Do you belive everything you read in the print media?

Do you see any proof? They may be correct but they don't give themselves much credibility making a blanket statement like that. I'm sure their motor puts out some ponies but would it do better on duel carbs? We don't know because they just state the single carb "picks up bottom and mid range throttle response". They may be right, but because DirtWheels didn't take the time to correctly back up this claim, we are left wondering if it is just marketing jive.

I think Freez is right....there is a very good reason that the duel carb setup is better....and the proof is in the results most big name builders are showing time after time.

FYI...at four stroke wars the Turbo EFI from Kenz and KMS did pretty well. Last time I was in AZ I spoke with the builder at Kenz about using just the EFI. He was not recommending the EFI because it was still far from perfection. To prove his point he showed me the prototype (a single throttle body) and the manifold looked very very restrictive. His point was that they would not have been able to make any power without a turbo force feeding it. For easy jetting changes his recommendation was using the FCR's unless KMS figured out the duel Fuel Injection system they were working on.

 

so do you connect two small filters directly to the carbs when disconnecting the vacuum tubes? or do you connect them at the ends of the tubes when they connect to the intake runners?

do you just plug the hole in the intake runners or the you connect them together?

oh yeah, since I haven't look, what does the tube that connects between the two carbs do? the one that is open-ended that bolts to the two screws that hold the rubber cover over both carbs.

thanks

 

[quote]
Originally posted by: bpotter
Do you belive everything you read in the print media?

Do you see any proof? They may be correct but they don't give themselves much credibility making a blanket statement like that. I'm sure their motor puts out some ponies but would it do better on duel carbs? We don't know because they just state the single carb "picks up bottom and mid range throttle response". They may be right, but because DirtWheels didn't take the time to correctly back up this claim, we are left wondering if it is just marketing jive.

I think Freez is right....there is a very good reason that the duel carb setup is better....and the proof is in the results most big name builders are showing time after time.

FYI...at four stroke wars the Turbo EFI from Kenz and KMS did pretty well. Last time I was in AZ I spoke with the builder at Kenz about using just the EFI. He was not recommending the EFI because it was still far from perfection. To prove his point he showed me the prototype (a single throttle body) and the manifold looked very very restrictive. His point was that they would not have been able to make any power without a turbo force feeding it. For easy jetting changes his recommendation was using the FCR's unless KMS figured out the duel Fuel Injection system they were working on.[

I don't want to argue. because really don't matter to much. But I know Edelbrock set up is a superior to yamaha original twins nonsense. Maybe FCR are much better, but they cost twice so much and if twin set up is so good on single cylinder engine, why not more bikes are not running them ? Did you ever drive Raptor with Edelbrock on it ? I run both set up and with Edelbrock you can feel much better throttle response and bike feel much stronger in mid range. But if nothing will show in power, jetting alone is a worth off this set up. IMHO
rnuts

 

your correct...it's not worth arguing...I'm glad you like your single setup.

Trust me...I completly agree with the jetting problem...I cuss every time I ride in a new location. Far too much work to get the jetting correct...so I just guess and if I miss a little I let it slide and live with it.

But I personally wonder why anyone would want better throttle response from a Raptor. Mine is instantaneous, bump the throttle away you go, many times ripping your arms off.

To answer your question; "why more bikes are not running them?"

Answer: The head and port design....The head was designed for twins unlike most bikes that were designed for singles.

Was this a good choice by Yamaha? I don't know. For cost reasons alone I would think they would have rather used one carb. Saving a few hundred dollars per Raptor adds up quick.

Maybe you should be asking why bikes don't use twins.

Honestly, I think they should have staggered the carbs so that the second carb doesn't start opening until the first one is 1/2 or 3/4 open that would provide the best overall drivability in all conditions.

 

Well, for those of you that think singles are better, here are some more info to bite on.

The DS650, uses a single carb. Makes good power, but nothing special. BMW used that exact same motor on the F650's and yes, they had a dual carb setup on the BMW configuration. It made stacks more power in that configuration, compared to the same motor being used in the DS650. BMW actually used 2 X 36mm Mikuni CV carbs to feed that motor.

Some of the older racing Ducati bikes also used dual carb setups for their V configuration motors. Meaning 4 carbs for a twin motor. Why, much better throttle response and power output was higher.

The 2 X 33mm carbs on a raptor has the flowing capacity of a single 48mm carb. Then, air velocity is much higher thru two smaller openings than a single big opening.

