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nickw Big Brick Rider
Joined: 12 Aug 2010 Posts: 72 Location: Essex, VT USA
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Posted: Sat Sep 04, 2010 9:44 pm Post subject: K1100LT Fan replacement scheme |
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Hello:
I am new to this forum and have scoured the subject of K1100 OEM fan motor failures to the point that I have made a new fan mounting for an aftermarket (SPAL) fan the fits the envelope of my K1100LT and promises to fulfill the task of cooling without wasting my wallet on a replacement OEM fan assembly.
I have written a detailed explanation of the problem and my solution to an expensive replacement. This is in the form of Word document and I will be glad to post it or send it to anyone interested to get some feedback on your thoughts.
If anyone can tell me how to post the document, please do.
Thanks,
Nickw _________________ "It's not what people know, it's that they know so much that just ain't so!" (Apologies to Will Rogers)
93 K1100LT
(2) 79 Suzuki GS850's (In limbo)
65 Triumph TR6S/C ( sold)
2009 Suzuki SV650
2009 Suzuki DL650 |
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Flying Duck PsyKotic Waterfowl
Joined: 27 Jan 2005 Posts: 10082 Location: Bumf***, WA
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Posted: Sat Sep 04, 2010 11:57 pm Post subject: |
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Ever heard of cut-n-paste? _________________ 93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE |
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SugarHillCTD Site Admin
Joined: 10 Oct 2007 Posts: 4240 Location: Now in Eastern Pennsylvania
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Posted: Sun Sep 05, 2010 6:52 am Post subject: |
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Nickw,
First of all, WELCOME to the nut house. Essex, Vt? You are in Frank's Motorcycles backyard. We are just about 2 hours straight east in NH.
Good luck with your repairs.
John _________________ John & Cathy
'92 K100RS4V Pearl White SOLD
'04 K1200GT
IBA Several-SS1k, BBG, 50CC NYC to S.F. |
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miKeinWIs Mad Brick Rider
Joined: 29 Jun 2009 Posts: 143 Location: Birchwood, WI
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Posted: Sun Sep 05, 2010 7:20 am Post subject: |
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Welcome. Never mind the duck--he's a computer geek.
I am interested in what you came up with. After the fan blade slipped forward and holed the original radiator, the rad repair lasted only 2500mi (albeit it DID get me to and back from the Black Hills) A used rad is working fine but I have found a 7" car fan for winter install.
After pulling the rad twice in 5 weeks I'm a little tired of it all.
Looking forward to your report
Mike _________________ '97 K1100LT
Bought 6/30/09 w/26,750 miles |
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Rafal Flying Brick Rider
Joined: 05 Jan 2009 Posts: 257 Location: Wroclaw, Poland
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Posted: Sun Sep 05, 2010 12:15 pm Post subject: |
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Hello!
I have replaced the radiator 3 core and fan to SPAL type recently. I have discovered that 7" fan is a bit too big. A lot of fan housing cutting and precise fitting between frame pipes - nasty job . Of course with narrow radiator is not an issue. IMHO 6" would be perfect for 3 core radiator.
Best regards _________________ Rafal
K1100RS is a real beast (in Marrakesh Red)
K75S is a real beauty - she has gone , but not to far .
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nickw Big Brick Rider
Joined: 12 Aug 2010 Posts: 72 Location: Essex, VT USA
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Posted: Sun Sep 05, 2010 3:40 pm Post subject: |
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I am not totally without faculties, it isn't obvious to a noobie where things go therefore i ask.
The file is about13M, but here goes: (looks like the pix didn't paste, how about a little help, Duck?
1993 K1100LT @ 59,887M August 26, 2010
I recently purchased this bike from its second owner who had purchased the unit @ 5,000 miles and used it regularly until two years ago when he bought a GS1150. The bike had been stored inside in a heated location and looked and rode very well with a new battery installed.
I rode it approximately 100 miles when I encountered an overheating condition in slow cruising around town. I was less than ¼ mile from home, so I parked it and waited for it to cool.
Being new to K-Bikes, I inquired of my local dealer who said that it was probably the fan and that would be the smart place to start, as he said: “Its either the fan is stuck or the fan impeller has come loose on the shaft and rubbed its blade tips into the radiator causing pinhole leaks.”
Being a vintage bike mechanic by trade (The Classic Bike Experience), I felt “how hard could it be to take the fan out?
