TAT, starting out a 500 ft, what about Colorado, how much change for Main jet??

Planning to do the TAT, very soon and will start out at 500 feet, with a 160 main jet, when going over the Colorado passes is it worth while to swap out the main jet??? If so how much smaller should I go, 1 or two sizes or more??? I don't have clue.

Hard to say you did not list your set up info. Motor, carb, etc.

Yeah..Will need to know your carb , jet kit?..... I am thinking that you have done 3x3 and have a free flow pipe ,with a 160mj....And what altitude will you be mostly riding at ?....

Dyna jet, 3x3 mod, 434 bore,stock pipe, 160 main jet, some of the passes will be 8,0000 to 12,000 feet.

The stock carb on the S is very adaptable to elevation changes. Mine is jetted for 4000' and runs well from sea level to as high as I can go around here (8000'). I would suggest you jet for the average elevation before you leave on the trip and keep it that way for the whole trip.

There was post about a year ago about riding to 17000' without changing jets and no issues.

Here is the link to lots of jetting data: http://www.thumpertalk.com/forum/showthread.php?t=959845&highlight=

I ran the entire CO portion of the TAT on my E model (slant FCR 39mm) with Eddies jetting for <1,000 feet in Texas and my DRZ did perfect. I brought the OEM FCR jet (142) and a 150 as insurance but never needed to swap them out - ran the FCR with a 160 the whole way. No doubt I was down on power but it didnt hesitate or stumble at all. I was worried because people claim the FCR doesnt do as well with altitude changes but I was up at 13,000 feet with no issues on my Texas jetting.

I live at 500 feet w/ the 160 MJ, and it's fine, just wondering if it would need a drop to say a 155 or something more drastic, 145 or smaller??

Dyna jet, 3x3 mod, 434 bore,stock pipe, 160 main jet, some of the passes will be 8,0000 to 12,000 feet.

With 434 bore and stock pipe 150mj should be big enough for your 500ft elevation...it's guna be way too rich for high elevation if your leave the 160mj in...

Which DJ kit and what is current clip position?

It's a Dyno Jet Stage 1 kit, needle 2nd from the top, it runs very well and has returned 52-55 mpg. I haven't tried a smaller main jet, but ya really think 160 is too big for 500 feet??

Thanks Craigo for your feedback, it's greatly appreciated!!

I haven't tried a smaller main jet, but ya really think 160 is too big for 500 feet??

For Big Bore and stock pipe.....Yes...

155mj for BB with open pipe and 150mj for BB with stock pipe...

BTW...your BB will be restricted to produce top end hp with the stock pipe...and the stock carb needs to go as well....

I had a FCR- but it punished me on mileage 42mpg vs, 52-55mpg, plus the throttle acceleration was to responsive for me. I would rather have the low end torque than top end HP.

Thanks for the opinions!!! 150 MJ is going in.

Had the 150 MJ in today, well it wasn't the right size jet. The bike was surging or cutting out at 55-65 mph. Kind of jerky, a problem which I've had before. Guess I forgot to mention the spark arrestor has been punched out by the DPO. So I looked at the plug and it seemed a little to lean, so up w/ the size to a 155 MJ. Took it for a short test ride and no surging present yet. Must be pretty close, if the bike surges any I'll raise the needle to the third from the top.

Remember , you are jetting it for your high altitude trip ?..It's going to get richer as your altitude increases....

yeah, it surges so much at 500 feet w/ the 150mj, I had to move up to the 155. Sure don't want to be running lean till getting to the higher elevations!!! That ain't good!!! I'll be taking a 150 and maybe another smaller one. If it runs too rich a quick switch will cure it.

The plug with the 150 was too light tan for my taste, don't need a piston meltdown.

I was talking in reference to the needle setting....not meaning you to keep the 150mj in now..your exhaust is somewhat opened so the 155mj should be close....

Craigo thanks for taking the time to respond. The jet is so much easier to switch than changing needle clip position, as I have to pull the carb to do that as I 've never had much luck w/ the needle going back in the right spot, always had to help w/ my fingers.

Are you saying the only adjustment for higher elevation should just be dropping the needle a notch or two???

The clip 2 position should be ok...the stock carb is reasonably tolerant to altitude change....

Edited by CraigoDRZ400sm

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