No matter how you look at it, those two 33mm carbs outflow most single carbs on the market.

The problem is that most people don't have a clue how a CV carb actually work and how to set it up correctly. They much rather throw it out and start with a different carb and then say the duals are bad. They are not bad, the guy tuning them have no skill.

I also mentioned before that with the two single carbs setup you have a direct feed to the head, No turns, no sharp bends, nothing, just one smooth intake. Great for airflow

With a single carb setup, you introduce corners and bends to the head and this is sure to slow down intake velocity even further. You are messing with the flow and no head likes curves and bends on the intake side.

Would you make a exhaust with tight bends in it??? No, so why do you think the intake side can handle sharp bends and curves? It can't! Any guy that knows how to flow a head will tell you that sharp corners mess up flow. That is a fact.

Then a last bit of info, just to prove to you how a small bend affect power output.

On the dyno I used the stock carbs, but removed the airbox. I fitted two K&N's directly to the rubber intakes that lead to the carbs. Run it on the dyno and got the figures. Then I took straight pipes, fitted that to the same carbs and installed a single K&N on it. The straight pipes created about 1 to 2 HP more right across the RPM range, compared to stock rubber pips with a slight bend. Even a slight bend mess up performance.

Now with the single setup you are introducing a crude, intake with very sharp bends and you still think it will make more power than a duel carb setup with direct feed? NO way!

Like I said before, you cannot compare the stock carb, that are set up like hell from the factory, to a single carb. The factory setup is way of. Just setting the floats correctly will add 3 HP to the stock setup, without touching the jetting or anything else in those carbs. It also produce a more linear power delivery after 6000 RPM, and this helps the raptor to make power for much longer. I have proven this on about 10 different raptors.1st learn to tune those CV carbs, before you start making these claims.

All the raptors I have fixed the carb setup run and even spank YFZ450’s With a pipe, open lid, jet kit and the carbs fixed, the raptors make between 45 and 49HP easy. A YFZ with a pipe, cam mod, jet kit and no lid makes about the same power.

Put them up on a drag or even a top speed run and the raptors are in front. Again I am not talking about one or two here. I am talking about 5 to 10 raptors that I personally have set up and constantly beat YFZ450’s from all over the place with all kinds of mods.

 

A DS makes every bit of that with a single carb. And that single carbed DS runs right there with that Raptor with its fixed duals every step of the way, weighing in at 70 lbs. more outa the box.

The single carb intake made for the raptor is shorter and has a sharper transition than the DS single carb intake, the DS's is longer and not as ubrupt in the air direction change, so the potential of a single carb on a raptor with that particular intake will most likely not be as ideal as the DS's.

I have no need to argue single vs. dual in terms of HP, there are single carbed DS's running just as strong as dual carbed raptors all over the country, and some of the strongest took some titles at FSW this year. The BMW F650 motor is not apples to apples with the DS motor, the cams are different and there is not enough space for the velocity boot between the filter and carb on the bike among other things, but above all else turning a single bike tire vs. a whole 4-wheeler axle with two big heavy tires is a whole nother ball of wax and will of course yield quite a bit different result on the dyno.


thansk alot for the info you provided in the Bomb forum sixsixT, its very much appreciated! we'll let you know how all that works out, in a couple weeks!

 

I hear where you are coming from Hightower, and I am very sure there are DS that keep up with the raptors or beat them real bad.

I have to date done about 10 DS's on the dyno and about 15 raptors. I use dyno tyres and the same dyno. I calibrate the dyno before each and every run.

I even went as far as having DS's and raptors on there within 15 minutes of each other and there is very little difference between air and atmospheric pressures that might effect the dyno ready in a big way.

I have tuned Ds650's, BajaX's, you name it. They had from Yoshi slip-on pipes to Full Ron woods exhaust pipes. Without airboxes, with airbox, Lid on, lid off, cut slider springs, dynojet kits, gas flowed intakes, K&N, foam and even paper air filters, you name it, I have tried them all. With a stock engine, the Bombs with bolt on mods, make between 40HP and 42HP. Nothing more. I also like to mention that all of these bikes are tuned with a air to fuel ratio meter and we did experiment with different jets. All the other shops in the area with dynos report similar findings, so the dyno I use is not out.

On the exact same dyno, with the exact same tyres, on the exact same day, the raptors with similar mods make 3 to 7HP more. I am able to get 40 to 42HP out of a stock raptor with a stock exhaust and no airbox lid. With a full exhaust and setting the carbs right, 45HP is peanuts. With a bit more work and you can get 47 to 49HP without touching anything on the motor.

