Late-model CR125 crank seal issue - what is it?

I've seen a couple of references to "the crank seal issue" regarding late model CR125s. Did a bunch of the bike come through with leaks or something? Which side? I have an '06 with all of 1/2 hour on it - I don't think I have a problem, but it gives me something to look out for.

thanks - JayC

yeah honda quality went out the window on this one.......I have a 07 cr125 fouling plugs and it's usually the rh clutch side that leaks in the tranny fluid...

I bought a brand new 2007 CR125R about 3 months ago that fouled plugs and thought it was a crank seal issue, but after rejetting the carb with a 35 pilot and a 28-69 needle on the 3rd position from the top, a BR8ES spark plug and the idle screw at 1-1/2 turns out it runs great and doesn't foul plugs anymore. I initailly switched the main jet to a 420, but went back to the stock 430 after finally settling on the 35 pilot jet. This carb is very finicky on jetting. I also run 32:1 Golden Spectro with 93 octane Marathon Premium pump gas. Mike

I bought a brand new 2007 CR125R about 3 months ago that fouled plugs and thought it was a crank seal issue, but after rejetting the carb with a 35 pilot and a 28-69 needle on the 3rd position from the top, a BR8ES spark plug and the idle screw at 1-1/2 turns out it runs great and doesn't foul plugs anymore. I initailly switched the main jet to a 420, but went back to the stock 430 after finally settling on the 35 pilot jet. This carb is very finicky on jetting. I also run 32:1 Golden Spectro with 93 octane Marathon Premium pump gas. Mike

yeah I done a pile of stuff to our 125 and we still have the fouling issue...The best way to know if it is the seal is to ride and then drain your fluid and that will tell the tell...

Is there any truth to the story that if you run a vent tube into a glass of fuid while running, and it bubbles that the crank seal is leaking? I still want to check mine, even though it is a brand new bike. I tried to get it running the other day, but it was in the 40's and I gave up even after changing plugs and only getting it to fire a couple of times. I did gain a bad blister on my kicking foot thoough. Hard starting is often a symptom of a bad crank seal, but it might just have been too cold, even though I warmed up the shop first. Mike

Is there any truth to the story that if you run a vent tube into a glass of fuid while running, and it bubbles that the crank seal is leaking? I still want to check mine, even though it is a brand new bike. I tried to get it running the other day, but it was in the 40's and I gave up even after changing plugs and only getting it to fire a couple of times. I did gain a bad blister on my kicking foot thoough. Hard starting is often a symptom of a bad crank seal, but it might just have been too cold, even though I warmed up the shop first. Mike

Well I think the best way is to change the tranny fluid ride the bike for a day then change it and see how much comes out....Usually when you first change it and ride it is when you will see most of your fouling occur....

Since I got the jetting sorted out, I have not seen any fouling with the exception if the bike sets for days without riding and then on the first start up it will puff out some noticeable smoke, and might foul one plug before it cleans out. I haven't seen any noticeable trans fluid loss yet, but once the smoke cleans out after that first start up, I have no fouling issue at all, until maybe after it sets again for a long time. Mike

I bought a brand new 2007 CR125R about 3 months ago that fouled plugs and thought it was a crank seal issue, but after rejetting the carb with a 35 pilot and a 28-69 needle on the 3rd position from the top, a BR8ES spark plug and the idle screw at 1-1/2 turns out it runs great and doesn't foul plugs anymore. I initailly switched the main jet to a 420, but went back to the stock 430 after finally settling on the 35 pilot jet. This carb is very finicky on jetting. I also run 32:1 Golden Spectro with 93 octane Marathon Premium pump gas. Mike

I have same year bike, and I think I have same issue, I get a lot of oil spilling, spark plug fouling, etc. I can order 35 pilot jet, but what about 28-69 needed? where can I buy one of those? and lastly did you bike have same issues as I listed before? please help!!!

yeah I done a pile of stuff to our 125 and we still have the fouling issue...The best way to know if it is the seal is to ride and then drain your fluid and that will tell the tell...

could you please explain this process, I was trying to do similar thing, but never could any results

We still have the same 2007 CR125R with no changes from the jetting I mentioned, now with a fresh Wiseco piston and I opened up the idle mixture screw another 1/2 turn to lean it slightly at idle, and it runs great with no plug fouling for months at a time. We have a Pro Circuit R304 shorty silencer on it otherwise. Occasionally the float level needs re-set as the float needle tip and seat deteriorates slightly over time and new ones are expensive. I buy the solid core BR8ES # 3961 which are more dependable than the standard BR8ES plugs with the removable tips. I ordered the 28-69 needle from my local Honda dealer with the part # listed in the owners manual as optional. There is a little spooge from the 32:1 Golden Spector and 93 Octane Marathon pump gas, but I can put up with that because with over 100 hours of casual, but extended hi-rpm running around the local black top roads here in the country the original piston looked perfect with great mixture color. We upgraded to the Wiseco for durability. Mike

Edited by MRW4274

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