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Jetting Problem?

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New to this forum, although I figured this would be a good place to get some good answers.

 

I bought a 1993 CR250 about a month ago. Needed some fixing up, but that's all done.

 

The bike is running rich, from the looks of the plug and the oil at the end of my silencer. It'll start in 1 kick usually, but it smokes a good amount even after it warms up. Initially, the smoke is white in color. After it gets warmed up, it becomes a defined light blue. The carburetor has been taken off many times, cleaned thoroughly. It has a 175 main, 55 pilot, 1368 needle with clip on second position, air screw was 1.5 out, it's currently at 2. The reeds are in good condition, the right crank seal isn't leaking - the fluid is still full after I changed it, it has a FMF fatty and a FMF powercore silencer. Recently did a compression test, it read 180 while it was cold. Brand new UNI air filter and spark plug. It doesn't foul spark plugs, they just turn noticeably black.

 

In first and second gear if I'm just easing on the throttle it'll get to about a 1/4 throttle and then just sputter, almost like it's starving for fuel. The bike doesn't bog or act like it wants to shut off, it feels like something is blocking the exhaust. Whenever I reach this point, that is when the smoke really comes out of the exhaust. It runs great in third, fourth and fifth. Hits power band and everything. 

 

I'm wondering, in your guy's opinion, what it sounds like I need to do. I apologize for the long post, just wanted to get the most information out there as I could.

 

Thank you all.

 

-Lee

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I had the same problem, i ended up raising the clip position (dropping pin) cleared right up.

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What premix ratio?

 

32:1 using Castor 927.

 

I had the same problem, i ended up raising the clip position (dropping pin) cleared right up.

 

I've raised it from the third position up to the second position, I don't know if I should raise it to the top position or not.

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Also, I rode the bike to get an estimate on where on the throttle the sputtering/smoke is happening at. It's definitely above a quarter throttle, maybe even half throttle. In first gear, I cannot remotely max it out. I get about half way and smoke just pours and the bike starts to sputter. It doesn't cease until I shift. If I'm in third gear and get on it right away, right before I hit power band I'll notice a slight sputter, a puff and smoke and then I'm on my way, nothing too noticeable though. However, I did notice what I think is a leak where the exhaust enters the motor at. I'm thinking I'm going to need to replace those seals in there, I don't know if that would have much affect on this particular problem or not. 

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You could run a leaner (like 40:1 premix and reduce the oil) then lean the jetting across the board. That would deal with the excess oil and rich running..

You can try just moving the needle. How is the bike at WOT?

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You could run a leaner (like 40:1 premix and reduce the oil) then lean the jetting across the board. That would deal with the excess oil and rich running..

You can try just moving the needle. How is the bike at WOT?

 

I thought 40:1 is richer than 32:1? I've already dropped the needle by moving the clip from the third to the second position. WOT the bike runs great, but only in third gear and on. I can't get passed half throttle in first or second gear without it sputtering and smoking like hell. 

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40:1 is a leaner mix than 32:1. Do some research and find if the jetting is factory size jets and needle. If it is drop 1 size on pilot and go from there . You mentioned white smoke????? , is coolant level staying constant? main thing is put it at factory jetting , and only drop pilot at first,do the changes incrementally until it clears up,then get some new plugs and verify by color of ceramic whether you are too lean or not,,the instructions are available on this site . 40:1 is fine with a quality premix. Remember a lean engine is NOT a happy engine....tis better to spooge than seize

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You describe two issues. One of too much smoiking/spooge and the other of being too rich mid throttle and above.

So you decrease the oil mix and lean the jetting.

You may need a leaner needle

 

I actually realized that after I replied. I'll get that a shot. Makes sense.

 

40:1 is a leaner mix than 32:1. Do some research and find if the jetting is factory size jets and needle. If it is drop 1 size on pilot and go from there . You mentioned white smoke????? , is coolant level staying constant? main thing is put it at factory jetting , and only drop pilot at first,do the changes incrementally until it clears up,then get some new plugs and verify by color of ceramic whether you are too lean or not,,the instructions are available on this site . 40:1 is fine with a quality premix. Remember a lean engine is NOT a happy engine....tis better to spooge than seize

 

I returned it to factory jetting and set my float height accordingly. I have read, however, they suggest using a 1369N jet needle instead of stock, so that will be here Thursday, The coolant level is normal along with the crank seal, nothing seems to be leaking or going anywhere it's not supposed to me. But the white smoke is usually on start up, which i know is normal, but this is a large amount usually. It does have a slight idle problem, it'll barely idle. If i would be in second downshifting to first, if I'm not doing it quick it'll act like it wants to stall. 

