the DR650 thread

I think this is how it's supposed to work: on the California models there is a tube in the tank filler that is supposed to be a guide for refilling the tank. You're not supposed to fill beyond the bottom of the tube, which leaves some airspace at the top of the tank for the charcoal cannister vent to stay above fuel level.

That's why the fuel tank capacity is 3.4 gal for 49 states and 3.2 for California.

I've filled mine to the bottom of the tube, and a tad more without trouble. However on another vehicle I overfilled it and saturated the cannister so I'm wary of overfilling.

What you are implying is that it depends on the ratio between carb bore size & engine bore size, and from how low an rpm & how quickly you want to be able to open the throttle without hesitation, which is of course true, but by extension this means that if the slide carb's bore were large enough, even the DR might be helped by an accelerator pump if the throttle were opened quickly enough from a low enough rpm.

Agreed, especially for seat of the pants tuning, except that the tuner has to be able to tell the difference between misbehavior that is jetting related, and misbehavior that is related to how quickly and from how low an rpm the throttle is being opened. This can be somewhat difficult, since the jetting really needs to be evaluated under load, the throttle will need to be opened to create a load, and load can be fleeting since the bike will obviously accelerate.

On a proper brake dyno it doesn't really matter too much, although disconnecting the pump can help the CO trace level off sooner.

Indeed. An example of this is that on thumpertalk they recommend all sorts of gymnastics to restrict the pump shot when an FCR is installed on a DRZ400. In fact the pump shot is fine if the jetting is not off in space as it is if you use the jet needle they recommend.


Regards,

Derek

As I said, with a slow revving bike like the DR, the AP isn't necessary at all, but its nice to have all the same, and does improve response. By all accounts the BST can be made to work OK and it has no AP. With my FE650 Berg with negligible flywheel and bigger bore, too much AP makes it unrideable in the bush. Having an adjustable AP makes it easy to dial out for base setup, then dial in to suit. My 3 FCRs, Berg 501, 650 and DR650 all have an adjustable AP of some sort and is a definite advantage when setting them up.

FWIW, some more of my DRs FCR development is posted here and on:
http://www.advrider.com/forums/showthread.php?t=646076&page=27

Speaking of touring, we continue our way south in Mexico. The DR(stock carb) is doing great as usual from sea level to 12,000 feet.

We ran into some more of this cobblestone stuff again, but this time we turned back after about a mile of pounding- we'd like to avoid breaking stuff down here.



For those who think it's not that rough, come down here and try it. The riding is easy but the ride is extremely harsh.


So we took some easier roads, this farmland is at about 9,000 feet.



Lost or confused? Time to reprogram the GPS. Bicimapas coverage is pretty good but certainly not perfect.



I helped this guy tie his hand-truck to the back of his scooter with some twine. I know for sure he made it around the first corner.




Now here's a plug for the original, totally unmolested carb (except for carb mounted choke knob, and extended pilot fuel screw.) Never a problem, never lacks for power or response in touring situations: highway, twisties, in traffic, dirt roads, and rocky dirt roads. Reliably delivers 50-54 miles per gallon.



................shu (from Oaxaca, Mexico)

It isn't necessary on any engine (just open the throttle slowly enough), and if it improves response, some might argue that it's therefore necessary.

That's because the BST is a CV carb.

Do you mean that it's too responsive?

Agreed. Being able to adjust pump shot volume and duration is a good thing.

Regards,

Derek

I ran my dr hard in the dirt for several hours and the tube did not twist.

It's in the rocks/roots where you may need them.
Knobs + embedded rock/root that the tyre can't spit out the back and violently grips on. Can cause issues...

Crap, that looks bumpier than the road from Rollinsville to the tunnel. Not one of my more comfortable day rides. It does put me in my place though.

Totally unmolested carb..............are you knutz..........

Thanks for the pics and updates.

Yes, 122 kgs wet and blinged and 63 hp at the knobs. I have not ridden anything that has close to the hit, or linearity this has, including the latest EFI stuff. For single track and fire trailing, its awesome, but only with the AP dialed right back. You also ride it using lots of clutch, not the throttle. In slower going, its far easier to fine tune drive modulating the clutch than it is a throttle that is super responsive, even with the AP backed off. Totally different to the DR650 to ride. On dirt, the FE650 will light up the rear at any speed up to about 140 kph and launch, its like a huge puppy, just wants to go at the slightest provocation stretching the leash all the time. The DR even with the FCR and stuff, is like the old dog who just wants to lounge in the shade, but if you insist, well OK it'll go and cruise if you insist.

