the DR650 thread

[neo1piv014]

Originally Posted by JTB488

Look in the BST-40 bible thread, shows the needle and float together in one pic,looks to be aluminum in ours, but still the little rubber tip.

The BST Bible was what I went off of. That was where I noticed that my spring was missing a part. I just didn't see where to get at that float needle thing. After many frustrating experiences, I've learned better than to try forcing small, plastic parts around. Now that I know they come apart, however, I can check them out. I'm also looking at getting a TM40 for this bike before too long anyways, so this might all be a moot point, but it's always good to learn.

[Sierra Thumper]

Originally Posted by FatChance

The 7 year old yellow IMS tank on my DR650 is still yellow...

Lucky you
I have a plan to turn my yellow-that-used-to-be-white IMS tank white again. I found that using a scotchbrite pad with soft scrub with bleach helped quite a bit.....I just didn't want to spend 24 hours scrubbiing on it to get the best results. So I'm going to get some scotchbrite type pads for my electric drill, along with the softcrub, and use a slower speed to scrub the tank beyond belief.
Believe me that sob is going to be white again

[ER70S-2]

Originally Posted by neo1piv014

The BST Bible was what I went off of. That was where I noticed that my spring was missing a part. I just didn't see where to get at that float needle thing. After many frustrating experiences, I've learned better than to try forcing small, plastic parts around. Now that I know they come apart, however, I can check them out. I'm also looking at getting a TM40 for this bike before too long anyways, so this might all be a moot point, but it's always good to learn.

You'll have to learn how a carb works, one way or another.

Something like this from the BST-Bible:



Hides in here on our DRs.

[neo1piv014]

Originally Posted by ER70S-2

You'll have to learn how a carb works, one way or another.

Something like this from the BST-Bible:



Hides in here on our DRs.

Ohhh! Yeah, I saw that part. I guess I just need to pull it out and check it for wear. So I guess I must have put something back together a little incorrectly. I thought it was running well, but now it has a very rough idle if you're not on the choke and pops like crazy on decel. I'm going to order that clip for my spring, and I guess I need to fiddle with my fuel mixture screw. I thought I had measured two full turns, though I could just be a quarter turn or so off when I reset it. Do you back the screw out to richen the mixture a bit?

[ER70S-2]

Originally Posted by neo1piv014

Do you back the screw out to richen the mixture a bit?

[neo1piv014]

Originally Posted by ER70S-2

Tell you what, I'm going to devise quick release systems for the side panels, seat, and fuel tank. Even if I don't become a millionaire, I'm sure I'll save about 10,000 man hours per year.

[doug s.]

Originally Posted by neo1piv014

The BST Bible was what I went off of. That was where I noticed that my spring was missing a part. I just didn't see where to get at that float needle thing. After many frustrating experiences, I've learned better than to try forcing small, plastic parts around. Now that I know they come apart, however, I can check them out. I'm also looking at getting a TM40 for this bike before too long anyways, so this might all be a moot point, but it's always good to learn.

definitely stop wasting your time - get a tm40 or fcr39. the bst40 is simply not worth learning about, imo...

ymmv,

doug s.

[ER70S-2]

Originally Posted by neo1piv014

Tell you what, I'm going to devise quick release systems for the side panels, seat, and fuel tank. Even if I don't become a millionaire, I'm sure I'll save about 10,000 man hours per year.

Ain't that the truth!!

[neo1piv014]

I've also learned a valuable lesson about why I need to get that god damned extended fuel screw. So I backed the fuel screw out about 1/2-1/4 of a turn. The bike fired up, with choke, but when I gave it throttle, the engine would sputter and die. Assuming that I had the mixture too rich, I screwed it in about 1/4 turn, put everything back in place, and fired it up again. It's about the same. The idle is still very "chuggy" and dies after about 10 seconds, and now, when I open the throttle any more than 1/3 or 1/2, the engine sputters and dies. I'm assuming that I'm running too rich, but I also know next to nothing about carburetors, so I might be a bad judge here. Does it sound like I'm running too rich?

[motolab]

Originally Posted by neo1piv014

I've also learned a valuable lesson about why I need to get that god damned extended fuel screw. So I backed the fuel screw out about 1/2-1/4 of a turn. The bike fired up, with choke, but when I gave it throttle, the engine would sputter and die. Assuming that I had the mixture too rich, I screwed it in about 1/4 turn, put everything back in place, and fired it up again. It's about the same. The idle is still very "chuggy" and dies after about 10 seconds, and now, when I open the throttle any more than 1/3 or 1/2, the engine sputters and dies. I'm assuming that I'm running too rich, but I also know next to nothing about carburetors, so I might be a bad judge here. Does it sound like I'm running too rich?

