Raptor spit and sputters and gets hot after rebuild - Yamaha ATV Forum
 
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post #1 of 11 Old 03-10-2019, 04:51 PM Thread Starter
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Raptor spit and sputters and gets hot after rebuild

Hello, I need help with figuring out what’s wrong with my raptor. I just rebuilt the top end because it had no compression the piston Was really worn. I put a 686 piston kit in it, and put it back together followed the service manual. When I started it it started just fine but started getting hot quick I hit the gas and it revved good, then I hit it again and it started popping and bogging. Not sure what is wrong with it has a new spark plug and well a new piston everything else is stock carbs are clean, could it be the timing chain, maybe valves? I did adjust the valves to spec and turned it to check again all was good. It does make a suction kind of noise every once in a while and has a slight ticking noise. I adjusted the timing chain like the service manual said too, not sure what else to do. Do I need to adjust the carbs? Any input is appreciated thank you!
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post #2 of 11 Old 03-10-2019, 08:42 PM
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are the carbs seated in the boot? you are describing a lean situation. what did the old plug look like. did you get the carbs back together correctly? adding the big bore would not make it lean but if you added a pipe or did air box work that would do it. did you measure your ring gap correctly? you say you adjusted the timing chain, did you check the timing. advanced timing could do it. did you put in a hi comp piston in it. my bet is the carbs are not seated or the boots are bad
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post #3 of 11 Old 03-10-2019, 11:09 PM Thread Starter
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Originally Posted by cory52000 View Post
are the carbs seated in the boot? you are describing a lean situation. what did the old plug look like. did you get the carbs back together correctly? adding the big bore would not make it lean but if you added a pipe or did air box work that would do it. did you measure your ring gap correctly? you say you adjusted the timing chain, did you check the timing. advanced timing could do it. did you put in a hi comp piston in it. my bet is the carbs are not seated or the boots are bad
Yes the carb is seated correctly I sprayed carb cleaner where the carb connects and nothing happened idle stayed the same. The old plug before I put the piston was a very black dry color. Yes I did aling the sprocket as per the manual specs. I did however snap one head pipe stud I have ordered the parts for it would that cause it to spit and pop like that? I didn’t mess with the air box nor put any other mods on it. How would I know if the timing was off without taking it apart again? I put it at TDC when I adjusted the chain but I will take another look tomorrow.
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post #4 of 11 Old 03-11-2019, 02:41 AM
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the missing head bolt could cause damage after some time to the valves but not immediately. if it is spitting and blowing fire from the front it could be the bad stud for sure but should not make excessive heat. but if it is backfiring out the carb or pipe probably not the issue. there is no way to check the timing without taking it apart and looking at the alignment marks and that is only going to confirm valve timing. it would have to be something like a partially sheared flywheel key causing the spark to be delivered early, its really a long shot but you asked for things that cause overheating.
is the overheat light coming on?
is the fan coming on?
did you burp the cooling system when you filled it, you may have an air lock
what color is the plug now?
are the air and oil filter clean?
how many heat cycles have you ran it through?
you say the carbs are clean, did you have them apart or have they just been well maintained.
are you confidant you gapped the rings correctly and got the spacing at least close?
what makes you think it is overheating (not trying to be a smart ass but knowing how you are gauging might help me)
again your description makes me think it is running lean but if it was running perfectly before the big bore and everything is the same the jetting should be right on or a little rich depending on how tight the motor is.
again not trying to be insulting but i dont know your experience level a new motor will make a lot of heat in the first five or six heat cycles during the break in.
the more questions you can answer and the better detail you can give will help me narrow it down faster.
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post #5 of 11 Old 03-11-2019, 09:42 AM Thread Starter
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Originally Posted by cory52000 View Post
the missing head bolt could cause damage after some time to the valves but not immediately. if it is spitting and blowing fire from the front it could be the bad stud for sure but should not make excessive heat. but if it is backfiring out the carb or pipe probably not the issue. there is no way to check the timing without taking it apart and looking at the alignment marks and that is only going to confirm valve timing. it would have to be something like a partially sheared flywheel key causing the spark to be delivered early, its really a long shot but you asked for things that cause overheating.
is the overheat light coming on?
is the fan coming on?
did you burp the cooling system when you filled it, you may have an air lock
what color is the plug now?
are the air and oil filter clean?
how many heat cycles have you ran it through?
you say the carbs are clean, did you have them apart or have they just been well maintained.
are you confidant you gapped the rings correctly and got the spacing at least close?
what makes you think it is overheating (not trying to be a smart ass but knowing how you are gauging might help me)
again your description makes me think it is running lean but if it was running perfectly before the big bore and everything is the same the jetting should be right on or a little rich depending on how tight the motor is.
again not trying to be insulting but i dont know your experience level a new motor will make a lot of heat in the first five or six heat cycles during the break in.
the more questions you can answer and the better detail you can give will help me narrow it down faster.
It is backfiring from the pipe not from the front which I don’t think the stud is the problem. I would have to check in a little while about the spark plug and the flywheel key, the light is not coming on nor the fan but it is getting quite hot rather quickly. I did not burp it when I put coolant in it, yes the oil filter and air filter are in good shape. The carb is regularly cleaned I have just barely cleaned it as well but I will take another look. As per the rings yes I got them how the manual said and made sure they stayed that way going into the cylinder. I’m not too sure what could be causing it to get hot but the backfiring is what was making me think something might have been wrong with the timing. Before i put A new piston, it was burning quit a bit of oil and a hint of blue smoke was coming out of the exhaust on start up, it also smelled like burnt oil. I was riding with my buddy one day and out of no where it started spitting and sputter it would go but it would bog. It idled quit rough so I cleaned the carb and it kept on doing it. I want to get this quad running before summer hopefully I can make that happen. I appreciate you helping out👍
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post #6 of 11 Old 03-11-2019, 10:21 AM
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if the fan and the light are not coming on it is probably fine. like i said until the rings seat they will make more heat. when i am breaking in a new top end i will start it, run it until the fan kicks on and the let it cool completely at least six or seven times then i will go do some break in rides. is the pipe glowing more that an inch or 2 back. what i would do next is confirm it is actually overheating run it up to temp and use a laser thermometer you will want to check several places in the rad to make sure they are even as it warms up check the upper and lower hoses and compare to the rad. check the motor and pipe as well. confirm that it is circulating water. i will generally squeeze the hoses to try to clear out any air trapped in the system

