Fuel Economy DJ Needle

[FossilB]

I got 135km from my last tank of gas before having to switch to reserve. My bike is an 03' with 14 tooth cs, jesse airbox mod, 155DJ main jet, 42.5 pilot 1 turn out, ground header weld, drilled slide, DJ needle on 3rd groove. guys with the stock DR's are getting 200km's plus before hitting reserve. my main jet is only a size larger than stock, and the airbox mod allows the engine to breath better so i would have expected a mild increase in fuel consumption but not this much. i'm putting it down to the DJ needle being shorter and too sharply tapered allowing too much fuel to be sucked through the needle jet / main jet. I'm thinking of replacing with a stock needle and shimming it up a bit in order to get better fuel economy. does anybody have any thoughts on whether this would work, and whether the bike will still run as good?

[DirtieR]

You should be able to get around the 18-19klm a litre with the dynojet set up.I get to around 180-190klm before switching to reserve.(DJ160 main,needle 5th groove,15t front sprocket and 45t rear,supertrapp ISD2)

[Blankwaffe]

If you have done the air box mod, the stock needle will not work at all. I tried several things recently considering mpg and that was one of them. My bike would not run worth a crap with an open air box and stock needle no matter how many shims you can stack in there. Its all in the needle too,so no matter what main you run it does not help.

From what I could see a slipon exhaust has no effect on the bikes overall performance(power,jetting or mpg) in stock form other than making more noise. Well the TB M7 I have did seem to take the initial flat spot out of the off idle bog with stock jetting and air box.

I discussed this in detail with the tech at Two Bros due to the fact they say run stock jetting. And he jumped up and down saying the M7 makes better power(on the dyno) than the stock exhaust even with stock jetting/air box.In fact he said the dyno tests they did on the DR650 was with stock jetting/air box and they saw an increase...which is also why they dont have any jetting specs for the DR650 other than stock.Personally I cant see it in the seat of my pants.

Anyway, opening up the very restrictive air box is what creates the flow and requires more fuel.Not so much the exhaust IMHO.The aftermarket exhaust cant flow anymore than the stock muffler when considering how little air is actually being drawn into the motor through the tiny snorkel.

Performance gains are only noticeable if the air box is modified and a jet kit is installed,which also causes mpg to drop as a result.

It basically comes down to you either run the motor with stock air box and jetting with less power and better mpg,or do the jet kit and air box mod for better overall performance and expect less miles per tank.

I tried going back to stock jetting,air box and muffler and it ran perfectly fine.Installed the TB M7 exhaust with and without the P3 insert using stock jetting and it ran the exact same with more noise.But the stock jetting and air box had such a mild manner compared to the Dynojet and open air box I could not stand it.Felt like I was towing something actually,so I chose to use more fuel.

With the Dynojet kit,air box mod and TB M7 Im averaging at about 46mpg depending on terrain and my throttle hand.

Stock I was well into the 50's again depending on terrain and throttle control.

That being said all I ride is back roads in the hills,so I have no long term highway mpg to offer.

In the end its worth the trade off for me to have the better performance offered by the jet kit and air box mod..

HTH,Im sure somebody that is more familiar with the subject can add better info.

[bgrzdr]

Best power and best mileage are not mutually exclusive. It's not an either /or situation. Properly tuned, your DR will run well AND get good mileage. My own experience: Stock-----------50 mpg

Dj needle(3),152 MK main, air box mod,'03 GSXR muffler--50mpg

FCR-MX emp-5, 152 main,Twin Air, mods above -----50 mpg

These are not steady cruise figures but general riding around here which is a mix of twisties and country roads. I can get into the 30's when I'm really honkin' on it but I'm talking about legal street riding. Lousy gas mileage in normal riding demands more tuning !!

[jonboat]

The stock needle will work with an air box mod!

I'm using an .080 shim, 160 Mik main jet (which is the same as a DJ 170). I have a K&N air filter and a Q2 slip on. My A/F screw is only out 1 1/4 turns.

My milage ranges from 46 to 49 mpg. I do have to ride pretty hard to get as low as 46. Thats even with a 14t front sprocket.

Also, NO drivability problems!

I know I could get more performance with another carb, I'm just not sold on the DJ kit.

I'd like to be able to spend 4 or 5 hundred on a new carb, then I would need to spend how much time and money to tune it. Besides I'm getting married soon, I'm gonna need all of my money.

The BST is OK, they do need work, but they are easy to work on!

