R100/7 Reserve?

Claim Jumper · 09-23-2010, 08:07 AM

Hey Guys, quick question. So last night i am on the freeway and I decide to open up the old girl (I have been doing a lot of work on it lately and have not had a chance to do WFO yet). Anyway things are going great and around 95 indicated it starts cutting out like it is running out of gas so I slow down, go to reserve and pull over and put in 4.5 gallons or so. Does this sound right for a stock R100/7 gas tank?

Thanks

Big John Sny · 09-23-2010, 08:22 AM

That is about where mine kicks in.

Claim Jumper · 09-23-2010, 08:30 AM

Great. I haven't run many tanks through this bike and I have hard time believing that it really is ready for the open road. It does run down the road well. Is there any special procedure for the two petcocks for reserve?

Big John Sny · 09-23-2010, 08:46 AM

just think of it as having two reserves. The one on the right is supposed to be a bit spaller for some years but it seemed to be pretty close to the same size on my 77 when I relined the tank. It is easier for me to reach the left hand reserve while I am riding, so if I am already on reserve I run on the right reseve untill it starts to sputter and kick on the left, or get to a gas station, whichever happens first. I am sure there are different methods for everyone. I heard that you can run one side in the on position and when it kicks go to the other side at on, then use the reserves one at a time to have more like 3 reserves, but that just seems like too much effort for me.

Claim Jumper · 09-23-2010, 09:26 AM

Great, thanks for the info. The funny thing about these bikes is that everybody says how simple they are, but every procedure you do on them is complicated and cunfusing (at least to me). I think that is why guys stick with them and become such big fans, once they figure out some of this crap they figure they might as well get another one...at least that is what I plan on doing!

bmwhacker · 09-23-2010, 11:58 AM

Quote:

Originally Posted by Claim Jumper

Great, thanks for the info. The funny thing about these bikes is that everybody says how simple they are, but every procedure you do on them is complicated and cunfusing (at least to me). I think that is why guys stick with them and become such big fans, once they figure out some of this crap they figure they might as well get another one...at least that is what I plan on doing!

My experience: As soon as you think you "know it all" something else shows up that will stump you...at least for a while. Old BMW ownership can be a humbling experience.

Claim Jumper · 09-23-2010, 12:06 PM

Quote:

Originally Posted by bmwhacker

My experience: As soon as you think you "know it all" something else shows up that will stump you...at least for a while. Old BMW ownership can be a humbling experience.

Heck yeah, humbling but gratifying! I have loved my newer bikes they don't require much wrenching and to me that is much of the fun of motorcycles. With the R100/7 I know there is always stuff I can fiddle with/learn/improve.

BKMLWR · 09-23-2010, 12:44 PM

just be sure to use both sides once in awhile, they will get stickey and then not usable when that 1st reserve runs out....then you have to stop and lay the bike on its side for a second....

Rapid_Roy · 09-23-2010, 01:45 PM

Quote:

Originally Posted by Big John Sny

just think of it as having two reserves. The one on the right is supposed to be a bit spaller for some years but it seemed to be pretty close to the same size on my 77 when I relined the tank. It is easier for me to reach the left hand reserve while I am riding, so if I am already on reserve I run on the right reseve untill it starts to sputter and kick on the left, or get to a gas station, whichever happens first. I am sure there are different methods for everyone. I heard that you can run one side in the on position and when it kicks go to the other side at on, then use the reserves one at a time to have more like 3 reserves, but that just seems like too much effort for me.

It's not too much effort. I have to do it often when I ride with my friend with extended range tanks. I just reach down and flip the left side up. If I don't reach a gas station, I start to panic when I go on double secret reserve.

In fact, I did run out because he was pushing it in SD.

Rapid_Roy · 09-23-2010, 01:46 PM

Quote:

Originally Posted by BKMLWR

just be sure to use both sides once in awhile, they will get stickey and then not usable when that 1st reserve runs out....then you have to stop and lay the bike on its side for a second....

Oops, this too.
BTW, I have about 40k on my /7, and I have loved every minute of it (except when I hit that deer).

fishkens · 09-23-2010, 01:55 PM

Bad deer.

