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Discussion Starter · #1 ·
OK people little help here needed. Just picked up today my FYZ (white) and before even taking it out for a spin decided to do all the mods. First bought a Yoshi full pipe, than put a K&N filter from Alba. I changed the pilot to a 48, main 172 and clip on 5th. position with 1.5 turns on the air screw. I got really brave and also did the cam mod with instruction I download from somewhere in this website. I put it all back together again and the bike is running really rough now with some white smoke coming out of the pipe which I’m hoping is only because everything is new. I can’t seem to make it idle, it wants to die :angry . Any ideas? I was so looking forward to go for a ride tomorrow :cry . Help!!!!! :what

Thanks,
 

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I did change the jets pilot 48, main 172 and clip on 5th. position with 1.5 turns on the air screw.
 

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What jettings should I use? Pilot? Main? Air screw adjustment? And Clip position?

Help would be greatly appreciated...
 

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Ok......your Needle did you change it? The stock one is to big-a-round, or fat, and doesn't let the proper amount of gas through. Go to your dealer, and get the YZF dirt bike needle. That should help it run smoother. I run it on the 4th clip. Next you might want to mess with the idle. They idle real low in the stock setting, and once you do the cam mod, it dosn't want to idle that low ever again. SO on the back side of your carburetor is a black knob. Turn it clock wise to raise the idle ( I think....either way turn it until the idle raises......you'll figure that out) Also turn your Fuel screw out some.....I turned mine to 2.5 turns out from bottom.
 

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http://www.ducatitech.com/2v/inside_fcr.html


That link should help you with working on the FCR carb.....


I am running a full curtis sparks exhaust, and my jetting is:

170 main jet
45 pilot
2.5 turns fuel mixture screw
YZF dirt bike needle 4th clip

My bike runs AWESOME.....but you'll have to turn the idle up some from stock to keep it idling ;)


DAMN I feel helpful tonight..... :lol
 

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Thanks merriman, I'll give it a try tomorrow, hopefully I get it diealed in just right.
I'll keep you posted.
 

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On question, those setting you posted:

170 main jet
45 pilot
2.5 turns fuel mixture screw
YZF dirt bike needle 4th clip

Is that with the cam mod?

Thanks,
 

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The cam mod is not going to big a big jetting change at all. You are only changing the exhaust event. It's nothing like changing the filter, exhaust or removing the lid. Those mods move more air through the motor and require large jetting changes.
If it won't idle, adjust the idle up a turn or so and try it. You also need to be out to about 2.5 turns on the screw with your setup. Start there and other than that you should be close.
The 5th notch on the stock needle is sufficient. A 172 main is a little small since you have exhaust but is not the issue is the quad won't even run.
The fact that once you get it running and it runs rough with white smoke coming out of the exhaust concerns me a lot. Sure you will get some burn off with new parts installed but not coming out the exhaust pipe. Are you sure you got the exhaust cam setup right?
 

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Even if you accidentally advanced the exhaust cam 1 tooth instead of retarding it, it will run ok......only on top end will you notice that it starts to studder, and it feels like there should be more power.

I have the cam mod.....but as stated it does not affect jetting. My bike runs spot on with the 170 main jet.....I still do not know why others are having to run such large jets :what Once you get your bike running properly ride it around for a little while, and take a look at the exhaust tip. It should be a med-dark gray. If it's a dark black sute (sp?) then your rich.....if it's a light gray / white your lean. That's a very general way to tell if your close on jetting.
 

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Barely Legal,

I followed the steps very closely and although it took me a while to set the sprocket 1 tooth back (clock wise), I marked the chain with the sprocket mark and I pretty confident it was done right. Just in case, is there any way to make sure it was done correctly after the fact?



Merriman,

Thanks for the tip, if I get the damn thing running good I'll keep an eye for the color of the exhaust tip. I haven't started the bike (kind of late, don't want to wake up the neighbors) since I adjusted the air screw which I had not done when I first did the mod and started the bike. What do you think the smoke is? I didn’t run it for that long but it was smoking, not a lot but it was there. Is 2 turns OK on the air screw?
Let me know,



Thank you both much
 

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the white smoke......I would have to see it, and hear your bike to be more accurate on my guess work but here goes. Since you have been messing with the jetting, you may have flooded the motor with more gas than it can burn at once, thus causing it pump it out of the exhaust in a white smoke. The white smoke would be intermitant , not a constant flow.......which that can happen. That is my bestest guest ;) Once you get it running, let it run for a little while and see if the white smoke goes away.....it should with in the first 15 seconds....

2nd unlikely guess:
Did you loosen the cylinder? tear a gasket? letting a small trickle of water enter the motor.......check over the motor for loose parts and make sure there's no coolant leaking into the cylinder I guess....there really shouldn't be though.....

You know my jetting, and how far I have the fuel screw moved out, so It's your call on your bike....it will be OK, but jetting is more of a science where small changes matter. And that 1/2 turn does affect the motor.
 

