DR650SE Index Topic #10- CARBURETOR/INTAKE

[Krusty ...]

Several schools of thinking here. Many opt to stay with exactly what the engineers at Suzuki designed. Others feel the need to make a good thing better, and the intake tinkering can go from mildly tweaking the stock CV carb to opening up the airbox and/or switching to a flatslide pumper. And if you're so inclined, do-it-yourself fuel injection is on the horizon, thanks largely to the relentless efforts of mx_rob.

Intake-wise, what's worked for you?


-AIRBOX MODIFICATION
-AIR FILTERS
-STOCK CARBURETOR [MIKUNI BST40] MODIFICATION
-MIKUNI TM-40 [HSR-40]
-KEIHIN FCR39-MX
-FUEL INJECTION?

[eakins]

my bike had dynojet mods when i bought it. it surged and the power was very abrupt on/off. hated it.

now:
-stock needle & raised up w/ 2 washers for more gas on the main
-stock jetting
-1 additional hole drilled in the slide for better throttle response
-spring not modified
-jesse's fuel screw now set at 1 turn out. had it out more for better idle but off-idle bog. now off idle bog at 1.
-carb fully cleaned w/ pine sol soak. this made a huge difference in how much better it ran even though it looked clean. a ton of dirt came out. safe on rubber. search for hondo's post.
-ngk iridium plugs for the best possible fuel burn.
-stock airbox w/ only snorkle gone
-twin-air air filter
-upgraded 2ndary air filter form procycle

bike runs well from sea level to over 13k that i've had it to. pulls strong and linear. i use a 14 tooth cs and i can off-road in 1st and pull 80 all day in top. 50 or so mpg

[Krusty ...]

From the factory, your DR650SE came equipped with a Mikuni BST40 constant velocity (CV) carburetor. You may begin your journey of enlightenment here:


The BST40 Bible

Airbox mod? If you plan to enhance your DR's ability to breathe, you will need to address the restrctive airbox. If your plans to tweak your carb include stay with the factory jetting, you won't likely need to do more than remove the snorkle at the top of the airbox. If you plan on doing more (bigger jets, Dynojet kit, etc.) you'll likely end up doing the "airbox mod".
Here's a picture, from the Keintech website:



www.keintech.com



mx_rob has been a man on a mission to improve the performance of the DR. He is a "fixture" over at ThumperTalk, and his early efforts focused on the BST40.

His website www.mxrob.com, has a BST40 section, including a link to this thread at ThumperTalk, comparing different needles.

Mikuni / Dynojet Jet Size Comparison
[from vmaxoutlaw.com]

Mikuni Dynojet 140 149.3 Flow rates based on size markings of Mikuni and DynoJet jets are not comparable. As a guide .. the chart to the left indicates equivalent sizes based on the diameter of hole in the jet. Mikuni jets are chamfered on the inside opening at the threaded end and Dynojets have a machined flat surface. Keep this in mind when using this chart. These physical differences will never allow an exact comparison. This chart is intended to be used as a tool to assist you in making a more accurate decision when selecting a jet size range or comparing tuning data where an opposing brand is being used. Actual jet sizes are highlighted with a gray background. DynoJet jets are marked according to the diameter of the hole in the jet .. ie: DJ150 = 1.5mm and DJ175 = 1.75mm. This is not true for Mikuni or most other OEM equivalent jets. This size Mikuni jet, (N102.221 Super BN), is marked according to its' flow rate, ie: 150 = a rating of 150 cc of fuel per minute. 150 142.5 152.0 145 154.7 155 147.5 157.3 150 160 152.5 162.7 165 155 165.3 157.5 168.0 170 160 170.7 162.5 173.3 175 165 176.0 167.5 178.7 180 170 181.3 172.5 184.0 185 175 186.7 177.5 189.3 190 180 192.0 182.5 194.7 195 185 197.3 187.5 200 190 202.7

