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Leaking carb and smoke CR250 TMX carb

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Hey guys,

 

 I just finally got to start and ride 2002 cr250 with TMX carb after top and bottom rebuild. It smoked a lot at first start up, then the smoke settled to less than half and at times no smoke. Runs great at all throttle positions. After riding and just sitting gas leaks out of hose that runs down off carb. It idled real low but I did not adjust because it ran so good even at low end when just lugging.

 

 Now about my riding style is slow and everyone said it would load up and bog or die but it did not do any of those things. I am running 50/50 sunoco standard and 91 pump with it mixed at 40 to 1 with belray H1R and the pipe did not have seepage but the side number plate had some oily residue not runny or slick but like a exhaust of vehicle .  Bike ran really good on trail ride and down open field. I had no low end concerns like everyone else but I ride way slower.

 

Just looking for some places to start looking if it is even a concern, or am I just paranoid. 

 

Thanks in advance for help everyone,

 

Robbie

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If gas is coming out the float bowl overflow hose, then I would suspect float height, needle/seat(float valve) or the oring between the seat and carb body.

Edited by knucklespisano

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The TMX works well sometimes, that's been my experience. Many are very glad they put an airstriker on. All the info you need is on this forum, just do a search. You can buy used or from JD jetting and others set ready to go. I'm really liking my 38mm cast smartcarb.

 

Cheers, Dave

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This sucks bike ran good but had white smoke and leak. Should I just get a airstrike carb? Real like the way bike ran, just not the smoke and leak... shucks.

White smoke is not caused by the carb. Sounds like water to me. And the leak is very simple no matter what it is. probably some grit in the fuel valve. You did install an inline filter didn't you?  Or your float level is incorrect. Details young man, its all in the details!

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TMX's are known to leak out the overflow when leaned over off center when parked. Not necessarily something wrong with the carb, I just rebuilt mine with new parts and set the float height, and the bike only has about 13 hrs on it.  A lot of the other TMX faithfull can back me up on this. Easy fix is to simple shut off the fuel when you park the bike. Another old school trick is to run extra length of overflow hose with a loop in it. If you look at the overflow hose it is on the bottom of the carb and is very easy to start a syphon effect if you leave the gas on.  Also I would not worry too much about he smoke unless it is heavy white smoke. My bike has more smoke before it is warmed up, more of the standard two stroke smoke though.  As for the TMX, mine has been pretty conscistent now that I have dialed it in, besides the air screw deciding to back itself out causing a WTF moment. 

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dryer "sootier" black on spark plug. not much at all and is not oily and wet. From pictures seen I would say rich but not like the oily wet plug like most talk about.

 

Where would the water come from? Could the smoke be from burning gear oil? I will pull plug again and kick a few times to see if there is wet feeling. This is driving me nuts. 

 

May also try sunoco standard straight at 32/1 and see if maybe I got some bad gas at pump. Will also take carb off and check to make sure float is not stuck. 

 

Just thought 40 to 1 since I am slow rider and a article I seen 

  • Many engines are over-lubricated at idle, sufficiently lubed at half throttle, and marginally lubed at full throttle. At full throttle for long periods of time, severe engine damage may result from insufficient lubrication.
  • As the engine size decreases and RPM's increase, oil migration times decrease dramatically.
  • Oil moves through and around internal engine components at various rates.
  • Oil retention on major engine components (after engine is stopped) decreases as RPM's increase.
  Recreational MotoCross / Enduro / X-Country Road Racing / Flat Track / TT 50 - 125cc 50-60:1 25-32:1 20-25:1 125 - 250cc 50-60:1 32-40:1 20-32:1 250cc + 50-60:1 40:1 25-32:1

Maxima Recommends: Oil/gas ratio must vary according to anticipated use:

  • Many lubricant producers recommend the same gas/oil ratio for all types of riding and racing. Maxima feels this approach is too general, and urges motorcycle owners to make their decisions based on the above research.
  • All of the above measurements are approximations, and should not be considered 100% accurate. They are meant to provide the browser with a basic understanding of two-cycle engine lubrication characteristics.

Well wish me luck.

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Water can come from a leaking head gasket or warped surface. If you are loosing coolant that might be the cause. Oil can come from a worn clutch side seal. Otherwise it is probably just not being completely warmed up. Good luck.

Edited by YHGEORGE

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The TMX can be dialed in to run properly. The S7 nozzle made a big difference for myself. Run the recommended mixture from the manual which is 32:1. 

Edited by Blaze45

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You're getting a lot of good advice here. Fuel out the overflow is an issue with the float or float valve. Either needs cleaned/replaced or float height is to high. Check coolant level for leaks, but my hunch is that you are probably fine. What are your current jets and what is your elevation? When I could get my tmx carb dialed in the bike ran like a raped ape, but the trouble was getting it dialed in and keeping it there. If jetting isn't your strong point and you suspect a faulty carb for whatever reason then the keihin carb is what I would do. Once you get it dialed in then you are good to go all summer other than an airscrew adjustment. That is assuming you ride about the same elevation each time. I want to clarify before I get flack that carb isn't going to be perfect at all temps and conditions, but it should be close enough to still ride if your not a jetting expert.

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I have a PWK I could sell. 4 hrs on it. Bought it from JD. 

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Ok.

 

I bought a cheap compression tester at auto zone and compression was 160 to 165. Now is this because the work was not done correctly or was it my fault.

 

I called the guy who did the work about the white smoke and he said it was my fault because I let it flood some how and a bunch of gas got in lower end and blew a seal most likely. I like the guy. He is very well known and everyone bragged on him. maybe just my luck. He had bike for almost 3 months for top and bottom end and suspension and tires. 

 

So question is: Could this be my fault in any way? If so I will take the hit and learn my lesson. If not how should I fix because I am already getting excuses from guy who did work and he has not even seen bike?

 

I think I need help to fix myself and just know that I got got.

 

What do you guys think?

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Was the compression test performed on a warm engine with the throttle being held wide open while kicking?

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So this engine tuner basically assembled the entire engine and you simply bolted back in the frame and fired it up, correct? Was the engine rebuilt to stock specs or was anything changed with the cylinder and/or head? Have you got the carb problem figured out yet? What kind of "break in" did you do and for how long? Everyone seems to have their own voodoo secret on breaking in an engine, but it wasn't until I started hanging out here that I learned the correct way to do. Growing up I was always taught to liberally oil the cylinder and piston and take it easy for so long and blah blah blah. Truth of the matter is these plated cylinders don't really require a break in. I now just lightly coat the wrist pin and assemble top end dry. Fire the bike up and take it through one heat cycle taking it semi easy. Let it cool down, retorque nuts and bolts and then ride the sob like its not mine. Babying these things in the beginning on top of being drowned in oil just lessens the chance of proper ring seal. I'd be curious on exactly how the engine was assembled and what your 'break in' procedure was. If you haven't put much time on the bike yet then I would say get the carb issue figured out and get out there and ride it. Maybe the ring hasn't had a chance to seat yet and all is not lost. If this is not the case I would verify the accuracy of the compression tester with another one and then if worst comes to worst pull the jug off and put a new ring on it after inspecting and measuring everything. I don't know what the 02's come with stock, but on my 06 I want to see at least 215. That is pretty high for most 250's though and it seems 190-210 is more common for other brands and years of the cr's. If the problem cannot be sorted out and the builder is unwilling to help then buy a service manual and start asking questions. If you are at all mechanically inclined you will kick yourself for having given someone else the money to do it for you.

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