Question about fuel cap leak, and tyre air pressure.

[bigkev81]

Hi guys,

I am currently stilling running in the engine on my 66cc R80 engine on my bike, so I am carefully monitoring my fuel usage. Anyways, when my friend had a look at my bike he told me my fuel cap was not good, as it was too loose and that I would lose fuel.
I didn't notice it initially, but today I did notice that I am finding fuel on my gas tank around the fuel cap. Is this anything to be worried about? Is wasn't completely wet, it looked more like condensation. But being in summer I doubt it is condensation.
Are there any fixes? Can I put some kind of a rubber gasket in my fuel cap? Or should I replace the fuel cap/lid completely?

Also, ever since I received my bike I have always felt that my tyres a little bit on the soft side, although i haven't ridden a bike since I was a teen so don't really remember how it should be. What PSI should the air pressure in my tyres be?

Below I have posted the specs of my Bike and engine in case they are needed to determine my tyre pressure, or how to solve my leaky fuel cap scenario. Have also included photos of the Tyre and the bike so you can see the gas tank setup. If You guys want a photo of the actual tank and gas cap let me know, and I'll take one with my phone. These are just the stock photos on the website of the shop I bought the bike from.

Kind Regards
Kevin Burton

BIKE SPECIFICATIONS

SKU	C310
Manufacturer	XDS
Product name	C310 Mens Beach Cruiser
Features	Mud Guards
Speed	8 Speed
Frame	6061 Alloy
Frame Size	19"
Fork	Hi-Ten
Handlebar	Steel Chrome W=700mm, H=245mm, 49°
Headstem	100mm, 30°, Alloy
Seat Pillar	Alloy
Saddle	Velo
Seat Pillar	Steel Chrome 27.2*300mm
Gear Shifter	8-Spd, Shimano
Rear Derailleur	Shimano
Crankset	44T*170mm, Steel/Alloy
Bottom Bracket	Sealed
Freewheel	Shimano 11-30T, 8Spd
Chain	KMC
Brakes	Tektro "V" Alloy
Pedals	Vp-813 PP/Steel
Rims	26*1.75"*14G*36H Alloy Machined
Hubs	F:KT-Q/R, R:KT-CYDR, Alloy
Spokes	Stainless Steel
Tyres	26*2.125", Kenda
Colour	Dark Grey
Year	2013

MOTOR SPECIFICATIONS
slant head for better compression
2.5L fuel tank
allen key bolts
8mm engine mount studs
66cc single cylinder
air cooled
2 stroke
bore & stroke 47mm*40mm
CDI ignition
power 3.3KW@ 7500rpm
compression 9:1
pedal start
2 stroke lubrication
fuel ration 16:1, 25:1 after running in
10L run in period
fuel consumption 2.5L/100km
rub bloc dry clutch
speed 60km +

 

[KCvale]

Nice build.
Your tank looks level so no problem there.

The cap has an internal vent and gasket to seal the bottom of the cap to the top of the tank, if it's not sealing to the tank it could be for a couple of reasons.

Usually it is from forcing the cap on or off, it bends the little tabs that hold the cap in the tanks groves.

Or it could be just be a bad/worn gasket, just add another gasket that size on top of the old one or buy a fatter one from the local hardware store.

Then again new caps are cheap ;-}

And you can run those Kenda tires as high as 50 pounds easy depending on your tube. More air means better millage with less wear but the high you go the harder the ride feels.

 

[butterbean]

The exact recommended psi can almost always be found on the tire itself. With KC's building experience, he is probably right, but I would check to be sure as over-inflation can eventually lead to a blowout. I use a hand pump with a built-in gauge. As far as the fuel cap goes, I have to disagree with KC just a little bit here, as I once had the same problem. I first tried doubling up my gasket, and that made it impossible to get the cap on properly. What I ended up doing was bending the tabs on the cap that slide into the grooves in the neck of the tank. This of course made the cap too tight, and it was not properly vented (but also no longer leaking). In order to vent the tank, I removed the cap from the tank (very important that you remove it for this fix) and used a small gauge drillbit to drill a hole in the top of the cap. The tank was then able to vent again. If your tank does not vent properly, you will have what's called vapor lock. This is when pressure in the tank prevents gas from flowing into the carb, and your engine won't run at all.

 

[butterbean]

To make the seal on the cap tighter, bend the tabs toward the top of the cap, but not too far or you wont get the cap on at all.

 

[Fabian]

Get yourself a locking fuel cap from JN Motors.

The locking mechanism of the fuel cap is completely useless, however, it does seal perfectly when compared to the (leaky) standard fuel cap.

 

[Fabian]

More air means better millage with less wear but the high you go the harder the ride feels.

I agree.

+1

I prefer comfort over speed. For general riding, my tyres are inflated to 20 PSI (front) and 24 PSI (rear), with the bike rolling on 26 x 2.125 tyres.

 

[butterbean]

My tires can go 35 to 85 psi according to the info on the sidewall. I inflate them to about 42 and being hybrid tires, I find them very comfortable at this psi while not sacrificing any mileage. I'm 285 lbs, and it's a 98cc engine geared at 12.44:1 with a top speed of around 30. I get 80mpg, and without looking over every minimal detail of what to do to get more, I would say it's pretty good for a guy my size.