BMW K bikes (Bricks)


You are not connected. Please login or register

View previous topic View next topic Go down  Message [Page 1 of 1]


1Back to top Go down   fuel in tank over heating Empty fuel in tank over heating Mon Sep 07, 2015 12:47 am

rawdonball

rawdonball
Gold member
Gold member
A have a German Mate riding an F800GS (??) - clockwise from Perth around Oz. I think he has till Christmas. He started having problems when he got as far North as Mount Magnet - he says he thinks it is the fuel pump and it sounds like it might be heat related.

This prompts me to ask a question I've had in mind for yonks - why is the fuel heating worse on some bikes than on others?

A BMW guru South of Brisbane told me the early K100 introduced in Oz experienced these problems regularly and OME cured it by fitting up-rated fuel pumps....

The logic isn't clear to me - why would circulating more fuel increase the heat loss more than the heat pick-up?

Unless the change to pump volume delivery was linked to return fuel being discharged into the air space in the tank as opposed to being via the old type non return valve which is under liquid most of the time?? I can imagine that this might then have resulted in the non wetted  (upper) part of the tank being able to contribute more to hear loss...

Any interest out there as regards batting this one around a bit?


__________________________________________________
'88 K100RT, '86 K75C, '05 Yamaha TTR250
    

2Back to top Go down   fuel in tank over heating Empty Re: fuel in tank over heating Mon Sep 07, 2015 1:24 am

Rick G

Rick G
admin
admin
AFAIK all the bricks were prone to it,my K1100 was so bad that I put a small cooler in the front on the grill in the return line.
Insulation around the lines helps as well as keeping the tank full as possible.
Aluminium foil crumpled around them, lots of layers and as wrinkled as possible for lots of area. Clark Rubber has rubbery insulation that is split for easy application, use white zip ties as they dont absorb the heat as much.


__________________________________________________
"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 1999 K1100 LT with a Big Block 1200
    

3Back to top Go down   fuel in tank over heating Empty Re: fuel in tank over heating Mon Sep 07, 2015 1:39 am

rawdonball

rawdonball
Gold member
Gold member
Aren't the white cable ties prone to UV attack?

I do hope other forum members will not be side tracked by cable tie and perhaps 'blinker fluid' issues....


__________________________________________________
'88 K100RT, '86 K75C, '05 Yamaha TTR250
    

4Back to top Go down   fuel in tank over heating Empty Re: fuel in tank over heating Mon Sep 07, 2015 1:44 am

indian036

indian036
Life time member
Life time member
rawdonball wrote:Aren't the white cable ties prone to UV attack?

I do hope other forum members will not be side tracked by cable tie and perhaps 'blinker fluid' issues....
UV will attack white cable ties, but until they fall off, they will reflect heat better than black ones. (Just don't tell Olaf, and especially, photoshop them out of any pictures.)

Given that the blinker fluid ducts pass near the tank for part of their passage, carrying away some heat may be an undocumented benefit. When did you last change yours?

Bill


__________________________________________________
1985 K100RT  VIN 0028991  My original Very Happy ROB the Red Old Bike   (Historic rego)
1985 K100RT  VIN 0029036  BOB the Blue Old Bike  (Historic rego)
1990 K100LT  VIN 0190452  Work in progress
1984 K100RT  VIN 0023022  Work needing lots of progress

1986 K100RT  VIN 0090542  Work needing lots and lots of progress
1993 K1100LT  VIN 0183046  Work in progress
1993 K75S  VIN 0213045  Tom the Triple (now on Historic rego too.)
    

5Back to top Go down   fuel in tank over heating Empty Re: fuel in tank over heating Mon Sep 07, 2015 2:15 am

rawdonball

rawdonball
Gold member
Gold member
As a proven 'hook line and sinker' guy, I feel it is already an over documented subject!

The back up fuel pressure relief valve incorporated in the fuel pump, strikes me as a potential source of variation. If one has a unit that relieves at a lower pressure than most - I presume this would mean that one would have to change the fuel filter more frequently but would it have an effect on the heat balance and therefore the equilibrium temperature of the fuel?


__________________________________________________
'88 K100RT, '86 K75C, '05 Yamaha TTR250
    

6Back to top Go down   fuel in tank over heating Empty Re: fuel in tank over heating Mon Sep 07, 2015 2:54 am

charlie99

charlie99
VIP
VIP
perhaps the question should be asked is your mate carrying stuff in a location that might contribute to heat retention around the tank - engine area ...front of tank and below ...maybe extra lights redirecting air flow away from the engine area ... tank bag with overhang etc ?

dave (tackler) has a similar machine ...I wonder if he has experienced similar

I would have thought that as heat affects the fuel that the viscosity would diminish affecting the pumping volume and pressure  .... in addition to the over pressure bypass relief valve never being able to be activated at higher temps  ...the machine might be running slightly leaner with the lower attainable fuel pressure and volume ...causing to run slightly hotter as well ..?? not to mention the absolute crap fuel out there ....89 ron at best I recon and quite possibly 10 % ethanol as well ...not the best

hope he is running slightly higher sae rated oils as well
\
was up in Townsville just a week or so ago ...nice 30 odd c near the coast.... cooking inland during the day .


