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Discussion in 'Thumpers' started by sleepywombat, May 1, 2006.
On the floor to the left of the kayak... Lol
For less than $1k, is there anything better than Racetech emulators and springs up front and Racetech shock shaft assembly and spring in the rear? This is for a Baja trip ~2k miles (mas o menos).
The net cost of my Ohlins rear and USD WP forks was under $1k after I sold the original stuff off.
I'm very close to owning a DR.
I have 2 questions:
At 6', and used to riding an XR250R (and DH mountain bike) and hoping to take this bike on either the TAT or CDT plus extra offroad touring credit next year, I am looking at RC High bars, Rox risers and high seat foam, plus an 18" rear wheel. Not looking to lower the pegs and reduce any ground clearance. Should that be an OK starting point for ergos?
2nd question: is a Q4 muffler fine or do I need to consider a header upgrade if the maximum performance mod I plan to do would be a carb, but probably sticking with just opening the airbox and replacing the filter. I'm generally skeptical on spending bones on headers if not overboring with cams, etc. I weigh 155lbs and pack light.
Great thread, but too much info to digest in a week (or a year).
You can progressively refine the ergos and find out. Lowering and rearsetting the pegs part way won't compromise ground clearance significantly, unless you use lowering plates. Cutting and welding the stock hangers is straightforward enough, or just making your own. The stock hangers are very tall. I can't comment on your exhaust proposal.
I didn't like the loudness of the FMF Q2 pipe my new DR came with, so I did a little research on the innertubes, and got a cheap pair of 1st generation Hayabusa pipes in fine shape. I considered trying to fabricate a 3-hole flange and midpipe, but didn't have several of the tools I'd need.
So, I got the left-side 'busa adapter kit from Jesse at Kientech.
Closeup of the flange
I removed the FMF, loosened everything up, from the header bolts on back, loctited the bolts, attached everything loosely, lined everything up, and then tightened it down into place.
Mid-pipe mounting point
All back together, with Dirtbagz rack
The 'Busa pipe is longer and probably a pound/pound and a half heavier than the FMF, but the fact that it never needs repacking, as well as the quieter (though still raw and fierce, esp at higher rpms) exhaust note made me decide to make the change. Now I just need to find a way to get a spark arrestor in there...
Next, it was time for a dyno run.
I'd already dyno'ed the bike with the FMF, and here was the result. The green line is the new 'Busa pipe; the red line is the old FMF.
When I ran my stock-exhaust, mildly-jetted old DR, it got a whopping 32 hp at the rear wheel. With the FMF, it topped out at 35.15; the 'Busa pipe was ever so slightly less at the top end, with 34.82 hp. The surprise, for me, was the rather improved low-end torque with the 'Busa pipe. It's slightly less torquey than the FMF at 6-7k rpm, but has notably more oomph pulling away from lights, up hills, and is, ahem, easier to wheelie.
Bike has a stage 2 Dynojet kit with a stock 40 pilot jet, 150 DJ main jet, needle on 4th clip, Twinair filter, and Jesse's cut airbox. Header is stock.
There's something wrong with the data in the chart, as the O2 can't really be 20-22.5% (ambient is roughly 20.95%). CO2 is also way too low. A good running engine should have upwards of 10%.
1. I am 6' and ride my DR650 with bar risers (1,5"?) and stock seat. I think that it suits me just fine that way. I have the 18" rear wheel and it is probably 1,5" taller in the forks and 2" in the rear. I can still get my feet down good enough, but I can't flat foot both at the same time.
2. I have the stock header and airfilter in an open airbox combined with a MXRob 39 mm FCR-MX (mated to a Lazer home-made slip-on). I have ground down the lug in the header a little, but have not gone crazy with it. So I would say no, there is no need. I'm 175 lbs and haul 30-40 lbs of gear with a 23 ltr fuel tank. The DR becomes pretty quick with that carb :)
All the best,
Yep, the dyno is old and crotchety, and the 02 and C02 numbers are highly suspect (in-pipe sensor may be at fault). Would that affect the hp or torque ratings? If so, back to the drawing board.
