what about a carb?

1693 Views 7 Replies 4 Participants Last post by jkkj, Dec 11, 2003

jkkj

Discussion Starter · Dec 10, 2003

Has anyone thought about just throwing another carb on? The factory is like a 38mm? With all that butterfly and vaccum needle crap no doubt(I haven't had mine apart yet to know for sure). The mighty top end grizzes have something like a 42mm.

The big questions are what bigger carbs on the market will hook up to the electronics, and what happens if you run the rinny with the carb electronics unhooked?

Has anyone ran with the electronics unhooked? What happened?

A carb, even just a replacement 38 would yeild a substantal gain? I think I know where a 40mm is laying around, I might just have to give it a try?

I guess the Main question you have to ask yourself is how bad do you want it to be and how far are you willing to go to get it there?

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Yellow650Rincon

· #2 · Dec 10, 2003

No, bigger doesn't always mean better in this case. You need the engine mods to be able to accept a bigger carburetor. The Rincon has a 37mm carburetor, not a 38mm. Now, unless the Rincon is breathing freely enough to accept a bigger carburetor, there is no point in putting a bigger one on.

The carburetor electronics are simply for the throttle posistion sensor (TPS) and ECU stuff. You NEED them hooked up, it will screw the whole system up if you don't.

By the way, what do you mean "all that butterfly and vacuum needle crap"? All carburetors have a butterfly, and I'm pretty sure they all have needle in them.

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bvstone

· #3 · Dec 10, 2003

Most CV carbs have butterflies. CR carbs and others don't. The cable hooks to the slide.

I would think you could bypass the electronics in the carb pretty easily. Other machines have similar setups and swapping carbs hasn't been a problem.

On my Z400, it comes stock with a 36mmCV carb. I took a 42mm CV off a Predator and bolted it on (after exhaust/intake/cam mods) and it made a HUGE difference, mostly on the mid/top end. Didn't loose botom end.

The rinny with a gutted exhaust could easily handle a 42mm as well. I'm sure there will be replacements soon. But it sounds like the ignition is the biggest bottleneck now (unless those guys making the rev box are just saying that to sell their product). AFter riding in the snow, I believe the 18hp thing... man did 5 inches slow it down... My z, pushing mid/high 40s in hp actually does better (unles syou high side of course)

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jkkj

Discussion Starter · #4 · Dec 10, 2003

Ok, The rincon has a 37mm carb.(I didn't have the info right in front of me and wasn't for sure, Thus the "Like a" and not "a".

What do you think makes a motor breath more freely? Don't just fixate on the exhaust. What goes out must come in. If you think that the honda 650 being fed to it's peak performance by a 37mm carb when a 660 Grizz is running "like a" 42.(Notice I said "like a" because I do not have the info in front of me and am not possitive what size it is.) It's all really about CFM not size.

I didn't really suggest putting a bigger carb on just one without a butterfly or a needle that is moved by vacuum, but if you need one with a butterfly and so forth then I am talking about a bigger one.

No all carbs do not have butterflies. Some have slides. This eliminates a lot of turbulance when the trottle is completely open. This increases CFM. On most slide carbs the needle itself is moved by the trottle. If I'm not mistaken the needle on the Rincon is not moved by the trottle, but by a vacuum situation. Thus the bladder and spring(You know the one every buddy is trimming to make weaker for better throttle respone. A weaker spring will react quick and to less vacuum.) in the top.

What do you mean by NEED the tps hooked up. Do you know what all the computer controls, and what the tps helps the computer determine what to do and when?(this is the real question) It doesn't control the fuel flow to the motor. The only draw back I can see is in auto mode it may not shift as agressively as you want it to, because it doesn't know it's at full throttle. In esp mode however I don't see it making any difference at all.

Here is a little real life experience for you on carbs. 35.5mm factory carb on a slightly built(the carb had been jetted and fiddled with and it had a Yoshi header and pipe) 400ex. It ran around 70 mph as paced by a 92 ranger, and the ranger could out accelerate it with the ex left in top gear. 36mm lectron(slide type carb) was added to the equation and the ex walked the ranger bad in the same situation and the top speed increased to the 80 mph range.

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jkkj

Discussion Starter · #5 · Dec 10, 2003

bv- I have a 40mm kehein laying around I might try.

As for the ignition, you can get a couple degrees of timming with a offset keyway for the mag. Has anyone thought about trying that?

Is the mid 40hp from a dyno? If your getting that much you've done a great job! The last MX national I ran in they were dynoing bikes and we didn't see many that could make it to 35. A guy that had pulled 35 had walked off and left the others in his b class heat. I didn't have my ex dynoed. I was afraid I would be to disappointed after all the time and money I had put in it. I was with a friend of mine that has a 710 raptor that felt the same way. He has recently went to a new yammy 450 do to to many breakages on the raptor.

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DEC

· #6 · Dec 11, 2003

If the air velocity through the carb is slowed down due to a larger diameter the pressure increases thereby creating less of a vacuum across the jet. Over cfm-ing the carb reduces the velocity to a point where vacuum isn't enough to suck fuel out of the jet. Granted at high RPM the flow will be free and there will be enough of a pressure drop for fuel to flow into the port but IDLE will be a problem. Now granted the rincon may be choked down by a small venturi through the carb but the size would need to be increased incrimentally to insure low-end torque doesn't suffer. That's why opening up the ports isn't a good idea for low end power.

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Yellow650Rincon

· #7 · Dec 11, 2003

It's very possible that the Rincon can handle a much bigger carburetor, they have detuned it in many areas the carburetor size may be one of them. jkkj, yes the TPS needs to be hooked up. The engine control unit (ECU) uses the TPS to determin when to engage the transmission. So if your TPS wasn't hooked up, and you left the quad in gear it would either keep moving or it would not move at all when you push on the gas. The transmission shifting and functionability would all be screwed up. So, yes, you need the TPS.

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jkkj

Discussion Starter · #8 · Dec 11, 2003

Yellow-you are so very right about the electronic engagement and disengagement of the torque converter/tranny. That had completely slipped my mind.

Wonder what all carbs have electronics on them and if any will hook up. The yammy 400s and 426s had tps. I'll bet the grizzy's does too. Maybe this weekend I'll swing by the yammy dealer and compare hookups.

DEC-It's true that a lack of velocity will cost you torque, but I still feel there is a lot of potential in the carb on this thing. Like you have stated too big will be bad. I'll just have to see what I can find out there and take it from there.

I can't believe that I am even thinking about doing anything to this quad. I bought it because I haven't raced all year and wanted to enjoy the trails in luxury and fourwheel drive. The rincon has impressed me already, but as most gear heads, I just want a little more. I've even found myself looking for shocks like axis, tcs, and elka for this thing.(What would I need something like that for?)

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