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Discussion Starter · #1 ·
Hello ALL! I am new to the site and I am hoping I can get some serious help. I have an 86 Fourtrax 250R. Ran great when I test rode it so I bought it. I went for a spin on it yesterday, was riding for about 20 minutes and all of the sudden got a back fire and it shut down. I couldn't get it to start back up. Couple times it sounded like it was going to start, but then gave me a kick back and ended up introducing my knee to the handle bar :blink:
I have taken readings like the repair manual I have and found that the STOP - RUN - STOP switch was not reading low ohms while in the off position. I switched it out with a two position switch to get the right readings. I now have infinite resistance in the RUN position and .3 in the off position. I was getting spark before I did this and I am still getting spark now. The plug fires nice and bright blue. I am using a BR8ES, I pulled a B8ES out of it.
My next step will be to grab a compression tester Monday morning and run a check on it. Just seems weird that all of the sudden that could be a cause....but I want to check everything.
I have also checked the readings on the coil to make sure those readings are right as well and they are good.
I can't help thinking that the back fire may have been the result of something that went wrong. Do the two strokes jump timing? With no valves....
I don't want to babble on too long, so if I have left some details out that are need to help, please let me know and I will be completely descriptive!
THANKS SO MUCH IN ADVANCE!!!! I am looking forward to a long stay here!
 

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Welcome to the forums. They can't really jump time, but they could shear the flywheel key. I would check and make sure you're getting fuel to the carb. Then, I would go ahead and check the compression and go from there. After you kick it a few times trying to start it, pull the spark plug and see if it is wet with fuel or not. You need to determine if the piston is drawing fuel from the carb, into the cylinder. On a 2-stroke, if the crank seals are bad, the cylinder can't get fuel as the piston has to draw the fuel around the crank, first, for lubrication and then into the cylinder and if the crank seals are bad, it will loose vacuum and won't get fuel to the cylinder. The crank is sealed off from the rest of the crankcase on a 2-stroke. Also, first, you might want to check the carb and make sure it's not stopped up. It could be a reed problem, too, but first you need to determine if the cylinder is even getting any fuel. That's all I can think of as it's been years since I've worked on a 2-stroke.
 

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Discussion Starter · #3 ·
Thanks for the quick reply. Yes, the plug is wet when I pull it out. I pulled off the carb and all looks good and clean. Pulled the bottom off to make sure the floats are moving freely as well. Everything looked great. Just really confusing to me that all of the sudden, BOOM and nothing after it has been running so good in the past couple of days since I bought it. I also checked the reeds and they looked good as well. They were moist with fuel as well.
 

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Discussion Starter · #4 ·
HELMUT, first let me say thanks!! I got curious and pulled off the stator cover. Sure enough, there was a little bit of moisture in there, from the looks of it, from a broken gasket. I also found the stator nut not even close to finger tight!! I was able to spin it with one finger and it came off the shaft quick. The key was also sheared. I left the side cover off to let it dry out and will head to the parts store in the morning for a key. I will look through the manual I have tonight and get the torque specs for the stator nut, because I am quite sure its not going to say finger tight HAHAHAHA!!!!!! I will keep ya posted, thanks again!!!!
 

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The sheared key is the problem, then. The manual says that the flywheel nut torques at 47-54 ft.-lbs. That seems a little low to me. I believe I would put some blue locktite on it, just don't use the red locktite or it will be hard to get off.
 

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Discussion Starter · #7 ·
Yes, I was thinking the same thing about the lock tight and my manual says the same for the torque spec too, so it must be right. I am hoping the key won't be too hard to find...but the hunt will be on first thing in the morning!! THANKS!!!!! I will keep you posted when the two stroker is stroking again!!!
 

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Man you guys beat me to it.I knew right away that the flywheel key was sheared.Glad you found the problem though.Good luck.The key should be easy to get at the honda place.
 

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Discussion Starter · #9 ·
ALL FIXED AND RIPPING THROUGH THE TRAILS AGAIN! Found a few other problems while I was fixing it too. Had to install a new on/off switch and also made some new bushings to hold the fairings in place tighter. Also I just wanted to let others know, if you have a CLYMERS manual, it tells you to put it in gear and hold the back brake.... But what it should tell you is to put it into 3rd gear and hold the brake or else you will keep turning the wheels and engine in first and second. Took a while to get that part figured out, but after that.... a few bolts later it was making that lovely two stroke sound again!! :) I went to AUTO ZONE and bought the assorted key package from the HELP section. After about 5 minutes with a file, it fit perfect....after a local place said it would take two weeks to get a key from HONDA. Thanks for all the help guys and I will keep checking out this site for all of my quad needs!! THANKS!!!!!!!
 

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We're glad you got it fixed and back riding again.
 

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Yeah I've made some homade keys before.The only thing you gotta watch is that it doesn't advance your timing any.
 

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Good to here you got it fixed! Welcome to the forums!
 

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Discussion Starter · #13 ·
Thanks for the heads up Billy250X. All is good. I am quite sure the problem was the prior owner not reaching the required torque like the book says. When I pulled off the cover the nut was so loose it spun off the shaft with one spin of one finger. The outer end of the key was the part that sheared off, so it kinda looked like a bite got taken out of it.
 

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Hello ALL! I am new to the site and I am hoping I can get some serious help. I have an 86 Fourtrax 250R. Ran great when I test rode it so I bought it. I went for a spin on it yesterday, was riding for about 20 minutes and all of the sudden got a back fire and it shut down. I couldn't get it to start back up. Couple times it sounded like it was going to start, but then gave me a kick back and ended up introducing my knee to the handle bar :blink:
I have taken readings like the repair manual I have and found that the STOP - RUN - STOP switch was not reading low ohms while in the off position. I switched it out with a two position switch to get the right readings. I now have infinite resistance in the RUN position and .3 in the off position. I was getting spark before I did this and I am still getting spark now. The plug fires nice and bright blue. I am using a BR8ES, I pulled a B8ES out of it.
My next step will be to grab a compression tester Monday morning and run a check on it. Just seems weird that all of the sudden that could be a cause....but I want to check everything.
I have also checked the readings on the coil to make sure those readings are right as well and they are good.
I can't help thinking that the back fire may have been the result of something that went wrong. Do the two strokes jump timing? With no valves....
I don't want to babble on too long, so if I have left some details out that are need to help, please let me know and I will be completely descriptive!
THANKS SO MUCH IN ADVANCE!!!! I am looking forward to a long stay here!
try checking thr rings,coil,or stator i when through the samething with my old blaster once it got hot it lost all power and then just shut off once it completly cooled down it would run like a champhope you get it figured out
 

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wonder if thats whats wrong with mine, it has fire and fuel to the plug even half ass starts when ya pull it but won't fire up
 
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