the DR650 thread

[neo1piv014]

Well, I got the clip thing for the big spring in my carb, but it's still doing the "quarter to half throttle open then die" trick it started doing yesterday. So, I set the idle mixture screw to 1 1/2 turns out, and it wouldn't even start. I got it to turn over once, but that was it, so I backed it out to two full turns out, and it started right back up. Once again, it wouldn't let me open the throttle to any real degree (even with the clip correctly in place now), so I pulled the carb back off the bike to check it out as per Mr. Motolab. Here's to hoping it isn't anything major.

[neo1piv014]

While taking it apart, I did notice a few things that escaped me the first time I opened this up. The first is the main needle. It almost looks like it's bent or crooked.


Having never seen a different one, I'm not really sure if this is wrong or not, but there it is. I also noticed that the O-ring that sits on my float assembly - the larger of the two O-rings that goes underneath my float weight - is able to spin almost freely around in it's notch. Probably worn out. So it looks like I'm going to have a bit more of a shopping list for the procycle folks.

[TinMan207]

Originally Posted by victor441

sure, I posted some when I made it at http://advrider.com/forums/showthread.php?t=822721
and it was definitely worth the effort, it is much easier for me to change tires with the wheel clamped down and at waist level

Many thank for the link!

What are you using above the hub and below your "wing-nut"? Some kind of spacer? Large Socket?

Again, thanks. LOVE the idea!

[jessepitt]

Originally Posted by neo1piv014

While taking it apart, I did notice a few things that escaped me the first time I opened this up. The first is the main needle. It almost looks like it's bent or crooked.


Having never seen a different one, I'm not really sure if this is wrong or not, but there it is. I also noticed that the O-ring that sits on my float assembly - the larger of the two O-rings that goes underneath my float weight - is able to spin almost freely around in it's notch. Probably worn out. So it looks like I'm going to have a bit more of a shopping list for the procycle folks.

That thing is definitely bent!

[neo1piv014]

Originally Posted by jessepitt

That thing is definitely bent!

What in the hell would have done that? There's only one place where the damn thing could go when putting it back together, and I've never had to force anything when working on this carb. Oh well. Looks like I'm in the market for a new needle in addition to O-Rings.

[motolab]

Originally Posted by neo1piv014

I also noticed that the O-ring that sits on my float assembly - the larger of the two O-rings that goes underneath my float weight - is able to spin almost freely around in it's notch. Probably worn out.

I wouldn't worry about that too much. What I would worry about is if the float cage does not fit snugly in the carb body, i.e. it falls out by itself, and/or requires zero effort to install, or if the o-rings otherwise exhibit evidence of hardening, shrinking, deformation (i.e. no longer having a round cross-section) or cracking.

Regards,

Derek

[motolab]

Originally Posted by neo1piv014

What in the hell would have done that? There's only one place where the damn thing could go when putting it back together, and I've never had to force anything when working on this carb. Oh well. Looks like I'm in the market for a new needle in addition to O-Rings.

Might I suggest an adjustable one?

Regards,

Derek

[neo1piv014]

Originally Posted by motolab

I wouldn't worry about that too much. What I would worry about is if the float cage does not fit snugly in the carb body, i.e. it falls out by itself, and/or requires zero effort to install, or if the o-rings otherwise exhibit evidence of hardening, shrinking, deformation (i.e. no longer having a round cross-section) or cracking.

Regards,

Derek

Ah. I had to use a little bit of effort to pull it out. It was definitely snug in there. So when I was putting the float assembly back into the carb, I was pretty strictly following the pictures from that BST bible post. When it was perfectly horizontal, the float was swinging out away from the carb body. When as I tilted it up to 60 degrees or so, the line on the float was running parallel with the edge of the carb body. Then, when I put the carb flat on the table, the float fell into the body like the pictures showed. I'm awful at explaining anything, but this is what I'm referring to:
http://www.advrider.com/forums/showthread.php?t=347184

[neo1piv014]

Originally Posted by motolab

Might I suggest an adjustable one?

Regards,

Derek

You definitely may. Any preferred source that I should snag it from?

[Paddle007]

Originally Posted by Adv Grifter

One correction, I would NOT screw the fuel mixture screw in "Snug". It has a very sharp point on the tip which can be damaged from over tightening. Just screw in till it bottoms ... never force it, it will last a LOT longer this way and be more effective when fine tuning.

1.5 turns out works for me too at most altitudes. (I'm at sea level but ride frequently at altitude). When I'm up high I LEAN out the mix and go in a half turn or so on the Fuel mixture screw. Works a treat. At 12,000 PLUS ft. I got the DR idle to smooth out and starting recovered to normal ... and leaner settings save fuel!

I'll back you up on that. I had a friends DR with the TM40 carb that was kicking my behind with running problems. One of the problems was no adapter ring and the second was the tip of the mixture screw was broken and stuck in the bottom of the hole. No air could pass through and it created some strange running problems.

[neo1piv014]

So with everything put back together again, jacked up needle and all, I got it back on the bike, and she fired up like nothing had ever happened. I let it warm up, verified that it idled without the choke after a minute or two, and took her for a ride. Knowing I have a messed up needle may be inducing some bias in the testing, but the fueling feels a little odd now. Nothing I can really put my finger on, but that's getting replaced, so we'll see. I've also noticed that it pops a good bit on deceleration/engine braking. It's not terribly annoying, and I might just be noticing it now because I usually ride with earbuds in place. Should I just hold judgement on this thing until I get the needle replaced? Thanks to everyone for chiming in on yet another of my little projects.

[motolab]

Originally Posted by neo1piv014

You definitely may. Any preferred source that I should snag it from?

Well, http://advrider.com/forums/showthread.php?t=528038.

Regards,

Derek

[neo1piv014]

Originally Posted by motolab

If you intend to own carbureted motorcycles in the future, I recommend procuring an angle-drive screwdriver, which will be universally applicable.

Regards,

Derek

What angle-drive screwdriver are you using? A quick glance around the hardware stores in my area showed a few right angle screwdrivers, but they were all quite stubby. If there's a nice, thin one, I'd get that in a heartbeat.

[BergDonk]

Originally Posted by acesandeights

Typically, as the contact patch decreases the contact pressure increases. As you lose floatation you often increase bite, or traction due to the smaller contact patch. I have more experience in offroad truck tires, but if you want to increase traction, you often need a narrower tire. There are trade offs and conditions can dictate what works in a given situation, but riding desert sand might favor a wider tire, where you need more floatation, and forest single track might favor a narrower tire, where the narrower tire has more traction.

What is interesting about this is that, all other things being equal, which of course they almost never are, if the only change is the tyre width, keeping the same type and construction of tyre, and the same air pressure, as the tyre gets narrower, the pressure at the patch increases, which flattens the contact patch. The net result is that the surface area of the contact patch is more or less the same, but its shape gets progressively narrower and longer. Arguably more relevant when talking about 4 wheeler tyres which of course have a nominally flat tread.

A wider leading edge to the contact patch creates more flotation on soft surfaces. In fact sand is like going up a hill all the time. The tyre sinks in and is always climbing up the front edge. Make it narrower, and its a steeper/deeper face to climb out.

A longer contact patch can add stabilty compared to a wider one. Its why we prefer 21" fronts to smaller ones with wider tyres on our dirt bikes. The contact patch isn't much different in size, but the shape is longer, hence more directional stability.

Make sense?

[Tex76]

Hey guys, anyone know where I can get a black rear fender? I've been changing plastics and I've ordered the rear black twice and both times they email me a couple days later canceling the order because its not available. What gives?


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