Dave & Brian's XR650L Carb Mod Is Love

[dirtzilla]

Bought a '93 XR650L a couple of weeks ago from a man who was the second owner of the bike. He told me "a lot of guys like to do all sorts of carb mods, but this thing was PLENTY quick for me, so I left it stock." I ran into Dave Closs and Brian Jackson's carb mods EVERYWHERE on the net when looking into this bike (yeah, it ran SCARY well for me also, but I'm GREEDY FOR POWER AND QUICKNESS...can you EVER have enough?!) and decided to do it. (she already had the smog junk removed) Ordered the jets, started looking for the washer when it suddenly occurred to me that the guy I bought if from didn't REALLY know if the carb HAD been done....went out and looked at the mixture screw, and found that the tab had been filed off! THAT's why she's already quick! Dave and Brian are everywhere!

Here's my question (finally!); Someone has put some sort of putty, goop, adhesive, silicone, caulk (...?) between the mixture screw and the stop on the carb. Does this mean that they had problems keeping the mixture screw from loosening / rotating itself out (or in?)? If not - why else might they have done this?

Here's a pic;

http://www.geezerglide.com/temp/dzgoo/dzgoo.jpg

[Dual_Dog]

Here's my question (finally!); Someone has put some sort of putty, goop, adhesive, silicone, caulk (...?) between the mixture screw and the stop on the carb. Does this mean that they had problems keeping the mixture screw from loosening / rotating itself out (or in?)? If not - why else might they have done this?

Here's a pic;

http://www.geezerglide.com/temp/dzgoo/dzgoo.jpg

Couple things come to mind. The pilot circuit could be too lean and they overcompensated for this by backing out the pilot screw so far that the threads no longer keep the screw in place. It might have vibrated out. I know because I had this happen. 3.5 turns out is the max that will hold, and that's still too much. Between 2-3 turns is where it should be.

Or the spring might be lost/gone and the goop is keeping it from spinning on it's own.

From the picture it looks to me that the screw is way too far out. Check out how many turns out it is now. It's possible it needs a larger pilot jet. My $0.02.

[XR650L_Dave]

It almost looks like the casting (where the screw threads into) has been filed down or broken. Or, as DD says, it might just be out too far or missing the spring.

Dave Closs

[dirtzilla]

Dual Dog and Dave-

Here's a close® up;

http://www.geezerglide.com/temp/dzgoo/dzgoo4u2.jpg

So I may have incorrectly jumped to the conclusion that this was done in the process of the carb mod? I thought FOR SURE that it looked like the tab was ground off on the mixture screw-- hard to tell from the goop on it, but I think I see air where the tab should be.

Guess I'm gonna have to still pull the carb apart to find out, huh? When I do this, I'll knock off the goop and see what's what with the mix screw. "Casting ground down" ?! This doesn't sound like a good thing. Does that mean I'll need a new carb body? The horror....

Actually, check out the close® up pic link (this message). If you (Dave) saw the uneven part of the casting and thought that this meant it was ground, I THINK it's just some goop on there.

[ghoti]

It looks like the tab on the bowl has been broken off an JB welded back on Where's the push throttle cable?

[dirtzilla]

Where's the push throttle cable?

Uh...yeah.....it's not there, is it?

The throttle works fine without the push, although I have no XRL experience to compare it to. The spring seems to snap the throttle back to closed quickly when released. By the looks of the dirt buildup I'd say she hasn't had a PUSH cable on her in YEARS. With this in mind - what is the PURPOSE of the PUSH cable?

It's quickly becoming apparent that I'm over my head on this one. I've called in reinforcements (someone who doesn't have his head up his ) and we'll perform exploratory surgery this weekend.

Any advice on what we should be looking for (and any parts we should be prepared to replace) when we pull this carb would be greatly appreciated.

Thank you all for your help.

[ghoti]

The push cable is there to assist closing in the higher vacuum 4 stroke motors. Probably just double overkill on a CV carb. Make sure to have hex socket cap screws for the bowl and top of the carb. I also have them in the throttle cable bracket. If you put the choke lever to full on it's easier to install. That nut is plastic so be extra careful. A new cable is $40.00.

[XR650L_Dave]

I'd pull the carb just to know what's going on, but if its running fine that can wait.

I'd pre-order all the screw parts- screw, spring, washer, o-ring, just in case that thing falls out.

dave

[dirtzilla]

The push cable is there to assist closing in the higher vacuum 4 stroke motors. Probably just double overkill on a CV carb. A new cable is $40.00.

So, when the throttle spring snaps as I'm descending down that hill I should hope that I'm very familiar with the kill switch, huh?!

Make sure to have hex socket cap screws for the bowl and top of the carb.

I believe the sizes are on my shopping list;

#4 washer

4-4mm X 10mm

4-4mm X 16mm

Any idea why I'm buying a #4 washer?!

I also have them in the throttle cable bracket.

