Twisted fuel inlet tube

My 1996 DR650 had been stored for five years.  It was put away and stored properly, so after an oil change and wash it fired right up.

However, once under way, it would hesitate and bog under wider throttle openings such as before an upshift.  I tried SeaFoam and non-ethanol gas, but the behaviour didn't change.  I then ordered the $40 USD Moose carb rebuild kit, removed the carb, cleaned it with Pine-Sol as per the ADV Pine-Sol degreaser thread, and reassembled using all the new parts except the air jet and the fuel screw which I replaced with the extended fuel screw from ProCycle.

 

AFTRreassembled.jpg

Clean, rebuilt, ready to go.

 

Back together the bike fired up again without incident and was/is running fine after adjusting the idle.

But, I couldn't leave well enough alone ...  :banghead:

I have the IMS tank and stock petcock, so the fuel line to the carb had a couple of kinks in it due to the layout:

 

In-linefilter.jpg

Small kink between petcock and new in-line filter, bigger kink between filter and inlet tube.

(I removed the small filter from the inlet tube.)  Also fuel flow is 'uphill' which may be an

issue getting the last litre or two out of the tank.

 

I had read in a few places on the Internet that people had success turning the pressed in fuel inlet to either 9 o'clock or 3 o'clock to improve fuel flow, so I opted for 3 o'clock.  I gripped the full length of the inlet tube (wrapped in a piece of cloth) with vice grips and started to apply pressure.  I didn't move, so I tried tapping it.  It still didn't move so I applied more pressure and it started to go.  However when I pulled the cloth off to check progress this is what I found:

 

Kink1.jpg

:doh:   

 

I twisted it back a fraction, but was mindful that it would likely not open up again and may well snap off.  Putting it back together I used thicker walled 5/16 automotive fuel line (instead of the OEM), shortened the piece between the petcock and the fuel filter to reduce the bend in the piece between fuel filter and the inlet tube, and ended up with this:

 

Newhose.jpg

 

Newhose2.jpg

The fuel line isn't kinked any more, but now the inlet tube is!  :banghead:

 

I had the bike out for a two-hour test drive on the weekend; there are no leaks and it seems to be running well.  There may have been a slight hesitation once or twice, but it was also a bit windy so it may have had nothing to do with the kink.

I know I should probably quit before I make things worse, but that kink is going to bother me ...

After searching around the net a bit I found a 2008 thread on this site by Lukas from Austria, in which he did the same thing to his Mikuni then actually snapped the inlet tube off his FCR while trying to reorient it.  His 'temporary' solution was to extract the broken fitting and press in a piece of plastic ballpoint pen housing.  I used to read Lukas' posts frequently here before I put my bike in storage.  Is he (are you) still around?  If so, did he/you come up with a more permanent solution for the inlet tube?

Further mining of the web (which is what got me into this fix in the first place  :facepalm: ) found that owners of several Harley models have an issue with a pressed-in fuel inlet tube on a Keihin CV carb.  It's a plastic and brass fitting that tends to harden, crack and leak over time.  There are some good tutorials on replacing this fitting by tapping and pulling the old one, then replacing it with a solid brass part.

 

img-cvp_fuel_inlet_thumb__11493.14053465

The Harley replacement part for a Keihin carb.

 

If I can confirm that the bore of the tube that the fitting presses into is the same on the Keihin and the Mikuni I might give it a try.  I could press it in with the 3 o'clock, rearward orientation.  Has anyone tried this? Maybe I'll see if one of the retailers of this part will take a digital caliper to the press-in portion for me.

If that won't fit, it may be possible to tap the inlet bore on the carb--although I suppose Mikuni would have threaded the hole if that were the best option. :unsure: In my layout, a straight single fuel barb would actually work best, like this:

2967.jpg

But I'm not sure whether there is enough metal to cut proper threads.

So, has anyone else twisted their inlet tube and successfully replaced or repaired it? (I doubt it's possible to take the kink out, but I'm all ears.)

Since the bike is running well I'm not in a hurry (Lukas said he just used his Mikuni as is/was), but knowing that it's kinked will slowly drive me   :crazy: .

Thanks in advance.  :cheers:

 

 

 

My 1996 DR650 had been stored for five years.  It was put away and stored properly, so after an oil change and wash it fired right up.

