DT175 Yamaha Enduro issues

[Yakman12]

Yeah I do actually beat the cr*p out of it quite regularly...

Dave I completely agree, I have a KDX200 Enduro bike and it is smooth at low speed / revs, much much better than my DT.

One other thing I have noticed...

Just as it is about to run out of gas (ie: I have to switch to reserve) it suddenly starts running a whole heap smoother... after it dies, I flick to reserve and its back running rough again.... very odd???

I'm only getting around 70-80km a tank as well.

[merv]

So that makes it sound like the float level in the carburettor is too high.

[F5 Dave]

or float jet dribbling gas. might be onto something there.

[Yakman12]

Brilliant!

I'll pull out the float jet and see if I can get a replacement.

I'll check the float height also.

Silly question, but how the heck do you measure the float height? I've looked online and people seem to be using vernier calipers or specialist tools.

Is there a cheat way to do it?

[ktm84mxc]

If it's getting 70-80 k's per tank the carb is flooding, do you turn the petcock off when you've finished the journey?

[merv]

Silly question, but how the heck do you measure the float height? I've looked online and people seem to be using vernier calipers or specialist tools.

Is there a cheat way to do it?

Usually you can do it with a small ruler as long as you can find the right setting measurement i.e. at what point the needle valve is meant to close in mm to say the bottom of the float from the body of the carb when the bottom of the carb is off if that makes sense to you.

[Yakman12]

Cool thanks Merv.

ktm84mxc yes I do turn off the petcock (occasionally forget, but not often).

If I'm chewing through gas I'm guessing my float level could be too high.

[merv]

You can tell if it's float valve problem by leaving the fuel tap on when you stop the bike provided its not a vacuum tap if it is put it on prime. If it starts leaking fuel out the breather pipe after a while then it's buggered otherwise adjusting float height might be all it needs.

[F5 Dave]

And it might be some fluff behind the valve seat preventing the valve closing, it might be during running it leaks with vibration but almost seals at a stop. It might be that o-ring around the valve seat so pull it out & look. To reseat the valve, drop a small ball bearing in it & give it a tap with a centre punch (don't go silly).

[Oscar]

Sounds like the power band bearing to me.

[Yakman12]

F5dave are you talking about the float valve? Didn't realise it needed to be re-seated?

It is an odd float valve, just a washer on the seat, no o-ring.

Oscar... 'power band bearing'... are you taking the piss?

[F5 Dave]

Yeah he's hilarimouse.

"It is an odd float valve, just a washer on the seat, no o-ring"

oh yeah like this
http://www.smebike.com/image/cache/d...26-250x250.jpg
rather than
http://www.smebike.com/image/cache/d...25-250x250.jpg

er, hold on just try here

http://www.smebike.com/carburetor, p...amaha-4?page=2

[Yakman12]

Looks a lot like this actually:

http://www.smebike.com/image/cache/d...25-500x500.jpg

[F5 Dave]

cool, I don't see those types often, just make sure it is clean underneath. The reseating isn't often required but can be handy if you think it looks a bit messy & has been leaking.

[Yakman12]

Update time.

Checked the float height, I have it set dam near perfect (21mm according to the interwebs).

Still having the same issue though, I have ordered a new float-valve and seat... will see if that helps.

Also I discovered this morning (a rather cold morning as well) the bike will start with one kick, dead cold with no choke! Strange?

I now have two symptoms that make little sense to me:

1. I don't need any choke to start the bike from dead cold.
2. Just as its about to run of of fuel, it runs perfectly smooth (like it should).

More thoughts anyone?