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Old 05-05-2011, 05:52 PM   #31
Ladd
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Joined: Jan 2007
Location: Asheville
Oddometer: 25
Tried Dynojet kit and airbox mod - better throttle response but still surged no matter what I tried. Got the TM40 and it is awesome, so smooth. I can lug around in 5th at 30mph and roll on throttle with no bucking and no surging on interstate. Fuel economy suffered a little bit but it is worth it.
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Old 05-05-2011, 07:17 PM   #32
Dakar Dan
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Location: Bendigonia
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I'd recommend staying with the stock set-up with only light mods (snorkel out, drilled slide and raised clip, adjustable air-fuel screw and hex-key carb bolts) in conjunction with the stock pipe as a reliable, economical ride. I also replaced my cable choke with a manual one due to sticking early on, as well as ditching the vacuum petcock when I got an IMS tank. Think of this as an easy "Stage 1" step.

The DynoJet kit is only adequate at addressing some of the stock carb's shortcomings and if you're going to go down the path of fettling, then save your bucks towards the FCR carb. IMHO "Stage 2" mods like this are really still a compromise around the BST-40's CV design.

As for "Stage 3", if you fit an aftermarket pipe and perform any airbox surgery, you really begin to out-gun the CV carb. It's then a slippery slope of experimentation unless you commit to a pumper carb as well. I now run a TK alloy pipe with stock header (will have weld ground down when I get it ceramic coated later), FCR39_MX carb (ex-MxRob), open top airbox with Twin Air filter. Bear in mind that this is all bolt-on work without any internal engine mods (cams, piston etc.) or porting/ valve jobs as a true Stage 3 progression would entail.

This combo makes the DR a different bike altogether. It doesn't transform it into a snarling, ill-mannered beast but certainly gives it more of an iron fist in a velvet glove feeling. Starts easy, runs smooth, no more farting at the table and excellent throttle response all the way through the range. Economy has dipped slightly but with the better tractability, I'll be returning to the higher stock ratio at chain & sprocket change time, which will restore some fuel range again. It's been said many times before but the overwhelming feeling is that this is the carb that the bike should have left the factory with in the first place, making it into a true thumper.
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Old 05-07-2011, 12:36 PM   #33
Rumlover
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Quote:
Originally Posted by Dakar Dan View Post
I'd recommend staying with the stock set-up with only light mods (snorkel out, drilled slide and raised clip, adjustable air-fuel screw and hex-key carb bolts) in conjunction with the stock pipe as a reliable, economical ride. I also replaced my cable choke with a manual one due to sticking early on, as well as ditching the vacuum petcock when I got an IMS tank. Think of this as an easy "Stage 1" step.

The DynoJet kit is only adequate at addressing some of the stock carb's shortcomings and if you're going to go down the path of fettling, then save your bucks towards the FCR carb. IMHO "Stage 2" mods like this are really still a compromise around the BST-40's CV design.
I pretty much agree with most of what you said. However I would give the BST carb a little more credit. I think with some basic mods as you mentioned, and include a few bucks for a few jets and an adjustable needle (or jet kit if prefered), the stock carb can be made to purr and provide some pretty good bang for the buck. I think some just don't have the patience/desire to keep tinkering with it to get it right. I will certainly agree that it will never have the immediate punch of a pumper carb, but it can make good power and run pretty much flawlessly with some careful tuning. For me it's just not worth the dollars to get a pumper (for now anyway )

Current setup:
Main - 142.5
needle - stock (modified/improved taper with one .040 shim)
Slide drilled with second hole (same size as original)
fixed D shelf problem with plastic washer cut to size
K&N filter
No backfire screen
Air box open about twice original hole size
Stock muffler
14/43 sprockets

Edit: Thanks 996DL and NordieBoy for posting those jet comparison charts here.

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Old 06-25-2011, 01:57 PM   #34
TripTheNinja
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Location: Maple Valley, WA
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'08 DR650 w/ FMF-Q4, K&N, Jet kit. Need help tuning.

First of all, thanks to everyone who contributes to this website chock full of information. I've gained a lot of knowledge from here and hope to contribute where I can. I'm doing my best to do all of my own maintenance, etc. so that I can be confident of fixing anything while out in the mountains or on long hauls away from home. Hopefully this question can help others as well.

I have an '08 DR that I bought used and in mostly stock form. I'm not doing any mods that require me to crack the case.
Last month, in an attempt to wake this bike up I purchased the FMF-Q4 exhaust, K&N filter and the "ASM-Jetkit" from Procycle. I stuck to the instructions that came with the jet kit. I'm currently riding in the humid climate of South Carolina mostly at 1000 feet elevation with weekend rides ranging up to 7000 feet.

I drilled the slide and did the air box mod (cut a big hole in the top). Procycle recommends using the #150 main jet for free flowing exhaust, setting the e-clip in the 4th groove from the top of the slide, and starting with the extended idle fuel mixture screw at two turns out.

