Carb Adjustments

Started by Josh_TN , Jun 17 2008 06:08 AM

46 replies to this topic

Crazed Geezer

Posted 22 June 2008 - 06:06 AM

#21

I just did all that stuff yesterday on my '08 with 600 miles on her now.

1. Pulled the snorkel

2. Ground the header weld down

3. Installed one #4 stainless washer under the needle clip

4. Drilled out the A/F plug and adjusted for smooth idle/snappy throttle response

Jumped on and I was very pleased with the increase in instant power and torque. She wants to wheelie now.

I did leave the backfire screen in there though... it's a pain but it keeps any chunks of foam or large crud from getting sucked in, just in case the filter falls out or something. I don't think it restricts the air flow all that much, unless I was to put a jet kit in.

Plus I live on a farm and ya never know when a mouse might build a nest in the airbox. :thumbsup:

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Josh_TN

Posted 23 June 2008 - 08:34 AM

#22

Well Friday night me and a fellow TTer started taking apart my brand new bike.  It was due for the 600 mile valve check so we decided to go ahead and do all the carb adjustments as well.  Put in the shim ground the weld...... you know the drill.

End result is a bike that runs smoother and has better throttle response.  I drove the crap out of it on SUnday afternoon, trails, highway, and city driving.  Was not easy on her by any means and I still got over 48 mpg.  I think that once I control my self and take her easy it should be virtually unafected.

So for the $.05 that the washer cost and a $2 ginding stone, I would definatley say that this was the best bang for the buck you can do!  THanks to you guys and especially MX_ROB!

GsVs

Posted 27 June 2008 - 08:50 AM

#23

To all that have done the :

Snorkel removal/Shim needle/adjust pilot ....

Please give an update to the change in your MPG.

I have a stock '06 DR650 that I'm using for commuting and back roads, so I want to keep the MPG's up (I'm getting 60mpg). For what I'm using it for - it has all the power I need but it could run smoother.

(Has anyone done a how-to with pictures ?? Besides the old roto-tiller I have never taken a carb apart)

Thanks !

Josh_TN

Posted 27 June 2008 - 10:34 AM

#24

GsVs,

The mod on the DR is really simple. If you know what a screw driver, drill bit, & grinding wheel are you are capable of doing this mod. SO far my mileage compared to bone stock is a little less. But I will attribute this to me whaling on the bike because I want to see what it will do. Now that I have had a week to enjoy it I will take it easy on her and report back as to what it did. If you search on this site you should find enough pics to get you going. If not let me know and I can email you some.

Josh_TN

Posted 17 July 2008 - 10:16 AM

#25

I have put approximately 700 miles on the bike since doing the carb mods. (remove snorkel.....shim......). SInce then my mileage has been a best of 49mpg and a worst of 44. THe bike runs absolutely great, the mileage just sucks. I was expecting a little hit but 10-14mpg hit kinda sucks. Any advice on what I can check. I know it is not running lean and it is smooth as butter at all rpms.

I am around 450ft above sea level and my mix screw is around 1.75 turns out from fully seated.

mxrob

Posted 17 July 2008 - 12:24 PM

#26

Josh_TN said:

Measure the amount of shim you used and reduce by 1/2. Hobby shops have some really thin brass washers. Run your pilot screw as closed down as possible while still maintaining a smooth idle. Any more than that and you are just wasting fuel and trashing your oil. You should be able to come up with a happy medium in there somewhere. I know there is an exact mixture that will give the best performance and fuel economy.... if we had fuel injection we could go there. But the reality is a tapered needle can't possibly give the correct amount of fuel at all engine loads. Finding the best compromise based on what is most important to you is all we can do.

Josh_TN

Posted 17 July 2008 - 12:34 PM

#27

mx_rob said:

I used a .029" shim. It was the closest to the .030" everyone seems to be using. You think I should still cut by half? ALso is there any danger of running too lean if I use the smooth idle rule? THanks for the help.

