Hose/line routing

[Fallout_rain]

Thank you in advance for any help.

I'm having such a hard time with these hoses. Does anybody have a reference guide or could tell me off hand how they're routed. I've searched the interwebs and so many posts here. I'm sorry for the late question but I would really appreciate some advice.
I just rebuilt the carbs but of course forgot to take pictures of the hoses before hand.
I'm specifically talking about the hoses running off of the carbs.

[FJmonkey]

The routing in the posted image is correct. It is shown on the OEM air box, if you have one. The routing is not intuitive and often done wrong, myself included. With the hose going under, it lines up properly with the petcock when the last few inches of tank is lowered into position. 

[Pat Conlon]

Mark covered the fuel line...
In case you're asking about the vent hoses...
There are 6 hoses. 4 smaller choke vent hoses and 2 larger fuel bowl vents. (Each fuel bowl vent serves 2 carbs)
All are run between the engine case and frame at the back pointing to the ground.
In the case of fuel flow out any of the hoses (abnormal) you do not want fuel pooling at the top of the engine case.
Some folks merge the lines, but I don't do that. I like to keep them seperate lines and number them, that way when I get a problem with fuel flowing, I can know which carb or carbs are the culprit.
Don't kink the lines. They are vent lines. They either draw air in the choke circuit or equalize the air in the fuel bowls.

Hope this helps.  Pat

[Mike 86 in San Dimas]

Here's a photo from my 86.
Mike

[Mike 86 in San Dimas]

Crap just found this photo I saved. OEM box is in the attic. Took the tank off for nothin

[Charlie-brm]

Once I got "stranded" a few times within an hour after the first time I re-installed the carbs on my '84 I finally saw the light and never got it confused.
You're a lot luckier than I am if that's working. Mine always got pinched by the tank. Goz'under.

?? Maybe because with the Unipods there is more headroom for the petcock hose? I'm using Unipods now but it still goz'under.

[Pat Conlon]

I recall something about Yamaha having an incorrect fuel hose routing diagram on some bikes.
I think they had some sort of recall notice to dealers on this issue.

On my '84 the hose diagram shows the single line from the petcock running under *both* branch lines, and not under one branch line like Mike's diagram shows.

Wonder what the GFSM shows?

Like Charlie, I just know what works and what doesn't, learning the hard way. The oem fuel line is soft and when hot, it does not take much to kink it.


The harder aftermarket fuel lines are prolly less prone to pinching.

[FJmonkey]

I ran my '86 for many years with the line over with no issues. Then I started having fuel starvation issues and began the search for the root cause. I fixed the line routing but not the problem. Then I did the flapectomy with no improvement. Then did the suck test and found the petcock was failing. I opted for an 84/85 to gain the Prime feature and did not really care for the electric reserve function. That seemed to fix it till the problem happened again at a rally. Randy swapped out my fill cap and I had no issues that day. Randy took my fill cap apart and found the problem. The white plastic bit that holds the orange/brown flappers was put in upside down preventing the tank from venting. So I caused a problem to fix a problem and I fixed a problem that really was not a problem. The line routing is important, some have no issues but others have. It is a PIA when reconnecting the line to the tank but it makes one less thing to worry about.

[balky1]

I recall something about Yamaha having an incorrect fuel hose routing diagram on some bikes.
I think they had some sort of recall notice to dealers on this issue.

On my '84 the hose diagram shows the single line from the petcock running under *both* branch lines, and not under one branch line like Mike's diagram shows.

Wonder what the GFSM shows?

Like Charlie, I just know what works and what doesn't, learning the hard way. The oem fuel line is soft and when hot, it does not take much to kink it.


The harder aftermarket fuel lines are prolly less prone to pinching.

My diagram is the same like yours. Under both lines. I ran it that way and over both lines, never had a problem. With OEM or aftermarket hose.

[mr blackstock]

G'day,

I cracked the sads with my fuel line routing very early on, decided to go my own way, and after a few years has remained problem free.

[SausageNips]

Where does the fuel filter go on this setup?

[big r]

What year are you looking at. The early models 84 to 87 or 88 did not have filters. Someone will correct me if I am wrong but I think the only models that had a fuel filter were the ones with a fuel pump Big R

[SausageNips]

Yeah, I think it was added after the fact.  Should I not have one?  I have aftermarket filters (no box)

[FJmonkey]

You only need to remove it if you are having problems with fuel flow. If you keep it, then keep a spare under the seat. Or a way to bypass it if you get stuck on the road. The problem will be when the filter is clogging and fuel level is low. Not really the best time. I would remove it and go Commando.

[mr blackstock]

G'day,
I have my fuel filter at the far left in the picture.  I have two inches of pipe coming off the petcock, then the filter.  When I lower the tank the filter sits in the depression on top of the air box.  That is the only place I could put it without fouling something else.  If you want a close look: https://www.youtube.com/watch?v=0VvnXuv16Yk&feature=youtu.be

If you decide to use one, make sure it is bike specific and not a car one.  many people would suggest you do not need one, but I guess it is up to you to weigh the pro's and con's.

Cheers, Gareth