swag Posted September 16, 2006 Report Share Posted September 16, 2006 hey guys I may be moving from the east coast of canada to the west. My elevation here is sea level. Where I am moving is 2274ft. I run a 2 into 1 setup, pod, mx porting, fmf fattys, cool head 20 cc domes, +4 , 100 octane. my current jeting is a 48 pilot and a 20 main. runs great. My wife and son also have close to the same setup. Question is...... is there a thread on here somewhere that can give me a ballpark starting point? Mine and my wifes carbs are 38mm pwk's and my son runs a 40mm lectron so his is easy as pie. Oh yeah we are all on the third slot from the point on the needle. And also is that enough diffrence in elev to need some tighter domes? See i think i will be fine because we have some foothill type "mountains" that are about 700-900 ft tall and i can see very very little diffrence. We are also right on the water (atlantic ocean) Any help at all would be great. And I realize that there is probably a thread that was just on here telling me exactly what i wanted but i could not find it with a search. Thanks Swag Quote Link to comment Share on other sites More sharing options...
locogato11283 Posted September 16, 2006 Report Share Posted September 16, 2006 im confused...a 20 main?? you will most def need to be jetting down to compensate for the higher altitude..here at 1000 feet above sea level in 33, 35 and 39mm pwk our jetting runs right at 45 pilot and 160 mains, give or take a main size either way depending on temperature... Quote Link to comment Share on other sites More sharing options...
dajogejr Posted September 16, 2006 Report Share Posted September 16, 2006 A rule of thumb is one main jet smaller for every 1000 ft above sea level you go up... Just a rough guesstimate.... Depending on what your current compression is...and if you run race gas or not, you might be able to bump up your compression (1 cc dome size down to 19cc) to make up for some of the compression you're going to loose by getting "high".... Quote Link to comment Share on other sites More sharing options...
swag Posted September 18, 2006 Author Report Share Posted September 18, 2006 im confused...a 20 main?? you will most def need to be jetting down to compensate for the higher altitude..here at 1000 feet above sea level in 33, 35 and 39mm pwk our jetting runs right at 45 pilot and 160 mains, give or take a main size either way depending on temperature... sorry i had a typo. my main jet size is a 200. sorry. Quote Link to comment Share on other sites More sharing options...
dajogejr Posted September 19, 2006 Report Share Posted September 19, 2006 200 main is probably about right, maybe a little rich for a 2 into 1 setup. I've been told and read they like a much larger main than a 2-2 setup. IF it is jetted correctly for sea level, pickup a 190 and a 195.... Always try rich and work your way down... Quote Link to comment Share on other sites More sharing options...
swag Posted September 19, 2006 Author Report Share Posted September 19, 2006 200 main is probably about right, maybe a little rich for a 2 into 1 setup. I've been told and read they like a much larger main than a 2-2 setup. IF it is jetted correctly for sea level, pickup a 190 and a 195.... Always try rich and work your way down... thanks dajogejr that helps. 1 size perthousand is the info i was looking for. Quote Link to comment Share on other sites More sharing options...
dajogejr Posted September 19, 2006 Report Share Posted September 19, 2006 thanks dajogejr that helps. 1 size perthousand is the info i was looking for. Well...hold on a sec!! Keihin jetting is different than Mikuni. It might be 1 to two sizes on Keihin...but, you'll be safe either way!! Quote Link to comment Share on other sites More sharing options...
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