Melted down 1998 700 Triple last winter, mag cylinder detonated, caught a ring and scarred the jug.
We just replaced piston, jug, etc., cleaned the carbs, replaced the plugs.
Found 2 things off in the carbs..first the pilot jet of the magneto carb was plugged, which we cleaned and blew out with air. Also the fuel screws on the magneto were set at 2.5 instead of stock 1.5 off bottom.
So we started it up, but the mag cylinder still was not firing. Checked the mag side cylinder for spark, and it is getting spark. Checked fuel pump for gas flow, none of the 3 lines was plugged.
So I need to know, considering we cleaned carbs, fuel is pumping, and spark plug is firing...what else could I check on this mag cylinder to find the problem?
We just replaced piston, jug, etc., cleaned the carbs, replaced the plugs.
Found 2 things off in the carbs..first the pilot jet of the magneto carb was plugged, which we cleaned and blew out with air. Also the fuel screws on the magneto were set at 2.5 instead of stock 1.5 off bottom.
So we started it up, but the mag cylinder still was not firing. Checked the mag side cylinder for spark, and it is getting spark. Checked fuel pump for gas flow, none of the 3 lines was plugged.
So I need to know, considering we cleaned carbs, fuel is pumping, and spark plug is firing...what else could I check on this mag cylinder to find the problem?
By the way compression is 120/120/120....
grapeape
New member
Check the carbs again. The last time I had a cylinder not fire it was due to a piece of paper towel I had the bowls sitting on and managed to tear off a dime sized piece while installing the bowls.
Are the little white plastic rings that go down by the main jet still there? They should fit tight on the tube in the carb. if they are loose, throw them out or replace them. I had this happen, they slide up and interfere with the floats. Had a couple burn downs before I figured that out. Have had no issues since removing them. Also- What is your jetting?
FJViper
New member
I would agree with grapeape. Those triple carbs can be a pain. Inlet needles good? Top hat filters clean? Re-check those pilots. Sometimes they look clean but are not completely. Make sure there is in-fact fuel in that carb. Reeds good and sealing correctly? Are the plugs wet to show its getting fuel?
On a side note, I just fired up my Viper yesterday after sitting all summer. Carbs were spotless, everything good to go. Spark etc. and it took about 18 pulls to fire. Was just about to give up hope when it finally did fire. Smoked out the entire neighborhood. Neighbors probably thought my house was on fire.
Keep us posted....
On a side note, I just fired up my Viper yesterday after sitting all summer. Carbs were spotless, everything good to go. Spark etc. and it took about 18 pulls to fire. Was just about to give up hope when it finally did fire. Smoked out the entire neighborhood. Neighbors probably thought my house was on fire.
Keep us posted....
Has to be a carb issue, I would check the screens and pilots again. When you have them apart be sure to blow out the carb circuits with air also.
You can also check and make sure that carb has fuel in the bowl before tipping them over. That will rule out a pump or needle sticking closed issue. Check float height levels also.
You can also check and make sure that carb has fuel in the bowl before tipping them over. That will rule out a pump or needle sticking closed issue. Check float height levels also.
old gas will do it every time, it doesnt take much. happened to me almost 3 years ago
75% of the tank was fresh gas too
75% of the tank was fresh gas too
Ditto on the the carb clean. Does cylinder begin to fire at higher RPM/different fuel circuit. Was tank cleaned out before? Replace fuel filter? Check boot for leaks? What do the reeds look like? Choke plungers adjusted correctly? Plug wet or dry after idling? All 3 Pilots spotless after running? Clip spark wires back 1/4"?
Few things to look at and then report back.
Few things to look at and then report back.
Some updates
Okay thanks for all the ideas..
Someone mentioned the main jet washers screwing up the floats somehow, and they were pretty loose when I took those apart so I could replace those for $7.32 each.
My father in law tried a vacuum pump on the fuel pump and thinks the fuel pump is shot...I guess I wonder why 2 cylinders would fire and one not if the fuel pump was shot, but I don't know much about how the pump works..
