routing the fuel lines

[DGXSER]

Anyone have pics of how they have successfully ran in-line fuel filters with the stock airbox and petcocks??

After I got my carbs completed, I found I had two cylinders dead at idle and was developing a bad miss when running and barely kept it running. I had installed inline fuel filters (Briggs and Stratton from HD, about 2" in dia. and mayeb 1" deep). I put them between the intake plenums between the carbs and the factory air box between 1-2 and 3-4. I routed the fuel lines from my petcocks to a T and then across the top of the intake plenums to the fuel filter on the opposite side of the bike. I found the fuel lines on one sode of the bike at the petcock was getting pinched off.

No matter how I tried to work these lines, I always end up with one of the lines form the petcocks getting pinched off and not letting fuel flow to the carbs. Even moved the filters below the intakes for more room for fuel lines, still they get pinched making the turn from the petcocks to go across the bike. I find that I need to have the fuel lines go down form the petcocks and not across or they get pinched. The only way I can see to get them in would be horizontally below the intakes just before going into the carb Ts. From what I have read, that can cause air lock issues.

I finally gave up and pulled them back off. No more problems with fuel flow. I do want to put them on, but it is pointless if I can not get them in and still feed fuel to the carbs.

Appreciate any pictures of what someone got to work with the stock air intake setup.

[bikerphil]

fuel line routing

Don't have a pic, but I ran mine (79 Special) as follows. First, cap off the front two outlets (L+R). Don't need that prime position anymore. I'm assuming you aren't running the octy. Run your left petcock line with in line filter above the airbox boots and down between boots 3+4 to the right 2 carbs. The filter should be about at the center of the airbox. Do the same with the right petcock to the left 2 carbs down between boots 1+2. No need for any T's. There should be enough room for the 2 filters on top of the boots near the center of the airbox.

[DGXSER]

Its the capping of the prime that I have not done Phil. That will probably help alot. What did you use to cap it?

[bikerphil]

I just used a short legnth of fuel line with a sawed off bolt stuck in there (no threads just the smooth shank part) and clamped it. Ya can't see it when it's on the bike. I once tried those vac caps, they weren't neoprene, and you can guess the rest.

[digitalsam]

Using Phil's suggestion, I routed mine as you see below. I have enough play in the line to lift the tank up on a 4x4 block. This way I can reach most of the parts I need to access. I can also hang the tank from the ceiling if I need more room. Bike bandit sent me three feet of yellow line instead of clear which accounts for the three "dirty" tubes. That will change when more cash flows my way.

As always, I am open to any suggestions. The only trouble I had was making sure that there wasn't too much line so that the fuel lines contacted the hot engine. I am not sure, but I think that would be a bad idea.

[dbeardslee]

Don - 2" diameter fuel filters seem kind of fat. I've got a couple napa gold 3027's you can have, if you want them. They're used, but lightly, and still flow great. They're about 3/4" diameter, and look just like these Wix 33027's:

[Larrym]

Eye of the Beholder

I went with a routing with clear/translucent fuel line which goes down from each petcock, down between the outside carb intakes, connects to large clear fuel filters at the lowest point, runs sideways then up to the fuel tees.

The fuel tees are pointed down instead of up.



My current working theory is that any air/bubbles in the fuel lines/filters are able to rise and exit at the high points: petcocks and fuel Tees. The filters are at the low point of the "U". In this position they are easily viewed and replaced when they show debris. The filters are exposed to more air flow for the cooling which has prevented the dreaded "vapor lock" in the Arizona 90+ degree heat and if it were to occur the absence of fuel in the filters would be recognized. As another bonus of this "unsightly" arrangement, any water in my fuel collects at the low point/filters where I can see it before it makes it into the carbs.

My solution isn't going to win any pageants. But a filter out of sight is generally out of mind as well.

[BigDick]

no pictures handy but my filters are 3-4" away from the petcocks routed as everyone else has. My lines do lay on the motor, I have not seen any heat damage and the motor has had plenty of opportunity to get good and warmed up, maybe it's not a concern?

[DGXSER]

Wow, I forgot I even started this thread.

Doug, I honestly do not run inlines, but I also have pulled my petcocks out and seen with my two beady little eyes that the filters are intact, in place, and clean. I also have seen the inside of my tank and know it is decently clean, even if I did not have a boroscope to look in with. (private joke)

Everytime I tried to route my lines like that I had issues with air lock in the lines. I finally gave up on it and have run since Jan on my current setup with no ill effects I can see or sense in how she runs.

[oseaghdha]

What's it supposed to do?



I dikked around with this issue until I settled on this configuration.
Left feeds 1-2, Right feeds 3-4. Capped Prime, no crossover, maybe 7" of line per side.

Tigon line and M/C type filters from the local shop, with some slinky type spring stuff I stole off a set of Virago carbs I had laying around.

There is enough slack to R&R the lines from the petcocks, but no more than that. I can unbolt and lift the tank about 1 inch. Zero opportunity for kinks or contact with the engine.

When I want to synch or tune, I have a couple of extentions I made, for use with the tank turned around backwards. Takes longer to get them from the tool box than to install them.

I figured the system spends 99.9375% of its operating time running down the road, why engineer the fuel lines for synching and tuning?

Previously, I had longer lines with bigger filters and had issues with reduced fuel flow when the tank was low or going onto reserve. I think there was a loss of siphon or similar effect. With this arrangement I have zero fuel delivery defects.