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CR85R- fouling spark plugs

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Sep 30, 2003
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#1
I have a CR85R and i just bought it a month ago and already i have had to replace the spark plug 15 times i alos took it to the dealer and they said rejetting it would fix the problem but it still fouls plugs
 

Chili

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#3
Is the rider tending to putt around instead of ripping this bike "on the pipe"? If the bike is new and assuming everything is fine mechanically then your probably still too rich on the jetting. Have you rejetted the bike as the dealer suggested? If so what changes have you made?
 

23jayhawk

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#4
Have you done any re-jetting on this bike? Can you say what the current pilot and main jets are?
 
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#5
If you are riding on trails or are just not an overly agressive rider you might want to try a hotter spark plug. Maybe a BR9, or even BR8 if you are going pretty slow.
 
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#6
Originally posted by bdf112
I have a CR85R and i just bought it a month ago and already i have had to replace the spark plug 15 times i alos took it to the dealer and they said rejetting it would fix the problem but it still fouls plugs
15 Times?!

Normally, most kids foul some spark plugs when they first get the bikes since they are new and take it slow when breaking it in, and plus most bikes foul plugs when they are new, but 15 plugs, that should NOT be happening after a month, since the bike should be completely broken in by now.

Is he properly warming the bike up before he rides? A VERY common mistake by people. You have to warm these bikes up for pretty long before you ride it. Expecially now if you are entering the bitter cold weather like it is here (down to 6-10 degress (F) here these past nights) - So thats one suggestion. You can never warm it up for too long, so try warming it up for much longer than you have been and see if that helps.

And is he riding it hard? Or putting around in first or second gear? Ride it like a bat out of hell, and if he is riding it slow or moderatley slow, try and give it a good high rev while holding in the cluctch to keep the carbon fiber build up off the plug. And when hes riding, ride out in the top of the gears. So ride in the top of second, in stead of the bottom of third gear.

Did the dealer jet it for you? Or did you jet it?
 
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Apr 26, 2003
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#8
Run Klotz at 36:1 or 40:1 with a splitfire sparkplug. This combination worked for my problem on my yz. Also, if your bike is like mine, give you bike a slow easy warmup. This usually prevents any problems with plugs fouling. Last but not least... if you foul them when your riding fees up and realized that you not getting on the pipe hard enough if at all. good luck
 
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Apr 23, 2003
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#9
We have a 04 CR85r and my son has ridden it 3-4 times so far. Not 1 fouled plug. He is still a beginer and is not really in the powerband yet. No problems so far....

Steven
 
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#10
Another thing that you should be sure to do is before you shut off your bike after running it is to be sure to burn all the fuel out of the carberator. Just turn the fuel off and ride it around for a second after your done riding.
 
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#11
Red Rider 53 said:
Another thing that you should be sure to do is before you shut off your bike after running it is to be sure to burn all the fuel out of the carberator. Just turn the fuel off and ride it around for a second after your done riding.
How often do you reccomend doing this? After every ride? I have never heard this before, but I will try it sometimes, since it sounds like a good idea :)

BTW, deffinetly warm the bike up for a while. One of my biggest mistakes with my kx-125 was that I was NOT properly warming it up enough and was fouling plugs rather quickly. Besides that, I need to play with the jetting, but try warming it up better.
 
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#12
Tilyu,
I burn all of the fuel out of the carb every time I ride it. Even if I just start it up and listen to it or something I will put the fuel on "on" so it will start but then put it to "off" while I am listening to it.
 
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Jun 23, 2002
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#13
We had a 2003 cr85 with the same plug fouling problem , our bike was ridden hard but still fouled plugs.mostly on the startline before a race .We rejetted it run a Br9eg plug run oil ratio at 40:1 changed the crankshaft seals but still fouled plugs .We replaced the CDI black box and never fouled a spark plug again. Now have a 2004 cr85 and have never fouled a plug. I hope this will help.
 
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Jan 2, 2007
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#14
I got a 2003 CR 85 , and a few quick questions ...
i go through plugs like i change pants and it sucks i re-jetted , my needle is on its leanest , my air screw has been adjusted but i still foul plugs in about 8 hours of riding , which is prob about 2-3 days of riding , i run the fuel in the carb with the feul off till it dies everytime before i take it in , and its deff not bec i dont rip on it enough everytime i come around a turn i have it pinned im always in a powerband. also if u can tell me the color exactly when u take out the plug when u ride for about 10 min because mine at the tip is liek a blackish its dry but almost looks burnt and i know its suppose to be a light brown but let me know if there should be any black at the tip .. pleaase help me with this its driving me nuts it makes me just wana sell it and buy a 4 stroke
 
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Jan 2, 2007
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#15
and another thing when u say u gota warm it up i knwo ur not suppose to let it idle or too long iits really never supose to be iddled thats how ur **** fouls , but how do u warm urs up like ill start it up give it about a quarter throttle every 3-4 seconds for about 30 seconds ... and i dont have alot of white smoke that shows im burning oil.. i use BR10eg'S i used a br9 but that only lastes like 3 hours of riding had more life on the r10's let me know if this is normall and this is how the 2 storkes bikes are and let me knwo how logn the plus shoudl last