yz125

[yz125j]

Hey guys

i just bought a yz125 yesterday I have bin riding my das crf250x for about 1 month now and decided i wanted to buy a 125 2-stroke so i can race next summer. I went riding this morning and after about 2 hours i stop it and sat for about 5 mins. I tried to start it and it wouldn't(i started it this morning with 4 kicks and it was 40 degrees!) I ended up changing the plug and got it started. I got home and put the bike away. about 3 hours later i went to get it out again, kicks fine one start, runs for about 3 mins, i pull out and i stalled it =/ i try to start it and it wont start. so my questions are:

1) What size gap in the plug do i need?
2) What oil mix should i use and what oil? im doing a 50:1 with klotz tc-w2 and 92 octane fuel.
3) where can I get an owners manual?
4) If I start racing what will I need to put on the bike?

Thanks alot guys

 

[X-Rider]

to get a manuel u could try and google it...as for your oil brand i would go to your closest yamaha dealer and they have shelves full of it, just make sure its the rite one, and to start racing u dont really need to put any on the bike at all...maybe a pipe if u have enough cash or air filter or whatever u think u need(more torque, horsepower, speed etc...)

Good Luck with the bike!

 

[snowskater101]

i dont know for a fact but i think you need more oil in the gas. ive got a yz250 and it calls for 24:1 or 20:1 depending on the oil you mix.

until you know for sure i would use something around 35:1 just to be safe. its better to run a little richer than leaner mix-wise if you're unsure on a two stroke.

 

[Jeromeo]

I run 32:1 opti 2 oil in my bike. Or the yamalube 2R racing oil. Do you know how to hot start?? Open the throttle and kick it. See what happens... otherwise may be your jetting....

 

[Morvo]

Sounds like the plug is fouling. What does the plug look like after the bike stalls/cuts out?

 

[Jeromeo]

if your plug is fouling it's time to JET YOUR BIKE... YEEE HAW. it's not as complicated as it sounds

 

[yz125j]

ya i started to hot start today and it runs great. but if i dump it on its side it wont start. also if i try to pull out up a hill it will sumtime bog out and stall.

 

[rmc_olderthandirt]

Laying a bike down can often cause the carburetor to flow gas and flood the engine, which will make it very hard to restart. You might want to check all the overflow tubes on the carburetor and make sure that they are routed properly. The should essentiall lead down immediatly as they exit the carburetor. If one or more takes a round-about path it could cause the overflow to not over flow properly.

It also sounds like the jetting is basically in need of some work. Either that or you are not keeping it wound up enough. Two strokes have a definate power band and if you fall below a certain RPM they will just fall flat on their face, power wise. Two strokes will also tend to foul plugs if you don't run them hard enough to get the plug hot.

Starting going up a steep hill on a 125 can be a challenge. You may need to slip the clutch a lot to get going, then once you are moving you need to keep the engine way up in the RPM. You simply can not go up the hill slowly.

The first step would be to make sure that you simply aren't trying to ride a two stroke like it was a four stroke. Keep the RPMs high, let it scream.

Second step would be to check the temperature range of the plug. Get the bike running and warmed up. Put a brand new plug in it. Go for a ride, preferably long and representative of how you ride. At the end of the ride shut the bike down without an excessive amount of idling (Like ride in hot, shut down immediatly). Pull the plug and look at the color of the ceramic around the center electrode. Do a search here or google the internet to find "reading spark plugs" and compare the color of your plug. I suspect that you may need a hotter plug. Note: A plug is "hot" or "cold" based on how easily it can get rid of heat. A "cold" plug can transfer its heat more easily to the cylinder head and thus it runs cooler. A plug that doesn't run hot enough will not burn off the oil and other deposites and it will foul. A plug that runs too hot will self destruct and cause "pinging" and possibly engine damage. You can buy hotter or colder plugs that will fit your bike. For example, if you are currently running a NGK BR9ES a BR8ES will be an exact replacement that is just a bit hotter.

The next step is to settle on an oil mix. 50:1 is very much on the light oil side for a dirt bike. I run 40:1 (synthetic oil) in mine, many people run 30:1, and the manual specifies 24:1 if you are running regular oil. More oil will in general be better for the engine but worse for the environment. The oil mix will have a small impact on the jetting so pick a mix and stick with it.

Finally you will want to adjust the jetting. Do a search of this forum, it has been discussed many times.

As for a manual, go to just about any bike shop and look for an after market manual such as Clymer's. Most shops will have a reasonable selection and since your bike isn't that old I would expect them to have one. They should cost about $30 but they are worth having.

Rod

 

[yz125j]

that helped alot. keeping it wound up was the answer. i have NGK 2411 B8ES plugs in it now. i just got a manual off of ****. Im thinking of going with 32:1. Im going to buy new oil(Mobile MXT2) tomorrow and stick with it. I was also wondering whay is the recomended plug gap for the bike?

 

[Jeromeo]

your clymer manual will tell you the right gap you need for the bike. I forget what it was. I just gapped it last week. Actually I don't think it needed to be gapped from the package the measurements were bang on for me. But that was one plug I never measured the other one. You'll love that bike my friend. Such a beautiful machine to just whip around. I would suggest you run Opti 2 or motul oil in that bike at 32:1. I've never tried Mobile MXT2 so I wouldn't really know how good it is.