Jump to content

New YZ125 2000 advice needed


Recommended Posts

Hi all,

I have recently purchased a 00 YZ125 for a bit of fun in the dirt.

I am about to do the top end for the first time but have a couple of other issues.

1. 2 stroke oil is coming out the PV gasket/thick rubber seal. My plan is to remove, clean and replace rubber seals/orings and gaskets. Its really pissing out when running... There is also a bit out the breather aswell as exhaust but not compared to the heavy flow from the gasket.

2. Gearbox oil is leaking somewhere around what looks like the gasket under the head. Is this possible? Its not excessively smoking.

3. Check oil bolt is cross threaded so i will be removing clutch cover, fixing thread and inspecting clutch.

4. Bike came with Breg9 plug and ran fine, put in breg8 and bike died while riding for 20mins. Put in old plug and started first kick. I have not read the plug properly but new #8 plug looked wet.

5. A handfull of times going from 4th to 5th i hit false neutral while high in the revs. I have since slowed down the gear change in them gears and ensured i firmly clicked up and it has not happened again. Never popped out of gear. Is this a problem waiting to happen?

6. Bike sounds like shit and farts in very low revs, i know its a 2st but listening to others mine sounds off. Its not major bog just not crisp at all or smooth. In high revs it is perfect.

Id like to get it all fixed right the first time. Will i need to remove the engine to do this?

Aparently the bike had new top and bottom end aswell as gearbox as it was popping out of 6th gear. Pipe and muffler near new also. Air filter is clean and running 32:1 to 36:1 motul. Gearbox oil fresh motul.

Any help would be very much appreciated from people with experience and knowledge. New here and 1st post, ps i got a manual and basic know how.

Cheers

Edited by AUSmoker
Link to comment
Share on other sites

Point 1: On older bikes the shaft of the PV will wear out the opening it passes through.

Solution a bushing or for a make shift solution teflon tape and a modified spacer forcing the shaft not to wiggle around too much.

 

Point 2: It should be impossible to have gear oil seeping from the head. Gear oil stays normally in the gear box.

 

Point 3: Yeap.

 

Point 4: Breg9 should be the stock plug, the Breg8 is for 250's

 

Point 5: could be.

 

Point 6: Most likely your jetting is way to rich for you riding style.

 

Everything quite easy to solve, not difficult at all and with the help of a manual easily done by yourself  🙂

Link to comment
Share on other sites

Is it ok to run a #8 plug? I do ride pretty hard but sometimes putt around with my nefew. I will wait until the new top end is do e before messing with the carb, but i have never jeyted before so dont want to mess it up.

If i could clean up the bottom end a bit i would be happy.

Dont want to be in the middle of nowhere stranded again because of a #9 plug.

Link to comment
Share on other sites

Also regarding the gearbox leak, could it be an internal oil seal leaking somehow? Im hopimg its the rh gasket but its hard to tell exactly where its coming from. Will be pulling exhaust off soon to try and see it better.

Link to comment
Share on other sites

1. Replace both seals located on either end of pv linkage arm

2. Do you mean under head or cylinder?

.4 use the correct heat range plug or you could run into pre ignition or other heat problems.

5. False neutral between 4th and 5th is more likely to be holding the shifter up too long whilst holding on the throttle.

.6 Sounds like you need to re jet your carb and look at top end wear.

Removing the whole engine is not necessary but removing your head and cylinder for inspection is highly recommended. Don't believe anything about new top or bottom ends when buying a bike (unless receipts provided) as everyone claims to have installed fresh top end on a bike for sale.

  • Like 1
Link to comment
Share on other sites

I snapped my dodgy spanner trying to take the cylinder off, so have to wait to get to that. The cylinder didnt have any scoring in it. Hows the piston and head look, i have not cleaned it. I was expecting more black sludge since so much is coming out the pv.

Can you use a socket and wobbly bar for 3 out of 4 nuts? If not how do you torque it to spec?

The oil looks like its from the bottom of the cylinder, i will try and get a pic.

20150104_010626.jpg

20150104_010500.jpg

20150104_010451.jpg

20150104_001532.jpg

Link to comment
Share on other sites

I snapped my dodgy spanner trying to take the cylinder off, so have to wait to get to that. The cylinder didnt have any scoring in it. Hows the piston and head look, i have not cleaned it. I was expecting more black sludge since so much is coming out the pv.