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OK I will take a stab at this, you jetting sounds spot on to me, and Merriman the reason that he does not need to turn his Mixture screw out as far as you is because he has a 48 pilot and you only have a 45 pilot.

I am not soo sure about the white smoke I kinda think it is just extra fuel that has not had a chance to really burn off cause you have not been able to keep it running.

Now for the cam mod did you turn the cam clockwise or counterclocwise?
Clockwise is correct.

When you jetted did you move the carb much? You may have messed up the TORS system, you can override this by cutting the two wires at the thumb throttle and grounding them together, this will not harm anything as I and everyone else had to do this when installing the twist throttle.

Keep us informed of what happens.

Scott
 

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Discussion Starter · #16 ·
Well fellows, my worst nightmare has happened. When I was doing the cam mod I had a really hard time jumping the sprocket 1 tooth back (clock wise per the instructions). After almost an hour of playing with it I finally was able to move the sprocket but in order to do it I removed the sprocket from the chain which was no big deal since I had marked the chain with the mark of the sprocket and used a tie wrap to secure the intake sprocket as per instruction. Last night as was laying in bad I couldn’t sleep wondering why the damn thing wouldn’t run right and started to think if I had line up the mark on the chain to the right mark on the sprocket since it has two marks. So I got up at 4 am opened the whole thing again and sure enough, it was wrong. I can kick my self in the ass for doing such stupid thing, no wonder the bike was running like crap. So now I’m trying to line up the whole thing back up again and forgot to put a tie wrap on the intake and the fricken chain comes out of the intake sprocket. I am really screwed now, I’m going to take the bike in o the shop so they can line up the whole thing again and hope that when I ran it for the first time with exhaust cam on the wrong spot I didn’t cause any damage. My brother is a mechanic and has several motorized toys which he takes apart all the time and I’m going to ask him to help me and try to do it myself. The only problem is he is up in Washington and I’m in Southern California so he will have to give me instructions over the phone. If anyone knows a good mechanic in my area please let me know just incase I can’t do this myself. This really sucks and have no one to blame but myself. The worst is I didn’t even get to try the bike yet!!! I’ll let you know how it goes.

Thanks for the help
 

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merriman the best way to check your jetting is by checking the sparkplug, just by looking at your exhuast tip dont tell you crap as to wahts actaully happening in the cylinder. for example: you take out the sparkplug to check on the jetting, you notice that its very white but as you look down the into the sparkplug you see little balls or bubbles on the cone of the plug. you wonder what that is so you ask a knowledgable mechanic and he gives you the bad news that its jetted so lean that its been detonating and peices from your piston are blowing off and melting to the cone of the sparkplug.

now how would you find something like that by checking your exhuast tip?
 

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Discussion Starter · #18 ·
Good news, I got a little help from my bros and the bike runs good now. We disassembled it and put the timing back lining up everything and the sucker fired right up. I rode it a couple of times up and down the street and everything seems fine. I did notice though that the pipe is turning blue/purple, is that the right color? Should I run for a bit and than pull the spark plug out to see the color? If that’s the case what color should it be?

I have the main at 172, the pilot is 48, the needle is at the 5th. slot from the top and the air screw is set at 2 turns. Is this a good start?

Thanks for the help
 

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Originally posted by DigitMXTracks@Oct 19 2003, 12:43 PM
merriman the best way to check your jetting is by checking the sparkplug, just by looking at your exhuast tip dont tell you crap as to wahts actaully happening in the cylinder. for example: you take out the sparkplug to check on the jetting, you notice that its very white but as you look down the into the sparkplug you see little balls or bubbles on the cone of the plug. you wonder what that is so you ask a knowledgable mechanic and he gives you the bad news that its jetted so lean that its been detonating and peices from your piston are blowing off and melting to the cone of the sparkplug.

now how would you find something like that by checking your exhuast tip?
I said it a very general way....not the BEST way. I know checking the plug method is best......But if your Piston was falling apart inside the motor because the jetting was soooo lean, then your exhaust tip would be white well before your piston started falling apart :| .....thus noticing your tip is white, you could jet up, and prevent this. Like I said it's a general way to tell if your close on jetting with out taking the bike apart to check the plug. ;)
 

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bad yfz,
the color of your pipe is fine don't worry, as for the spark it should be a light brown like a carmel color. If it is white and kind of powdery it is lean, if it is dark brown or black it is rich and you should adjust accordingly. The place where you tell if the jetting is right is the ceramic white that is where you should see the change. The best way to test is to get a new plug and put it in, then warm up the bike and do at least 3 full throttle runs under load. meaning race down a road (preferably off-road) a couple of times get back to the house and take the plug out as soon as possible. check the color and make sure to check the tip of the plug throughly to check if the tip is the same as it was when you first put it in. then re-jet, reinsert and test again if it was wrong.
 
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