Bigger Al · 09-23-2010, 06:37 PM

Quote:

Originally Posted by bmwhacker

My experience: As soon as you think you "know it all" something else shows up that will stump you...at least for a while. Old BMW ownership can be a humbling experience.

It's worth it, though.

boxerboy81 · 09-23-2010, 09:05 PM

If this is a new bike to you, one of the things I'd suggest is to remove the tank, drain it, remove the fuel taps and inspect them.

Don't be surprised to see lots of red flaky stuff if you haven't already done this. That's the tank liner and one of those "they all do that sir" things.

I'd flush and clean the taps and the tank, and compare the lengths of the tubes. If they've been trimmed then you'll have a shorter reserve.

It's a 24 litre "S" tank right?
Fuel Tank Capacity: 24 litres / 6.34 gal US. 3.78 litres per usa Gall.
This is how I work it....
If the tap tubes are as they were when new (and not cut shorter) then you should run for 21 litres (5.5usGall) before res #1. I do right tap to res. then. Another 1.5litres of use to 22.5 litres (5.95usGall) to res #2. I do left tap to res. then...and look for a top up soon.
In reality it's a tad under 24 litres to empty. I think it's very difficult to actually squeeze the full amount in there.

On average I get about 15kpl, but that depends on how I'm riding at the time. Mountain riding with the rpm seldom below 5K the usage can go down to 10.5kpl. (about 40mpg)

So I figure that when I get to 1st res I have 45 ks absolute max distance to go, more if I'm careful with the throttle.

Over time with more use, your cerebral fuel gauge will know what your tank is doing re: fuel left and when to fill. You'll make your own calcs often enough.

Claim Jumper · 09-24-2010, 01:31 PM

Thanks for the info boxerboy. I had the tank off in the spring when i lined it with POR 15 and I rebuilt the petcocks then. At that time only one of the petcocks had an in tank fuel filter so I replaced them both.

Sniper X · 09-24-2010, 03:52 PM

HAHA!

I JUST posted a thread on this exact same question about a week ago! My 1978 R100RS goes on reserve right at 145miles....and there is at least 2 gallons left in the tank at that point. BTW when I fill up when it goes on reserve, almost exactly 4.5 gals go in!

09-23-2010, 08:30 AM	#3
Claim Jumper ^OP will work for knobbies Joined: Feb 2002 Location: Boise, Idaho Oddometer: 519	Great. I haven't run many tanks through this bike and I have hard time believing that it really is ready for the open road. It does run down the road well. Is there any special procedure for the two petcocks for reserve? __________________ ChrisGo 04 XB12R Firebolt 99 KX-250 77 BMW R100/7

09-23-2010, 08:46 AM	#4
Big John Sny Gnarly Adventurer Joined: Jul 2009 Location: Irving, Tx Oddometer: 466	just think of it as having two reserves. The one on the right is supposed to be a bit spaller for some years but it seemed to be pretty close to the same size on my 77 when I relined the tank. It is easier for me to reach the left hand reserve while I am riding, so if I am already on reserve I run on the right reseve untill it starts to sputter and kick on the left, or get to a gas station, whichever happens first. I am sure there are different methods for everyone. I heard that you can run one side in the on position and when it kicks go to the other side at on, then use the reserves one at a time to have more like 3 reserves, but that just seems like too much effort for me. __________________ 4 out of 3 people have trouble with fractions. 1999 Ducati Monster, 1979 XS650, 1989 Concours

09-23-2010, 09:26 AM	#5
Claim Jumper ^OP will work for knobbies Joined: Feb 2002 Location: Boise, Idaho Oddometer: 519	Great, thanks for the info. The funny thing about these bikes is that everybody says how simple they are, but every procedure you do on them is complicated and cunfusing (at least to me). I think that is why guys stick with them and become such big fans, once they figure out some of this crap they figure they might as well get another one...at least that is what I plan on doing! __________________ ChrisGo 04 XB12R Firebolt 99 KX-250 77 BMW R100/7

09-23-2010, 12:44 PM	#8
BKMLWR Wondering around... Joined: Feb 2009 Location: North Carmel Oddometer: 3,633	just be sure to use both sides once in awhile, they will get stickey and then not usable when that 1st reserve runs out....then you have to stop and lay the bike on its side for a second.... __________________ Sometimes I get off the bike before it has come to a complete stop.... Another Proud Small Scale Faker...... Praise You In This Storm LifeSong

09-23-2010, 01:55 PM	#11
fishkens Further... Joined: Nov 2009 Location: Seattle, WA Oddometer: 5,146	Bad deer. __________________ Forging ahead, down a false trail.

