BMW K bikes (Bricks)

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MartinW


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Last summer three of us did the Paul Bellthorpe memorial motocross ride on a really hot day. The Bricks got a real workout on what is a vey hilly rough four wheel drive track. Both Paul and Mick complained of excessive tank temperature while mine was still comfortable. After running the heat shield for 2 years with no more overheating problems, I decided to build a Mk 2 version to fix a inherent problem with the Mk1 version. 

While the Mk1 version cured the overheating problems, it added a couple of problems. In order to balance the throttle bodies/idle adjust the fuel rail with injectors has to removed and the heat shield removed. You then have to refit the rail/injectors and balance the throttle bodies, and then remove the rail and refit the heat shield. 

At the moment I'm in the process of doing a modified heat shield that is in two pieces the bottom part slides under the rail and the top half screws onto the tabs on the bottom half via Nutserts. While the bottom part of the shield will still be fixed the top half will be removable allowing access for maintenance. If it works I'll post some pictures, it's in a design as you build stage at the moment.
Regards Martin

    

MartinW

MartinW
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Pictures of the Mk 2 version at this stage. The Mk1 was made using .6mm aluminium the Mk2 uses 1.5mm aluminium. It just requires the mounting tabs to be shortened and a bit of filing, polishing and cutting the foam insulation to fit. I've decided to bolt the two parts together with three 4mm bolts into Nutserts. Hopefully I'll finish it and mount it early next week.
Regards Martin.
Overheating Fuel Solution Mk1 & New Improved Mk2. - Page 2 P7230110
Overheating Fuel Solution Mk1 & New Improved Mk2. - Page 2 P7230111
Overheating Fuel Solution Mk1 & New Improved Mk2. - Page 2 P7230112



Last edited by MartinW on Wed Jul 22, 2020 7:34 pm; edited 1 time in total (Reason for editing : Added dimensions)


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K75s Hybrid
    

StandardK

StandardK
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Silver member
Patent Pending I hope...ingenious

Regards

Dan

    

jcd06

jcd06
New member
New member
Nice craftmanship Martin.

This is a picture of my solution.
The insulation prevents the fuel hose to get heated by the air coming from the radiator.
It worked well in 40 degrees ambient, driving about 80km/h. I can't tell what it does in traffic jams.

Overheating Fuel Solution Mk1 & New Improved Mk2. - Page 2 P2050010


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MartinW

MartinW
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Because of the heat sitting in traffic in Queensland summers I had to go a bit further. All under tank lines have been insulated with tight fitting thick foam insulation. The under side of the tank has been fitted with double sided reflective insulation. The Mk 1 version worked well and greatly reduced fuel temperature, so the Mk 2 version should hopefully work just as well.
Regards Martin.


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charlie99

charlie99
VIP
VIP
a good idea martin 
hope it works out ok


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

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OOverheating Fuel Solution Mk1 & New Improved Mk2. - Page 2 Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

MartinW

MartinW
Life time member
Life time member
Thanks Charlie hopefully, maybe, possibly fitted by Monday. Too many projects not enough time, I should never of retired.Overheating Fuel Solution Mk1 & New Improved Mk2. - Page 2 610153


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charlie99

charlie99
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VIP
yeah i feel your sorrow and understand the "no time" issue 

started another hair brained project myself , when a motor (broken ) and a frame (also in bad need of a LOT of TLC ) came my way for the right price care of Smithy and a local mate Alex 

just came to mind to explore a lot of the back roads that im unwilling to take Gerty down too far 

still to fix the motor but thats in hand but an awful lot of time spent on eliminating rust all over the frame and parts , the previous owners must have had a ball playing with it  before retiring it with a run out of oil (several times ) event , then parked it out in the weather for years 

just a taste of the progress 

Overheating Fuel Solution Mk1 & New Improved Mk2. - Page 2 20200610

Overheating Fuel Solution Mk1 & New Improved Mk2. - Page 2 20200711


Overheating Fuel Solution Mk1 & New Improved Mk2. - Page 2 20200712


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

'86 K100 RT..#0090401 ..."Gerty" ( Gertrude Von Clickandshift ) --------O%OOverheating Fuel Solution Mk1 & New Improved Mk2. - Page 2 Au-log10

'86 k100 rs.. #######..  "Fred " (f(rame) red ) ( Fredrick leichtundschnell ) - -
bits and pieces from many kind friends across the k100 world ...with many thanks ..
    

MartinW

MartinW
Life time member
Life time member
Overheating Fuel Solution Mk1 & New Improved Mk2. - Page 2 112350 Wow a blast from the past, and looking good. I have a soft spot for Suzie  two strokes, I raced TS125 Duster fitted with a OEM Suzuki  motocross kit in the early 70's. Followed by a TS 185 Sierra for trail riding. The DR's were pretty bullet proof, how many cc's? Beside Paul and Matt leading us astray I am trying to avoid dirt these days, although the Bricks do seem to cope well.
Stay safe regards Martin.


