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my new 89 yz250 wont start!

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Hi,yesterday I just bought an 89 yz250 that had sat in storage for the last two years for 550. The guy said the carb would need cleaned to run, got it home and took it off and apparently he had drained it before storage because it was spotless but I cleaned it anyway. Put it on and kicked it for a while and nothing but it fired once. finally I pulled the plug and it was moist but not wet so its getting fuel so I put a tiny shot of starting fluid and it fired right up and ran great but it gradually reved higher and higher and would rev really high when I turned the handle bars. then it started to spew coolant out the overflow. so I shut it off, let it cool a while and tried to start it again and it needed fluid again to start. Then I shut it off and started it a few times without starting fluid. Then I left for a while and now it wont start or even fire with or without fluid, with or without choke, open or closed throttle. it has spark still, whats the gap supposed to be? it fell when I took it off and I opened it to .035. Any help would be greatly appreciated!

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This is my first 2 smoker so I don't know how the compression should feel, im used to 250 four strokes. ill check compression today when I get my checker back from my friend.

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Take the jets out and blow carb cleaner thru them. May need to replace the pilot altogether, as it tends to clog for good after sitting. Set the air screw 1.5 turns out. Make sure the floats move. Start with all of that first. And if your handlebars cause throttle response, the cable is routed incorrectly or shot. Motion pro makes a cheap replacement. Good luck

91 YZ 250

05 RMZ 250

99 PW 50

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rechecked carb and the pilot is spotless. looked at the cable and it does seem to be shot. the plug seems to be getting wet but it doesn't smell like gas it is like oil all over it. I don't even know what to think about that.

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Hang on. Your getting absolutly nothing?

 

Start with the following:

 

1. Pull spark, hold it to case, and have a friend kick the bike over (or do it yourself if your balance is good) - If spark is there move to #2, if not issue is spark

2. Check there is fuel in the bike, drop the bowl, or open bowl release to see if its full of gas. If so move to step 3, if not you have blockage between tank and carb

2.b - clean out the main and the pilot. 

3. Remove carb from intake, and twist throttle  - you should see a small spray of gas, also twist throttle a few time sand see if you smell gas. No gas you have a bad/dirty, misadjusted carb, if gas is squirting move to step 4. 

4. REmove spark plug and check compression. Stick a comp tester into the sparky hole, and give it 5 or so kicks with throttle all the way open. See if you have comp. If compression is there move to step 5. If no compression rebuild motor. 

5. Check timing. 

 

FAST - Fuel Air Spark Timing make sure its all there - it should at least cough. 

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I have good spark, good gas flow, the carb isn't squirting mist when I twist the throttle with the carb out of the bike. I have a compression tester but I don't think its very accurate because I have been getting different readings but they are all a100 psi +- 5 psi. like I said the tester may not be accurate at all. the thing should be at least doing something with the starter fluid but nothing. oh and the timing is still spot on. could I have a crank seal out so it has a lot of tranny oil in the crank case, like enough to prevent a fire?? 

Edited by countrybumpkin

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well I got it to start running again, it was a bad spark plug cap. put a new one on and it fired right up with a little starting fluid. rechecked compression with a good snap on tester and it still was 100psi. what is spec for compression on these bikes?

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no the threads were considerably shorter than the new plug.

Congrat's on new to you ol'school YZ.Let's see some pics. Plug is in a bad spot right-Might be a good time to pull tank -clean-Fresh plug --new cap--fresh'n up waterproof all electrical before re-installing the tank. Rebuild carb- Reed valves-How are they ? Go from there. Again congratulations.

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well I just put in a  plug and cap and it helped a lot. I don't have access to a motorcycle compression tester but I could take it to the local shop and see if tey will do it. I already totally redid the carb and the reeds looked fine, the guy put in new boysen reeds about year ago he said. I am mainly worried now about the coolant overflowing when I am at a stand still for more than like a minut, then if I start riding again it will quit. any ideas on that? thanks for the responses!! keepem coming

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This is why your PSI is low.

 

Get a compression tester made for a dirt bike for a more accurate reading.

A compression tester with a short reach threaded end will not drop the compression.  Most are made in 3/8 reach so they work with any length plug threads.  The hose that goes to the tester has ten times the volume of the threaded end.  Once the tester shows maximum compression (throttle wide open, choke off, air filter off) that is all the engine will put out.

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