Two weeks later, I’m a lot smarter and a lot more informed, thanks to K11OG, which was the first place I went after talking with a friend K-Biker.
I’m sure the stories of anti-theft systems are legion, but if you are determined not to do any damage (I read the MaxBMW price fiches) you will proceed slowly.
It took me two weeks of part-time plodding, but I got everything apart without breaking anything, and found this:
Pic 1
This is a close-up of the brush holders which have both partially melted due to high currents experienced when the bearings became stiff from (age, lack of lube, whatever). The fuse for the fan had NOT blown.
Dis-assembling the fan was a lesson in BMW design philosophy, and I was not impressed by the complexity of the package and the simplicity of the bearings or the fan blade attachment design.
After checking prices for new fan assemblies, (unbelieveable), I checked E-bay and was still quite shocked at the prices for well used components.
Ordinarily I believe OEM design is better and smarter than most things aftermarket suppliers come up with, but in this case,the words from my local dealer kept coming back: “Its either the fan is stuck or the fan impeller has come loose on the shaft and rubbed its blade tips into the radiator causing pinhole leaks.”
For him to react this quickly and be that sure engenders a niggling doubt about the robustness of this particular component. That, plus the fact that BMW only supplies complete fan assemblies at a horrendous price causes me to further think that there has to be a better way.
Pic 2 Another view which shows relatively little wear on the armature, indicating the bikes primary use was highway cruising and had little need for the fan during the past 17 years.
(Brush holder removed for clarity of photo)
During this process, my K-biker friend called me up and pointed me to an E-bay source who was peddling replacement fan motors for a (somewhat) reasonable price by BMW standards.
Now my choices are: $80 + for a replacement motor or $320+ for a new fan assembly.
By now I have decided that a used motor/fan of this design is a time bomb waiting to slag my engine with another melt-down.
Still not comfortable with the design philosophy, I start down the re-design road: What size and type of fan can I find which will fit here?
Another perusal of K11OG brings up stories of people adding thicker radiators from earlier bikes and one where somebody said they put on a 10” aftermarket fan, albeit with few details and no discussion of the projects success or otherwise.
Measuring up the OEM fan unit, I start searching for an 8” fan which looks to fit the envelope.
I found two; and 8” unit from Derale and a 7.5” unit from SPAL. Close inspection reveals them to be almost exactly the same envelope, just a difference in where the measurement is taken. Both are about 400 CFM capacity and draw about 5.0 amps at full chat.
Searching Amazon and E-bay, I found many more of the SPAL fans available and I nailed one for $35 plus shipping.
Now that I have a decision and direction, I have to make some adaptor plates to fit the SPAL fan to the OEM radiator.
First step is to trace the outline of the OEM fan housing to identify the mounting points in relationship to the fan/radiator center lines. Tracing around the housing with a large black Sharpie, I get this.(courtesy of the USPS for drawing material) Next step is to lay in the SPAL mounting holes, see below; a 6” square centered picks up the four 1/4” mounting holes.
Using the fan housing again, I lay out the bracket area with the help of a red pen and a 1.00 washer to radius the ends of the bracket design. The housing was used to radius the fan side of the bracket to ensure no airflow obstruction. After this, connect the radii with straight lines. It would take a piece of metal 3” wide by 7.0” long to fabricate the brackets.
I choose to use 1/8” aluminum for the brackets, reasoning that the OEM housing was that thick, so the OEM rubber mount will fit and the flat head screws will have the same amount of material to clamp up. Raising the fan shroud 1/8” from the fin surface will not induce a great deal of airflow loss, but if you are worried, a bit of adhesive-backed weather seal will seal that gap. This fan unit is a full inch shallower than the OEM design, so no clearance worries on the back side.
When the SPAL fan arrived, the next step was to verify the mounting hole locations and drill them in the brackets.
This picture shows the brackets mounted to the fan before fitting the fan. The plan is to center the fan and minimize the airflow obstruction created by the mounting brackets. As you can see, the brackets cover a significantly greater portion of the cooling fins than the original fan support legs (outlined in red)
After placing the fan on the brackets and carefully marking the correct locations for the attachment bolts, I removed all the metal that I felt was unneeded for purposes of lightening the weight and increasing natural airflow.