Kazaroo

Posted 17 July 2008 - 12:43 PM

#28

Hi - Newbie here. '08 DR650 with about 650 miles. Love it, but I want a little more out of it. As suggested above, I've searched for pictures for the carb mods. I had trouble finding them, but found pics of the header weld grind. I'm experienced with auto and marine engines, but not bikes, so if anyone can find/send/or link me to some pics for the carb mods, I'd appreciate it. The header weld grinds seem pretty obvious, but I saw one thread where the outside of the header was welded for additional strength before the internal weld were ground. Is this necessary? Also, what about the upper chain guide? Dealer says leave it, threads here say @#%$ can it. Opinions? Thanks!

bigboy292000

Posted 17 July 2008 - 01:59 PM

#29

Kazaroo said:

...so if anyone can find/send/or link me to some pics for the carb mods, I'd appreciate it...

Here you go:

http://www.thumperta...ad.php?t=655692

PS. It ran way too rich with that many washers! Yanked out most, left just over 1 mm of shim.

Kazaroo

Posted 17 July 2008 - 02:55 PM

#30

Thanks!!!

Anybody else about the chain roller or welding the header before grinding?

SH650

Posted 17 July 2008 - 05:04 PM

#31

The upper chain roller has to go unless you want to lose it and the steel it is attached to, this is a must fill the hole with silicone and forget it, the header weld is necesary if you think it looks thin after you grind away the weld take it easy and slow and only smooth it out and you should be fine without welding, i never did and so far so good

Josh_TN

Posted 23 July 2008 - 08:08 AM

#32

Finally got her right! I kept playing with then mixture tank by tank until my last tank. I averaged 53 mpg with a good mix of city and highway. Runs great no surging or rattle at low rpm, is within 2-5 mpg of what I was getting stock. ALso worth noting that the air temp here has been between 95-102 F lately. I think that when it gets a little cooler it should do a bit better.

GsVs

Posted 24 July 2008 - 01:17 PM

#33

Josh_TN said:

Hey Josh ....

Define "right" ... did you reshim ??

Josh_TN

Posted 25 July 2008 - 06:13 AM

#34

GsVs,
My set up is now a .030" shim. THe snorkel removed, screen still in(I live in the stix and we have mice), and the mixture screw aproximately 1.5 turns out from seated. I am around 450 feet above sea level. Hope this helps. ALso worth noting that the mpgs are based on normal riding and no more than 65 mph and a good mix of city and highway commuting. ALong with some twisty backroads. Hope this helps.

Slave2Fishing

Posted 25 July 2008 - 09:11 AM

#35

I have shimmed the needle and removed the snorkel and I am getting approx 50 mpg (all city). But I think it running a little rich because it will start with no choke. Runs fine otherwise. Does anyone else start with no choke? I am in Florida.

DR Da-da

Posted 25 July 2008 - 09:44 AM

#36

Slave2Fishing said:

Slave2Fishing,
I have an '07 bone-stock and live in south Alabama at about 200-300 ft ASL. My bike starts without the choke and will (usually) idle fine. Occasionally, it will stall once within the first minute - but only about 25% of the time. I keep it garaged, so it's always "room temperature" when I start it.

Craig

snb92

Posted 25 July 2008 - 10:03 AM

#37

Slave2Fishing said:

I live on the coast in South Texas so I would assume a comparable atmosphere in relation to your location. I have noticed in the warm months, especially summer when it's hot, no choke needed to start. Winter time when its cool to cold, It helps alot to apply the choke (I can still get it started w/out it, it's just hard to and there's no reason to not use the choke).

Slave2Fishing

Posted 26 July 2008 - 04:29 AM

#38

Thanks Guys for the replies.

boatxr

Posted 26 July 2008 - 08:37 PM

#39

shim needle with 2 washers, pull the snorkle, pull the backfire screen, add adjustable fuel screw, remove rear most lower muffler drain bolt for a little better flow. bike will run well and won't potentially surge if you go the DJ kit/airbox cut out mod. power is strong and linear plus i also added ngk iridium plugs to help with the burn. i'm very happy whereas when i had the DJ/airbox mods it never consistently ran well.

Crazed Geezer

Posted 27 July 2008 - 04:06 AM

#40

Josh_TN said:

I have practically the same exact settings on my '08, except my A/F screw is 1 1/4 turns out, and I ground my header weld. I left my screen in for the same reason (mice!) and my altitude is only 150 ft. higher. Runs great. Seems like we both arrived at the same tune so that tells me we're probably doing something right. :ride:

I do more gravel county roads than pavement and run in 3rd gear a lot so my mileage is a bit less at around 48 mpg, but I bet if we traded bikes and rode them around our own stompin' grounds the mileage and performance would be the same on either one.