The pilot screw should only be used to tune the idle mixture. Anything that is not idle is the responsibility of other components. Correspondences on CV carbs:

Low rpm all throttle positions: float height, needle base diameter, emulsion tube outlet size
WOT operation overall: main jet
WOT operation between HP peak and red line: main air corrector
WOT operation below red line: jet needle shape
1/4 throttle opening: jet needle clip position
1/8 throttle opening: pilot jet size
1/16 throttle opening: pilot jet size
idle: mixture screw adjustment

Realistically, the float needle condition should be verified and the float height set before the idle mixture is adjusted.

Procedure:

Hold the carb in one hand and hold the base of the float cage tightly against the carb body with the index finger of the same hand. Rotate the carb so that the float tang just contacts the float needle's spring loaded plunger, but does not depress it. With the float height setting tool set to the desired height, use the other hand to drop it down over the float so the tool's posts contact the bowl gasket surface and the posts are square to the body (front to back - the tool takes care of side to side). Flip the tool to check both sides (as the float may have some twist in it). Bend the float tang until the tang on the float height setting tool just contacts the highest point on the float, but does not depress it.

Procedure for setting idle mixture:

Start the engine and warm it up. Lower the idle speed below the factory spec. Starting from a setting that is known to be lean (1-1/2 turns is likely but not guaranteed to be), adjust the fuel screw to obtain the highest idle speed. Adjust to 1/8 - 1/4 turn richer than that. Then, adjust the idle speed back to 1500 rpm.

Once you have the correct fuel screw setting, there should not be too many reasons to have to revisit very often. I'm therefore not a big proponent of extended fuel screws. If you intend to own carbureted motorcycles in the future, I recommend procuring an angle-drive screwdriver, which will be universally applicable.

Regards,

Derek

[ER70S-2]

Screw it in snug, back it out 1-1/2 turns, ride. Some time ago (39,000 miles or so), I was browsing the internet and I kept seeing 1-1/2 turns. Sounded good to me. I've since bought the extended fuel screw and messed with it. I'm still at 1-1/2 turns, give or take. At my altitude (6000 +), I'm satisfied; although I've heard that riding a TM-40 or FCR will ruin me forever (or until I convert).



Yesterday, my baby turned 40.



205'd by motolab

[planemanx15]

Originally Posted by neo1piv014

Tell you what, I'm going to devise quick release systems for the side panels, seat, and fuel tank. Even if I don't become a millionaire, I'm sure I'll save about 10,000 man hours per year.

Thumb screws...made all the difference

[TinkerinWstuff]

got my single track setup. 18" rear wheel with 90/90-18 and drive hub with off road gearing.

I have a street tire for the 17" rear with another drive hub and highway gearing.



I've also made a different dog bone plus the larger wheel gives me about an extra inch of ground clearance.

[neo1piv014]

Originally Posted by motolab

The pilot screw should only be used to tune the idle mixture. Anything that is not idle is the responsibility of other components. Correspondences on CV carbs:

Low rpm all throttle positions: float height, needle base diameter, emulsion tube outlet size
WOT operation overall: main jet
WOT operation between HP peak and red line: main air corrector
WOT operation below red line: jet needle shape
1/4 throttle opening: jet needle clip position
1/8 throttle opening: pilot jet size
1/16 throttle opening: pilot jet size
idle: mixture screw adjustment

Regards,

Derek

1/4 Throttle opening sounds about right for where it starts dying, and if I remember my names correctly, that's where the clip is missing from the spring. So if that clip isn't there, I'm guessing that's letting the jet needle move around incorrectly. If that was jacking with my fuel flow, then maybe that's causing it to die out? I don't get why this didn't happen before, and I'm damn near positive that I didn't see that clip when I pulled out the spring, but I've been checking around my work area just in case it fell out when I was pulling it out.

Originally Posted by ER70S-2

Screw it in snug, back it out 1-1/2 turns, ride. Some time ago (39,000 miles or so), I was browsing the internet and I kept seeing 1-1/2 turns. Sounded good to me. I've since bought the extended fuel screw and messed with it. I'm still at 1-1/2 turns, give or take. At my altitude (6000 +), I'm satisfied; although I've heard that riding a TM-40 or FCR will ruin me forever (or until I convert).



Yesterday, my baby turned 40.



205'd by motolab

I'll give 1 1/2 a try tomorrow when I'm ready to get dirty again. I'm right at the same altitude as you, so it's at least a starting point. I've been wanting to snag a TM-40 after the first review I read for one. Considering all the stupid stuff I spend money on, $450 really isn't all that much.

[neo1piv014]

Originally Posted by TinkerinWstuff

got my single track setup. 18" rear wheel with 90/90-18 and drive hub with off road gearing.

I have a street tire for the 17" rear with another drive hub and highway gearing.



I've also made a different dog bone plus the larger wheel gives me about an extra inch of ground clearance.

Woah. That's a crazy skinny rear tire. Does it still have enough traction with that narrower profile?