250 The 1999 YZ250
- Thread starter Trfsrfr
- Start date
Took the YZ out for a ride today, about 2 hours. It's still not right. Not too bad, but could be a lot better I think. Has issues from 1/4 to 3/4 throttle.
Beforehand I installed a new float needle vale, and re-set the float lower, or at least I think it's lower. This float is messing with me and I am fairly sure I dont know how to set it.
Anyway, did another high speed plug chop, and here are a couple photo's of the plug afterwards;
This is with the 168 MJ.
What do y'all think?
Beforehand I installed a new float needle vale, and re-set the float lower, or at least I think it's lower. This float is messing with me and I am fairly sure I dont know how to set it.
Anyway, did another high speed plug chop, and here are a couple photo's of the plug afterwards;
This is with the 168 MJ.
What do y'all think?
I think I am getting dumber.
My riding skills are improving but my mechanic skills are going away I think. The more I learn, the less I know.
I just fired the YZ up and I can turn the air screw all the way in and it doesn't die.
Isn't it supposed to die when this happens?
And it's still leaking fuel on the floor.
We've got a ride planned tomorrow with 7 people coming and I was hoping to further dial it in tonight before we set out in the morning, but I dont know now...
My riding skills are improving but my mechanic skills are going away I think. The more I learn, the less I know.
I just fired the YZ up and I can turn the air screw all the way in and it doesn't die.
Isn't it supposed to die when this happens?
And it's still leaking fuel on the floor.
We've got a ride planned tomorrow with 7 people coming and I was hoping to further dial it in tonight before we set out in the morning, but I dont know now...
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I think this is how it always goes, right?
Sounds like the float is too high still if I'm not mistaken (from the fouling plugs and leaking fuel).
Also, idle screw all the way in and no difference sounds like your pilot jet may be too large. Have you tried going down a size? I was having similar issues and a smaller pilot seemed to fix this. Is it still happy even after giving the throttle a small blip?
EDIT: I'm assuming the leaking fuel is from the overflow hoses btw and not the float bowl or somewhere else. That would likely be another problem.
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I screwed up this morning and raised the float level. For some reason I had in my mind that if the distance from the top of the float to the carb bowl mating surface was less, then I was decreasing the float height.
I got it now.
So tonight I "lowered" the float level to about 7mm (spec is 5.5 to 7.5), and since I figured I was leaning things out I also upped the MJ to a 170.
Fired it up in the garage, and while I'm not sure how it will do on the trail tomorrow, it's still leaking gas on the floor.
I figured by fattening up the MJ it would reduce my chances of burning this fugga down tomorrow morning.
I am spent.
I'm gonna run it tomorrow and see what happens.
Be back then.
I got it now.
So tonight I "lowered" the float level to about 7mm (spec is 5.5 to 7.5), and since I figured I was leaning things out I also upped the MJ to a 170.
Fired it up in the garage, and while I'm not sure how it will do on the trail tomorrow, it's still leaking gas on the floor.
I figured by fattening up the MJ it would reduce my chances of burning this fugga down tomorrow morning.
I am spent.
I'm gonna run it tomorrow and see what happens.
Be back then.
So here it is;
Bike ran like shit today, rode it 5 hours.
Until I was near WFO it sputtered nearly all the time.
Instead of doing a plug chop while WFO, I did one at the end of the ride when it was sputtering.
Plug is sooty black. No gas leak that I noticed.
Also, I had the GPS with me and we rode at 1500-1600 feet all day, which is where we normally trail ride.
Sometimes we get up on a mountain so probably at least 2000-2300
feet there.
So I think I need to go the other way. Gonna put that 168 back in there, and maybe even the 165.
Bike ran like shit today, rode it 5 hours.
Until I was near WFO it sputtered nearly all the time.
Instead of doing a plug chop while WFO, I did one at the end of the ride when it was sputtering.
Plug is sooty black. No gas leak that I noticed.
Also, I had the GPS with me and we rode at 1500-1600 feet all day, which is where we normally trail ride.
Sometimes we get up on a mountain so probably at least 2000-2300
feet there.
So I think I need to go the other way. Gonna put that 168 back in there, and maybe even the 165.
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Not only does alt play a part but temp/hum will also.
After how long of dealing with this issue, and after 5 hours riding today, and after putting in new larger jets last night, and after seeing the CR80's plug look just as sooty and hearing it sputter as well, and after going smaller on the YZ's MJ and having it get to the acceptable mocha brown color it was 2-3 weeks ago and it running better then, I think I have to go back to that.
I think I was making progress then.
So I think I'm going to put in the 165 MJ and one size smaller PJ on the YZ, and try the 117 MJ on the CR80 and run them.
I never really paid attention to the altitude on my GPS before, but my riding area is apparently at least 400 feet higher and above than what I originally thought it was.
And yes, it's winter-time here now, and very dry as normal.
Maybe tomorrow I'll swap those jets out.
I think I was making progress then.
So I think I'm going to put in the 165 MJ and one size smaller PJ on the YZ, and try the 117 MJ on the CR80 and run them.
I never really paid attention to the altitude on my GPS before, but my riding area is apparently at least 400 feet higher and above than what I originally thought it was.
And yes, it's winter-time here now, and very dry as normal.
Maybe tomorrow I'll swap those jets out.
Thanks for that link Mike, it has helped.
So after reading that, and after reviewing the video from last weeks ride, and seeing that both my yz and Zach's cr have the same black sooty plug, and the same almost missing, loaded up, too much fuel engine sound, I am happy that I have only a couple sooty plugs and no engine melt-downs.
So what I have decided to do is still err on the 'chicken' side as Andy mentioned, and drop the pilot jet one size in each bike first, before I go ahead and start going leaner on the MJ.
That will happen this weekend, and I will let y'all know how it turns out.
It has to be the safest route, yes? As in, wouldn't it be better to be lean on the PJ than on the MJ at WFO?
So after reading that, and after reviewing the video from last weeks ride, and seeing that both my yz and Zach's cr have the same black sooty plug, and the same almost missing, loaded up, too much fuel engine sound, I am happy that I have only a couple sooty plugs and no engine melt-downs.
So what I have decided to do is still err on the 'chicken' side as Andy mentioned, and drop the pilot jet one size in each bike first, before I go ahead and start going leaner on the MJ.
That will happen this weekend, and I will let y'all know how it turns out.
It has to be the safest route, yes? As in, wouldn't it be better to be lean on the PJ than on the MJ at WFO?
If you are too lean on the pilot or in the mid or on the top it could lead to an issue. If you turn the airscrew more than 3 turns out and it doesn't change the idle then it's too lean. If you turn it all the way in and it doesn't change the idle then it's too fat.
Someone correct me if I'm wrong
According to the article Mike linked above "the pilot circuit affects the entire throttle range. When you are at full throttle, the main jet is the primary fuel metering device, but the pilot is still delivering fuel as well, adding to the total amount of fuel that your engine is receiving.", so my thought is that since both bikes sputter up to WFO, the plugs are black, and to still err on the caution side, then I should start with installing a smaller PJ first, then retest.
Am I on the right track, or am I still growing dumber?
Am I on the right track, or am I still growing dumber?