[SkunkWizard]

reference pic
TM-40 & stock

[macdesign]

Let's establish one thing up front - My DR doesn't see any dirt at all.
It's a city commuter, which is currently being made even more so (read - being motarded), and a damn good one at that
So, I'm after anyones views or experience on dumping the airbox entirely and running a pod filter or similiar.
In the stock of bits and pieces to play with there's obviously the standard carb and exhaust as well as a TM-40, an FMF Q4, a GSXR titanium can, and finally a FMF oversize front pipe/Hindle rear (to suit the X40X can).
I'll probably end up mucking about with them all but don't mind not having to "re-invent the wheel".

[Krusty ...]

TM40-6 (HS40) manual from Mikuni:
http://www.zodiac.nl/instructions/234862.pdf

[shu]

I'm pretty happy with the stock carb/airbox set up on the DR. It has been totally reliable and I never have to mess with it. I live at 7500 feet and ride above 11,000 feet on Colorado passes often, and have put in many miles at sea level as well. The bike always starts and runs well with no hesitation or misses from idle to redline. (If I want more power, I usually choose my other bike.)

Just my .02.............shu

[plugeye]

cut box/ twin-air AF
39mm fcr-mx, jetted normal except:
38pilot 50leak EMP-3 magic-racing screw 1.0 turns out

[996DL]

07 DR650 with stock exhaust at 2200 ft asl...

Full Jesse/Kientech airbox mod, TwinAir foam air filter, Uni pleated filter replacing useless oem foam cannister, drilled slide, exposed oem mixture screw @ 1 turn out, Jesse's recommendation of 155 DynoJet mainjet for oem exhaust, and Most Importantly in my case: DynoJet needle set one step leaner than instructions, to Completely Cure the common off extended idling flat spot: (DJ needle's clip set at 3 down from top).

This setup performs perfectly and routinely yields 60mpg Imp gal / 48mpg US gal. My DR is used as a "roadie" with a taller 16 tooth frt sprkt and ridden like I want to keep it for the long run, with no banging off the rev limiter, nor treating the transmission like a 125 motocrosser.

996DL

[inire]

Bump

Coz my bike only gets 40-45 mpg and i dunno why.

[kalsop]

Originally Posted by inire

Bump

Coz my bike only gets 40-45 mpg and i dunno why.

I have a question, my carb doesn't seem to shut down quite quick enough between shifts. The only mods done are air/mix screw 1-1/2 turs out and shimmed needle. .32/.09 mm. Any thoughts?

[eakins]

Originally Posted by kalsop

I have a question, my carb doesn't seem to shut down quite quick enough between shifts. The only mods done are air/mix screw 1-1/2 turs out and shimmed needle. .32/.09 mm. Any thoughts?

start by cleaning it with pine sol soak (google for hondo's thread)

you might have sticky/gummed throttle cables or throttle tube.

[kalsop]

Originally Posted by eakins

my bike had dynojet mods when i bought it. it surged and the power was very abrupt on/off. hated it.

now:
-stock needle & raised up w/ 2 washers for more gas on the main
-stock jetting
-1 additional hole drilled in the slide for better throttle response
-spring not modified
-jesse's fuel screw now set at 1 turn out. had it out more for better idle but off-idle bog. now off idle bog at 1.
-carb fully cleaned w/ pine sol soak. this made a huge difference in how much better it ran even though it looked clean. a ton of dirt came out. safe on rubber. search for hondo's post.
-ngk iridium plugs for the best possible fuel burn.
-stock airbox w/ only snorkle gone
-twin-air air filter
-upgraded 2ndary air filter form procycle

bike runs well from sea level to over 13k that i've had it to. pulls strong and linear. i use a 14 tooth cs and i can off-road in 1st and pull 80 all day in top. 50 or so mpg

What size washers did you use?

[ER70S-2]

Thanks to Northyork:

http://www.advrider.com/forums/showp...ostcount=35442

[kalsop]

Thank you.