V8 Bike Riders Forums banner
1 - 6 of 6 Posts

·
Registered
Joined
·
5,661 Posts
Discussion Starter · #1 ·
Well, finally got my fuel filler cap / paint chipping thing solved, and hope I can help anyone else new to the Boss, or older Harley style tanks. The Dope (me) finally got some fuel proof Dope, and a new set of Kurykin (sp) Caps. When I saw how the new caps worked, I got out 2 of my trusty strap wrenches, and discovered the caps on my bike came apart as well. The (r/h) inner filler cap was jammed to the threaded outer ring, and for 3000 miles worth, I had also been mechanically scrubbing the paint by unscrewing the whole darn thing, in addition to overfilling a few times. The new caps look nice (didn't want my sweety to know I didn't know how the old ones worked) so I kept them. Thanks to all for the sage advice!
HAWK88
Jack Phillips
 

·
Registered
Joined
·
1,435 Posts
Jack

I put a set of kuryakin paint savers on my 2002/350. the fill cap is vented. I filled the tank but not overly full and took her out for a run.
At 120mph the gas started to leak out the top of the cap enough that I could feel a spray on my face. I slowed down and it quite. All I could figure was a negative pressure built up over the cap that was enough to suck the gas out. What do you think being an airplane guy and all.
Bill
 

·
Registered
Joined
·
5,661 Posts
Discussion Starter · #3 ·
Gas Cap Venting

I agree that has lots of potential. There is a huge amount of air flowing above the rounded fronts of our tanks. Better airfoil shapes then some of the Crap (technical militery term) that we had hanging off our Grumman Mohawks. Also, when she's heeled over on the sidestand at the pump, when we stand'em up, the cap is a bit lower than the fuel level. Mountain Suggested I stop filling after the pump handle clicks off. I still get some venting thru the new Kuryakin R/H Cap @ speed, when full, and will solve it later this summer. There have been some wonderful threads of how to soldier a vent tube into the R/H crossover elbow, with detailed photos. I'll find those and send them to you, don't know how to do photos myself yet. I will install the vent tube, then plug the cap vents. Others have had great success doing that, and the new ones are non-vented.
Ride Safe.
Jack Phillips
HAWK88
 

·
Registered
Joined
·
1,435 Posts
Jack

You must have bothe caps usable. Mine has only one fill hole. The other is a blank with a cap for show. I fill in the upper side when on the sidestand. Have brushed by some of the talk on vent and none vent but disregarded because all was well until I went a little fast. My question is more curiosity than problematic since a comfy speed for me is under 80 leaning against my duffel bag and trying to keep the backs of my knees from getting like pemican. If it happens again I'll try switching caps since one is none vented now and see if it works. Sort of cool to be able to tell the guys at coffee that I went so fast the gas got sucked out of the gas cap. All in fun.

Bill
 

·
Registered
Joined
·
5,661 Posts
Discussion Starter · #5 ·
siphoning gas

I must have confused the issue, my 97 Boss Bike only has one functional cap as well, the R/H side. It is an older style, vented, and will siphon @ speed when overfilled thru the tiny holes in the top of the cap. The new caps on it keep it from running from the outer threads, as I buttered them well with Fuel Proof dope when I installed them. In the future, I intend to vent thru the r/h banjo crossover fitting under the tank, and seal the vents in the cap. If your Boss is like mine, the left cap is LEFT HAND THREADS, not interchangable with the right. If you seal the vent holes in the cap you must provide alternate vent to the tank. Hope I havn't further confused you.
HAWK 88
Jack Phillips
 

·
Registered
Joined
·
1,435 Posts
Jack
I forgot the threads were left and right. That will save me about 10 minutes of why doesnt this *#@$% thing fit. and the red in the face after I found out . I will be interested in the demon carb post also if that's the way you go.

Bill
 
1 - 6 of 6 Posts
Top