Jump to content

1984 yz125


Steve Butters

Recommended Posts

just got a yz125... its in great condition for its year, its been worked a bit... 50 over with wiseco piston, fires easy etc....fired it up and it started reving to the moon like it was gonna explode... pulled the carb off and one of the floats had broken off in the past, and instead of soldering it back on, the person put a screw in it...so the float was filling up causing it to run like piss...

im in the process of buying new floats for it, the needle and stuff all works good so im thinkin once i fix the float ill be ok.... does that problem sound float related? or should i check anything else out while the carb is off?

also, what all maintenance should i do before riding it? ive got crankcase oil, coolant, spark plug...anything else im over looking? and tips in general for a 2 stroke bike? ive never been on one, just 4 strokes... i traded my nintendo wii for this bike lol so im ok with it havin some problems

Link to comment
Share on other sites

never worked on a bike sorry if this is a dumb question, but how hard is it to check valve clearance?

Two stroke engines do not have typical valves like 4 strokes. They have an inlet valve aka reed valve. Do some google searches and read up a bitabout your bike and 2 strokes. They are really easy to work on. They tend to need rebuilt more often but it is cheap and easy. Have a blast, the two stroke power on those little 125 is addicting. You go from a no torque at all wimpy bogg, to screaming as pulling power in a blink of an eye!

Link to comment
Share on other sites

Two stroke engines do not have typical valves like 4 strokes. They have an inlet valve aka reed valve. Do some google searches and read up a bitabout your bike and 2 strokes. They are really easy to work on. They tend to need rebuilt more often but it is cheap and easy. Have a blast, the two stroke power on those little 125 is addicting. You go from a no torque at all wimpy bogg, to screaming as pulling power in a blink of an eye!

rebuilt as in? idk how many more times it can be rebuilt lol its already 50 over

Link to comment
Share on other sites

short answer: Yes, a bad or jammed float would make it rev sky high.

Oversize rebuilds usually are in increments of .25mm up to 1mm. For a small piston, anyway. So two more overbores, I suppose. Often the bore can be honed and fresh rings used, without going oversized again. So you have more than two rebuilds left on the motor.

edit: You do know you have to mix oil with the gas for that engine, right? Somewhere between 1:20 ratio and 1:32 ratio would be about right. Check the manual for details. Not motor oil, this is lube oil for mixing with gasoline.

http://www.yamaha-motor.com/sport/apparel/apscitemdetail/3/121/all/1/7462/detail.aspx

http://www.dansmc.com/2stroke_oil.htm

Edited by ReconRat
earl
Link to comment
Share on other sites

short answer: Yes, a bad or jammed float would make it rev sky high.

Oversize rebuilds usually are in increments of .25mm up to 1mm. For a small piston, anyway. So two more overbores, I suppose. Often the bore can be honed and fresh rings used, without going oversized again. So you have more than two rebuilds left on the motor.

edit: You do know you have to mix oil with the gas for that engine, right? Somewhere between 1:20 ratio and 1:32 ratio would be about right. Check the manual for details. Not motor oil, this is lube oil for mixing with gasoline.

http://www.yamaha-motor.com/sport/apparel/apscitemdetail/3/121/all/1/7462/detail.aspx

http://www.dansmc.com/2stroke_oil.htm

thanks...i know what oil to use, but wasnt sure on mixing gas yet... im gonna buy a repair manual for it and ill check the exact number in there...it was outta gas today, and i put a half gallon of whatever mix my gfs dad had for his chainsaw in it...just to fire it up

Link to comment
Share on other sites

can i mix gas in a can and let it sit? the manual with the bike says not to mix more than im going to use in one day and to dispose of the remaining fuel...

ide like to mix about 4 gallons at a time, and it will probably be 2-3months before i use all of it (bike is at my gfs house, and i dont really have anywhere to ride except at her place)

Link to comment
Share on other sites

if its going to be 3 months or so then you might want to add a fuel stabilizer to the mixture, but I don't see any reason why you couldn't do that. I doubt the oil will stay suspended in the gasoline very well, so best give the can a stir before each use

Edited by wrillo
Link to comment
Share on other sites

  • 2 weeks later...

yota, you probably are on the pipe a lot too though eh? not just putting around the yard or whatever?

the way i understand it is that the 1:32 provides adequate lubrication for riding hard in the upper RPM range, on the pipe most of the time. like during a race. after all, this IS a race bike :)

when you are just putting around in the yard, 1:32 is too thick for those low RPM conditions and you can start to foul plugs, so you should run a little thinner mix if you are not riding hard.

i could be mistaken about that though, im sure someone on here will straighten me out if i am :)

Link to comment
Share on other sites

i run 32:1 in a 87 125. It may be rich and smoke a bit but better to be rich than too lean and burn a hole through the piston. rebuild the piston and rings after every year or two of riding depending on hours. make sure all the bolts and screws are tight. bikes of that edge tend to lose shit once in a while :)

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...