Great idea about looking for fuel in the bowls before tipping up, that could help isolate the problem.
Another issue is I just took the bottom of the carbs off and did the main and pilot jets etc...we skipped the needle jet because it had been a long day..not sure if that could be part of the issue, because this cylinder is not firing at 1000 to 2000 rpm on the stand....
Okay thanks for all the ideas..
Someone mentioned the main jet washers screwing up the floats somehow, and they were pretty loose when I took those apart so I could replace those for $7.32 each.
My father in law tried a vacuum pump on the fuel pump and thinks the fuel pump is shot...I guess I wonder why 2 cylinders would fire and one not if the fuel pump was shot, but I don't know much about how the pump works..
Great idea about looking for fuel in the bowls before tipping up, that could help isolate the problem.
Another issue is I just took the bottom of the carbs off and did the main and pilot jets etc...we skipped the needle jet because it had been a long day..not sure if that could be part of the issue, because this cylinder is not firing at 1000 to 2000 rpm on the stand....
Rustman
New member
I would almost 100% say it is a plugged pilot. Even after cleaning they can gum up very quickly if old gas is in the system somewhere.
The main jet washers you are referring to are actually called fuel baffles. They are there to ensure main jet receives fuel during bumps, not being level and jumps at half to full throttle. They become weakened and loose their shape/grip over time (especially with the ethanol) but that would really only effect 1/2 to fuel throttle when the main jet is primarily used. Mine were yellow and the new ones I bought were white. Therefore, if cylinder is not running at idle, but catches on at higher RPM, it is not the position of the fuel baffle. Other things I mentioned before need to be looked at.
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If it is not a pilot jet issue. you may have a bigger issue...
When you said you cleaned the carbs did you only clean the jets? You may need to dig deeper and clean the rest of the circuits and blow air through them just to be sure that their clean. Also look through the jets and visually make sure that they are clean and open.
If all of this was done you may have an issue with the crankcase seal on that side of the motor or a possible hole in the crankcase not allowing you to intake fuel for combustion in that cylinder. try and spray carb cleaner by the magside crank seal area.
When you said you cleaned the carbs did you only clean the jets? You may need to dig deeper and clean the rest of the circuits and blow air through them just to be sure that their clean. Also look through the jets and visually make sure that they are clean and open.
If all of this was done you may have an issue with the crankcase seal on that side of the motor or a possible hole in the crankcase not allowing you to intake fuel for combustion in that cylinder. try and spray carb cleaner by the magside crank seal area.
mattysmith440
New member
I could bet my 2001 srx on it that you pilot in that carb is plugged. I had the same problem that I JUST figured out. I had completely cleaned every little piece of the carbs, puts them back on the sled, and still wouldnt run on my pto cylinder. Cant be a carb issue cuz I just cleaned them, right? WRONG. After putting a new stator, coil, and cdi, I was left clueless. After I posted on here, I figured hey, ill listen to the guys on here and check the carbs one more time. Sure enough, my pilot jet was plugged solid. If your cylinder fires up when you whack the throttle to it, thats your problem. Drain your tank, clean the hell out of it, replace your fuel filter, and replace with fresh gas. After running a tank through your sled take the carbs off and clean them again, as there will still be a bit of old gas in your fuel pump, lines, etc. I'll be very surprised if your pilot isnt plugged!!
Okay thanks for the help..here are the things I am going to try...
(1)Replace fuel filter (never done this..this is the one in the tank right? any help on how to do this would be great)
(2)Check and clean pilot jets again
(3)Replace fuel baffles
The other thing I would like to clean is the screens I have seen in some pics but not sure how to get to them?
Let me know what you think and I will let you now how it goes...
(1)Replace fuel filter (never done this..this is the one in the tank right? any help on how to do this would be great)
(2)Check and clean pilot jets again
(3)Replace fuel baffles
The other thing I would like to clean is the screens I have seen in some pics but not sure how to get to them?
Let me know what you think and I will let you now how it goes...
staggs65
Moderator
for the screens you need to remove your floats. the needle seat where the float needle goes in is removable, the screens are in there.