Can you use a socket and wobbly bar for 3 out of 4 nuts? If not how do you torque it to spec?

The oil looks like its from the bottom of the cylinder, i will try and get a pic.

Head and piston look ok but you can't see cylinder honing whilst piston is at tdc. If oil is leaking from cylinder base gasket I suggest you replace the gasket and while the cylinder is off have it measured for wear and roundness.

For cylinder base studs you will need a ring spanner to remove and a torque wrench ring spanner adapter to re torque like the one made by motion pro. Cheap tool but handy to have for any bike.

That powervalve shaft seal needs to be replaced before you have more of a mess.

I would stick with the factory recommended plug and rejet until the bike runs smooth. Using a different plug can be problematic and is masking a jetting problem.

  • Like 1
Link to comment
Share on other sites

Having a closer look it almost looks like its the clutch side gasket only leaking. Some of the oil however travelled towards the front of the bike and uphill? Maybe turning etc would cause this.

Im kinda glad im pulling it apart, there was no nut at all holding the bolt in the top of the rear shock. Plus its something to do when I cant sleep.

20150104_142408.jpg

20150104_142204.jpg

20150104_142200.jpg

Link to comment
Share on other sites

Ok so there was a heap of black oil in the powervalve, it looked way to runny to be normal. Also there was no rubber gromet on the powervalve shaft or even a gasket on the cover.

I dont think the cylinder and piston looked too bad at all. Checked the crank for up and down play and there was none, however felt a fair bit side to side, is that normal?

What's the trick to putting in the piston circlips on either end. I was practicing with the old one and seemed pretty difficult. Also any trick to getting rounded off phillips head bolts out? Two on one off the powervalves are shot.

20150104_235302.jpg

20150104_235252.jpg

20150104_234403.jpg

20150104_234355.jpg

20150104_234347.jpg

20150104_234342.jpg

20150104_231549.jpg

20150104_231537.jpg

20150104_231520.jpg

20150104_231511.jpg

20150104_231506.jpg

20150104_231501.jpg

Link to comment
Share on other sites

Ok so there was a heap of black oil in the powervalve, it looked way to runny to be normal. Also there was no rubber gromet on the powervalve shaft or even a gasket on the cover.

I dont think the cylinder and piston looked too bad at all. Checked the crank for up and down play and there was none, however felt a fair bit side to side, is that normal?

What's the trick to putting in the piston circlips on either end. I was practicing with the old one and seemed pretty difficult. Also any trick to getting rounded off phillips head bolts out? Two on one off the powervalves are shot.

Oil in the pv is normal but yours looks excessive which is likely a jetting problem as mentioned.

All missing and used paper/metal gaskets will need to be replaced as they compress when torqued and won't seal properly again.

Side to side play is fine on the crankshaft.

No real trick to installing piston pin c clips but I advise you to put a rag or paper towel down around the crankshaft so they don't fall down in there resulting in you needing to split the cases. Also make sure the open ends of the c clips are facing the opposite side of the c clip coutouts in the piston as shown in the pic.

For stripped Phillip heads make sure oil and all combustible fluids are removed and use a little heat from a propane torch around the head and use an impact driver or easy out.

1420407517830.jpg

Link to comment
Share on other sites

Thanks for your replies, waiting on parts.

Is it normal for a bit of coolant to leak onto the crank? I did empty it but when I lifted the cylinder some ran in there. Did my best to wipe it off by rotating it but there may be some still in there.

Can you blow air through the head or what??

Link to comment
Share on other sites

Looking at the reeds, they have very slight chipping on the corners. Do these need to be replaced? They do not effect the seal but im worried parts will keep coming off.

Whats are the best reeds for the stock cage?

I figure replace things now and ride it fresh, then sell it worn out.

Link to comment
Share on other sites

Just ordered some Boyesen power reeds (dual stage), heavy duty tusk clutch, magnetic drain plug, new air filter, rear brake pads and a nut and bolt spares kit.

Will need to replace linkage bearings and wheel bearings at some stage but just want to ride it at the moment!

I did grease the rear shock bearings as they were basically seized.

Now waiting on a heap of parts including a new piston. Once all bolted up I will have someone jet it and it should be sweet.

Debating whether to run ATF, motor oil or specific gear oil. Any suggestions??

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

×
×
  • Create New...