from you last description i dont think your problem was low compression, carbs or jetting. it sounds like you had the problem prior to replacing the top end. confirm that the diaphragms for the slides are good but i think you might have an electrical issue. i am not as good with the raptor electrical as i am the yfzs. it sounds like you have the service manual. i suspect you may have a flaky stator or pickup. confirm that it is not the reverse revlimiter causing your issue its pretty common and there are tons of threads on that subject. check the crank sensor and all of the harness connections/grounds. then follow the electrical trouble shooting section in your manual. dont worry we will get it figured out before summer. hopefully digger will check in soon he is really good with the 660s.
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post #7 of 11 Old 03-11-2019, 10:13 PM Thread Starter
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Originally Posted by cory52000 View Post
if the fan and the light are not coming on it is probably fine. like i said until the rings seat they will make more heat. when i am breaking in a new top end i will start it, run it until the fan kicks on and the let it cool completely at least six or seven times then i will go do some break in rides. is the pipe glowing more that an inch or 2 back. what i would do next is confirm it is actually overheating run it up to temp and use a laser thermometer you will want to check several places in the rad to make sure they are even as it warms up check the upper and lower hoses and compare to the rad. check the motor and pipe as well. confirm that it is circulating water. i will generally squeeze the hoses to try to clear out any air trapped in the system