I did just that and it ran like a raped ape. Only problem was that it backfired real bad on deceleration and when switching gears. I played around with just about every combination of jets (145, 150, 155), 3rd and 4th grooves in the needle, and idle screw adjustments (adjusting from 2 turns out after 10 minutes of riding). All of the settings provide better performance from stock, however...

-The 145 main jet backfires the least (at the 4th groove in the slide) and has the least power and response. Barely better than stock.

-The 150 main jet set at the 3rd groove has the better power however backfiring a bit more.

-The 155 main jet set at either the 3rd or 4th groove run good however it smells rich in any setting.

My goal is to get the best performance with no backfiring. If it's not possible to rid the bike of backfiring I can live with it. Any suggestions?

Thank you.
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Old 06-25-2011, 03:11 PM   #35
NordieBoy
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Quote:
Originally Posted by TripTheNinja View Post
My goal is to get the best performance with no backfiring. If it's not possible to rid the bike of backfiring I can live with it. Any suggestions?

Thank you.
The only way with an aftermarket pipe is putting on a Keihin FCR39MX carb with the air cut valve.

The stock carb has no air cut valve/coasting enrichener.
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Old 06-25-2011, 03:27 PM   #36
ER70S-2
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Location: SE Denver-ish
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Decelleration Popping, Worse With Aftermarket Exhaust

Originally posted by LexTalionis:

"Two or three posters yesterday asked about DRís backfiring, probably on deceleration. Didnít see an answer, so hereís mine.

Most street bikes with carburetors have a decal circuit built into the carb to meter in a bit of fuel on closed throttle, to prevent or greatly reduce backfiring on deceleration. My KLR has this, as has every pure street bike Iíve owned. The simpler DR carb does not have this circuit, hence you will be hearing more backfiring than other bikes you may own or have owned.

This is not a problem, rather it is simply a characteristic.

Lex

P.S. As an aside, the rubber diaphragm in the decel circuit of my KLR has a tear in it, and so my KLR now backfires almost as much as my DR."
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"BTW, I don't do style. It's a dirt bike, not some girlie dress-up thing." -

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Old 06-26-2011, 05:47 PM   #37
sagedrifter
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Joined: Apr 2006
Location: Jacksonville, Alabama
Oddometer: 1,408
Quote:
Originally Posted by TripTheNinja View Post
First of all, thanks to everyone who contributes to this website chock full of information. I've gained a lot of knowledge from here and hope to contribute where I can. I'm doing my best to do all of my own maintenance, etc. so that I can be confident of fixing anything while out in the mountains or on long hauls away from home. Hopefully this question can help others as well.

I have an '08 DR that I bought used and in mostly stock form. I'm not doing any mods that require me to crack the case.
Last month, in an attempt to wake this bike up I purchased the FMF-Q4 exhaust, K&N filter and the "ASM-Jetkit" from Procycle. I stuck to the instructions that came with the jet kit. I'm currently riding in the humid climate of South Carolina mostly at 1000 feet elevation with weekend rides ranging up to 7000 feet.

I drilled the slide and did the air box mod (cut a big hole in the top). Procycle recommends using the #150 main jet for free flowing exhaust, setting the e-clip in the 4th groove from the top of the slide, and starting with the extended idle fuel mixture screw at two turns out.

I did just that and it ran like a raped ape. Only problem was that it backfired real bad on deceleration and when switching gears. I played around with just about every combination of jets (145, 150, 155), 3rd and 4th grooves in the needle, and idle screw adjustments (adjusting from 2 turns out after 10 minutes of riding). All of the settings provide better performance from stock, however...

-The 145 main jet backfires the least (at the 4th groove in the slide) and has the least power and response. Barely better than stock.

-The 150 main jet set at the 3rd groove has the better power however backfiring a bit more.

-The 155 main jet set at either the 3rd or 4th groove run good however it smells rich in any setting.

My goal is to get the best performance with no backfiring. If it's not possible to rid the bike of backfiring I can live with it. Any suggestions?

Thank you.
Make sure your pilot jet is really clean, what your describing is a back fire or decel pop?

If its back firing at idle through the carb its the pilot circuit or an air leak at the carb boots.

If its popping through the exhaust on decel, thats normal. 2 1/2 turns out on the pilot should help in the decel popping. A 150 main jet is all you need with exhaust and a cut air box. Mine popped very little at 2 1/2 turns out while living in Florida. But, it is pretty rich, 1 1/2 to 2 turns out is better usually.

The Q4 is loud compared to stock and your probably just hearing the pop from a straight through exhaust. The Q4 is at least 10db louder and it keeps getting louder with use.
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Old 06-27-2011, 06:17 PM   #38
TripTheNinja
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Joined: Mar 2010
Location: Maple Valley, WA
Oddometer: 10
Quote:
Originally Posted by sagedrifter View Post
Make sure your pilot jet is really clean, what your describing is a back fire or decel pop?
It's popping through deceleration. After working through the many variations of jets and settings and riding from 700 to 6500 feel in elevation, I believe that the 150 jet is the way to go. Funny how I started with the suggested settings and played around with every variation. Now I'm back to the original suggested settings. I just didn't expect the pop.