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K75s Hybrid
    

MartinW

MartinW
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Life time member
Yaaay finished and mounted. I didn't own or desire to purchase a Nutsert gun for three Nutserts so I used the bolt and slightly oversize nut method to attach the Nutserts. A bit of fettling was needed, but the unit assembled easier than the Mk 1 version. I didn't have to trim the insulation around the injector clips due to a tighter fit around the injector mounting cups. The whole unit was assembled on the bench greased with a bit of silicone grease on the "O" rings and it slid easily into place and bolted up with no problems. A slight bend had to be put on the lower shield to clear the injector electrical connectors and a corresponding bend placed in the top shield. The top shield was fitted with a piece of the doubled sided insulation glued to the back, and it was attached to the lower shield with non stainless steel  Allen bolts, which will be upgraded. Access to the idle screw and throttle bodies is now not a problem.
Regards Martin.
Overheating Fuel Solution Mk1 & New Improved Mk2. - Page 2 P7270116
Overheating Fuel Solution Mk1 & New Improved Mk2. - Page 2 P7270117
Overheating Fuel Solution Mk1 & New Improved Mk2. - Page 2 P7270118


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DadofHedgehog

DadofHedgehog
Silver member
Silver member
@MartinW wrote:Yaaay finished and mounted. I didn't own or desire to purchase a Nutsert gun for three Nutserts so I used the bolt and slightly oversize nut method to attach the Nutserts. A bit of fettling was needed, but the unit assembled easier than the Mk 1 version. I didn't have to trim the insulation around the injector clips due to a tighter fit around the injector mounting cups. The whole unit was assembled on the bench greased with a bit of silicone grease on the "O" rings and it slid easily into place and bolted up with no problems. A slight bend had to be put on the lower shield to clear the injector electrical connectors and a corresponding bend placed in the top shield. The top shield was fitted with a piece of the doubled sided insulation glued to the back, and it was attached to the lower shield with non stainless steel  Allen bolts, which will be upgraded. Access to the idle screw and throttle bodies is now not a problem.
Regards Martin.
Overheating Fuel Solution Mk1 & New Improved Mk2. - Page 2 P7270116
Overheating Fuel Solution Mk1 & New Improved Mk2. - Page 2 P7270117
Overheating Fuel Solution Mk1 & New Improved Mk2. - Page 2 P7270118
Following with interest. A propos of nothing at all, I seem to recall that water (liquid) cools 17,8 times better than air. This factoid implies that cooling the liquid components, if achievable, will lower overall system temperatures much more than cooling the air circulating around the system's surfaces.


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PRESENT:
1995 K75T.  I am the 3d owner.  Bought it in June 2019 with 6,242 miles on the odo.
1991 K100RS 4-valve attached to a 1990 Flexit sidecar. I am at least the 3d owner. Bought with 21,00+ miles on bike's odo.

PAST:
old (indeterminate age) Ural + sidecar
1997 Buell S3T Thunderbolt
1982 BMW R100CS
1974 Kawasaki KZ400
1970 Suzuki Titan
    

MartinW

MartinW
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Life time member
Dadof the MK1 did all the things that I wanted to achieve plus some. It no longer stalls on hot days in traffic, which was the goal I was aiming for. Secondly the tank temperature has been brought down a comfortable level which was a bonus. The aim of the Mk 2 version has now solved the maintenance access issues. And due to reduction of gaps in the insulation and the  aluminium thickness which has over doubled from .6mm to 1.5mm it should in theory insulate the rail a bit better. Unfortunately temperature testing will have to wait till summer as it is still winter here and we are experiencing a cold spell of 21C today. Also a side benefit of the new design it will allow me to experiment with reducing the height of the top part of the shield from it's height of 60mm down to various other heights.
Regards Martin


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Dai

Dai
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@MartinW wrote:we are experiencing a cold spell of 21C today.
You had to say that, didn't you? We're damn lucky if it ever gets that high even in mid summer!!!


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'83 K100 upgraded to K100RS spec, '87 K100RT
Others...
'78 Moto Guzzi 850-T3, '79 Moto Guzzi 850-T3 California,'93 Moto Guzzi 1100ie California
    

MartinW

MartinW
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Unfortunately we have rather a tough time in winter. But we don't complain and soldier on through it all, stiff upper lip and all that. Blizzard
Regards Martin.


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gabriel

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@MartinW wrote:Bob I used a laser temperature gun to determine the temperature of the tank and the fuel rail. I determined that the fuel was getting too hot when it would stall and die in traffic on 30C+ days to the point where it was dangerous and I nearly got rear ended, multiple times. The temporary cure was to run with a full tank of fuel which stopped the fuel from overheating or avoid traffic on 30C+ days. 30C + days on the main roads were never a problem.
Regards Martin.

