Smoking and slipping... what the heck!?!

[plumma]

Today I was out riding for a good 3 hours on my 02 CR125, pretty much the whole time it was slipping in almost every gear (somtimes it would go away) and smoking like huge amounts when i would be in neutral or gunning it in gear.. also there was alot of oil runoff on the cap of my silencer.

I adjusted the idle screw on the bike, tweaked the clutch freeplay, and finally drained the gas tank to narrow it down. I'm running 92octane and honda racing oil. It just seems like its bogging in the low rpms and there isn't too much responsiveness. Once I get out of the boggs it seems to open up good.. give me your input, cause I need all i can get right now! thanks.

 

[KXtrailrider]

Check your trans oil, maybe you lost your right crank seal. Ed

 

[plumma]

It's holding oil fine, I just drained the oil and found a very dark color, almost black.. I just put new oil in like a day ago. I'm guessing the dark oil is from my clutch slipping? right now I am thinking the smoking might be carb related. I'm going to tear the entire carb apart and inspect and clean everything. thanks for the input, please keep it coming!

 

[mobrown]

Check your coolant

Check your coolant to see if it is green or another color. If you coloration in it then you have blown a head gasket. If you have blown a gasket then there is a reason behind that... not merely that the gasket blew.

Did you clutch stop slipping after you adjusted it? You may need a new clutch. I seriously doubt if your carb is the problem... sounds like another problem.

 

[sick 96 250]

Also check your jetting, if its off by a lot when you get into certain sections of the throttle it can not respond well and lose a ton of power. Also look into your power valve assembly, see if its working properly and its clean. I thought my clutch went out on me because whenever i got into the higher RPM's the bike would fall flat. Ended up my powervalve wasnt hooked up and once it was back together correctly it worked fine. Check you top end, may need a top end if your gaskets and seals are ok. My buddies 125 would smoke when he got on it and after we did a top end it was fine. If you say its bogging in the low RPM's check your pilot jet, could be to lean or to rich. There are a ton of options it could be so gradually eliminate them one by one. Good Luck

 

[plumma]

I just recently rebuilt the bike top to bottom, Like a couple weeks ago.. so I'm not thinking it's piston or ring related.. and yes the clutch continues to slip even when I adjust the cable, I have adjusted it so many times that I am starting to think it has to be a carb issue. And I have put in a new clutch also. But it continued to slip even WORSE. Like really bad. So I put the old clutch back in to see if that might be it, but I am not making any headway.. I even replaced the clutch cable.. man I'm really confused. I'll check the jetting and air/fuel adjuster screw when I disassemble it. thanks for the input guys!

 

[sick 96 250]

Did you re-jet after you did the top end. Every top end I have done I had to re-jet because as the piston got worn I was re-jetting it to ride better. Once the new top end was in the bike ran like poop untill it was re-jetted. What jets are you running also? Did you check the power valve?

 

[plumma]

I have never messed with the jetting because I've never had a problem till after the rebuild.. The carb is completely stock, so I'll take it out and read my manual on the correct jetting procedures. As for the power valve, I just cleaned it with the rebuild and I thought I put it in the correct way. I'll start with the jetting first.Thanks for the input guys, you are helping me out immensely!

 

[Bodge]

How are the chain and sprockets? Also on the "new clutch" did you replace all the plates(fibers and drive) and the springs?

 

[sick 96 250]

Was it slipping before you did the top end? Re-check that powervalve, i have a feeling you didnt hook it up right so when you hit a certain RPM it isnt opening up which will cause high revs but no power. I'm not sure about your jetting but I think something like 385-392 should be around your main and you pilot at 31-33 with the clip on the 3rd clip down on the needle and of course air screw 1.5 turns out. Let us know what you come up with. Good Luck :cool:

 

[plumma]

Hey thanks for the feedback, It wasn't slipping before the rebuild as bad, but I guess I'll check to see if the power valve is in working order. Thanks for the jetting info, I'm going to tackle that first. As for the new clutch, it was a Tusk clutch kit. I think the kit is no good, cause the slipping didn't stop. My chain and sprockets are fine, so, now I'm turning my attention to the carb. Thanks for the help, I'll let you know my results when I'm done!

 

[Tdel]

If the clutch is always slipping you were most likely reducing you throttle and not getting on the "pipe" which would result in the exhaust not being hot enough to burn off all of the premixed, ie more smoke and spooge. My RM-250 requires regular thrashing and smokes like a bitch on slow the tight trails unless your on it. Replace the clutch and reevaluate your jetting when you can get the power to the ground.

