Chasing that fuel smell

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Ansimp

Well-known member
Supporting Member
Joined
Jan 27, 2013
Messages
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Location
Brisbane Australia
My Bike Models
1981 GL1100 “Rats Nest”
1998 GL1500c Val
1987 CBR1000f “The Pig”
1991 CBR1000f Red
Ever since I have owned Val and she has lived in the garage I have always noticed a bit of a fuel smell when entering the closed up garage. I played with the fuel cap filler seal as documented here and felt like I had achieved a positive result. I still noticed some smell but only on a really hot day (plenty of those here in sunny Queensland) so I wasn’t too concerned. I noticed lately a more pronounced smell and Val hasn’t been ridden for over a month :whip: :doh: and when I was having a sniff around I noticed one of the carby bowl drain/breather tubes was hanging off. I only tackled the LH side bank as it was accessible while the bike is on the wheel stand in the garage and one side was enough of a PITA.
The little short one was the rear LH carby and it was hanging off the carby bowl
New hoses installed
Tools used in the job including an old roll of gates vaccum tubing.
 
[url=https://classicgoldwings.com/forum/viewtopic.php?p=201250#p201250:135bxn0h said:
Dadster » Wed Mar 14, 2018 12:06 pm[/url]":135bxn0h]
Did that solve the problem?
Only just finished the LH bank and still need to check/do the RH bank, also the weather is a bit cooler atm so I still need a hot day with the garage locked up. Let’s hope it does fix the vapour issue. :beg:
 
:popcorn: :popcorn:

My 1500 has the same problem sometimes. Fuel smell is a bit strong at times, but I haven't figured out where the heck it is coming from. Doesn't matter how much fuel it has, cold/hot weather, parked for a week, or just ridden....it's really erratic. Might be something similar to what you found.... :yes:
 
Finally did the rh side. I had to drop the LH bowl tubes and the rear main drain off the plastic manifold to allow the plastic drain manifold to pull out the rh side to attach their new drain tubes. The rh front bowel tube was a pita to install as the plastic heat shield was restricting access and clearance. The centre rh one was also difficult due to the idle adjustment screw. Finally gave the wheels a light polish and then went for a late afternoon/evening ride to a customers place.
 
I'm not sure how the drain lines would create a fuel smell, Tony. Shouldn't be any fuel in them unless you've used the drains lately. A more likely suspect would be one or more of the many "smog" lines associated with the PAIR valves and air injection. Similar to the 1200 setup, there are lots of lines that, while they don't carry fuel, they do carry vapors and are notorious for deterioration. Lots of folks (myself included) have eliminated them proactively - BEFORE experiencing vacuum leaks.
 
I can’t see if the Valkyrie carbies are similar to the CBX carbies in design but when I met with Mike Nixon in 2013 he told me that the CBX carbies could cascade excess fuel via the drain tube manifold. Mike said that because of this there was a service instruction to delete the 6 port drain manifold and run individual lines so that the lower carbs (LH side on the side stand) could not overflow with excess fuel that would then wind up in the cylinder. He explained that there was an overflow/ vent circuit that fed to the drain tube which I wasn’t aware of. I haven’t identified this circuit myself on any Carbies but I will say that there is definitely a fuel smell from those drain hoses when they are damaged. The rh front drain hose actually had some fuel in it. Val is a UK AUS spec bike that doesn’t have the secondary air system on it but does have a TPS sensor on the rear rh carby for the ignition module. I can’t find any information on this part but you can see it in the picture.
 
The carb design itself is not all that similar. Valk carbs are much simpler. The drain manifold design is QUITE similar. The '79 CBX had that design and it killed a bunch of cases. The #1 cylinder (downhill) got drainage from any cylinder overflow and was usually hydrolocked - often blowing out the case by that rod! A vacuum petcock was introduced for 2nd year CBX's ('80) and the drains were modified away from that central manifold. (I removed it from my '79 based on Nixon's recommendation).

The Valk's simpler design has fixed floats. Not adjustable. If they're off, replace the float. If you have fuel in a drain line, the needle/seat are probably leaking on that carb AND the petcock isn't closing properly. Bad omen. I'd look into it closely.
 
Thanks Darrell. I am in no great hurry to pull the carbs unless I am really convinced that I have a major problem. At the moment Val is running great apart from a little rich and thirsty. I would rather be spending money on fuel than repairing a cooked lean engine. :yes:
 
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