85cc dads!

[portero72]

Howdy, all. I’m new to the 2t world and will likely have a ton of questions now and again, but my first is about fuel consumption. My son’s 13 85sx seems to go through a good bit of fuel. I know 2t bikes in general use a lot more fuel than do 4t, but Im not sure what I should be expecting. The stock 1.2 gallon tank is good for his 30-40 minute races, but he occasionally runs with the big bikes and I don’t think there’s any way one tank would be enough for a 60-75 minute race. I’m open to the idea of buying a larger tank (IMS 1.8), but would just like to know what I’m experiencing is normal.
BTW, it’s a 13sx that came to us with an EBR built engine. Starts easily and runs fast and well, as far as I can tell (I’ve always ridden 4t). It does spooge a bit, but not enough to drip. I’ve not messed with jetting, cuz if it ain’t broke….

 

[woodsguy]

I can't answer your question but isn't that what runs in Super Mini with us in the am races? I've never seen them refuel nor run out.

 

[woodsguy]

If jetting is off you could be using more gas. I had a 250sx that never was right and it was painfully close in 1 hour race.

 

[portero72]

I can't answer your question but isn't that what runs in Super Mini with us in the am races? I've never seen them refuel nor run out.

I’m betting you are correct. Haven’t raced on a Sunday in forever, but I know they have their own class with the big bikes. Wonder if any of them run oversized tanks.

Santa brought him the bike, so I haven’t had much time to get used to it, and Saturday was his first time racing it. He’s well pleased, to say the least. I’ve got a JD kit in a box for it, but I wasn’t sure it’s appropriate for a built engine.

 

[woodsguy]

Found this picture of a little friend, note fuel coming from hose! If the float is occasionally sticking you could be throwing raw fuel out. Just a thought.

 

[woodsguy]

It's 10 years old, might be worth checking.

 

[portero72]

It's 10 years old, might be worth checking.

Prior to Diamond Willow, I put a loop in the drain hose but didn’t see any in the tube after the day was done. I’ll keep checking.

 

[Dao]

welcome to the smoker's club!

i agree w/ rob...
chances are good that if mpg is too low, then fuel is/could be leaking out the carb while he's riding it.

check/reset your carb float level. wouldn't hurt the jetting to lower the float level 1-3mm from specs just to be absolutely sure it's not causing leakage. The freestyle guys typically lower the float level by alot so the bike don't flood / flame out while doing quadruple flips and all sorts of crazyness.

while you're in there, check the black rubber tip on the float needle.

it should have smooth taper sides like pictured.

If there's a groove cut into the taper side, and/or the shape is distorted/deviated from overall shape, then
it's worn, needs replacing. Instead of buying that one part, it's cheaper to buy a rebuild kit.

FYI:
2013 85 SX uses a Keihin PWK 28mm carb. It's a very good carb.
All Balls PWK 28 carb rebuild kit is just as good as OEM rebuild kit.
And....i wouldn't mess w/ intalling the JD kit until you are done w/ the finalizing your fuel economy issue.

 

[woodsguy]

Hope you get it sorted out!

 

[Dao]

back when we chased TSCEC:


10 yr old Son on YZ85

7 yr old Son #2 on JR80

me on CR250