I don’t want to go down dyno results, as I believe you have to look at the gains, not the total gained from before and after and not total HP output. In stock form the DS makes more power that a stock raptor, but the raptor show massive gains when you start adding bolt-on parts. The DS pick up power, but much lower improvements per item you add.

Then, if you don't want to believe the dyno result, we have local drag races and those same DS's loose by about 1 to 2 bike length on a 300 ft drag. Consistently with different riders, ranging from skinny to fat guys!

The dyno shows more power out of the raptor, plus it is way lighter. There is no way that mod for mod a DS will beat it. I have lots of friends with bombs and I think it is a stunning bike. When these guys ride one of these raptors I worked on, they all come back and admit that they can feel the power and it is much quicker than their own bombs.

The YFZ450's are struggling to beat the raptor and the only YFZ450's that trade wins with these raptors are the ones running 13:1 compression pistons, race gas and gasflowed heads. If they don’t have extensive mods, the YFZ450’s are left behind.

I don’t want this to turn into a DS vs Raptor vs 450 mess. The DS with the single carb is not showing the dyno number the dual carbs are showing.

The BIGEST trick on the stock raptor carbs is to set them up right. I have seen raptors with high compression pistons, cams, you name it make 40HP on the same dyno a modified stocker makes 45 to 49HP. It is all in the carb setup. To start they arrive from the factory out of calibration and all messed up.

If you don't fix the mess, the DS runs circles around the raptor and a 450 eats it for breakfast. I have yet to find a Yamaha dealer or even most of the ATV shops that set the carbs up right. About 98% of all raptor have a big problem with the stock carb setup and of you race one of these guys, then you sure as hell will beat them with a DS.

Also note this is not a single DS or raptor I am talking about here. I talk about a good handful of guys that ride and race these things on a weekly basis. Some of these DS’s are from race teams, so they damn well know what they do to these things.

Dual carbs make more power in my opinion. If you don’t; want to believe me, then please feel free to do so.

Also note that I am talking here about quads that are running stock motors and only have bolt on parts.

Once you open the motor, it is the guy with the most cash that wins.

 

!WHEW!

You winded me [img]i/expressions/face-icon-small-shocked.gif[/img]

 

OK, I'm not a Raptor owner but would like to post a question or statement about the single carb theory.

Being that the Rappy motor is a 4-stroke and the 3 intake valves open all together why would it not benefit to machine a single open plenum manifold to fit across the entire intake area of the head and keep air flow more constant and consistent. Is there a barrier within the head design or bike design that would keep that from being possible? Seems to me that this would eliminate the 50/50 problem and the intake tract could be kept smaller (not too small) until closer to the head to keep the carb signal better to increase throttle response and torque.

Just curious, Thanks Bubba

 

Freez I think you hold the record for the longest winded posts in the history of the forum, LOL. Not just this one, but all of them. And they are always topped off with no charts. If I had the dyno time that you have, I would have all kinds of charts showing how this compares to that, etc. I know you are trying to help people, because I don't see how anybody could spend as much time as you typing and talking without it being genuine in nature with the intent of helping. But I do think you would get farther if you actually show something.

Freez you are not comparing apples to apples and you know it, and you know it very well I think. There are many reasons why the raptor motor is capable of making more HP than the DS motor with only bolt-ons, and you know this. The size and weight of every component in the DS is much greater than anything inside the Raptor motor, and this is no secret. The flywheel, the big stator that puts out 290 watts, the big counterbalance, the dual cams, the beefed tranny, the 530 chain and sprockets, the heavier axle, the heavier .190 rims vs. the Raptor's .160, etc., etc., etc.


Now the dual carbs may very well indeed make more peak HP than a big single, and this I will not argue, but the difference between the two is not that drastic in my opinion.

But furthermore, the whole entent of putting this single carb on the Raptor is not for the purpose of power gains, or attempted power gains, but rather convenience. Drag racing is not always the top priority on every rider's mind. Dual CV carbs suck *** to try and tweek everywhere a guy goes in this country, and sometimes we Flatlanders vary 5K from one place to the next, hitting everywhere from sea level to 10K all in the same week on ride trips. Top that off with a much more explosive throttle response that a flatlside with a pumper offers, making log hopping and rut jumping that much easier on high speed rough trail runs, and you've got yourself one heck of handy bike for the guy who is in it for the Ride, rather than the win.