I'm just still researching carbs and want to know pros and cons of flatside vs CV carb. I can't find much about the difference on the net.

Best I can tell is that a flatside carb is better for higher RPM, but doesn't work as well at lower RPM unless it has an accelerator pump. It also seems to be more efficient for the same throat diameter.

The CV carb doesn't flow quite as well, but is more consistant across all RPM ranges. Thus why the factory would use them.

I'm looking specifically for a carb for use at higher altitudes for my 96 Sportsman 500 (non-HO), and am still debating between a stock 40mm 500 HO carb or the hot seat performance flatside 36mm w/ accelerator pump.

Can anyone enlighten me any more on flatside vs CV carbs?

Oh, I forgot to mention that I"m going to do the 600 stroker kit, so that's why I'm looking for a carb that'll flow better. I've also decided to just go with a HO type stock cam.

 

I did of research on this a while ago for my scrambler 500. Unless your going to race stay away from the flatside carb, this carb was made for 2 strokes. Putting it on a fourstroke will create rough idling and black smoke, this information is right from hotseat technical. And several shops I talked to stopped selling this carb as buyers had jetting problems setting the carb up. Good for racing as it dumps plenty of gas in the chamber but not for trail riding. Also one guy that races in the open class with the 500 engine ( featured in dirt wheels mag) had four stroke tech bring it up to a 628 and they had the best results staying with the stock cv carb. JMHO

 

wow... seems powerful enough to convince me.

I've been looking for at least a week now for a anyone selling a stock HO carb and I just can't find one.

Any Idea where I can get an HO carb new or used?

 

I got mine on ebay for around $60.00 used.

 

With a flat slide carb, when you move your thumb the needle/slide moves in lock step with the throttle. More thumb, more air/fuel.

A CV carb needle/slide moves according to how much air is entering the carb--hit the throttle, cable opens the butterfly, air rushes in, decrease in air pressure around the mouth of the carb causes slide to overcome spring tension and rise, pulling the needle out of the needle jet (with the slide, of course!) and adding more fuel.

CV's are better all-around carbs because of the way they operate. Since the slide opens according to how much air is entering the carb, they naturally compensate for changes in weather and altitiude. You'll still lose power at high elevation, but if you were to ride back to back with a flat slide, you'd be amazed at the difference.

Flatslides are great for making peak power, but the drivablity is subject to weather and altitude. If your picky with jetting (notice every change in altitude, weather, temp etc..) and aren't concerned with peak power, then the CV is the way to go.