Stock CV style carb off a early raptor 350 or suzuki z400, with a raptor intake manifold. 34mm for more torque and reponse and 38mm for more top end. (up to 85mm bore).justrandy said:What's the best carb size for the webcam .390 cam type rider?
because you will loose torque with a flat slide design and since the this is a slower reving 2 valve motor it doesn't really take advantage of the flat slide carb. You do gain it back at the top end but it just doesn't have that broad range of power and response.justrandy said:Why not a non-cv type?
Flat slide carbs basically can flow more air per MM and over say a CV or round style of carb of the same MM. They also effectively meter fuel better then other styles of carbs as the vacuum signal is greater at those jets. I find I have to run smaller jets then both stock and round slide carbs that are used on this engine per given of mods. One thing I will say is that I found that my bottom end is flat in the power and then really starts to pick up in the mid range and top. This was just after dialing in the jetting and getting it dead nuts on, comparing to a CV. A CV style will mantain maxium airflow volecity at a wide range of rpm points and throttle position. Which means maxium torque. I found when I'm coming up a big hill and lugging the engine if I give it a bunch of throttle fast the engine will start to become flat on the power slightly, now with my CV carb I can gas the bitch and she will stay in the meat the whole time.justrandy said:I thought the whole idea of flatslide was bottom end???
Here's a quote from the Sudco catalog, "Mikuniâ€™s original flat valve (flat slide) carburetor, the TM Series Carburetors provide significant performance improvements over older design round slide carburetors. Air flows faster and smoother through the TM Series venturi due to the flat slide configuration and the jet blocks which help create a smoothbore effect. The high velocity of the air flow means a stronger vacuum at the needle jet, providing more precise metering and better throttle response."
Faster flow means more bottom end and probably less top end.
A lot of DR350 carbs were absolutely HORRIBLY setup at the factory. Even if you keep the stock airbox and exhaust, a proper jetting will clean it up enormously.YamaRider said:I've noticed with the CV carb on my dr350s that they really do have crappy throttle response compared to most carbs.
Yeah, i already found that site, it is a great source of information for the dr's, that's where i'm getting most of my ideas. Right now mine has the stock exhaust and the 3" hole cut in the top of the airbox with a k&n filter, and from the best i can tell it seems to be dialed in pretty close, at least through the midrange, at least based on plug chops. I haven't checked it at full throttle yet, and i think it could use a little work getting the idle circuit tuned right, the idle isn't as steady as i think it should be. I'm trying to wait until i get an aftermarket exhaust for it, then i'll get one of the t-handle fuel screws and a jet kit and see what i can get out of it.Griff said:A lot of DR350 carbs were absolutely HORRIBLY setup at the factory. Even if you keep the stock airbox and exhaust, a proper jetting will clean it up enormously.YamaRider said:I've noticed with the CV carb on my dr350s that they really do have crappy throttle response compared to most carbs.
My old DR was the same way, as is A LOT of the guys DR's on my site. Register and maximum-suzuki.com , you wont find a better DR forum for tech stuff anywhere.
I don't know if I would call the low end brutal for a 350 for what ever mod you do but that is totally cool!justrandy said:I found with the stock carb I could open the throttle up fully and then start counting before it revs all the way out. With the 38mm mikuni roundslide I have now, the response is instant and lowend is brutal. Just punch the flipper and the front end comes up.... No delay or stumble.... Even with this air filter and no box: http://www.knfilters.com/search/product.aspx?Prod=RX-3770
I'm waiting on another needle to see if I can refine the off-idle cruising, but for trail busting it seems there's little room for improvement (other than a cam and more rpm). I think a dial-a-jet would probably clean up any inconsistancies in fuel mixture and add even more throttle response.
You guys are just used to it, I'm coming from a 250 quadsport so... But you have to admit, warriors are torquey for their size.jasonp said:I don't know if I would call the low end brutal for a 350 for what ever mod you do but that is totally cool!
Sounds like maybe you want to richen up on the pilot jet?
Ok, that was a mouth full... and youre say'n some scary things.justrandy said:I can't.....
....a puzzle to me.
Yeah I would focus on getting the pilot jet spot on first then main jet. Sounds like your trying to get your top end set using your needle jet which isn't correct and you will find that you will have problems no matter how many needles you've tried.justrandy said:You guys are just used to it, I'm coming from a 250 quadsport so... But you have to admit, warriors are torquey for their size.jasonp said:I don't know if I would call the low end brutal for a 350 for what ever mod you do but that is totally cool!
Sounds like maybe you want to richen up on the pilot jet?
I can't go bigger with the pilot because my air screw will fall out. My first though after that was to get a bigger needle-jet, but I figured that would just screw everything else up. So, I've been thru a 6DP1, 6DH3, 6DP17, and a 6F8 needle. Waiting on a 6F5. If that doesn't work, I'll probably have to change needle jets and start over with the needles. My slide is the middle-of-the-road 2.5. I doubt I'll need to change it.
The 6DP1 came with the carb and had good bottom end, but wouldn't rev out even on the last clip (don't remember if it was top or bottom clip).
The 6DH3 was close, but lacked the bottom end of the 6DP1
Can't remember how the 6DP17 was.
The 6F8 was the last one to try and its pretty good on both ends, but the off idle is too rich... So, the quad either goes full-balls or barely at all... There's no inbetween. Kinda hard to keep it on the trail like that, lol. The front wheels push too much with the back 22's lifting them everytime I gas it.
Anyway, not bad for a $100 carb and a $75 air filter. Think I got the FMF for $50, but had to weld it back together since the guy cut it apart for some reason.
I highly recommend those dial-a-jets though... They're awesome. But I want to get the jetting close as possible first... Its like a puzzle to me.
Right a air screw would be on the side of the carb and does the oposite as a fuel screw. You must have a carb off a 2 cycle, 2 stroke snowmoblie? I really haven't heard of anybody doing it but I guess what ever works for you. I would have bought a carb kit off ebay and could have got it for cheap already set up. I would go ahead and call sudco and tell them what you got and they will help get the needle right. where do you put that o2 sensor? If it is not a wide band or right next to the head then you will not have enough heat for it to be acurate. What type of guage are you using?justrandy said:The pilot jet is right on. The screw is an air screw, not a fuel screw. Turning it out adds more air. So, if I go to a bigger pilot (which I did and had to take back out), the air screw is too many turns out for the spring to hold it in. So, therefore, my pilot is as big as it can be.
My main is right on as well. I have an o2 sensor hooked up, so I can tell what's what. I just have a little rich spot as soon as I open the throttle. Once the throttle is opened, everything is good. Just the part of the needle that controls the first part of the throttle opening is too small.
My o2 sensor.