The results shown in the next picture are the finished brackets before painting. The surface shown is the side which fits closest to the radiator. The mounting holes are countersunk with an 82 degree included angle to allow ¼” flat head bolts to be used without digging into the radiator surface. The outer profile is taken from the radiator so that the brackets do not stick out beyond the radiator mounts at any point. The row of holes in the middle of the bottom bracket is for lightening and airflow.
The brackets are mounted to the fan assembly with ¼-20 countersunk screws and nuts for final fit testing.
In this picture you can see one of the attractive added features of this fan; an E-clip retains the blade assembly to the shaft, rather than total reliance on a press-fit a la OEM design.
This pictures allows the svelte cross section to be shown to maximum with my big feet supplying the scale and appropriate support. Fan = 2.05 plus .125 bracket = 2.175 thickness total.
Here you can see the fan assembly first mounted to the radiator. Two 6 mm bolts of the appropriate thread pitch are used to replace the OEM countersunk fasteners. A fit check on the bike shows no apparent reason for the use of the countersunk fasteners, so I used hex head screws from the “Metric Fasteners’ jar on my workbench. The upper mount hole uses the OEM rubber grommet and fastener.
Here you can see the new fan assembly compared to the OEM fan assembly. The tags are the weights of each.
This picture illustrates the relative height of each fan assembly (plus my nice pink rug)
Installation will begin after I complete all the tests I should do while the cooling system is apart; Thermostat test, pressure cap test, et.c.
I have made detailed notes and dimensions of the finished brackets and will supply that data to interested K11OG members free of charge. If you would like a full size pattern of the brackets (scanned) or would like to have a fan replacement kit supplied please contact me. If the interest level is high enough, I will build some.
I will post updates of the modification as the K1100LT accumulates miles.
Facts known about BMW OEM Fan:
OEM PN:
Fan diameter at blade tip: 6.50”
Number of blades: 7
Fan assembly thickness: 4.25”
Motor type: brush
Weight of fan assembly: 1 lb. 6.2 oz.
CFM Unknown
Current Draw Unknown (Fused @ 15 amp)
Facts about CBE replacement assembly kit:
Brackets:
1/8” aluminum custom fabricated
Fan:
PN SPALType VA14-AP7/C-34A 12V Puller
Fan diameter @ blade tip: 7.50”
Number of blades: 10
Fan assembly thickness: 2.175”
Motor type unknown
Weight of fan assembly: 2 lb. 3.5 oz oz.
CFM 440
Current Draw 5.5 amp
Nick W _________________ "It's not what people know, it's that they know so much that just ain't so!" (Apologies to Will Rogers)
93 K1100LT
(2) 79 Suzuki GS850's (In limbo)
65 Triumph TR6S/C ( sold)
2009 Suzuki SV650
2009 Suzuki DL650 |
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garynali Mad Brick Rider
Joined: 17 Apr 2010 Posts: 79 Location: Hervey Bay, Australia
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Posted: Sun Sep 05, 2010 4:46 pm Post subject: |
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Nice work Nickw and well detailed. The first time mine failed ( dry bushes leading to excessive current draw with no circuit protection actually working) I couldn't believe what an overpriced bit of junk the OEM is. Next time i'm going your way.
Thanks
Gary C |
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miKeinWIs Mad Brick Rider
Joined: 29 Jun 2009 Posts: 143 Location: Birchwood, WI
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nickw Big Brick Rider
Joined: 12 Aug 2010 Posts: 72 Location: Essex, VT USA
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Posted: Wed Sep 08, 2010 11:29 am Post subject: |
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Thank you for the kind words and help in posting. That is a hell of as lot of work for all the pix I have. I may not get to it for quite some time. If anyone really needs to see the pix, I would rather e-mail the file by splitting it into two chapters if possible. I tried it once as a whole file and it is too big for my server to handle.
The fan you show looks a lot like the one i am using, but beware of the total outside envelope! the lumps on the outside may have to be ground off on the top side. I had to grind the (unused) mounting bosses flush to the shroud to get it between the frame tubes at the top half. My fit is quite snug, but the radiator will bolt up without putting undue starin on the shroud.
