Can't get cr125 started

[DConwheels]

This is my first bike as an adult and I am trying to do my own work on the bike. It is just a leisure toy for me but i enjoy the time working on it and riding. I have a '93 Honda CR125. I was not able to start the bike with the kick start cold. It would start by popping it into gear while coasting down hill. Once it ran for a while it would kick right up. The speed and acceleration was limited. Also it was spitting oil bad. I just did a new top end (except piston). I also put some other parts on that were either missing or needed replaced. After putting the bike back together I still have the same problem. Any idea? Please help!

Things done:
1. All new fluids
2. Gaskets
3. New exhaust vavle washer and clip
4. New exhaust manifold washer
5. Packed silencer
6. Cleaned air filter
7. New Piston ring and clips
8. Cleaned out carb.
9. Tightened chain
10. Examined Reeds

 

[keithb7]

Did you take a compression test before you put new psiton rings in? What is the compression now? So as of now you can get it running if you pop it in gear rolling down a hill, is that right? When it's warmed up, then it seems to start fine, however still seems low on power and acceleration is poor. All these symptoms are the same after the work you did, as they were before?

When the bike is warmed up and running, is it smoking quite a bit and spewing black goo? What does the plug look like?

 

[CRazy250]

did you clean your carb, are your powervalves working?

 

[DConwheels]

I have not done a compression test. Keithb7 everything you have said is correct. The plug is oily.
CRazy the carb is clean but I have not done anything with the power vavles.

 

[wornknobby]

for one I would definitely check the power valves. Otherwise if someone before you had put them in without timing them correctly the powerband will be off completly. Allowing one valve to be open and another closed at idle, while also allowing one closed at full open throttle and another open. Do you have a manual? if not I highly recommend one, it will help you with all sorts of things that you are about to incounter as you start to learn about your bike.

 

[sick 96 250]

pull your carb and let us know what size the jets are that are in it. Your prob jetted wrong which is causing the problems. I doubt your power valve is the cause of the hard starting.

 

[keithb7]

If the plug is black there is most definately an air/fuel mixture problem. This is almost always caused by improper sized jets in the carb. The jets need to be properly matched to the amount of air flow entering in through the carb. Air quantity will be affected by it's temperature, humidity and altitude above sea level. (another controllable factor that affects air flow is a very dirty air filter on the bike). Another symptom of improper A/F mixture is the black splooge spewing out the exhaust pipe.

When you cleaned the carb did you take note of the numbers stamped on the pilot and main jets? If so, post them here so we know what you have in there.

It is quite probable that your hot, or warmed up engine aids in the combustion of the A/F mixture. That is why the bike seems to run fine once it is warmed up. Think of a diesel engine, it is very very difficult, sometimes impossible to start when it's in sub zero temps. A hot diesel engine easily starts. The warmed A/F mixture burns easier.
A diesel has no spark plug where your bike does, I am just using this as an example to show where warmed fuel ignites easier.

Make sure your air filter is clean, there's not bird or rat's nests in the air box, then work your way into the jetting. Think about the flow of air from when it enters your bike through the filter all the way through your carb, reeds and intake ports to the cylinder to where it is compressed and ignited. Once the A/F mixture ignites, the spent gases need to exit the cylinder through the exhaust port. If they don't the bike can't suck in enough new fresh A/F mixture. Then is runs like crap, sputters, hard to start, etc. That is why there have been suggestions to check the power valves in the exhaust side. If the power valves are not functioning properly, the spent exhaust gases can't escape. There is only so much room in the engine, and it needs to be filled with as much fresh A/F mixture as possible. So getting the exhaust out is important.

I hope I didn't confuse you. My intent was to try and explain so you can trouble shoot and hopefully find the problem. Check the jets and get back to us.

 

[DConwheels]

You are not confusing me at all (yet)! I looked at the carb and here are the settings with the manuals specs:
Main Jet 168 manual says 172
Piolet Jet 58 manual says 58
Jet needle clip position 3rd groove manual says 3rd groove
piolet air screw 1.5 turns out
The air filter just got cleaned and oiled

It seems that when I kick start it nothing happens when I am not usling the throttle, if I open the throttle any amout it makes a little better attempt. That is as far as I have gotten
As for the exhaust valves, When I opened that up earlier the B clip was missing, the collar was in the bottom of the housing and the vavle rod assembly was stuck behind the drive shaft lever. I replaced the parts missing and it seems to be working now.