09-23-2010, 08:07 AM	#1
Claim Jumper ^OP will work for knobbies Joined: Feb 2002 Location: Boise, Idaho Oddometer: 519	R100/7 Reserve? Hey Guys, quick question. So last night i am on the freeway and I decide to open up the old girl (I have been doing a lot of work on it lately and have not had a chance to do WFO yet). Anyway things are going great and around 95 indicated it starts cutting out like it is running out of gas so I slow down, go to reserve and pull over and put in 4.5 gallons or so. Does this sound right for a stock R100/7 gas tank? Thanks __________________ ChrisGo 04 XB12R Firebolt 99 KX-250 77 BMW R100/7

09-23-2010, 08:22 AM	#2
Big John Sny Gnarly Adventurer Joined: Jul 2009 Location: Irving, Tx Oddometer: 466	That is about where mine kicks in. __________________ 4 out of 3 people have trouble with fractions. 1999 Ducati Monster, 1979 XS650, 1989 Concours

09-23-2010, 09:05 PM	#13
boxerboy81 Stay Horizontal Joined: Jul 2009 Location: Oz, Australia Oddometer: 1,642	If this is a new bike to you, one of the things I'd suggest is to remove the tank, drain it, remove the fuel taps and inspect them. Don't be surprised to see lots of red flaky stuff if you haven't already done this. That's the tank liner and one of those "they all do that sir" things. I'd flush and clean the taps and the tank, and compare the lengths of the tubes. If they've been trimmed then you'll have a shorter reserve. It's a 24 litre "S" tank right? Fuel Tank Capacity: 24 litres / 6.34 gal US. 3.78 litres per usa Gall. This is how I work it.... If the tap tubes are as they were when new (and not cut shorter) then you should run for 21 litres (5.5usGall) before res #1. I do right tap to res. then. Another 1.5litres of use to 22.5 litres (5.95usGall) to res #2. I do left tap to res. then...and look for a top up soon. In reality it's a tad under 24 litres to empty. I think it's very difficult to actually squeeze the full amount in there. On average I get about 15kpl, but that depends on how I'm riding at the time. Mountain riding with the rpm seldom below 5K the usage can go down to 10.5kpl. (about 40mpg) So I figure that when I get to 1st res I have 45 ks absolute max distance to go, more if I'm careful with the throttle. Over time with more use, your cerebral fuel gauge will know what your tank is doing re: fuel left and when to fill. You'll make your own calcs often enough. __________________ R100RS Gallery, over 1000 pictures... boxerboy81 screwed with this post 09-23-2010 at 09:12 PM

09-24-2010, 01:31 PM	#14
Claim Jumper ^OP will work for knobbies Joined: Feb 2002 Location: Boise, Idaho Oddometer: 519	Thanks for the info boxerboy. I had the tank off in the spring when i lined it with POR 15 and I rebuilt the petcocks then. At that time only one of the petcocks had an in tank fuel filter so I replaced them both. __________________ ChrisGo 04 XB12R Firebolt 99 KX-250 77 BMW R100/7

09-24-2010, 03:52 PM	#15
Sniper X De Oppresso Liber Joined: Jul 2006 Location: Central New Mexico, 7420ft above sea level Oddometer: 30,789	HAHA! I JUST posted a thread on this exact same question about a week ago! My 1978 R100RS goes on reserve right at 145miles....and there is at least 2 gallons left in the tank at that point. BTW when I fill up when it goes on reserve, almost exactly 4.5 gals go in! __________________ "I claim to be frightened of horses but do so only to get out of attending parades. It's peculiar but ...it works. The Horses get it. Straight Out Da Trailah!

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