holes. Clean the tips off with a paper towel (or preferably a "lint-free" cloth...) moistened with gas, and squirt a little carb cleaner down the holes. Be advised here that if the O-rings on the screws are cracked or deformed, they are not available separately, you have to buy the whole screw. But they're only about $6 each.

 

[pauls1150]

Also - You mentioned that your dealer adjusted the valves...
The factory spec is a bit too tight. I sent mine (also an '04 RT) to the sloppy side of .007 intake, and the sloppy side of .013 exhaust, per Rob Lentini's recommendations. It's a tiny bit noisier, but my bike starts easier, idles better, and spins up easier this way. It also helps ensure a proper vaccuum (and measurement thereof) at your idle test.
Valves must be adjusted "DEAD COLD"; an hour or two after running the motor isn't a good idea. There are lines on the cam sprockets - rotate the rear wheel (in 6th gear, Forward ONLY) to point these straight out horizontally, verify that both valves on that side have a little juggle, and that's where you measure & adjust if necessary.

 

[SCOOTRP125X]

Be advised that if you adjust just the right-side Big Brass air screw, your throttle body sync is now mis-adjusted. Get a differential gauge (like the Twin-Max) and adjust both of them so you have a balanced vaccuum. You can verify the cable sync at ~2500 rpm while you're at it.
An erratic idle may also be caused by junky buildup in the idle air tube(s) restricting the flow. Pull the brass air screws out and examine their tips, and shine a flashlight down the holes. Clean the tips off with a paper towel (or preferably a "lint-free" cloth...) moistened with gas, and squirt a little carb cleaner down the holes. Be advised here that if the O-rings on the screws are cracked or deformed, they are not available separately, you have to buy the whole screw. But they're only about $6 each.

Thanks for the tip on the BBS. I have adjusted my TB's enough to know that I dont want to screw up the balancing.

 

[SCOOTRP125X]

Also - You mentioned that your dealer adjusted the valves...
The factory spec is a bit too tight. I sent mine (also an '04 RT) to the sloppy side of .007 intake, and the sloppy side of .013 exhaust, per Rob Lentini's recommendations. It's a tiny bit noisier, but my bike starts easier, idles better, and spins up easier this way. It also helps ensure a proper vaccuum (and measurement thereof) at your idle test.
Valves must be adjusted "DEAD COLD"; an hour or two after running the motor isn't a good idea. There are lines on the cam sprockets - rotate the rear wheel (in 6th gear, Forward ONLY) to point these straight out horizontally, verify that both valves on that side have a little juggle, and that's where you measure & adjust if necessary.

I'll put your recommendations for valve clearance in my Clymer book for the next time I do the valves myself.

 

[rad]

Think simple, first. Just check your vent and overflow tubes down by your right foot peg. If they get clogged with road grime it can create the same symptoms you are experiencing.

 

[pauls1150]

Simple First is always right on! It can save many headaches and lots of grief.

For a wealth of tech articles, check out the Internet Riders at http://www.ibmwr.org/

 

[SCOOTRP125X]

Think simple, first. Just check your vent and overflow tubes down by your right foot peg. If they get clogged with road grime it can create the same symptoms you are experiencing.

Thanks. I was going to do that before pulling everything apart. The overflow tube from the gas cap area rusted on my last month and I used some florist wire and compressed air to clean it out. I did poke the wire up the vent hoses from under the bike in each tube before I figured out to blow compressed air from the top. Maybe I pushed some gunk up from the bottom of the canister vent hose to cause a clog.

 

[SCOOTRP125X]

caps

I read the IBMWR article on removing the canister. What are the "caps" that are used to cover the holes on the throttle bodies? Are they available at an auto parts store and what would I ask for?

 

[rad]

I read the IBMWR article on removing the canister. What are the "caps" that are used to cover the holes on the throttle bodies? Are they available at an auto parts store and what would I ask for?

Rubber nipple caps that go where the line was under each TB when removed. The size..?

Print the photo below and take it to the auto parts store. See the rubber cap on the bottom?

 

[SCOOTRP125X]

Rubber nipple caps that go where the line was under each TB when removed. The size..?

Print the photo below and take it to the auto parts store. See the rubber cap on the bottom?

Thanks for the picture. I did not get to the bike today, first thing tomorrow morning. Are the caps going on the nipples where I attach my TwinMax when I am doing a TB sync?

 

[pauls1150]

I believe the caps are 3/32"; they are the same ones as what is on the "older" K-bikes' vaccuum ports. P/N might be (?) 13 54 7 694 924.
I've had these slip off (due to age, rot, and/or vibration), so now I also cinch down a little tie-wrap around them so they can't slip off. The tie-wrap is sacrificial, and does need to be carefully cut off at the next TB sync.
If they slip off, you'll notice a higher idle speed; and you're now sucking unfiltered air.

 

[rad]

Thanks for the picture. I did not get to the bike today, first thing tomorrow morning. Are the caps going on the nipples where I attach my TwinMax when I am doing a TB sync?

yes

 

[DrPaul]

I read the IBMWR article on removing the canister. What are the "caps" that are used to cover the holes on the throttle bodies? Are they available at an auto parts store and what would I ask for?

1/8" rubber vacuum caps are readily available from most any auto parts dealer. Some riders have chosen to connect the two TB nipples with a piece of the tubing you have left after cannisterectomy. I would be interested to learn what proven benefit that interconnection provides. Anyone?