from you last description i dont think your problem was low compression, carbs or jetting. it sounds like you had the problem prior to replacing the top end. confirm that the diaphragms for the slides are good but i think you might have an electrical issue. i am not as good with the raptor electrical as i am the yfzs. it sounds like you have the service manual. i suspect you may have a flaky stator or pickup. confirm that it is not the reverse revlimiter causing your issue its pretty common and there are tons of threads on that subject. check the crank sensor and all of the harness connections/grounds. then follow the electrical trouble shooting section in your manual. dont worry we will get it figured out before summer. hopefully digger will check in soon he is really good with the 660s.
Ok so I took another look at the raptor today, I checked where the stator goes stator is good I had replaced it last year. I couldn’t get to the flywheel key as I don’t have a puller bummer. I checked the carb again all is good, I do however think it’s an electrical problem as well. The reverse limiter is already grounded my park brake did give me some trouble before so I fixed it but the problem stayed the same after firing it up. I did have the problem prior to doing the top end, I did let the air out of the coolant system seems to get a little less hot. Like I said it started when I was riding with my buddy it was some rough trails we were riding and it started bogging and sputtering. I did see a red wire that was connected to the reverse limiter green wire it went no where 🤷‍♂️ Not sure if it’s of importance.
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post #8 of 11 Old 03-12-2019, 10:25 AM
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did you test the stator and pickup with a meter? if you just used a cheap ebay one it could be the issue even though its new. however ruff riding normally causes connection issues. from here the first thing i would do is clean and re tighten any ground connections, bypass the parking brake switch altogether, disconnect, clean and seal all of the connections with dielectric grease. dont use to much and just use it to help seal the connector. dont just gobb it in there.

if you are talking about the green and white stripped wire that goes from the reverse switch to the cdi there should not be any other wire connected to it. it appears on the wiring diagram that switch is normally open and closes to ground when the machine goes int reverse and activates the rev limiter. that was possibly a failed attempt to bypass the rev limiter. i am guessing a little on the switch being normally open but that is how its drawn on the diagram and most of them are. i would at the very least check the green and white to the reverse switch and the green and yellow to the to the parking brake switch. check the whole wire for shorts and test the switches. confirm that those switches are indeed normally open. it sounds like it comes and goes and those are the most likely suspect's
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post #9 of 11 Old 03-12-2019, 10:55 AM Thread Starter
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Originally Posted by cory52000 View Post
did you test the stator and pickup with a meter? if you just used a cheap ebay one it could be the issue even though its new. however ruff riding normally causes connection issues. from here the first thing i would do is clean and re tighten any ground connections, bypass the parking brake switch altogether, disconnect, clean and seal all of the connections with dielectric grease. dont use to much and just use it to help seal the connector. dont just gobb it in there.

if you are talking about the green and white stripped wire that goes from the reverse switch to the cdi there should not be any other wire connected to it. it appears on the wiring diagram that switch is normally open and closes to ground when the machine goes int reverse and activates the rev limiter. that was possibly a failed attempt to bypass the rev limiter. i am guessing a little on the switch being normally open but that is how its drawn on the diagram and most of them are. i would at the very least check the green and white to the reverse switch and the green and yellow to the to the parking brake switch. check the whole wire for shorts and test the switches. confirm that those switches are indeed normally open. it sounds like it comes and goes and those are the most likely suspect's
Ok thanks, i will have to try these when I get the chance. I did not test the stator with a meter I am planning on checking it again. When I got the bike it wouldn’t charge the battery so I changed the stator and the regulator at the same time and all was good until now. It might be what is causing it I am going to make this bike run right!!! Hahaha I will report back when I get the chance to work on it again. Also do I have to ground the park brake wire if I recall correctly there where 2 wires going to it one black and one green and yellow. Wasn’t sure if I had to ground it or just cut it.
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post #10 of 11 Old 03-12-2019, 07:28 PM
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if memory serves you just unplug it. the switch is normally open, applying the brake closes the switch to ground. unplugging it would trick the machine into thinking the brake was never on. i have deleted a few machines this way but my 660 was deleted when i got it so i have not done it hands on.
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post #11 of 11 Old 03-15-2019, 09:52 PM Thread Starter
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if memory serves you just unplug it. the switch is normally open, applying the brake closes the switch to ground. unplugging it would trick the machine into thinking the brake was never on. i have deleted a few machines this way but my 660 was deleted when i got it so i have not done it hands on.
Ok so I am back with a report. So after taking the carbs out messing with the air mixture screw I got it running a little better but still bogged. So me and my buddy were looking at the electrical cables and checked the ignition coil we found that the little tab looking thing that was connected to it was loose. It was just sliding in and out of the coil, so we squeezed it and turned the bike on and now runs like a beast 💪. It must have come loose when I was riding the uwharries mountains. Thanks for helping out Cory 👍
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