Ok, hightower. Tell me what dyno charts you want and i will see if I have done the testing.

If you visit some of the other web forums, like ones specifically for Yamaha, you will see the work I have done on the carbs, mods and extensive dyno testing done on the raptor. I tested, stock to full out bolt on mods, with about 6 different slip-on pipes, about 4 different full pipes, without airbox, with airbox, lid on, lid off, K&N vs Foam. You name it, i have tested most of the producst and differant set-ups. I have done about 5 to 6 different DS's. Not so extensive as the raptor, but the DS runs I have is with slip-on, full pipes, K&N, foam, No airbox lid, with airbox lid and some extensive carb mods you will not find on this web site.

The only reason I have not posted any is that this web site will not allow pictures to be uploaded directly and you have to 1st create it on other web sites and then post links on here.

Here is one run that compares a DS (Full Ron wood pipe, Dynojet Kit, Carb mods, K&N, modified intakes on airbox, with lid on) vs Raptor with Sparks full exhaust, L&A intake with K&N, Dynojet kit and carb mods.) Both bikes are running stock motors.

Here are some dyno reports I had on hand.

Red lines are HP and green lines are torque (NM) Raptor solid lines DS broken lines.

Raptor vs DS

I can tell you one thing. The 5 valve head, couple of extra cc and cam profile is not giving the raptor this edge. Its the carbs, plain and simple. They flow stacks more air with very little restriction. You all gasflow heads and install bigger valves to get more power, yet you introduce more bends and curves by going single carb setup. In anyone’s books, its a BAD thing for power. Period! Tuning two carbs is no sweat. Its damn easy of you know what you are doing.

The next chart shows the same DS650 vs YFZ450 with minor mods. The YFZ dyno run is cut short and only shows till 8500 RPM. It makes power all the way past 10 000 RPM. Since these where done, most YFZ450's pump out 47 to 49HP with cam mod, different jetting, open airbox and full pipe on this dyno.

Red lines are HP and green lines are torque (NM) YFZ solid lines DS broken lines.
DS vs YFZ450

Have any of you DS guys tested the dual carb that come of a BMW 650? What was the outcome of the dyno reports, or are we going according to seat in your pants without any test results? The BMW might have different cams, but it is not going to add about 5 to 7HP over the DS setup. The problem on the DS is the single carb. Actually it is the size of the single carb and that intake. Once you bolt on a bigger carb the DS gains more power. I said this before two 33mm carbs or in the case of the BMW setup, 2 X 36 mm carbs have a combined flow capacity larger than any single carb available for the DS or raptor. Why go for a smaller carb when everything else you make bigger inside the motor? I am talking about bigger valves, glasflowed intake and head, cams and so on. Please tell me that? Use the dual setup to flow the air you need. A single is not going to give it to you. Next time try putting the different setups on a flow bench and see which setup flows best. DUALS!!!

If you look at the volumetric efficiency between the raptor setup with dual carbs and the DS, you will see that the DS is struggling to breath. It has very poor efficiency above 4500 RPM and even worse between 6000 and 7000 RPM. All thanks to the single carb setup. When are you guys going to see that Bomb put that setup on there as a restriction and not as a performance part? Even adding the single bigger carbs is not addressing the efficiency problem correctly. If you look at the BMW setup it’s efficiency is right up there with the best and matches the raptors efficiency perfectly. All thanks to dual carbs! You can add cams all you like, it is not fixing the efficiency problem. Your flow problem is the single carb.

 

Freez, I think your arguing with yourself.[img]i/expressions/face-icon-small-smile.gif[/img] I don't think anyone disagrees that duals will put out more peak power when properly tuned. But like I said before, a well tuned single will do as good if not better then poorly tuned duals and that's a very likely senerio. And you get rid of those bouncing slides, vacuum slide carbs belong on street bikes not off road.

 

Okay I give up,
The massive difference in rotating mass between the two motors is mythological and does not exist.
The massive amount of difference between the drive train of the quad vs. the bike does not exist.
The massive difference in throttle response from vacuum slide to flat slide pumper does not exist, and every rider, racer, mx'er, tt'er out there who disagrees is full of it.
The fact that it takes an hour to rejet a raptor and 1 minute to rejet the DS when we travel from Olahoma to Walden Colorado is really a wild imagination.

Come to think of it, why did Bomb put that stupid single carb on the rotax motor? Just think of all the time I could've spent in camp turning wrenches so I'll have that slight edge in the drags that we spend 1% of our time doing, instead of all that fun saddle time I put in Bowling behind the Mountain the other 99% of the time!!! Who wants to bowl anyway, bowling is for pussies, flat land is for the real riders!

 

one thing is for sure that CFM requirements are a function of RPM
and since the raptor motor is not a screamer compared to the 40/450 class motors
I highly doubt that the engine needs dual carbs
a large single will most likely provide enough CFM for this engine but dramatically increasing throttle response and low end torque
also make it less sensitive to jetting changes due to weather and altitude

 

I still figure if one carb is good enough for my 1450cc Harley making over 70 HP , it ought to be good enough for an engine 1/2 that size......I'd rather be riding!