i have been fighting with my DS on jetting ever since i owned it... (most of it is due to the fact i keep switching parts...)

right now ive got a big gun cdi
KN filter
White brothers pipe (12 discs)
and MBRP headers

right now im running a 175 main, stock pilot, needle on 4th richest position, and fuel screw at approx 2 1/2 turns out....

when i went to adjust the fuel screw, i used the method where you adjust it all the way out till it stumbles, then all the way in to where it stumbles...then set it in the middle of those two points....

i am having trouble with that method as it dosnt really change much from 4 turns out, all teh way in to 1/2 turn out! (im assuming that when its nearly bottomed [1/2 turn out] that it only stumbles because once it gets all the way in, it loses all fuel?...just a guess)

i would really like to get my jetting spot-on or as close to it as possible... because its just not that much fun riding a machine that is only HALF dialed....

i keep thinking its running rich for the reasons that upon startup it has quite a bit of black smoke....
then i get occasional backfires out the pipe....and the overall powerband is just weaker than usual.... (seems to stumble too much...)

but then it also has lean symptoms.... IE... when we were riding at the badlands my fan kept turning on... and we were riding in 30 degre weather.....
i also noticed a lot more heat even though the 4 layers i was wearing.
along with an occasional backfire through the carb/intake....


i have also noticed that my quad will occasionally die for no apparent reason....and the tach will jump up to 5-7K and just stick..... and the only way i can restart it is to turn the key off, then back on....but then it will start just fine.... (is this related to jetting ? engine temp?)


im considering having my quad taken in to my yammy dealership to have them do my valve checkup (i never did have it taken in for its 10 hour maintenace thing, and i now have 50 some hours on it.... with 7 oil changes on it)

is it really that hard to do? (i know i have to have feeler guages and some other special tools...) but if i dont have those (which i dont..) is it still worth it to go buy them and do it myself?

and im also looking into getting the stronger clutch springs... as i run 22's in teh sand and snow and would like to save my clutch from eventually burning up....

where can i purchase these and does anyone have a write-up on instaling these? (and what Percent of increase should i get?)

lots of questions...
thanks in advance for the help guys!

 

The clutch springs i would go with a 40% stiffer spring or 60%. On the jetting i have no idea, I would try to lean it out just a little more than u have it. The fuel screw is suppost to be 3 turns out. Look at the springs and other cool upgrades for the ds on www.on-dunes.com or www.albaaction.com

 

Jetting: There are three main circuits
to 1/8 or 1/4 throttle - Pilot jet
1/4 to 3/4 throttle - Needle
3/4 to W.O.T. - Main Jet

Your idle adjustment screw has NOTHING to do with anything above idle (1/8 throttle - it is more of a fine tuning adjustment for the pilot jet.)

Hot = Lean (not enough fuel)

More basic info that is helpful to know when jetting:
Heat expands and so does reduced pressure (i.e. higher altitude)
So, again (this may be a little basic for you) colder weather means you are getting more air molecules in your cylinder per explosion) Higher altitude means you are getting less.
More air = lean condition = more heat off engine / fan running.

So, if you ride normally at 50 degrees and then go riding at 30 degres, you may have to jet up!

Check out other posts about valve adjustment. You should learn how to do it yourself if you have some mechanical ability.
There are links to the F650 site that have good instructions.

Dying while on the trail??? That's odd. What model year do you have? How old is your battery? Any other charging issues? Search for "Voltage Regulator" and check yours.

 

thanks for the info, knew 90% of it (all but the fuel screw adjusting idle only!) but a good refresher! [img]i/expressions/face-icon-small-smile.gif[/img]

maybe i should concentrate on my pilot more than..... (it seems that very few people on this board change thiers?)

i ride 800 ft/above sea level most of the time

 

bartlett i didnt see your post....

ya i do still have the old one, but it did it probably 2-3 times with that one, and now its done it i beleive once since i installed the new cdi... so im thinking thats not the cause..... ive also had the black smoke on startup before and after the big gun cdi install....

any ideas then on what would cause it to blow black smoke upon start up? (the only thing i can think of is bad rings...but i REALLY hope thats not my prob...)

 

i know this will only help on part of your problem,but if your engine doesnt stumble after opening your airscrew 3 turns out u proberly need to go to a smaller pilet jet............its just my opinion but it seems to me if your bike is getting hot it sounds like its running lean. i ran a 190 on my main when i ran the stock carb at about 800 to 1200 elevation and it ran great........hope that helped.

 

wow 190?

was that mikuni or KN aka dynojet?

i run the mikunis, but also have some dynojets

 

dyna jets......im sorry i should of specified...lol

 

my engine used to get hot and it backfired when i let off the throttle real bad,and it was hard to get started if it was cold...........it turned out i had some bent valves. i ended up trashing my head in the end.( i hope thats not whats wrong with yours)

 

Im thinking your pilot jet is too small, because theres no difference from 1/4 turn to 4 turns out, id go 1 or 2 up on the pilot.
Heres a guide to jetting and sympoms of lean and rich.
jetting

Lots of info on the rotax is at this location.
rotax