the DR650 thread

Do you have any dyno charts with CO traces to share?

Regards,

Derek

as long as I'm happy, no need for paperwork.

I've been meaning to get some shorter bolts and do some work to the bottom of the case. It rattles and moves around back there when I'm moving around off road, but for just commuting to work and back, it isn't a problem. One idea I'd heard was putting a U-bolt around the rack right at the front so it's attached front and back. I was also planning on putting wing nuts or something that's removable by hand so I don't have to break out the tools each time I want to take it off.

I am constantly reminded " The more I learn it becomes apparent how little I know." I gain knowledge which only leads to more questions. I have been using an Innovate unit to help with fuel trims and it has become obvious that there is alot more to the process. An exhaust gas analyzer is in my future. I am an auto tech with more years of experience than I'll admit and can use it professionally when I get to tune carbs on the street rods when they come in. They are typically set up with an out of the box carb recommended by some salesperson on the phone. The owner may think it runs good but a properly setup carb can wake up the sleepy beast.
Motolab.......Thank you for your input and help.
And you who are content with your ride, ride on and keep the rubber side down.

Tuning a carb on a DR is no more of an enigma than on any other bike. It is true that there will be variations based on the exact modifications that were performed, but there are trends, and those will always hold. For example, in relationship to a needle shape such as OEM/non-USA OEM/KTM/FP, a needle with a shape like the DJ needle will always tend to create a CO trace shaped more like the one in the chart I posted. In relationship to stock, the large main jet required by an opened airbox will also tend to create a CO trace shape more like the one in the chart, which of course means countermeasures should be taken instead of installing a needle such as the DJ that exaggerates a then already existing negative trend.

During what combination(s) of throttle position and rpm does this lack of response manifest?

Verifying that the jetting is correct is always beneficial.

There should be more power available from the opened airbox and it absolutely requires jetting changes.

A rich condition will behave worse when hot. A lean condition will behave worse when cold. The ignition timing and compression should be conservative enough as standard (temporarily use supreme to be sure) so that you can safely lean out each circuit until you just get a lean misbehavior. A good rule of thumb is to then richen from that cusp by 2-3 jet sizes/1-2 clip positions.

The compression and ignition timing on a DR are probably such that the improved cylinder filling afforded by a flat slide carb will nothing but beneficial, but I'd still want to have a look at NOX or a cylinder pressure trace to be sure. Perhaps a move to premium would be in order. Some are annoyed by the heavier throttle pull of the TM. To get a sense of the tuning challenges, see http://www.advrider.com/forums/showpost.php?p=18991504&postcount=66600 (everything mentioned there about the FCR applies to the TM as well).

Regards,

Derek

Be aware that the extra octane that premium has often comes from the addition of ethanol. Ethanol fuels are also inherently oxygenated, which is beneficial unless the mixture is already too lean without it. With the proper jetting, ethanol can make great power, and I prefer ethanol to the light aromatics often otherwise used to improve octane, because they are incredibly toxic and don't add any oxygen. I think the main drawbacks to ethanol are that it sucks up moisture if not stored in a sealed container (which then leads to poor running and corrosion of components), that it's bad for most rubber except Viton, and that it gums up the works pretty bad if allowed to sit in a carb and evaporate (I don't know if this last item is a factor of ethanol in general or only of ethanol/gasoline blends).

Regards,

Derek

I'm glad you are happy with the way your bike runs! However, without data, what you are talking about is in reality purely subjective, unquantified, unproven, and therefore of little use to others.

Regards,

Derek

Bravo!

Regards,

Derek

If a number of individuals on this forum with the Dynojet kit are happy with the performance of their bikes that is of use to me. Subjective and anecdotal data has a place as do dyno charts but not everyone has a dyno operation near by.

I would agree with you if even just one person could provide a dyno chart for a DR650 using a DJ needle with a reasonably flat CO trace. Neither asking here, nor searching on the internet has produced any result. On the other hand I know from first hand tuning experience with countless CV carbureted engines what to expect from a shape such as that of the DJ needle and we have a dyno chart to back that up.

Regards,

Derek

I like the Pro Cycle needle because it can be adjusted. The stock needle I was shimming with washers. The Pro Cycle kit worked very well for me (150 main jet) and stopped the surging. I also opened the air box, drilled the slide and installed an adjustable air fuel mixture screw. My 2009 idles and runs much smoother since the mods. I wish I had a dyno chart of before and after the mods.
P.S The mods cost me a couple miles per gallon but I think it was worth it.


QUOTE=motolab;19701580]I would agree with you if even just one person could provide a dyno chart for a DR650 using a DJ needle with a reasonably flat CO trace. Neither asking here, nor searching on the internet has produced any result. On the other hand I know from first hand tuning experience with countless CV carbureted engines what to expect from a shape such as that of the DJ needle and we have a dyno chart to back that up.

Regards,

Derek[/QUOTE]

My dog loves me. Your statement applies equally with that claim as well but that still makes whatever I say no less true for my own needs...

Unless you are a competitive racer subjective results are all that really matter.
I think that most DR riders will be perfectly satisfied with making their bike run well enough to be fun to ride and still get decent fuel economy. Sure, it would be nice if there was a needle available that would give a perfect flat co trace with an open airbox but at this point such a needle does not exist. It certainly isn't the non-US OEM needle.

I have stock carb, stock jetting, stock air box, i installed the DJ needle only, bike runs like a pickle seeder, it went from the stock crappy throttle response, could hardly pull the front wheel off the ground, had no low end, to running very smooth, has lots of low end, you can let it get down and crawl at a little less than 1/8 throttle, wanna pull that front wheel in 1st, just whack the throttle.

Fact of the matter is it will flip you if you are not careful, i have nailed second a few times and lifted the front wheel.

MPG went from upper 50s to 50MPG

How do I get rid of the Triceratops that seems to be always at 1/3 throttle?

Your dog loving you would be very hard to quantify and even if it were possible, the data would be irrelevant to others simply because your dog's love for you bears no relationship to them. The results of jetting are on the other hand relatively easy to quantify and far more relevant to others.

Regards,

Derek

Lean mixtures are probably not a huge problem on the DR in stock form as long as they don't produce symptoms, however the engine will run hotter at the intersection of throttle position and rpm in question. On the other hand, overly rich mixtures are a problem even if they do not produce symptoms (remember that the amount richness required to produce them is far more than the amount of leanness), ranging from causing poor mileage, to causing carbon deposits (which are abrasive to the cylinder wall & rings and get pounded into the valve faces & seats) to fuel washing the oil off of the cylinder walls (which will cause cylinder wall and ring scuffing). The 9.5% CO indicated in the chart is rich enough to be an issue, as rich misfires usually begin in the 10-12.5% range.

What data are these assertions based on?

Regards,

Derek