Nick W _________________ "It's not what people know, it's that they know so much that just ain't so!" (Apologies to Will Rogers)
93 K1100LT
(2) 79 Suzuki GS850's (In limbo)
65 Triumph TR6S/C ( sold)
2009 Suzuki SV650
2009 Suzuki DL650 |
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Flying Duck PsyKotic Waterfowl
Joined: 27 Jan 2005 Posts: 10082 Location: Bumf***, WA
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Posted: Wed Sep 08, 2010 11:42 am Post subject: |
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Just curious but for comparison does anybody know what the CFM of the OEM fan is?
Nick: Do you have a gut feel as to whether the SPAL fan has a higher or lower CFM?
On another note, I've found some 3.5" 120 CFM 12V computer fans that should fit in the side grills of an LT. I plan to experiment with a pair of those. Since the radiator fan pushes up (into the tank) and back I think having some fans that push air directly out of the engine compartment might be helpful. _________________ 93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE |
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nickw Big Brick Rider
Joined: 12 Aug 2010 Posts: 72 Location: Essex, VT USA
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Posted: Wed Sep 08, 2010 4:15 pm Post subject: |
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I don't have much of a clue, as the Beemer apparently never worked while I rode it. I've heard that they can be heard over the engine noise, but I'm sure the SPAL is somewhat louder based on the noise bench-testing it.
I tested a few of those little 3.5 " fans but they are so quiet it's hard to believe they move much air. Perhaps if they were wired to run all the time they would serve to assist the ram air effect over the radiator. They don't draw a lot of current. _________________ "It's not what people know, it's that they know so much that just ain't so!" (Apologies to Will Rogers)
93 K1100LT
(2) 79 Suzuki GS850's (In limbo)
65 Triumph TR6S/C ( sold)
2009 Suzuki SV650
2009 Suzuki DL650 |
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Flying Duck PsyKotic Waterfowl
Joined: 27 Jan 2005 Posts: 10082 Location: Bumf***, WA
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Posted: Wed Sep 08, 2010 4:18 pm Post subject: |
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The ones I'm looking at draw about .75A each and supposedly move 120 CFM. They're not very expensive so I figure it's worth a try. They also have some caveats about them making a fair amount of noise. Other 3.5" computer fans run about 40 CFM and are supposedly quieter but I don't think noise is an issue on a bike like it would be in a computer housing. _________________ 93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE |
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nickw Big Brick Rider
Joined: 12 Aug 2010 Posts: 72 Location: Essex, VT USA
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Posted: Wed Sep 08, 2010 6:02 pm Post subject: |
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Update on the installation foibles of my SPAL fan: I have had to remove the extra (unused) mounting brackets on the fan housing to make a (very) snug fit between the frame tubes. It works, but If I were to make another set of brackets, I would move the fan mounting holes down about 1/8" to center the new fan shroud in the existing open area. The space claim is so close, I had to rotate the lower left hose clamp by about 90 degrees to keep the clamp body from hitting the shroud.
Component testing revealed a failed pressure cap gasket which may have been the result of the loss of fan capability.
Nickw _________________ "It's not what people know, it's that they know so much that just ain't so!" (Apologies to Will Rogers)
93 K1100LT
(2) 79 Suzuki GS850's (In limbo)
65 Triumph TR6S/C ( sold)
2009 Suzuki SV650
2009 Suzuki DL650 |
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Jim Site Admin
Joined: 17 May 2003 Posts: 3840 Location: WHERETHEFUNNEVERENDS
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Posted: Wed Sep 08, 2010 7:11 pm Post subject: Fan install |
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Nick - I hope you got some pix of the final install. _________________ Jim
1997 K1100LTSE 94,000 - has gremlins!
1995 R100RT Classic 16,650 crashed - repairing
1992 K75RTP 46,000
1992 R100R 24,000 - FOR SALE
"We shall not all die, but we shall all be changed." |
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supercat1 Flying Brick Rider
Joined: 11 Aug 2009 Posts: 458 Location: Hoboken, NJ
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Posted: Wed Sep 08, 2010 9:48 pm Post subject: |
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nick, an option would be to upload your word document to mediafire.com and then post a link to it here on the forum. we would then all be able to dl it at will.
