Problems after elevation change

[offtosleep]

I recent moved from about 3500 feet to 6500 ft elevation. The blaster is a stock unit in every way EXCEPT a Uni-filter. The bike has been sitting for about 30 days while finished moving. I took the carb apart and used the Mikuni Pocket Tuner which indicates the need for a Main Jet change from the stock 230 to a 210. I put a genuine Mikuni 210 Jet in and it ran okay, but there was a little hesitation at about 3/4 throttle. Considering the Uni-filter, I thought, okay, maybe a 220. So switched it out and it ran better but occasionally at the 3/4 throttle mark it has a brief 1 second hesitation and then straightens out. It runs like a raped ape at wide open and down low although on a rare occasion I do get a slight hesitation down low as well.

I pulled everything apart, did a leak test on it and it holds 7-8 psi for 5 minutes no problem. Compression is about 150 psi. Turned the Air/Fuel mixture screw all the way in and backed it out 1.5 turns. No change at all.

I'm kind at a dead end. Any help would be great!

 

[Blaaster]

Your elevation could call for the needle to be one slot leaner, I am not certain about it, but it may be worth a try!

Have you re adjusted the idle for the elevation change?

If nothing changed when you messed with the air screw, something is out of whack with the idle circuit?

 

[Awk08]

start at the bottom and work up thru the jetting ranges.........

check adjust floats
http://www.blasterforum.com/threads/float-heights-and-how-to-adjust-them.50565/

adjust airscrew/pilot
http://www.blasterforum.com/threads/adjusting-your-airscrew-pilot-jet.51060/

lower the needle clip until it bogs, then back up 1 clip position, usually the middle clip position, but it's worth checking especially at that elevation

plug chop for main jetting
http://www.blasterforum.com/threads/how-to-plug-chop.53237/

 

[jus_me]

at 3/4 throttle are you holding at 3/4 or progressing through 3/4 throttle and it gets better as you go to full throttle? or staying at 3/4 and it cleans up?

 

[Blaaster]

It is possible to perform a plug chop at 1/2 and 3/4 throttle as well as WOT.

 

[MercMenace]

at 6500 ft base line should be a 200.
add 1 for uni filter, 210, possibly a 220.

Needle should be 1 slot leaner.

grab a 32 pilot jet, you may or may not actually need it. at 6500 ft you are in a grey area concerning the pilot.

Temperature will play into your pilot selection. stock if it is hot, 1 lower if it is cold.



Baselines from my experiments with altitude.

0-1999 stock
2000-3999 220
4000-5999 210
6000-7999 200

 

[MercMenace]

I ride between 5200ft and 8500ft. I have gotten really good at jet changes on the trail.

 

[Awk08]

good info merc !