By any chance do you know the size?

[XR650L_Dave]

I think the ones in the bracket are 1 (or 2?) sizes larger in diameter.

Dave

[ghoti]

I don't know what size the screws are in the bracket. I'm kind of a pack rat and save screws and hardware from things I throw away. I had some stainless ones the were perfect

[dirtzilla]

The pilot circuit could be too lean and they overcompensated for this by backing out the pilot screw so far that the threads no longer keep the screw in place. It might have vibrated out. I know because I had this happen. 3.5 turns out is the max that will hold, and that's still too much. Between 2-3 turns is where it should be.

Or the spring might be lost/gone and the goop is keeping it from spinning on it's own.

From the picture it looks to me that the screw is way too far out. Check out how many turns out it is now. It's possible it needs a larger pilot jet. My $0.02.

Tore into it tonight and damned if you weren't right on the money! The spring was missing AND it was turned out about 5 1/2 turns! They drilled the holes correctly (although sloppily - left many burrs), but the washer was wrong. It was about 1 1/2 times as thick as recommended, but worse that that, it was too large in diameter. This meant that it kept the needle from seating in all the way. I'd estimate that the thickness it held the needle out was about 3 or 4X the recommendations from Dave and Brian. The jets they had in it were 160 and 52. Also had silicone holding in, or sealing the diaphram.

Snorkel out, K&N Air Cleaner in, stock exhaust.

Any thoughts? Is it surprising that it ran great?

We put in the correct washer and a new mixture screw assembly. How are you supposed to put the head on the end of the screw? Glue it? Crimp it? Leave it off? Gonna put in the 158/55 tomorrow and see how she runs. The 55 isn't as long as theirs - was I sold the wrong jet?

[XR650L_Dave]

They were sold the wrong jet- the correct pilot jet is the short one.

Was the 160 a keihin jet?

The silicone on the diaphragm, was it sealing a rip? Just to hold it in place?

It is suprising that it ran well, I can't wait to hear how it runs with the new setup.

dave c.

[dirtzilla]

Was the 160 a keihin jet?.

I believe so. When I find it again, I'll report back.

The silicone on the diaphragm, was it sealing a rip? Just to hold it in place??.

Just holding it in place. Diaphram was in good shape.

It is suprising that it ran well, I can't wait to hear how it runs with the new setup. dave c.

Yeah, Dave- me too! I have yet to do any post-jetting dirt riding. I drove it on the highway from my friends house and it's been in my garage since. I was going to go out yesterday, but decided to blow the carbon out of my stock pipe as per the Honda Service Manual instructions. "-POP-" went the bolts holding the clean out covers. Called a friend for help and he recommended I not ride it until I had time for him to weld the covers back on. It was at that point that I noticed the extreme shredding on the outside of my knobs. ? So I'm dead in the water until AT LEAST this weekend.

I CAN tell you a little about the highway, though. There was a definite feeling of smoothness through the RPM's that it had lacked, and it was far easier (TOO easy) to hit 75 without trying. I used to think she started to act "strained" at around 60 or 65 (geared 13 / 44). After the Jets, even at 75 it seemed like I could probably eek out a few more MPH pretty easily, although I didn't try (I'm nervous without a tach.). I'll know a lot better when I get her dirty, because the street is, well...not her element.

[dirtzilla]

OK- finally got 'er put back together, tuned, maintained and spent a couple of quality hours riding about 20 miles of trails yesterday. (I rejetted, following D & B's cab mod -- TO THE LETTER. The slide was already drilled by the previous owner.)

Dirtzilla is running top notch. As I said earlier (referring to my road ride) she's amazingly smooth now through all RPM's. In the dirt, this was evident in spades. I could go from idle to wide open with no "dead spot". Before my re-jet, there was this weird dip in power from idle to (any kind of) high revs. Now she'll go like a scared monkey when pushed, and like NOW.

I got in a bit over my head when a mud ditch ended up being deeper than I had reckoned for; before I could plant a foot I (instinctively) goosed the throttle and - viola! - I was launched out onto the other side. I am confident that whenever I need that power, it's THERE -- not waiting for me on the other side of the power dip. This makes the "trials" riding (maneuvering 4X4 truck ruts, setting up for a stream Xing, etc) much less stressful.

Ah....she looks so pretty dressed all in mud.....

Cheers, Group. ? Thanks for your help.

[XR650L_Dave]

And the AAAV Army grows a little bigger...

Dave

[dirtzilla]

And the AAAV Army grows a little bigger...

AAAV = Advanced Amphibious Assault Vehicle ?!

[Dual_Dog]

And the AAAV Army grows a little bigger...

AAAV = Advanced Amphibious Assault Vehicle ?!

I've got the _AAV part: All-terrain Assault Vehicle. Triple "A" is for "Air-cooled?"

[XR650L_Dave]

JJJJust aaaaa liiiitlle mmmis tttyping.

ddddddd