 

[plumma]

I'll try and do what I can with the carb and clutch. I'm going to start with the carb first. then the clutch if it continues to slip. thanks for the feedback!

 

[sick 96 250]

oh yeah another thing i totally overlooked. Check your reeds man, if they are chipped or cracked or not sitting flat on the cage you will lose power also. Good Luck :cool:

 

[plumma]

Yeah, I'll definitely check the reeds.. well, looks like I'll be busy for a bit! I'll try and keep you guys updated. thanks!

 

[plumma]

Did you re-jet after you did the top end. Every top end I have done I had to re-jet because as the piston got worn I was re-jetting it to ride better. Once the new top end was in the bike ran like poop untill it was re-jetted. What jets are you running also? Did you check the power valve?

What exactly do you mean by "re-jetting"? replacing the main or pilot with a diff size jet? cause I just cleaned the carb and checked the reeds and it's still smoking and spooging like INSANE amounts while idling and getting on the powerband. help me please!

 

[ellandoh]

give us a grocery list of what youve checked so far and latest symptoms

first thing comes to mind is coolant or oil got in your lower end or bad , separated gas from last year

 

[ellandoh]

What exactly do you mean by "re-jetting"? replacing the main or pilot with a diff size jet? cause I just cleaned the carb and checked the reeds and it's still smoking and spooging like INSANE amounts while idling and getting on the powerband. help me please!

this is my favorite jetting help

Spanky's jetting guide:

A correctly jetted carb makes a tremendous difference in the torque, midrange pull, top-end pull, and over-rev of your engine. If you have never jetted your bike correctly, you will almost certainly gain some performance at some point in the bike's powerband. A cleanly jetted pilot circuit can be the difference between having to clutch the bike out of a turn or not. The needle can make all the difference in the world for the power of the machine in most situations, as it controls the throttle range that most riders spend most of their time using. A correctly sized main jet could mean the difference between being able to rev out high enough to not have to shift one more time at the end of the straight, or the power falling flat on top and requiring you to make that extra shift.
Are you fouling plugs? Many people will tell you all sorts of band-aid fixes, from running less oil, to running a hotter plug. Both are incorrect fixes for plug fouling. It's all in the jetting.
The only way to know what jetting changes you will need is by trial-and-error. No one can give you jetting specs, because every bike is different, every rider has a different style, and jetting is totally weather dependent. Unless the person telling you what jets to use is riding an identical bike, on the exact same track, at the same time, his recommendations are meaningless.
Jetting is fairly simple, and is a useful skill to learn if you ride a two-stroke and want it to perform at it's best.
It's very important that you start with the pilot circuit. The reason is simple. The pilot circuit affects the entire throttle range. When you are at full throttle, the main jet is the primary fuel metering device, but the pilot is still delivering fuel as well, adding to the total amount of fuel that your engine is receiving.
Before you start to rejet your bike, you need a clean air filter, a fresh plug (actually you need several plugs to do plug-chop tests for the main jet), and fresh fuel. One important detail: Make sure the engine is in good mechanical condition. If your engine has a worn top-end, fix it first. Trying to jet a worn out engine is a waste of time. The same goes for reeds that don't seal properly, and a silencer that needs re-packing. Worn reeds will mimic rich jetting, and worn rings will mimic lean jetting.
Before you start the jet testing, install a fresh plug. Set the float level to the proper specs, an incorrect float height will affect your jetting all across the throttle range.
Warm the bike completely, and shut it off.
As already stated, start with the pilot circuit. Turn the airscrew all the way in, then turn it out 1.5 turns to start. Start the engine, and turn the idle screw in until you get a slightly fast idle, or hold the throttle just barely cracked, to keep the engine idleing. Turn the airscrew slowly in, and then out, until you find the point where the idle is fastest. Stop there. Do not open the screw any farther, or your throttle response will be flat and mushy, and the bike may even bog. This is only the starting point, we will still have to tune the airscrew for the best response.
Now is the time to determine if you have the correct pilot installed in your carb. The airscrew position determines this for you, making it very simple. If your airscrew is less than 1 turn from closed, you need a larger pilot jet. If it is more than 2.5 turns from closed, you need a smaller pilot jet.
Once you have determined (and installed it if it's necessary to change it) the correct pilot jet size, and tuned the airscrew for the fastest idle, it's time to tune the airscrew for the best throttle response. Again, make sure the bike is at full operating temperature. Set the idle back down (the bike should still idle, despite what you read in the Moto Tabloids), and ride the bike, using closed-to-1/4 throttle transitions. Turn the airscrew slightly in either direction until you find the point that gives you the best response when cracking the throttle open. Most bikes are sensitive to changes as small as 1/8 of a turn.
The airscrew is not a set-it-and-leave-it adjustment. You have to constantly re-adjust the airscrew to compensate for changing outdoor temps and humidity. An airscrew setting that is perfect in the cool morning air will likely be too rich in the heat of the mid-day.
Now, it's time to work on the needle. Mark the throttle grip at 1/4 and 3/4 openings. Ride the bike between these two marks. If the bike bogs for a second before responding to throttle, lower the clip (raising the needle) a notch at a time until the engine picks up smoothly. If the bike sputters or sounds rough when giving it throttle, raise the clip (lowering the needle) until it runs cleanly. There isn't really any way to test the needle other than by feel, but it's usually quite obvious when it's right or wrong.
Last is the main jet. The main jet affects from 1/2 to full throttle. The easiest way to test it is to do a throttle-chop test. With the bike fully warmed up, find a long straight, and install a fresh plug. Start the engine, and do a full-throttle run down the straight, through all gears. As soon as the bike tops out, pull the clutch in, and kill the engine, coasting to a stop. Remove the plug, and look deep down inside the threads, at the base of the insulator. If it is white or gray, the main is too lean. If it is dark brown or black, the main is too rich. The correct color is a medium-dark mocha brown or tan.
Once you have a little bit of experience with jetting changes, and you start to learn the difference in feel between "rich" and "lean", you'll begin to learn, just from the sound of the exhaust and the feel of the power, not only if the bike is running rich or lean, but even which one of the carb circuits is the culprit.
The slide is also a tuning variable for jetting, but slides are very expensive, and few bikes need different slides, so we won't go into that here.
Keep in mind, even though this article is intended primarily for two-strokes, four-strokes also need proper jetting to perform right, although they are not quite as fussy as their oil-burning cousins. The only real difference in the two is with the pilot circuit. Two-strokes have an air screw that you screw in to make the jetting richer, and screw out to make the jetting leaner. Four-strokes, on the other hand, have a fuel adjustment screw that you screw in to make the jetting leaner, and out to make it richer.

