Jetting revisted yet again

[yz250roost]

Hey guys,
Sorry for another jetting post but here it goes. While out at the desert this weekend I found that my PC platinum pipe was turning somewhat yellowish on the header part, the bike was dripping a small bit from the overflow onto the pipe, but that part is only a small area, the whole header where it makes the u turn back the other way is turned a tarnished yellow color, this led me to believe that I was running lean, causing excessive heating of the pipe and turning the color, but the thing is I'm getting excess spooge between the pipe/silencer, what in the world is going on here. could it be too rich of pilot jet and too lean needle, I'm getting frustrated, just when you think you have things figured out......thanks in advance...by the way make sure that your main jet is tightened when you put it back in the carb...learned the hard way.
Jeff

 

[flynbryan]

jeff i saw that you said that you were riding in the desert. i imagine you had sustained full throttle periods. that can definately cause the your bike to get rather hot. i would say either yet your bike richer on the main(which if you have to go to rich it will feel slugish in acceleration) or easiest thing....take a break. :confused: when you through some slow sections and shortened full throttle sections in your ride your bike has more of an oppertunity to cool down some. i know that team green was or still is running a system that during prolonged full throttle applications can be implimented to richen the full throttle part of the carburation. dont know if its something available to the public,but its interesting. hope i helped w/out being a stickiler for the obvious :)

 

[yz250roost]

Thanks for the advice, and now come to think of it we rode a good 25 miles or so in 5th gear on flat roads, with high speeds, so that seems pretty logical to me, now if I could just get the spooge cleared up....

 

[flynbryan]

PJ1 sells a cleaner burning oil for the arenacross series. i believe its called gold series. and if all else fails........buy a four-stroke :) no premix....although i understand its silly to get one to solve a spooge problem i love them :yeehaw:

 

[Rcannon]

by the way make sure that your main jet is tightened when you put it back in the carb...learned the hard way.




Jeff

Is it just me, or does everyone want to hear this story? I imagine that was a fun one to figure out!

 

[Buzz Bomb]

About the pipe, I think plated pipes can change color due to heat even if the bike is running fine. My friend had a plated pipe turn blueish right around the exhaust port on his CR80 and never had any problems. The bike ran fine. I wouldn't worry too much about it.

 

[yz250roost]

Ok Rcannon I will leave you in no more suspense. Here it is.... We were out at Dove springs, and I knew about this trip a few weeks in advance, so I did the whole "dial in the jetting" ordeal. This included taking apart the carb and changing needle clip positions. Well we get out to the desert and we take off on our first ride, mind you the bike was running perfectly the day before, and I start hitting this really deep whoop section, well I throttle up to full to make it up on top of the whoops and this horrible BWWWAAAAAAH sound eminates. I check to see if I had remembered to turn the gas on..I did. Ok now I'm starting to be concerned. So maybe it's just a little cold...yeah that's it I'll just wait a little bit. 30 minutes later the bike is still running the same except occasionally the bike won't come down to idle and will get stuck 1/2 throttle, which scares the crap out of me. So now the bike won't climb any hills and I can hardly go past 40mph (approx.) at this time my axle nut decided to come off along with the chain adjuster. After 30 minutes of looking for these parts we decide to borrow one from my buddies bike back at camp. I wait alone in the desert for 45,minutes. It is now getting dark and I am determined to fix this thing for good riding tomorrow. With minimal light I take off the carb and put the jetting settings back to normal (but I didn't take off the bowl). Put carb back in and subframe on and try again. nope still bogging. mess with air screw, still no difference. I've got it the silencer must be clogged. Nope sorry try again. Change jetting back to what I had before, still no change. Put in a new spark plug and check intake side of air boot. Nope everything is perfect. Ok I give up and have a hot dog then go to sleep really peeved. In the morning I go to Mojave KTM to see if they can work on the bike (I need an axle nut anyways) sit in the parking lot for 2 hours because they don't open till ten on saturdays. Get in there and they don't work on Kehin carbs and the axle nut is 14.00. Imported from Austria you know! Get back to camp and decide to take floats out to see if they are the culprit, and once I got the bowl off the main jet fell right into my hands.......If I would have only taken off the bowl in the first place. The main jet was bouncing around in the bowl creating a sometimes rich and sometimess lean condition. And sometimes landing in the perfect spot to where it wouldn't let the needle come down, resulting in stuck throttle, I felt so stupid, if these symptoms happen, check that first! hope that cured your curiosity
Jeff