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1Back to top Go down    Collapsing Fuel Return Line on Fri Feb 09, 2018 4:42 pm

MartinW

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A few week ago I suffered intermittent bad running, this was due to the fuel return line collapsing where it bends at 90 Deg to enter back into the tank. I tried a few solutions but it eventually collapsed again, the collapse mainly occurred on really hot days in traffic around 39 C. I tried at least 5 different ways of routing. I removed the fuel cooler which was causing one of the problems due to the fuel line needing rerouting. I trimmed back the line about 1.5" to do away with the point where it was collapsing. All these measures worked from anywhere from a couple of days to a couple of weeks. I have it cured at the moment with a rather ugly solution. I extended the hose by about 10" with a barb joiner ran the hose up through the steering head and looped it around and back into the tank. All the bends are now large with no possibility of kinking, and the K75s fairing covers it all up. However I went in search of springs to go over or in the fuel hose in order to solve the problem,and make it a little bit neater. A guy I deal with at Pirtek put me onto these Unicoil which are a modern interpretation o the old spring trick. Autobarn has them in various sizes $20.00 Au or Ebay has the identical ones for $8.00 Au plus $8.00 Au postage.https://www.ebay.com.au/itm/5-16-Stainless-steel-UNICOIL-Hose-coil-suit-hose-OD-14-16mm/152678074659?
When it arrives I'll post the results, although I can't see there being any problems with it at this stage.
Regards Martin.

    

2Back to top Go down    Re: Collapsing Fuel Return Line on Fri Feb 09, 2018 4:59 pm

Inge K.

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If memory Razz .......RT did use something similar on the fuel return line just after the FPR, a couple of years ago.....succes all the way back to the tank.


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Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

3Back to top Go down    Re: Collapsing Fuel Return Line on Fri Feb 09, 2018 5:03 pm

MartinW

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The vacuum line on my 75 from the No 3 throttle body vacuum port to the FPR has a spring over it.
Regards Martin.

    

4Back to top Go down    Re: Collapsing Fuel Return Line on Fri Feb 09, 2018 5:12 pm

Inge K.

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@MartinW wrote:The vacuum line to the FPR has a spring over it.
Regards Martin.

That is standard from the factory.


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Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

5Back to top Go down    Re: Collapsing Fuel Return Line on Fri Feb 09, 2018 5:25 pm

Inge K.

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RT didn't use something similar 5 years ago, it was exactly the same.....



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Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

6Back to top Go down    Re: Collapsing Fuel Return Line on Fri Feb 09, 2018 5:54 pm

MartinW

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I waiting for someone in the US to post the price of the Unicoil in the US.
Regards Martin.

    

7Back to top Go down    Re: Collapsing Fuel Return Line on Sat Feb 10, 2018 11:11 pm

blaKey

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Martin, have a look here...Post 59.

Got it from Flea Bay here in Oz.

Did the job.


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K100RS 1986 RED!

Dress for the ride and the potential slide.
    

8Back to top Go down    Re: Collapsing Fuel Return Line on Sat Feb 10, 2018 11:27 pm

MartinW

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Thanks BlaKey I ordered one from Autobarn on Friday it's supposed to arrive tomorrow. The local Pirtek guy is really helpful, and I really don't buy that much off him.
Regards Martin.

    

9Back to top Go down    Re: Collapsing Fuel Return Line on Sun Feb 11, 2018 5:19 am

Inge K.

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@Inge K. wrote:If memory Razz .......RT did use something similar

Wrong again ......Sorry Blakey......at least it was on a RT.


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Inge K.
K100RS -86. (first owner), K1100LTSE -94.
    

10Back to top Go down    Re: Collapsing Fuel Return Line on Wed Feb 28, 2018 6:00 pm

glennpm

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Hi Martin,

The spring would work for sure. Are you sure you had it plumbed with fuel injection hose and not just fuel hose. Fuel injection hose is thicker, made for higher pressure and shouldn't have kinked.

For info: https://grassrootsmotorsports.com/forum/grm/fuel-line-vs-fuel-injection-line/39652/page1/

Glenn

    

11Back to top Go down    Re: Collapsing Fuel Return Line on Thu Mar 01, 2018 3:01 am

MartinW

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Definitely the right type of hose. It just requires a sharp bend and the collapsing only occurred on really hot days 39C in traffic. So with the spring it's not a problem.
Regards Martin.


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12Back to top Go down    Re: Collapsing Fuel Return Line on Thu Mar 01, 2018 8:24 am

glennpm

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Good fix with the spring and I can see how the heat would cause it.

Best regards,
Glenn

    

13Back to top Go down    Re: Collapsing Fuel Return Line on Thu Mar 01, 2018 1:15 pm

Two Wheels Better

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@MartinW wrote:I waiting for someone in the US to post the price of the Unicoil in the US.
Regards Martin.
Amazonia the Destroyers


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1987 K100RS, '93 Framed K11/K12 engine 'Big Block', '09 K1300GT, '07 K1200R, '04 R1150RT, '95 R100 Mystic, '77 R75/7.
Sniff...can you smell that? I think it might be bullsh*t.

    

14Back to top Go down    Re: Collapsing Fuel Return Line on Thu Mar 01, 2018 1:32 pm

MartinW

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Typical, you can buy an Australian designed device cheaper in the US than you can in OZ.
Regards Martin.


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K75s Hybrid
    

15Back to top Go down    Re: Collapsing Fuel Return Line on Thu Mar 01, 2018 1:39 pm

Two Wheels Better

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@MartinW wrote:Typical, you can buy an Australian designed device cheaper in the US than you can in OZ.
Regards Martin.
Potential reasons: the tyranny of distance, the 78 cent dollar, economics of scale, and some bastards just mark things up higher in OZ. Strewth.


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1987 K100RS, '93 Framed K11/K12 engine 'Big Block', '09 K1300GT, '07 K1200R, '04 R1150RT, '95 R100 Mystic, '77 R75/7.
Sniff...can you smell that? I think it might be bullsh*t.

    

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