Hi Martin

Is it possible your engine is overheating due to a faulty fan. Please check your fan and actually see it functioning correctly.
I appreciate the effort that’s gone into your solution, but wonder how much of an issue it is.
Take care.

Gabriel


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;BMW; 1984 BMW k100..frame number 6228?
    

MartinW

MartinW
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Gabriel the engine cooling is fine, the fan comes on when it's supposed to and I have an override switch fitted. I've never had a problem with coolant overheating. What happens in my case was fuel vaporization caused by heat build up on hot 30C plus days in traffic. After sitting at lights you'd go to take off and the engine would cough splutter and stall, or nearly stall. The cars behind you would be expecting you to take off and as a result of the stalling nearly rear end you.This would only occur at around 2/3 empty, the solution at the time was to run a full tank of fuel. 

Other Brick riders have suffered a variation in that the tank would become unbearably hot to touch. Quite a few members have fitted inline fuel coolers to alleviate the problem. I tried a fuel cooler but it only worked at speed didn't work in traffic. I'm a member of a local Trades Guild and one of the members is a heat engineer and after discussing the problem with him I came up with another idea. Rather than trying to get rid of the heat after the fact, don't let the fuel heat up in the first place. I ran the first heat shield for 2 years and it solved the stalling problem, and it also greatly reduced the tank temperature. The Mk 2 version now allows access for tuning.

BMW acknowledged that there was a problem and removed baffles from some bikes and insulated the fuel rails in others. If you have a Haynes Manual it is covered in the book under fuel and lubrication 6.9 part 13 titled Tank insulation. As stated all my fuel lines are insulated as well as the under tank. I've used a laser thermometer to record temperatures and the shield has reduced the rail and tank temperatures by more than half.
Regards Martin.
Overheating Fuel Solution Mk1 & New Improved Mk2. - Page 2 Fuel_t10


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Packo

Packo
Silver member
Silver member
I think we all agree that fuel overheating in the K series is an issue.
This is the way I "overcame" the problem, but before I go any further I must say I have not taken any temperature readings, but I do think that the tank is noticeably cooler on hot days. 
I inserted a "T" piece in the line from the tank to the fuel rail
One line then from the T to the fuel rail 
One line then from the T to the FPR
Blanked off the other end of the fuel rail
Theory being that most of the fuel will circulate from the tank thru the FPR back into the tank, the engine using only what is required out of the fuel rail. In conjunction with other methods like insulating fuel lines and tanks etc further cooling should be able to be achieved.
I have had this in place for 3 years now and seems to work ok but as stated previously I have no figures to back it up. I am not going to put it back to original to take temp readings but would be interested to hear findings if someone else could be bothered.
Sorry Martin , not trying to hijack your thread


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83 K100 HRD Outfit
77 R100RS
1992 K1100 Outfit
1983 K100
    

DadofHedgehog

DadofHedgehog
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@Packo wrote:I think we all agree that fuel overheating in the K series is an issue.
This is the way I "overcame" the problem, but before I go any further I must say I have not taken any temperature readings, but I do think that the tank is noticeably cooler on hot days. 
I inserted a "T" piece in the line from the tank to the fuel rail
One line then from the T to the fuel rail 
One line then from the T to the FPR
Blanked off the other end of the fuel rail
Theory being that most of the fuel will circulate from the tank thru the FPR back into the tank, the engine using only what is required out of the fuel rail. In conjunction with other methods like insulating fuel lines and tanks etc further cooling should be able to be achieved.
I have had this in place for 3 years now and seems to work ok but as stated previously I have no figures to back it up. I am not going to put it back to original to take temp readings but would be interested to hear findings if someone else could be bothered.
Sorry Martin , not trying to hijack your thread

That's pretty neat.


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PRESENT:
1995 K75T.  I am the 3d owner.  Bought it in June 2019 with 6,242 miles on the odo.
1991 K100RS 4-valve attached to a 1990 Flexit sidecar. I am at least the 3d owner. Bought with 21,00+ miles on bike's odo.

PAST:
old (indeterminate age) Ural + sidecar
1997 Buell S3T Thunderbolt
1982 BMW R100CS
1974 Kawasaki KZ400
1970 Suzuki Titan
    

MartinW

MartinW
Life time member
Life time member
There are a Kluster of us going for a four day ride so I'll get some temperature comparisons. But the real test will be in summer in traffic. I had a few spare 3D printed 75s badges in blue. I couldn't help myself so painted one black and mounted it on the upper shield to break it up. I need to get some more 1.5mm aluminium to make a couple of different height top shields to see if that makes any difference and I also want to paint one shield black.
Regards Martin.
Overheating Fuel Solution Mk1 & New Improved Mk2. - Page 2 Mk2_he10


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