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I posted a thread before, but it got all jumbled up 'cause of things I forgot to mention.

 

The bike is a 1993 Honda CR250

It is running very rich and blowing white smoke.

 

Now, the jetting is as follows:

Main JET : 175

Pilot JET : 55

Jet NEEDLE : 1368 (Have a 1369N, will be installing tomorrow)

Clip Position : 2nd

Air Screw : 2 turns out (Was 1.5)

 

The bike is running rich from the looks of the plug (Fouled the first plug today) and the oil at the end of the silencer. On start up, it'll pour smoke, normally white in color, while idling a bit high. I'll warm the bike up and it will continue to blow white smoke however when it warms up, there is a tint of blue in it. This leads to the next problem, when it warms up the idle drops dramatically, I cannot idle without touching the throttle. In first and second gear the bike sputters, it only happens above 1/4 throttle, if i easily increase my throttle amount it'll eventually get to a point of "stopping", the bike will sputter, pour white smoke (blue tint) and will not increase speed, it as if my exhaust is being blocked or the bike is starving for fuel. In third gear however, if I crack the throttle the bike will increase speed, hit power band and barely sputter if at all, but it still blows this smoke. 

 

I have tried adjusted the idle (part of my choke) but it seems to have no effect. I've tried adjusted the idle up by the throttle, it helps a little but I'm afraid to increase it anymore because of the high idle at start up. 

 

I changed the transmission oil, filled it to the correct height and to this day it is still at the same height. My coolant level does not drop, it remains full no matter how long or hard I ride the bike. I did a compression test and it read 180 psi while the bike was cold. 

I'm running a 32:1 mixture with Castor 927 oil, new UNI air filter, new spark plug and new FMF powercore silencer. It was suggested I increase the ratio and then lean the bike out, which I might if no one else has any opinions. 

 

**Sorry for the long post, had to include all details**

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I posted a thread before, but it got all jumbled up 'cause of things I forgot to mention.

 

The bike is a 1993 Honda CR250

It is running very rich and blowing white smoke.

 

Now, the jetting is as follows:

Main JET : 175

Pilot JET : 55

Jet NEEDLE : 1369N

Clip Position : 3rd

Air Screw : 2 turns out (Was 1.5)

 

The bike is running rich from the looks of the plug (Fouled the first plug today) and the oil at the end of the silencer. On start up, it'll pour smoke, normally white in color, while idling a bit high. I'll warm the bike up and it will continue to blow white smoke however when it warms up, there is a tint of blue in it. This leads to the next problem, when it warms up the idle drops dramatically, I cannot idle without touching the throttle. In first and second gear the bike sputters, it only happens above 1/4 throttle, if i easily increase my throttle amount it'll eventually get to a point of "stopping", the bike will sputter, pour white smoke (blue tint) and will not increase speed, it as if my exhaust is being blocked or the bike is starving for fuel. In third gear however, if I crack the throttle the bike will increase speed, hit power band and barely sputter if at all, but it still blows this smoke. 

I'm also noticing a slight leak where the exhaust meets the motor, it seems as it is leaking premix out of there, not a lot but it's definitely there. I know i'm going to replace the washer or seal that's in there, but it seems like I'm losing premix there, so that tells me there is a possibility of it coming right of my exhaust. The bike seems to go through a lot of gas, I'm not an expert on two strokes, but if I were to ride for an hour non stop, the gas would be below half, close to empty. 

 

I have tried adjusted the idle (part of my choke) but it seems to have no effect. I've tried adjusted the idle up by the throttle, it helps a little but I'm afraid to increase it anymore because of the high idle at start up. 

 

I changed the transmission oil, filled it to the correct height and to this day it is still at the same height. My coolant level does not drop, it remains full no matter how long or hard I ride the bike. I did a compression test and it read 180 psi while the bike was cold. 

I'm running a 32:1 mixture with Castor 927 oil, new UNI air filter, new spark plug and new FMF powercore silencer. It was suggested I increase the ratio and then lean the bike out, which I might if no one else has any opinions. 

 

**Sorry for the long post, had to include all details**

 

Thank you for any information!

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