I am in the middle of putting some mods on my 99' 400 sport. Evertyhing is going really well so far but I'm not looking forward to installing the bored stock carb in place of my stock carb. I have a feeling something will go wrong with the swap and then I won;t know where to begin troubleshooting. Should I finish putting it together and get it running and then try and swap out the carb? Here is what I have done so far: roller clutch, clutch kit, HD belt, ported cylinder, .020 overbore, new wiesco piston, 12:1 head, RCR pipe. All I have left right now is to put the reeds and carb back on along with the plastic, tank, etc. and it should be running. Like I mentioned everything is going really well so far and I am amazed how much easier it is to work on this quad compared to my Mustang [img]i/expressions/face-icon-small-smile.gif[/img] Should I break the motor in with the stock carb and then do the swap?

 

The bored stock carb is exactly the same except for the machining inside, If RCR did yours as he did mine he gave a couple jetting reccomendations and I went from there, I ended up running a 280 main in mine since I also did the airbox mod at the same time, Other than going up from the 270 he suggested that was the only re-work I had, If you have any ? just drop me a line[img]i/expressions/face-icon-small-wink.gif[/img]

 

If you can't pop for a flatslide anytime soon. Consider the UFO. It's pretty easy to install, and smooths the airflow kinda like a flatslide.

Ken

 

Rockey,

I think you'll be some what disappointed with the stock carb, and to a smaller extent, the bored carb. Even without the porting I found the stock carb's limit early. I went to a 38 mm Mikuni TMX, because at the time, it was the only game in town. I since have graduated to a 39mm Kehin PWK. It flows MUCH better than the 38mm and slightly better than the 42mm TMX taperbore (Rick Ritter proved this on a flow bench, so don't hate me for saying it).

When I had my last rebuild, I jetted the machine really rich (two sizes), double mixed the gas to oil ratio (20:1 at the time) and babied it for the first tank of gas. After the first tank, I re jetted to the correct jetting, then let the engine warm up properly and finally ripped on it. I'd put the bored carb on, jet it with at least a 290 main and lower the clip on the needle for the first tank. For the first tank, try not to take it over 1/2 throttle, varying speeds and RPMs to let the rings break themselves in. ALWAYS make sure the motor is warmed up before ripping on it after the first tank of gas.

 

Ditto. Put the bored carb on, jet rich, run a tank of fuel (even half will do), then re-jet, and start saving your pennies for a 39PWK.

Ken is a big fan of the 42mm and has has good luck with his (although it's basically a bored 38TMX), like Mike I prefere the PWK over it. Both are definately huge improvements over the OE, even when bored.

 

With an engine like this I would use this in your bored carb :

Main --> 320
Needle --> stock , but richened one notch richer than center .
Pilot --> stock

This will be a good (safe) starting point. Lean out one step at a time if needed.

 

Rick,

Thanks for shipping everything so early. I got a chance to put the quad back together and get it broke in today. I was going to swap in the bored carb but after I took the float bowl off I saw that removing the float pivot pin did not look easy. I think I am going to need some in detail instructions to do this. After I got the rings seated I put the 300 main jet in because the 310 was crapping out. I let it rip and it feels great. I think with the bored carb I will try the 310 jet again. Exactly how long should it take to swap the carb out?? Thanks for the replys so far.

 

Once again that RCR service shines through...TOP NOTCH!!!!