Exactly. I spun a tire when I wheelied over a ditch and made contact on the far side with the rear tire under hard acceleration. Pulled the stem right out of the tube. I had a rimlock the next time out.

Regarding the accelerator pump you said:

Seems to me that's the point of a lot of this thread. I think most people would agree that a properly jetted CV carb performs reasonably well as long as the inherit lag in throttle response is acceptable. A slow(er) roll on makes that lag imperceptible and while maximum power output will ultimately be achieved to the rider it can feel a bit sluggish. Anyone who has ever ridden a modern 2-stroke understands what throttle response is all about. You best be holding on when you snap open the throttle open on something like a RM250. I don't think anyone expects that kind of instantaneous kick from a big 4-stroke single but it is definitely big time fun in the dirt. I think a lot of the crazy stuff people do to their DRs is to try and move them in that direction. Hence the cutout airboxes, drilled slides, and often grossly rich jetting we read so much about.

Is it that the accelerator pump makes the engine too responsive when there are large/quick changes in throttle opening, and also when they are small/slow?

Regards,

Derek

I'm sure you're absolutely right.

Regards,

Derek

I've ridden cobblestone like that ... usually what works is MORE SPEED!
Go fast and you float over most of it. This is the real test of your suspension. But certainly easier said than done.

In Death Valley there is this Volcanic rock section that is also tough on a heavy bike. On a dirt bike I can hammer through. On the DR had to slow down ... which makes it worse. You try to keep pace UP but tricky on this stuff. You have to avoid the BIG rocks that are everywhere on the track. Lots worse than it looks in pic.


Hope all is will in and around Oaxaca! One of my favorite areas! Hope you get to ride over the mountains out to Puerto Escondido/Puerto Angel. Lots of dirt roads in those
mountains.

After some mods the lag in mine is non existent (or at least imperceptible), even when opening the throttle quickly. And it will pull without hesitation from a low close to 2000 rpm (if the tiny tach is to be believed). The stock low rpm shutters and shakes are pretty much gone. Patience and a little luck got it there, and mileage is still 50mpg.
I am sure it doesn't have the snap of the aftermarket carbs, but I am pretty happy with it.

If you have stock junk do not top off. If you must top off you can keep the stock tank and remove emissions stuff, plugging carp ports with Vacuum caps. Your gonna need to plug the port in the right side of the tank with something gas proof. Your cap is still going to have a tough time venting with gas in it.

The way I dealt with the issue is put the acerbis tank on and strip all the emissions stuff. Now the only thing that needs to vent is the cap, which it does thru a long hose. Still need to cap all vacuum ports etc. Its quite easy, and you have a bigger better tank.

Yes

Using the BK mod, I currently have the stroke set at <> 0.1 mm



The way I set it up is that the washers are the same thickness as the plasitc cover, and with the bolt length, the exposed thread is about equal to the stroke, or the gap between the end of the bolt and the lever. Here its at <> 1 mm, which was OK until I got the jetting sorted, then way too much. Readily adjustable from the outside with 2 x 8 mm open end spanners.

At the risk of getting further off the subject of DR650s, this was just posted over on UHE:
http://www.husaberg.org/forum/viewtopic.php?f=20&t=17254

A CR500 chasing an FE650.

The guy that set up my FE650 on the dyno routinely did CR500s for short circuit racing over here, porting etc. He reckoned that my FE650 put out about 3-5 hp more than a good CR500.

Here is the plot as my FE650 evolved:


The Dyno Dynamics dynos show quite different numbers to the more normal Dynojets, and Carl said that applying his conversion factor mean that the 43 DD hp <> 63 DJ hp. No one who's ridden it will argue the point. His ported CR500s on this dyno showed 37-38 hp.

Whatever the numbers say is mostly irrelevant, its about the before and after and how it rides. A dyno is a means to an end, just a tool, and only as good as the tuner.

How about this for a curve? The flat shape of the torque. Its my 1400GTR, aka C14:


My 2 x 650 4t singles are chalk and cheese.

Sorry, back to DR650s.

So I am about to attempt to install the "fork solution kit" (heavier springs and emulators) from procycle this weekend...any advice? Thanks!