Thank you! I will do bars and wheel first, and decide on the seat based on whether I get knee pain. I'm more concerned about that than flat-footing (my legs are pretty long).
Shouldn't we be seeing around 40 or so ft-lbs for the torque as well?
Excellent work sir!
Depending on your weight whether you can still use the stock rear spring.
I sent my rear shock to Cogent and had the upgrade. (Cogent has a damper adjustment) I bought .47 Racetech springs and the Cartridge Emulators. Did the fork work my self. That all cost about $750. Great improvement. (really great) I was able to still use the stock rear spring. If you are over 190lbs, you will want to get a heavier rear spring. That included will put right about $1K.
It is the very next thing you should do after a skid plate, handguards and a DJ kit. Makes it a different bike! Maybe even do it before the DJ kit
Yep, I'll need a new rear spring. Doesn't Cogent just rebuild your shock using Racetech components (maybe I'm way off)? I wonder why people use him if they can buy the Racetech shock shaft assy, or do the Gold Valve for even less? Not knocking Cogent, but I just don't understand what he does that Racetech doesn't offer as an assembly, or as a Gold Valve kit? Why would sending it to Cogent be better than the shock shaft assembly? Maybe Cogent isn't using Racetech components/Gold Valve?
Lots of guys run risers and Pro Taper bars. Good set up.
Most custom seat makers can build a "Tall" version, raising you up at least an inch, maybe two? Should help transitioning from seated to standing.
What is your thinking on the 18" wheel? It WILL raise the bike up quite a bit, depending on tire you use. Other than that, what is the advantage? Where will you source the wheel? Will the bearings (Hubb and wheel) hold up with an 18" wheel? Also, fewer 50/50 and street based dual sport tires available in 18". Your choice. If doing "all dirt" then the 18" makes more sense.
In the end, Ergos are quite subjective. Mess around, try different things, go riding, make adjustments as needed!
If you're a trail rider ... then your first concern should be suspension. But since you're only 155 lbs. (lucky bastard!! ) The stock DR spring rates are not too bad for you ... but still will be a bit "quishy" for aggressive riding. The DR's handling (both ON and OFF road) responds really nicely to suspension upgrades. Just for future thought and upgrades.
I'm not an FMF fan ... I know them well, have used their products on dirt bikes (and street) since the late 80's. My DR650 came with an FMF pipe ... the rivets started coming out at 4000 miles. I sold it. Also, it was TOO LOUD ... and needed constant repacking. FMF pipes fall apart. IMO? JUNK.
The current hot set up for the DR650 is the Titanium GSXR pipe. It's not as light as the FMF but is super high quality ... will last forever, NOT TOO LOUD. Flows pretty well too.
HP and Torque are mathmatical.
HP= Torque x rpm / 5252
Torque= 5252 x HP /rpm
A DR making 40 ft lbs of torque at say 6000 rpm would have almost 47 HP...which would be nice...but probably not possible in stock form.
edit: 5252 is a constant number in the math...if you look at a dyno chart HP and Torque ALWAYS cross at 5252 rpm...if it doesn't something is wrong.
Cogent puts his own parts in the shock and you end up with a knob on the bottom of the shaft that has 30 clicks of rebound damping adjustment. Cogent also offers a hard anodize coating for a few bucks more that I believe is a good idea if the shock is of a certain age, if you know what I mean.
see the red knob in the photo: not there with a RaceTech mod. you live with the damping as it comes. Cogent is adjustable.
205'd by Rusty
They add rebound damping.
Reusing our stock shock body keeps the remote oil resevoir, additional oil capacity adds to cooler running and longer service life. I have 27,xxx miles on my Cogent.
Horsepower can be misleading. 2 engines making equal foot-lbs of torque will have different horsepowers if they are acheiving them at different RPM's. The engine making the same torque at the higher RPM will have a higher horsepower. Say a 125 makes 40 ft-lbs torque @ 10,000 rpm and a 650 makes 40 ft-lbs at 6500, the 125 will have more HP> I'd rather have my torque from a lower revving engine so it lasts longer
The old saying (If I remember it correctly) Power, light-weight, reliability; choose any two.