Posts
37
Joined
3/12/2018
Location
CA
Edited Date/Time
3/26/2018 9:34pm
Hey guys, new to the site.
I've ridden dirtbikes my entire life but never really worked on them. Got a 1998 yz 125 (bored out to 145) for my girlfriend to learn on.. (i know, powerful learner bike, lol).. and I decided to go for a project bike to save some $$..
It would start with choke on but would idle extremely high (even if i played with pilot), and when choke is off it died. Since I got it i've been cleaning top to bottom. Changed tranny fluid, radiator fluid, spark plug, air filter.. drained gas and put new 94 octane 32:1 premix.. it was kicking over in 1-2 kicks but kept dying when choke wasn't engaged.. I figured the carb was the issue otherwise it needs more than a tune-up.. (maybe top end).. so i got some carb cleaner and compressed air in a can and cleaned out all those jets real nice with a guitar string.. put it back together and now it wont start at all!!
I made one mistake.. I think i unscrewed the fuel mixture screw without counting the turns.. so when i put it back in, the carb isn't getting what it wants anymore. Literally tried going all the way in and then 1 turn out at a time.. (while the idle (air) screw was set to 2 turns & 1/4) ... no dice. Got it to fire up once with choke, was still idling super high, turned choke off and tried to play with the screws and it died. Spent a solid hour (making sure i didn't flood it).. nothin..
(i put a tablespoon of 10w30 in the spark hole because i heard it helps lubricate the cylinder walls.. kicking over bike while holding kill switch.. anyways, i took it out and dried it off just to make sure the wetness wasn't the issue)..
Really hoping i can get some solid guidance on what to try before looking into a top-end kit..
Also, IF I need a new top end, will i use the standard bore 53.94mm or because it's bored out to 145 the size changes?
Thinking it might be the top end just the way i watched the prev. owner cold start and ride off without warming up.. heard that the expansion can ruin the piston or something.
Edit:
Oh, also the fuel line keeps popping off now since the carb clean... and unrelated sidenote: when i replaced radiator fluid it seemed to have all leaked out of the overflow? .. but i opened the cap and it was sitting at the top?
I've ridden dirtbikes my entire life but never really worked on them. Got a 1998 yz 125 (bored out to 145) for my girlfriend to learn on.. (i know, powerful learner bike, lol).. and I decided to go for a project bike to save some $$..
It would start with choke on but would idle extremely high (even if i played with pilot), and when choke is off it died. Since I got it i've been cleaning top to bottom. Changed tranny fluid, radiator fluid, spark plug, air filter.. drained gas and put new 94 octane 32:1 premix.. it was kicking over in 1-2 kicks but kept dying when choke wasn't engaged.. I figured the carb was the issue otherwise it needs more than a tune-up.. (maybe top end).. so i got some carb cleaner and compressed air in a can and cleaned out all those jets real nice with a guitar string.. put it back together and now it wont start at all!!
I made one mistake.. I think i unscrewed the fuel mixture screw without counting the turns.. so when i put it back in, the carb isn't getting what it wants anymore. Literally tried going all the way in and then 1 turn out at a time.. (while the idle (air) screw was set to 2 turns & 1/4) ... no dice. Got it to fire up once with choke, was still idling super high, turned choke off and tried to play with the screws and it died. Spent a solid hour (making sure i didn't flood it).. nothin..
(i put a tablespoon of 10w30 in the spark hole because i heard it helps lubricate the cylinder walls.. kicking over bike while holding kill switch.. anyways, i took it out and dried it off just to make sure the wetness wasn't the issue)..
Really hoping i can get some solid guidance on what to try before looking into a top-end kit..
Also, IF I need a new top end, will i use the standard bore 53.94mm or because it's bored out to 145 the size changes?
Thinking it might be the top end just the way i watched the prev. owner cold start and ride off without warming up.. heard that the expansion can ruin the piston or something.
Edit:
Oh, also the fuel line keeps popping off now since the carb clean... and unrelated sidenote: when i replaced radiator fluid it seemed to have all leaked out of the overflow? .. but i opened the cap and it was sitting at the top?
Best thing you can do is give it to someone that has a clue. Cuz you don't.
Is your spark plug connected ?
Are you getting spark?
Did you turn the gas off, lean bike over on its side and allow the fuel to dump out (in an eco friendly catch pan.... of course) ?
Plug is connected.
Getting spark.
Turned off the gas and leaned the bike on it's side to dump fuel (unfortunately not in an eco-friendly way).. but i have a pan, next time I will be conscientious of that.
The Shop
I believe the bikes are the same from '98-'03
Idling extremely high, might be an air leak. Maybe a crack in the rubber intake between the carb and the cylinder, or the crank seal behind the flywheel.
Good luck!
How about topping off the injector cream?
Good chance it's an air leak as mentioned above - which will toast your engine if run that way. And likely also would call for someone who knows their stuff on it. A leak down test should tell.
To the OP, how’s cylinder compression? Start with the basics and rule out the obvious. When I clean my carbs, I really only need some high pressure air to plow out the jets and ports in the carb, then hold the jets up to some light and visually check that the passages are clear.
Check float and float height setting ( see chart).
Check the filter screen in the fuel tank for dirt or dried fuel deposits.
Remove the carb and do a soak cleaning.
While you are there, check and or replace the reeds.
Paw Paw
Pit Row
It is a 200 mile round trip but it is worth it to me. My Wife and daughter jump in and off to the mall for them.
The best thing to do is find “that guy”, only hopefully closer to keep costs down for you.
I have done a few unstick the bowl operations. Bike will only run full choke when bowl is stuck.
Peely should have told him to check the sprocket bolts. I find this shit hilarious and sad all at the same time. I'm just falling in line with the hundreds of other vitards in throwing advice. Yet, mine is right.
Oh, and don't listen to these guys giving you crap. Your initial post made sense if you have a sliver of internal combustion engine knowledge, which they apparently don't have.
I’ve found over the years you’ll save time and frustration if you do things the right way.
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