Thirsty Evo 250

[jon0881]

Hi,

I did my second trial on the weekend with my 09 evo 250. Absolutely loved it despite it being very muddy and slippy. I fell on my ass twice just walking back to the bike to ride a section. I started 11am with a full tank of petrol. 10 sections which were small and 4 laps. The times i put the bike down i turned off the fuel and all day i could smell strong petrol smell. Being an 09 i was paranoid about a snapped frame and looking for cracks but found nothing. I couldnt see anything out of the overflow at the time either. At about 2:30 i ran out of fuel on a hill climb. I switched to reserve to finish just 3 sections and rode back and rand out of the reserve too!

 

Im pretty sure my first trial i didnt have the same problem but i guess ill check the float height as a start.

 

Any ideas other than that?

Edited January 9, 2017 by jon0881

[tshock250]

Ive had 2 Evos brand new and although both carbs were set up perfectly, every now & again fuel would pour out of the carb vents. I suspect floats sticking occasionaly  as there clearly is nothing else wrong on stripping them down.

If you can smell fuel then you need to have a really close look to find the source.

[totty79]

The fuel taps can leak, I've had to replace one, later bikes use a different design. It's worth a look.

[lineaway]

 You said 4 laps, you never thought to refuel while getting some fluid for yourself?

[dan williams]

I wouldn't do more than two loops on a tank of fuel. Mud tends to suck up fuel.

[jon0881]

I'd ridden Cowm on my scorpa all day and it sipped fuel. I was jsut paranoid about the smell of fuel all day and was hunting for a cracked frame and fuel leak. I guess i should hve fueled up after 2 laps. We took so long on the first lap we just cracked on before it got dark. I wont make the same mistake again. Dropping a 3 or even 5 on a section cleaned all day.

[overdale]

The 09 was the Evo where some of the frames cracked near the headstock but usually only if stressed probably by the more active rider. I think it was the bare aluminium frame with the fuel filler off-centre, if you have the one with the fuel cap on the centreline, the frame has been renewed or it's a later model and should be trouble free. Any cracks on the older frames can be welded up with the correct procedures.

Usually the Evos are very good on fuel consumption if not flooding, your model holds a little less that the later ones with hydroformed tank.

The other thing about the 09 was that it only had one vent/overflow outlet boss on the timing side of the carb and the pipe was originally routed downwards behind the engine. Later years Keihins had and overflow and vent tapping at the same point on that side with side one going down the back of the engine and the top one going up under the side panel of the tank open ended.

From what I remember of the 09, we ran the right hand vent pipe upwards behind the side panel which stopped it bogging when going down hills.

You mention laying it down at sections, even with the fuel off you always lose fuel out of the carb which will increase your fuel consumption, and may even start a syphon when the fuel is on if your overflow/ vent pipe does not have a little vee cut out of it as a vacuum breaker. You can save fuel by fitting a side stand of course. By all means check the float height, it's on the Beta website.

All proper overflow pipes have a little vee cut out to prevent syphoning. 

You can only take the bowl off the carb easily with it inverted as when the right way up, the floats drop and catch on the angle brass overflow pipe fitted to the carb bowl. Sometimes when cleaning the carb, people hold the floats between 2 fingers and bend them inwards a little, this makes the bowl very difficult to refit as the brass pipe fitted to the bowl won't easily pass the float and may even foul it when in operation. You can carefully bend the float out if it has been pressed in and it makes fitting the bowl easier. 

Hope this helps!

 

 

[dan williams]

The Keihin on my 2013 had two vent hoses but when I pulled them off to clean the carb I noticed only one hole was drilled. The other was just a blank aluminum stud. Gave me a chuckle.