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
1987 k100rs ########   "Red"  - (red sports rs TWB style )
1989 K100rt #009637   "Black Betty"  (naked rt ala Nigel , now sporting an rs main fairing )
    

7Back to top Go down   fuel in tank over heating Empty Re: fuel in tank over heating Mon Sep 07, 2015 3:59 am

rawdonball

rawdonball
Gold member
Gold member
Good points for me to forward to him thanks Chaz. 
When we were up in the Pilbara last week the two K bikes didn't seem to react to the fuel ever but the DR650 complained on a couple of occasions. 
Are you thinking that temperature related lowering of the fuel viscosity might reduce fuel pump volume to the point at which main FPR valve doesn't have to open at all to control pressure at a particular level of engine air intake. Further throttle opening would then result in leaner mixture and more heat (vicious circle effect)?


__________________________________________________
'88 K100RT, '86 K75C, '05 Yamaha TTR250
    

8Back to top Go down   fuel in tank over heating Empty Re: fuel in tank over heating Mon Sep 07, 2015 4:06 am

rawdonball

rawdonball
Gold member
Gold member
This would perhaps explain why BMW may have adopted the option of up-rated pumps as a solution...



Last edited by rawdonball on Mon Sep 07, 2015 9:55 pm; edited 1 time in total (Reason for editing : Auto edit caught me out)


__________________________________________________
'88 K100RT, '86 K75C, '05 Yamaha TTR250
    

9Back to top Go down   fuel in tank over heating Empty Re: fuel in tank over heating Mon Sep 07, 2015 5:11 am

charlie99

charlie99
VIP
VIP
the fpr would still be working ...kind of  ...flow will be reduced (and cooling effect as high pressure becomes low pressure, through a valve of sorts ) possibly near boiling on the way back to the tank by proximity and slow flow ...but severe lag in maintaining pressures is what in thinking rawdon ...especially at some kind of throttle opening speeds and delivery to the injectors ...but you got the drift I guess

you never really know what has happened during the assembly process ...could the return line be routed the wrong side of an interference ...had a mate recently with a brand new bike fail completely 16 k s out in the bush deep valleys

the assembler had routed the pump power cables across - close to the exhaust .....didn't take long to burn through the plastic resulting in pump failure ..blown fuse that could not be fixed ...dead $14,000 bike after 18 ks ...no phone works out there  and dickhead left the handheld radio  in the car
in the haste to test it all out

/

do you think that there maybe a possibility of picking up some air con refrigerant insulation pipe stuff  to overlay the fuel lines ...and installing it ...might help a little and cheap as anything to buy

just another thought ...some recent vehicles have an integral fpr in the pump housing ...so just insulating the pressure line may help on its way to the injector ....cant do anything about the accumulated heat if this is the case ...but to free up the cool air feed around the tank ? plastic panel air redirection maybe ????





good luck


__________________________________________________
cheezy grin whilst riding, kinda bloke ....oh the joy !!!! ...... ( brick aviator )

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%O
'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
1987 k100rs ########   "Red"  - (red sports rs TWB style )
1989 K100rt #009637   "Black Betty"  (naked rt ala Nigel , now sporting an rs main fairing )
    

10Back to top Go down   fuel in tank over heating Empty Re: fuel in tank over heating Mon Sep 07, 2015 6:02 am

AL-58

AL-58
Life time member
Life time member
My first K was an 85 K100RT.  The fuel would boil with monotonous regularity once it got about half tank on a hot day.  Generally I was glad to get off the bike anyway at the time (I dont like heat).  I'd also heard about the uprated pump being the answer.

Re the blinker fluid issue, how much does the viscosity of the fluid affect the blink rate and do you need a special viscosity fluid if using LED blinkers?

Al


__________________________________________________
'93 K1100LT
'08 F650GS (798cc)
'19 R1250RS

+ another boxer engined motorcycle and sidecar

"When I'm too old and too foolish to handle a sidecar I'll buy a Sportsbike"

fuel in tank over heating K-dogs10
    

11Back to top Go down   fuel in tank over heating Empty Re: fuel in tank over heating Mon Sep 07, 2015 9:00 am

rawdonball

rawdonball
Gold member
Gold member
Even the fifth year I spent trying to get through a four year degree is no help to me on the  blinker fluid issue....

Can we not get an electrical boffin somewhere to compare the current draw of fuel pumps with and without the fuel heating problem. The trouble is that there are too many variables like fuel viscosity and ambient temperature


__________________________________________________
'88 K100RT, '86 K75C, '05 Yamaha TTR250
    

12Back to top Go down   fuel in tank over heating Empty Re: fuel in tank over heating Mon Sep 07, 2015 10:50 am

92KK 84WW Olaf

avatar
Life time member
Life time member
I reckon the fuel lines, being directly behind the radiator and continuously circulating will eventually bring the fuel temperature up to ambient temperature behind the radiator. At 35c outside temperature and coolant at about 90c it has to be between the two, in slow traffic the radiated heat from the engine also increases it. As the level drops fuel is circulated more and the effect of the cooler fuel in the tank is surely lessened. Fuel in tank is cooler but can't fall below the same 35c.

Add a tank bag and there is even less cooling of the fuel in the tank.

A fuel pump in good condition will have less friction and therefore less heating. Other option is the often mentioned fuel cooler.


__________________________________________________
1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011157 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 58,200 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 51,800 miles.
1983 K100RS 0004449 Odette R100 colours 58,000 miles. Sprint fairing now 63,390 miles

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

Sponsored content


    

View previous topic View next topic Back to top  Message [Page 1 of 1]

Permissions in this forum:
You cannot reply to topics in this forum