[mastershake]

Keep the Dj needle I have the 170 main jet and lost some mpgs , I was running on 3rd clip down then moved to 2nd clip made it alot better. the lower the needle sits in the jet is less fuel the goes by until you slam it open then your main jet is wide open

[AndrewL]

A post by ProCycle on ADVRider on the same subject which fairly sums it up.

http://www.advrider.com/forums/showthread.php?p=7179813#post7179813

Cheers

[gixxstar]

Had a DJ kit in mine with a bone stock airbox for about a year. I get better mileage in my car than with that setup and I pretty much need as much range as I can get so I switched it back to stock and have been riding it like that for quite a while now.

[Blankwaffe]

Trust me fella's,Ive tried darn hard to find the middle ground using the stock jetting and or a Dynojet kit.Mainly because mpg and high gas prices.But I also expect to have the performance Ive seen the DR give by adding just the jet kit and opening up the air box.So I drawn to the performance end of it all.

Now I live at about 500-1200' above sea level and the humidity here is high most of the time.So my findings will vary with someone that lives at a higher elevation and less humidity.

To me there is one real option,either run the stock jet needle(shimmed or not) and air box,or open things all the way up and go with the Dynojet to get the most performance gains.To me its a night and day difference between the two,which is why I said what I did above.

The stock needle just gives the motor a flat power type of feel overall as compared to the DJ needle.

Removing the snorkel and shimming the needle is a good first step for a mild performance gain(that does run much better than stock) without loosing much in mpg.But does little to help with overall performance with an aftermarket exhaust other than make noise.Again power and performance is nothing near the DJ and open air box.

I had absolutely no luck trying to shim the stock needle enough to compensate for an open air box.I did get the bike to run well enough to ride but my plug readings were way too lean for me.In fact it was way leaner than the stock jetting and closed air box,especially in the mid part of the throttle.Ive even tried a colder spark plug.

Now I dont know if the free flowing exhaust had much to do with it or not,but I did not feel safe in running the motor that way.Im sure not going to recommend doing that to anyone else.

Ive tried different clip positions on the Dynojet needle and mpg can be increased by raising the clip to the third position just as MX Rob and a few others have said in the past.Seems to make the off idle and mid range a bit more crisp.But as MX Rob also warned me it does get lean on up in the throttle range with an open exhaust like my TB M7.Now I can run the P3 insert in the TB exhaust with the DJ needle in the 3rd and a 160 main and the bike runs perfectly throughout.I'd say thats probably an ideal setup for the stock exhaust as well if your running a DJ kit at my elevation and temps.

I tried the 2nd clip position on the DJ needle and it was LEAN.

This is all my opinion and was developed by my butt dyno and plug reading.So it may vary between each end user.

But IMHO if you open the air box up any further than removing the snorkel you better use the DJ needle or something.Opening up the air box increases flow dramatically and the stock needle is just too straight and fat to do the job.

Maybe MX Rob can add some better info.

In the end,yeah your riding habits does have a huge affect on mpg.Right now Ive got the DJ needle in the 4th,about two out on the air screw with a 170 main and the TB M7 with the end cap open.Ive rode the DR to work for the past few days(all pavement and smooth straight roads) doing exactly the speed limit and being calm with the right hand,and the mpg are edging up to right at 50 mpg from the way it looks at the moment.But I can say without a doubt that once I hit the dirt back roads,curves and up/down tight hills I will be right back down around 46mpg or less.

Basically Im chasing my own tail in the jetting and mpg search.I want the modified performance with stock mpg just like everyone else...guess I just need to control my throttle hand in the end....huh?

Sorry for the ramble folks,and I appreciate yall listening to my OCD.Ive lost several nights of sleep on how to attack this subject of jetting,overall performance and mpg.Those are the only options and answers Ive found.

I want the performance when I need it so I just have to behave otherwise to get the best mpg.

It would be nice if someone would develop a stage 1,2 and 3 line of kits for the current DR650's using the BST.That way a person could tune to each individuals preferences.

Procycle are you listening?

[DoubleD650]

........My bike is an 03' with 14 tooth cs,,,,,

Theres your problem,,,, put on a 16 if you want to more KM's/per liter....

Conditions allow that is,,,,,

[xr1million]

This might be slightly off topic but still have some relevance.

At MMI I saw 2 CBR1000's get dyno'd side by side. One had a two hoes slip on and the other was bone sock with a power commander. The two hoes bike made 8 hp. less than stock and the power commander bike made 11 hp. more than stock with just a little tune. I know i am comparing EFI to carburation but it is still basically the same.