cr 125 fouling plugs
- Thread starter Tcarn9
- Start date
- May 27, 2007
- 280
- 0
Your jetting is way to rich, do a search on jetting in this forum
robwbright
Member
- Apr 8, 2005
- 2,283
- 0
You changed the main jet? I recently dropped my main (step by step over a period of weeks) from a 460 to a 410 - and if it gets hotter/more humid, I may need to go to a 400.
I had NEVER fouled a plug before, even though I was running 4-5 jets too rich - which is REALLY rich.
Are you getting lots of "splooge" on the side panel and rear fender beside the silencer? If so, you're REALLY rich. My bike makes virtually no splooge now.
I had NEVER fouled a plug before, even though I was running 4-5 jets too rich - which is REALLY rich.
Are you getting lots of "splooge" on the side panel and rear fender beside the silencer? If so, you're REALLY rich. My bike makes virtually no splooge now.
rmc_olderthandirt
~SPONSOR~
- Apr 18, 2006
- 1,533
- 8
It is really quite simple. It is either running too rich, running too much oil or the plug is too cold.
Stock jetting may not be correct for the current configuration of the bike. Changing the pipe, for example, will often require a change in the jetting. Operating at a different altitude could require a different jetting. The bottom line is that you need to go through the proper steps to establish proper jetting. The proper steps include starting with a fresh plug, running under a typical load for a period of time, then pulling the plug and examining the base of the center insulator. As stated above, do a search on this forum it has been covered many times.
The gas/oil mix will influence the fouling but you should be able to run without fouling anywhere from no oil down to 24:1. Using a good grade of synthetic two stroke oil may help.
If the jetting is correct then the plug is probably operating too cold. In order to stay "clean" the plug has to operate at a minimum temperature. If it operates below this "self cleaning" temperature the deposits will build up and eventually foul the plug.
If you are already running the hottest plug available (if it is an NGK it will be the lowest number, ie, BR7ES) then I would suspect that you are simply not riding the bike hard enough. Most bikes don't have thermostats on the cooling system so if you ride slow the engine doesn't heat up to the intended operating temperature. Just a few minutes of hard riding every 1/2 hour or so should burn off the deposits and keep you going.
Rod
Stock jetting may not be correct for the current configuration of the bike. Changing the pipe, for example, will often require a change in the jetting. Operating at a different altitude could require a different jetting. The bottom line is that you need to go through the proper steps to establish proper jetting. The proper steps include starting with a fresh plug, running under a typical load for a period of time, then pulling the plug and examining the base of the center insulator. As stated above, do a search on this forum it has been covered many times.
The gas/oil mix will influence the fouling but you should be able to run without fouling anywhere from no oil down to 24:1. Using a good grade of synthetic two stroke oil may help.
If the jetting is correct then the plug is probably operating too cold. In order to stay "clean" the plug has to operate at a minimum temperature. If it operates below this "self cleaning" temperature the deposits will build up and eventually foul the plug.
If you are already running the hottest plug available (if it is an NGK it will be the lowest number, ie, BR7ES) then I would suspect that you are simply not riding the bike hard enough. Most bikes don't have thermostats on the cooling system so if you ride slow the engine doesn't heat up to the intended operating temperature. Just a few minutes of hard riding every 1/2 hour or so should burn off the deposits and keep you going.
Rod
Compression check, leak down check. How much over bored is it? Has anyone ported it. Replace the float valve. You may want to check your electrics, that it is operating within spec. The cr125's are usually fat on stock jetting. It could be more how it is ridden for some to have bad issues fouling.
helio lucas
~SPONSOR~
- Jun 20, 2007
- 1,020
- 0
if you already played with jetting, i would bet it is a bad crank seal (clutch side)... if the seal is bad then your engine is sucking oil from the crankcase... by the way, replace both...
Needle position. I had the same problem with my '03 YZ 250 and I know your pain. Tried everything from gas ratio to rejetting. I was almost about to give up when a friend told me to move the needle clip up one notch until it quits fouling. The clip was in the 2nd position, so I moved it to the top. I haven't fouled a plug since and that was 5 months ago. Make sure that you do a plug reading each time you move the clip. Pay attetion to your plug. Make sure it doesn't have white deposits from running too lean. You want the plug to be dry and a light brown or tan color.
- Nov 25, 1999
- 7,926
- 43
Simple test for you to perform and answer your question. Remove the clutch cover, wipe down the clutch basket(minimizes the sling off of oil), then start the bike. Spray a very short spritz of starter fluid at the crank. If the bike revs up, you have a leaking seal. You should be able to look and tell whether or not you need to split the case to change the seal. Whole process should take you about 20 mins.Tcarn9 said:
If the bike does not rev up from the spray, your back to jetting or plug temp. Jetting is really easy if you follow the jetting guide at the top of this forum. Just follow the rules that it lays out and you will have it setup properly in very little time.
- Nov 25, 1999
- 7,926
- 43
Raising or lowering the needle is not the place to start. You'll need to get some pilot and main jets. Read the jetting guide and follow it in order, you'll get it.
http://justkdx.dirtrider.net/carbtuning.html
http://justkdx.dirtrider.net/carbtuning.html
Tcarn9 said:
What state do you live in? How far are you from the top notch. I live in Ms, about 90 miles from the Tn state line. and everyone I ride with has their needle clip moved all the way to the top. You can try smaller jets, but make sure you do a plug reading each time.
- Thread starter
- #25
i live in central new york i moved that needle up one more notch and hasnt fouled a plug yet so im hoping that that will do it but in doing this does it affect the life time of the engine does it shorten it in anyway or harm it in any way? just wondering