So far:
Pro's
- Louder / safer
- Much better throttle response
- Overall a more exciting bike to ride
- Improved low and mid range power

Con's
- Top end power struggles from 70-75mph. Could still need some fine tuning
- Deceleration pop
- Loss of stealthiness while exploring in the mountains
- Have to upgrade to a better carb. to hit the sweet spot

Thanks for everyone's answers and advice!
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Old 06-27-2011, 06:38 PM   #39
sagedrifter
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Location: Jacksonville, Alabama
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Quote:
Originally Posted by TripTheNinja View Post
It's popping through deceleration. After working through the many variations of jets and settings and riding from 700 to 6500 feel in elevation, I believe that the 150 jet is the way to go. Funny how I started with the suggested settings and played around with every variation. Now I'm back to the original suggested settings. I just didn't expect the pop.

So far:
Pro's
- Louder / safer
- Much better throttle response
- Overall a more exciting bike to ride
- Improved low and mid range power

Con's
- Top end power struggles from 70-75mph. Could still need some fine tuning
- Deceleration pop
- Loss of stealthiness while exploring in the mountains
- Have to upgrade to a better carb. to hit the sweet spot

Thanks for everyone's answers and advice!
Well, we are only talking around 38 hp or so... Depending on load, 70 indicated will not come instantly.

If you can get 47 mpg or better your carb is probably good. I get 47 to 53 mpg depending on load and my mood. I find the bike likes 75 mph indicated or less. When traveling I run about 64 mph (around 70 indicated) on the GPS and get 50 mpg or better. My bike pops on decel and smoothly pulls to the rev limiter....
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Old 06-27-2011, 06:45 PM   #40
twigsnapper
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My popping decreased significantly when I repacked the Q4. Kinda miss it tho.
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Old 06-28-2011, 01:21 PM   #41
Rumlover
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Quote:
Originally Posted by TripTheNinja View Post
Con's
- Top end power struggles from 70-75mph. Could still need some fine tuning
There is no reason a well tuned DR/bst40 should not accelerate cleanly and fairly briskly to an indicated (stock speedo) 95 or even 100mph. It does start to flatten out around 90, but should still be moving up. Mine did it when stock at 4500'asl. Does it even better with some carb mods and improved gearing (14/43), and I weigh about 200lbs in my riding gear. I would look to fine tune the jetting a little more. Taping off the airbox some can give you an indication if you are lean or rich (if it runs better you are lean, worse you're rich).
Good luck

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Old 09-02-2011, 09:33 PM   #42
ER70S-2
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Location: SE Denver-ish
Oddometer: 4,938
DR Carb Needle Options

Thanks to the work of mx_rob.

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SUZUKI DR650SE INFORMATION INDEX
Quote:
Originally Posted by Threewheelbonnie View Post
"BTW, I don't do style. It's a dirt bike, not some girlie dress-up thing." -

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Old 09-14-2011, 08:16 PM   #43
basketcase
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Location: Roll Tide Central...
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Float adjustment

Can someone help me with the basic steps in checking the float for proper adjustment, and then adjusting it as (if) needed?

Thanks in advance,
Rick
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Old 09-16-2011, 08:07 PM   #44
ER70S-2
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Recently, I replaced the two o-rings on the float assembly. So, obviously, needed to check the float level. Manual says 14.7 + or - 1mm. Simple enough, turn the carb upside down and set the float level. Well, not really. Float level is supposed to be set with the float tab 'just' touching the needle valve. Inverting the carb 180* might compress the needle valve spring-----this isn't what they mean. Rotate the carb until the float tab contacts the pin in the needle valve, not 180* (upside down).

Someone brought this up recently, and is when I re-read the manual. YMMV, etc.
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SUZUKI DR650SE INFORMATION INDEX
Quote:
Originally Posted by Threewheelbonnie View Post
"BTW, I don't do style. It's a dirt bike, not some girlie dress-up thing." -

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Old 09-16-2011, 08:18 PM   #45
sagedrifter
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Location: Jacksonville, Alabama
Oddometer: 1,408
Thumb

Quote:
Originally Posted by ER70S-2 View Post
Recently, I replaced the two o-rings on the float assembly. So, obviously, needed to check the float level. Manual says 14.7 + or - 1mm. Simple enough, turn the carb upside down and set the float level. Well, not really. Float level is supposed to be set with the float tab 'just' touching the needle valve. Inverting the carb 180* will compress the needle valve spring-----this isn't what they mean. Rotate the carb until the float tab contacts the pin in the needle valve, not 180*.

Someone brought this up recently, and is when I re-read the manual. YMMV, etc.
It does not have to be exact down to a pubic hair etc..... hence the +/- part.

Put it on its side and the float should be parallel to the carb base... When you do that, its real close to .58"....
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