Jetting for Altitude, Ute Cup Prep

Paging Lineaway --

I'm in my first thirty hours on a 2014 GG 300 race. Keihin PWK. Pretty sexy. I don't know what jets are in it, but at 7400' it seems a bit rich, which reminds me that I should know what to do for the Ute.
Calls are in to Stan Hensley, but you know how he is... :eek1

Talked with Dale about jetting at the Colorado National.What he suggested and what I have been using on my 12 300 Raga is 55 pilot and 110 main,stock needle in second clip.That has been good to 9500 feet.Dale said a 105 with the 55 will work perfect above that.Head GG mechanic also said that was the combo they like to use. See how these combos work for you. Mark

Good! I opened it up this morning; current is 125 main and 45 pilot. Your advice concurs with what I'd heard, bigger pilot and smaller main.

Thanks for putting numbers on it, Mark.

While we're at it, what would we use at 2000'? Arizona has a couple sites that low. What do you run, Sting32?

I would try 50 pilot and 115 to120 on the main below 6000 feet. Mine seems to be very tolerant of jetting if you are anywhere close. I have found that above 6000 feet 55 and 110 work about everywhere.Below 6000 the jetting in the first sentence will work fine. Using good gas consistently helps also.

Asked once before on a different thread but how close to this jetting would a TXT Pro 125 run under 6000 (3000 to be specific).

Would also love advice on jetting my daughters beta REV 80 for 3000 as it seems to be running rich.

Both run ok but the 80 I think needs the most help. If it helps I could pull them both and post up what they both have in them now.

Thanks in advance.

Well then, my jetting must be for sea level. You're right, it's tolerant. The bike has been between 5000' and 7400' so far, and seemed a bit smoky at that higher.

Greydog, if you have been running rich for 30 hours your exhaust system might be full of crud and just need a sand hillclimb taken at full throttle to clean it out. Johnny, for jetting the 80 I would call Dan at Mossy Rock Trials in Big Timber,Montana. He had one and when I rode it it was running great.

Thanks mung, I will give him a call.

Just got back from riding at over 8000ft all weekend. At 115 and 50. Had been running 55 pilot and was not as crisp. 110 should be good at the Ute Cup. Have fun!

Thanks all.

Similar to what mung said; but make sure your spark arrestor is nice and clean as well. I once thought I had a nasty jetting problem at altitude. Played with jets to no avail. Contacted Bill Haskell and he advised me to check it. Totally caked over. Cleaned it; ran like a top

UTE CUP!!!

Lately, I use a propane torch between loops.

you know, my son is on me about this too -- says my bike always needs smoking out. Can't a guy just kind of pootle about, even on a trials bike?

Never have any issues with my 4RT.

My wife and daughter are not hard riders so I will take both of their bikes and give them a small work out or cleaning from time to time and it helps them run better.

Just my exp.

Just got back from 2 weeks of camp and ride on the 2003 KLR650 in Colorado. Hopped on the trials bike and it felt strange after the saddle time on a the bigger bike.

A very timely discussion on jetting Keihins! Going to Sipapu soon to ride the 2-day there. Altitude is 8,200 to 9,400 feet at the ski area. I set up my bikes at my NM cabin 1-1/2h north and east at 8,700 feet, the mid-altitude of Sipapu.

Last Year 280GG With Dell'Orto

I had exceptionally good performance there last year with my 280GG with Dell'Orto PHBL26-BS carb. I kept left the recommended richer 38 pilot jet alone and simply dropped the main to 110 main in lieu of the stock 118. (When I got back, I ended up staying at a 115 main at the ranch's 1,600 feet.) For Sipapu I changed one other hard setting, going in needle clip position from the third down from top to second down.

Then there were the usual soft settings of idle and fuel screw tweakings. The Dell'Orto uses a fuel screw so counterclockwise is more fuel. I found the change in altitude from the lower to higher sections at Sipapu enough to have to increase the idle setting as the loop gets closer to the top. Oh and then I reduced my proportion of racing fuel to regular gas to 25% to increase burn speed a smidgeon, but retain some of the mellowness benefits of racing fuel. (I'll imitate that this year on the 300.)

This Year 300GG With Keihin

This year I'll be on my Keihin-carb `11 Raga 300 with flywheel weight. The Keihin at altitude will be a new experience, but I can see from the recommendations that it's the same idea: richer pilots and leaner mains work at altitude. I've found from past experience the percent change for main jets to be around -7% by main jet number to go up 7 to 8 thousand feet regardless of carb brand.

Currently at 1,600 feet the Raga has the stock 45 pilot and a 120 main. You may be right, lineaway, about the 50 pilot, but where was your air screw at altitude? All bikes are individuals of course and there is no one right recommendation, only getting close. The 45 pilot my Keihin requires an air screw setting at 1,600 feet that is over rich at only 1/4 turn open. That begs for the richer pilot, so perhaps there is something to going up the pretty radical amount of +22% change by the numbers from 45 to 55. I'll buy both the 50 and 55, and probably go with the 55 first given my current very closed air screw.

The 115 main may work well for me, but given my bike likes a smaller main already I will probably first fit the 112 and take a 115 and a 110 as options.

I went to the 50 after I lost my air screw (luckily I had a spare). The 110-112 might be just right at Sipapu since we start at 8000ft. The boys left last night to set the sections this weekend. Should be another great weekend!

:huh:huh:huh

I might check my tire pressures.

See you guys there!!! Are you bringing Crazy with you?

KrAzy is still a maybe, but I'm working on him. Tomas Pantin from Austin might come as well. I'll be again staying at my cabin and driving down for the event days. Taos Pizza Out Back then becomes a natural daily stop for din din

Best pizza in Taos today. Back in the 70's it was House of Taos Pizza.
Back to trials stuff.

Opened up the Keihin this morning and looked at my plug. Very hot Champion RC14YC was really gunked up, and I found my air screw barely cracked open. I had been running a 120 Main, and 45 pilot. Air screw being what it was, I know the 45 pilot is definitely too small. I can't explain the gunked-up plug except for too much mellow riding.

I have a 50 and 55 Pilot. I think I'll go with the 55 given that's what the majority go for. I don't have a 110 Main. Smallest I have is a 112. So I recon I'll go 112, 55, and drop the needle to where the clip is just above the center and see what happens!