 

[plumma]

I just took out the carb, cleaned it and looked at my jets and they looked fine, I also checked the reeds. They looked fine. I have a recently repacked arrester. I adjusted the idle and fuel/air screw to try and lean her out. Nothing. Still smoking like crazy and oil is all over my arrester. The engine was jusr rebuilt top to bottom about 3 weeks ago. replaced clutch, and clutch cable. The bike isn't slipping as bad, but the smoke is what I think is affecting my performance. Also the fuel seems to be burning ALOT. I put in about a cup or two of gas in the tank to try and see how it ran, and after running the bike for about 10 min, there was hardly any gas in the tank!!! It has to be burning the gas EXTREMELY rich. right? there is my problem. thanks for the help!

 

[ellandoh]

the gas you poured in is it accessible to little kids or anything , youre positive its mixed correct , get a new batch id start with now , you built motor yourself?? if so go thru this list http://www.eric-gorr.com/twostktech/twotopweb_2t.html and double check your mental notes , rings face up , piston arrow correct direction etc.

take off pipe and finger the pv to see it moves freely if you can on your make model

 

[plumma]

Ok, i'll go through that list, and yeah no little kids are messing with my gas and oil, haha, anyways I'm going to try going back to "power punch" two stroke oil at my local westbay. I was using that before the rebuild. If that doesn't fix it then I'll open up the power valve case and see if it's in the correct position and if not try and udjust it. man, i'm getting frustrated..

 

[plumma]

Ok, just changed main jet to 390. Stock was 400. Now the bike doesn't smoke nearly as much. Also, plenty of power! I am very happy, now to take her out for a full ride sat! thanks guys for the feedback!

 

[sick 96 250]

I thought you said you checked the jetting like 5 times before? At least you tracked it down, you could prob still do some more fine tuning but if its up to your standards now good stuff :cool:

 

[plumma]

Well, I checked the jets and cleaned them, I didn't change the main cause I thought since it was running great before the rebuild then It should after. Now there is just a bit of spooge coming out the exhaust... must be buildup from earlier, oh well, at least I have plenty of power!

 

[plumma]

Just ripped it up like crazy!!

Well the bike is now performing to par. It is running extremely well, there is a large amount of oil coming out the arrester.. is that normal? might need a repack? anyways just thought I'd keep all you dudes posted!