However, once under way, it would hesitate and bog under wider throttle openings such as before an upshift.  I tried SeaFoam and non-ethanol gas, but the behaviour didn't change.  I then ordered the $40 USD Moose carb rebuild kit, removed the carb, cleaned it with Pine-Sol as per the ADV Pine-Sol degreaser thread, and reassembled using all the new parts except the air jet and the fuel screw which I replaced with the extended fuel screw from ProCycle.

 

AFTRreassembled.jpg

Clean, rebuilt, ready to go.

 

Back together the bike fired up again without incident and was/is running fine after adjusting the idle.

But, I couldn't leave well enough alone ...  :banghead:

I have the IMS tank and stock petcock, so the fuel line to the carb had a couple of kinks in it due to the layout:

 

In-linefilter.jpg

Small kink between petcock and new in-line filter, bigger kink between filter and inlet tube.

(I removed the small filter from the inlet tube.)  Also fuel flow is 'uphill' which may be an

issue getting the last litre or two out of the tank.

 

I had read in a few places on the Internet that people had success turning the pressed in fuel inlet to either 9 o'clock or 3 o'clock to improve fuel flow, so I opted for 3 o'clock.  I gripped the full length of the inlet tube (wrapped in a piece of cloth) with vice grips and started to apply pressure.  I didn't move, so I tried tapping it.  It still didn't move so I applied more pressure and it started to go.  However when I pulled the cloth off to check progress this is what I found:

 

Kink1.jpg

:doh:   

 

I twisted it back a fraction, but was mindful that it would likely not open up again and may well snap off.  Putting it back together I used thicker walled 5/16 automotive fuel line (instead of the OEM), shortened the piece between the petcock and the fuel filter to reduce the bend in the piece between fuel filter and the inlet tube, and ended up with this:

 

Newhose.jpg

 

Newhose2.jpg

The fuel line isn't kinked any more, but now the inlet tube is!  :banghead:

 

I had the bike out for a two-hour test drive on the weekend; there are no leaks and it seems to be running well.  There may have been a slight hesitation once or twice, but it was also a bit windy so it may have had nothing to do with the kink.

I know I should probably quit before I make things worse, but that kink is going to bother me ...

After searching around the net a bit I found a 2008 thread on this site by Lukas from Austria, in which he did the same thing to his Mikuni then actually snapped the inlet tube off his FCR while trying to reorient it.  His 'temporary' solution was to extract the broken fitting and press in a piece of plastic ballpoint pen housing.  I used to read Lukas' posts frequently here before I put my bike in storage.  Is he (are you) still around?  If so, did he/you come up with a more permanent solution for the inlet tube?

Further mining of the web (which is what got me into this fix in the first place  :facepalm: ) found that owners of several Harley models have an issue with a pressed-in fuel inlet tube on a Keihin CV carb.  It's a plastic and brass fitting that tends to harden, crack and leak over time.  There are some good tutorials on replacing this fitting by tapping and pulling the old one, then replacing it with a solid brass part.

 

img-cvp_fuel_inlet_thumb__11493.14053465

The Harley replacement part for a Keihin carb.

 

If I can confirm that the bore of the tube that the fitting presses into is the same on the Keihin and the Mikuni I might give it a try.  I could press it in with the 3 o'clock, rearward orientation.  Has anyone tried this? Maybe I'll see if one of the retailers of this part will take a digital caliper to the press-in portion for me.

If that won't fit, it may be possible to tap the inlet bore on the carb--although I suppose Mikuni would have threaded the hole if that were the best option. :unsure: In my layout, a straight single fuel barb would actually work best, like this:

2967.jpg

But I'm not sure whether there is enough metal to cut proper threads.

So, has anyone else twisted their inlet tube and successfully replaced or repaired it? (I doubt it's possible to take the kink out, but I'm all ears.)

Since the bike is running well I'm not in a hurry (Lukas said he just used his Mikuni as is/was), but knowing that it's kinked will slowly drive me   :crazy: .

Thanks in advance.  :cheers:

hello, did you afterwards resolve it, with putting new thread in? thank you

Hi Bart--you've resurrected a two-year-old post!

The short answer is no.  My twisted inlet tube doesn't leak and doesn't appear to significantly restrict fuel flow (the bike runs well), so I left it as is.  I did achieve enough of a bend to straighten out the fuel line--just not the way I intended.  As a result, I didn't need to pull the carb and try to tap it for a fitting, though I think that's the way I'd go if I had a broken or leaking inlet tube.  Good luck!

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