 

[keithb7]

Hmmm...This is getting interesting. Where are you located? At what elevation? When you cleaned the carb did you have access to compressed air to blast through the tiny fuel and air ports? With the bowl off the carb, with the carb in your hand I do this. As well you can confirm the main float it seating and opening properly. I wiggle the float up and down while blowing air into the fuel intake, you can actually hear the air stop and start.
At what ratio are you mixing the oil?

 

[DConwheels]

I am in SC at about 800-1000 ft elevation, I did not use compressed air to blow through the carb. I am using Golden Spectro at it's recommended mix, I think 50:1.

 

[trial_07]

Holala! Way too rich mixture! Lean it out to 32:1 or 40:1 at max.

 

[keithb7]

Too rich???? 50 parts gas to 1 part oil is not rich, it's lean! 32 parts gas to 1 part oil, or 40 parts gas to 1 part oil is a richer mixture than the current 50:1 ratio being used. 50:1 in my experience is not going to create a problems as described. Nor is 40:1 going to fix the problems described.

Now this is where I get confused. You claim to have a dark oily plug and the bike spews black goo out the exhaust. This is a no-brainer that bike is running rich.
Your pilot jet is stock, your main jet is considerably leaner than stock. Stock settings are generally rich, and you are a bit above sea level but not that much. The stock settings are usually richer than needed to be safer than sorry, based on sea level elevation.

I don't know what to say dude. I am at a bit of a loss here for more advice. Based on what you have told me, and I'm not there to see the problem first hand this is what I might do. Try a one or two step smaller pilot jet and noodle around with the pilot screw. The main jet seems fine. Do you have any other concerns that you think might be part of the problems you are experiencing?

 

[DConwheels]

The only thing I can think of is when I was doing the top end, the top of the cylinder and top of the crank cast had some gouges in it. It looked like a few spots were chewed up and the owner before me used a silicone sealant or something over the old gasket. since I have not gotten it started since I worked on it I don't know if that seal is real good or if that could be a problem. I feel like I have don't everything else to it a don't know where to go now. I begining to think I bought a POS and regret it a little. Especially if I am now wasting more money on trying to get it to run correctly. At what point do I cut my losses and unload the thing for whatever I can get for it? Would it be worth putting a new piston in since I did not do that but did replace everything else? The piston looked ok overall with one spot that had some carbon on it where it shouldn't be and a small rough spot on the top edge but I don't have the tools to do the measurements of the cylinder and piston. Thanks for the help

 

[keithb7]

I can help more if you like. I think it might be best to take if off here and you email me directly. Send me a personal message by clicking on my ID if you want.

 

[chevyss_98]

haha, i dont wanna sound like a retard, but are you sure you put your piston in correctly, cause that can easily screw things up man, gotta make sure where its labelled "exhaust" on the piston faces the exhaust, now the fact that it was fine before you did all this suggests something was changed to not work properly, you cleaned the filter, so that cant be it, you checked the reeds, cause that can REALLY screw things up if you have a chipped tooth, and your crankseal should be fine cause you were running it before

personally, i would take it back apart, and re-assemble everything like you did already replacing various items, im sure its something minor...i dunno why, but the Piston installation sticks out in my head, cause i remember doing my top ends, ive heard of ppl having the same symptoms by installing it wrong

let me know how it goes, it wont be anything too serious, goodluck

dont unload your bike on someone, cause ppl like me pick em up and make money from em, lol

cheers

 

[freakonaleash]

I wouldnt go taking it about just yet. AS you know, every engine needs three things to run. Air/Fuel Mixture, Compression, Spark, Deliever of the Air/ Fuel Mixture. So check. Does the bike have spark ? How does the compression feel, as long as its pretty decent than its not a problem. Whats your carb like, sounds rich ? What kind of premix are you running ? Shake the bike a lot before you try starting it up next time, the oil could be seperating from the fuel causing a horribly clogged carb. Id take the carb off and give it a full cleaning, than try starting it. Its unlikely that the piston or rings would be the problem. Carbs are usually the culprit. Though you already cleaned it, someting could be setup wrong. Double and Triple check it !