?recarbuerateing?

[graham300ex]

Right now I have a ricks hot shot cdi, white bros exhaust, uni air filter no lid, ported head. hotcam stage 1, 11;1 std. bore wiseco piston and will be racing this winter on the ice. Just wondering what the best way to recarb it would be, Buy a edelbrock? 400ex carb? and also what kind of jetting to use. What mm is the 400ex carb and does anyone no what the mm is on the edelbrock?
Thanks,
Graham

[dbc112]

I run similar setup, ported, triple angle valve, 2mm larger piston, Larger exhaust and uni filter.

I have a 400ex carb which is 39mm. You need the 400ex carb boot (thing that connects from carb to airbox) or you can try your 300ex. Its a tight fit, best if you take a hairdryer and heat it up.. makes life easy.


As far as jetting stock main is 148... With your higher compression I assume you are running race gas or leaded fuel.

I run leaded fuel with the stock 148... however (always one of these). I have run 152... The problem is, I bought my motor used and I am not sure what compression I am running. The gas I use is leaded with Octane Supreme leaded booster. I come in at around 108. The additive is a bit expensive about $20 per bottle, half bottle per tank but aviation fuel is about $4 per gallon cheaper than VP at $10.

The best way to figure your setup out is to get a wideband sensor and display (about $250 new). You cut a small hole into your exhaust and attach/weld this "bung" to attach the sensor. Optimal air/fuel ratio is around 14.7.. And with ATV's the readings can be off with the shorter exhaust...


Other than that, it is praying to the jet gods.. I would go stock and go up.. But in reality you may need to go down. This weekend I am trying a 140 main with the aviatioin mixture...

The standard test, run in a high gear at WOT check the plug.. On the white part of the plug- Dark is rich, light brown is lean. Check out jetsrus for a good guide.

Hope this helps, really isnt an easy pick for the correct jet size. 400 stock should be plenty though.

[graham300ex]

ok thanks for the info!

[bwamos]

Leaded/High Octane fuel is not needed with an 11:1 compression 300ex. 91-93 octane is just fine most of the time.

I agree that the 400ex carb is a great way to go. I would start with the 148 main and work from there as well. He may also end up needing a 40 pilot jet as well.