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04 yz125 spark plugs

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Hey all, i mostly trail ride. Im having trouble with BR9EG plugs, wondering what plug to run in this bike besides these. They are 10 bucks ea. So for a couple more are the iridium the ones to run? Appreciate your thoughts and advice

 

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Those are the one's you want.  9eg-9eix. But you could use br9es they cheap. But 9eg would recommend 

Edited by Motox367
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OP, for trail riding,

going 2 sizes smaller on your pilot jet, one clip position leaner on the needle clip,

and switching to a low flash point premix is perhaps all that is required to never foul a plug again.

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My brother swears by champion  N3C as the most reliable, and they are dirt cheap! I run  the 9es and never foul plugs but I'm not out hammering all day

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Buying expensive plugs for your trail bike is a waste of money. You can run the same plug electrode type all the Euro bikes use, like those on the NGK "ES" plugs.  I found out about "ES" plugs through jet ski racing (back in the two stroke days).  They cost $2.49 at any auto parts store.  I use them in all my bikes now.

Now for your specific application--here is what I do with my two YZ 125s (an 03 and an 06) that are used mostly for woods riding.  First, run 32:1 (any name brand oil will do) and get your jetting sorted.  I adjust my bikes seasonally with the temperature, but for woods riding at my altitude they are always a little leaner than stock.  Try moving your clip position first, but my guess is that you will likely end up changing the main and/or pilot a step or two.  

As for plugs, I always run an "8" for the woods (BR8ES).  If I take my bikes to the track, or if I am riding sand, I may switch to a "9", depending on how much load the engine is under (like a deeply tilled track vs a hard pack track).  

Actually, if you are not fouling plugs too often, you might just try an "8" plug and see if it solves your issues (NGK BR8ES) before you do anything else.  

Finally, one last issue, if you are really into fine tuning.  Using cross-referenced plugs from a different brand may give you a slightly different heat range that works really well.  For example, I once had an RM 125 that ran well on 9 NGK plugs, but it really liked the Champion cross-referenced plug.  And I had a Honda that seem to like the Autolite version of an "8" plug.  But this is probably more than your want to mess with...

Edited by rpt50

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Ok, plugs arent the issue, still fouling. I cleaned carb a couple times now. Installed carb kit ( floats could be out a touch). Reeds look ok. Idles good when cold. Bogs whe revved

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Sorry, hit send by accident lol. Doesnt clear out till high 3rd in power band. Then doesnt really idle when warmed up. After about 3 hrs trail riding, the plug fouls. Tranny fluid seems to be low so i top ot up. I was wandering if you guys think bad crank seals would cause all this. If so, is there a way to check them other than them..or do you have any other thought to why im fouling plugs.

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Have you rejetted yet?  How far are you from stock on your main, pilot, and needle clip?  What is your altitude where you are riding?

Edited by rpt50

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Put everything to stock. Couldn't read numbers on Jets that were in it, Needle clip was in second groove. I put in 3rd like speck says. Im at 300'

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It's been a few days, have you figured things out? $5 spark plug boot could be in order, screw off, screw on made a huge difference as far as idle goes on my son's bike. 

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I may have. Cleaned carb again. Seems better. Will try to give it a good run this week sometime.  

3 hours ago, Smoking 2's said:

It's been a few days, have you figured things out? $5 spark plug boot could be in order, screw off, screw on made a huge difference as far as idle goes on my son's bike. 

 

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Hey everyone, been a while but turns out crank seal was leaking. Meanwhile i played with carb. Mid Throttle to wide open seems good. Huge difference(for the better) at Low throttle and idle, it seems a little ruff at times. I went down 2 pilot screw sizes(as someone suggested ). Still needs a little something. should i adjust needle as well? If so move clip up or down. What about air screw. Appreciate any thoughts or suggestions

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