also, i know for a fact that those little computer fuckers can be not so quiet when run at full tilt all the time. my pc has space for 6 of them and with only 2 installed it is akin to a vacuum. 6 would be a wind tunnel i believe. but, at highway speed that sound will be lost by the wind noise anyway. in terms of how much air they actually move? well, if completely isolated they may move the quoted value, but in real life i doubt it. _________________ (formerly) 1993 k1100rs |
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Flying Duck PsyKotic Waterfowl
Joined: 27 Jan 2005 Posts: 10082 Location: Bumf***, WA
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Posted: Wed Sep 08, 2010 10:06 pm Post subject: |
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supercat1 wrote: | nick, an option would be to upload your word document to mediafire.com and then post a link to it here on the forum. we would then all be able to dl it at will.
also, i know for a fact that those little computer fuckers can be not so quiet when run at full tilt all the time. my pc has space for 6 of them and with only 2 installed it is akin to a vacuum. 6 would be a wind tunnel i believe. but, at highway speed that sound will be lost by the wind noise anyway. in terms of how much air they actually move? well, if completely isolated they may move the quoted value, but in real life i doubt it. |
Yeah, but if the radiator fan is going it's already generating a little pressure in there. (but directed up and back, not out the sides. My experiment will be to run them off of the fan relay so that when the Motronic kicks in the fan or I hit my fan switch it will turn all of the fans on. _________________ 93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE |
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nickw Big Brick Rider
Joined: 12 Aug 2010 Posts: 72 Location: Essex, VT USA
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Posted: Thu Sep 09, 2010 6:54 pm Post subject: |
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Thanks to those who wrote and suggested sites to upload the entire document. I will try that tonight.
Duck:
I am curious about the fan switch to manually kick the relay on, is there any issue with the Motronic being bypassed? I would like to add an alternative switch position but haven't clearly understood how best to wire in a switch. I have been waiting for some connectors i ordered to complete the installation and want to add an LED to show the fan is on so I won't forget and leave it on if I have a "Manual/Auto" function switch on the fan relay. I'm still a bit worried about turning the Motronic unit into a Moronic by frying its little brain.
How did you wire yours?
Nickw _________________ "It's not what people know, it's that they know so much that just ain't so!" (Apologies to Will Rogers)
93 K1100LT
(2) 79 Suzuki GS850's (In limbo)
65 Triumph TR6S/C ( sold)
2009 Suzuki SV650
2009 Suzuki DL650 |
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Flying Duck PsyKotic Waterfowl
Joined: 27 Jan 2005 Posts: 10082 Location: Bumf***, WA
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Posted: Thu Sep 09, 2010 7:27 pm Post subject: |
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All you need to do is tap into the blue/yellow wire for the fan relay. Have the switch ground it to trigger the relay.
Several of us here have done it and no Motronic issues. The Motronic is just grounding that blue/yellow wire.
For RSs, I've made combo hazard/fan 3 position OEM switches for some people since an RS only has 3 switch slots. _________________ 93 LT (x2)
94 RS
86-97 K75F(K75/100/1100 Frankenbrick)
86 K75C w/paralever, hi perf cams,TURBO!
91 & 92 K75Ss
91 K1
86 custom K100
14 WR250R
IBA #17739 (SS1K, BBG, 50CC)
Buy parts HERE
Last edited by Flying Duck on Thu Sep 09, 2010 7:30 pm; edited 4 times in total |
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nickw Big Brick Rider
Joined: 12 Aug 2010 Posts: 72 Location: Essex, VT USA
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Posted: Thu Sep 09, 2010 7:27 pm Post subject: |
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I opened a mediafire account and uploaded my (updated0 fan story)
I think this is the link: http://www.mediafire.com/?63c73rojcr633dj
Good luck _________________ "It's not what people know, it's that they know so much that just ain't so!" (Apologies to Will Rogers)
93 K1100LT
(2) 79 Suzuki GS850's (In limbo)
65 Triumph TR6S/C ( sold)
2009 Suzuki SV650
2009 Suzuki DL650 |
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drikko Flying Brick Rider
Joined: 20 Nov 2009 Posts: 1966 Location: Brisbane, OZ
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Posted: Thu Sep 09, 2010 8:39 pm Post subject: |
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That worked, well done! Great fix BTW, hope I never need it but have stored the file in case I do. Thanks for taking the time to write it up.
Cheers
Derek _________________ K1100RS '97
Laverda RGS 1000 '84
Jim Young Trailer Sailer 5.7M WB
DISCLAIMER:- Anything I say may have been when I was drunk so please don't take it personally.
'Bigamy is having one wife/husband too many. Monogamy is the same.'
Oscar Wilde |
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