1985 YZ 125-N Rebuild

nicko-31
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3/21/2016 4:36pm Edited Date/Time 6/4/2016 6:23pm
I'm having issues with this rear shock because the seal head apparently has a retaining clip on top of the head and the bottom of the seal head, can't get it out. Also the seal head from All Balls was wrong even though the package states that it's for my bike and year. The shock shaft is "NOT" a 14mm shaft but a 12.5mm shaft. WTF really !!! I guess they weren't supposed to be serviceable .Any help would be good.
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pete24
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Marlborough, MA US
3/21/2016 5:08pm
dont screw around with those chineese shock rebuild kits they suk, they last about as long as a coso pit bike, if i was doing anything vintage suspension wise i would call Race Tech
nicko-31
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3/22/2016 6:41am
pete24 wrote:
dont screw around with those chineese shock rebuild kits they suk, they last about as long as a coso pit bike, if i was doing anything...
dont screw around with those chineese shock rebuild kits they suk, they last about as long as a coso pit bike, if i was doing anything vintage suspension wise i would call Race Tech
I know you're bike is 2 year's newer Pete , is that where you sent out your shock to. It's just the seal head which I'm sure is Chinese but my budget is limited so I eather do this or scrap it altogether. This is going to be a racer rider not show bike. Thanks
pete24
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3/22/2016 7:17am
i did all my shocks myself but i am not a professional suspension guy
nicko-31
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3/22/2016 8:52am
I had a friend at Phoenix Syspension work on it but I'm waiting for the correct size bumper right now. I don't believe this shock was every intended to be rebuildable !! I called Pro Action and was at least given pressures to run 200 PSI.

The Shop

sjsingle1
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1/15/2014
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Fort Worth, TX US
3/29/2016 11:32pm
the shock on that yr has the dreaded double clipped seal head....you can get it out with enough perseverance and the right technique.......the alls balls seal head has a built in bumper which is all wrong for the shock.......race tech sells the better seal head with no built in bumper
nicko-31
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3/30/2016 8:47am
sjsingle1 wrote:
the shock on that yr has the dreaded double clipped seal head....you can get it out with enough perseverance and the right technique.......the alls balls seal...
the shock on that yr has the dreaded double clipped seal head....you can get it out with enough perseverance and the right technique.......the alls balls seal head has a built in bumper which is all wrong for the shock.......race tech sells the better seal head with no built in bumper
Yes I found this out the hard way, I'm waiting to assemble with new seal head from Race/Tech and shock bumper. The AllBalls seal head stated that it was for my year and model but was wrong. 85 KYB shock for 125 is 12.5 mm shaft and I received 14mm head.Crazy shit huhh !! Wink
nicko-31
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4/3/2016 5:39am
Does anyone know what the size of puller that I need for the Magneto (flywheel ) puller for this 1985 YZ 125? Lots of different sizes that I've seen so I don't want to order the wrong one .thanks
pete24
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6/3/2016 3:25pm
nicko, i got a pm from you and the site will not let me send one back i think you may have a problem in the drive of your power valve mechanism, did you take the ball ramp drive out of the case in front of the clutch basket? are all the balls in it? this would make the linkage very loose and noisy if a ball or two were missing its a pretty common problem on kx 80s, not so much on your bike but thats what i would look at
nicko-31
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6/4/2016 3:05pm Edited Date/Time 6/4/2016 6:20pm
pete24 wrote:
nicko, i got a pm from you and the site will not let me send one back i think you may have a problem in the...
nicko, i got a pm from you and the site will not let me send one back i think you may have a problem in the drive of your power valve mechanism, did you take the ball ramp drive out of the case in front of the clutch basket? are all the balls in it? this would make the linkage very loose and noisy if a ball or two were missing its a pretty common problem on kx 80s, not so much on your bike but thats what i would look at
Thanks Pete, I did respond via PM .I did as you recommended and took off the side cover and checked .All the balls were in there and they were.The linkage is just plane worn out. I had a second power valve mechanism and I'm going to try that out. It just makes a rattling noise .I also ordered a new Seal and O-Ring for the power valve assembly. I know a lot of people bag on this model but EG ported and Maxed out the bore and" it's no dog" .It does move right along. I lost the clutch all together when I tried it for the first time due to NOT having on the lock screw (Hay it was never there when I got the basket )on the clutch push rod. I'll check back when I retest it later. Thanks
nicko-31
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6/4/2016 6:23pm
Is it possible to have the Z spokes plated ?? Or do I need to buy new spokes ?? If I have to buy new is Buchanin the only source.
6/8/2016 6:39am
Nicko, if you think your powervalve linkage is worn out because you can't get the slots to align, there is a simple fix for this. K,L and N all use the same linkage



I measured everything up, and then removed one 1mm shim from the left side of the governor (see pic above) and put it on the right side of the spacer. This effectively moved the spacer that the linkage fork sits in over 1mm. It made a 5-6mm difference to the height of the linkage going up to the power valve. This "lengthens" the linkage and brings the groove in the linkage anti-clockwise back to the hole in the case.

See full write up here. http://forum.ozvmx.com/index.php?topic=39030.0

Also, i get my spokes zinc plated. Its cheap and gives them the OEM look. In fact, grab all your hardware, chain adjusters, axles, nuts and bolts, everything and take them to a zinc platers and get the lot done as a batch. Bike will look like new and cost is minimal.

You will probably find that your puller is an 18mm x 1.5 pitch

nicko-31
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6/8/2016 12:18pm
Thanks for all your help Dick, I will try that ASAP.Also tell me your thoughts on this linkage issues due to the fact that Eric Gorr decked the bottom of my cylinder along with the port work.Doesn't it seem like that would lower the cylinder enough to cause slack in the Power valve linkage ??
6/8/2016 4:51pm
nicko, i thought my original linkages were worn, slack, bent etc.. so i found a brand new one on Ebay, cost a fortune, and then compared them all. Measurement wise, there was no difference in all 3 linkages (2 x old, 1 x new). I then got a few govenors and set them to OEM spec. I could not set the power valve, as the linkage was way out of misalignment.



So, i played with the shim stacks on the governor. It only takes moving a 1mm shim from 1 side of the groove that the linkage sits in, to the other side to make a massive difference to the linkage. As you can see in pic, you need to align the slots, so that your powervalve is in the correct position at idle and then slowly gets pulled down (linkage moves up turning power valve anti clockwise a few degrees). By playing with the shim stack, you can get your linkage back to where it should be. This worked perfectly on both my bikes. I have not even bothered using the new linkage.
If eric decked your cylinder, it will affect the linkage adjustment slightly, but you do have some adjustment on the linkage. Make sure you governor is in good condition, bearings, shims, spring etc, as any slack in that will get transferred as slack in your linkage.
nicko-31
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6/9/2016 9:00am
I had this made by a friend at work.



6/9/2016 9:23pm
I see where your coming from. Nicely made. Your mate could probably start selling them as they are rare. You don't get that part when you find a new linkage. That will take a small amount of slop out where it slips into the governor groove, and it also may help with aligning the grooves and pins for the power valve adjustment. If you can't quite get it right, then adjusting the shims in the governor works wonders.
Cheers,
nicko-31
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6/13/2016 2:30pm
The Drama continues on this build, I was to go riding for the first time and had the kick starter get stuck in the down position. It would go back up but was very stiff. The PO had the wrong kick (I installed correct one )lever on this bike which came down on the counter shaft sprocket and chain. The end result was a cracked Left Case Half where the kick shaft goes through. Is it possible to buy just a Left side case ?? Or do they need to be a set ? They are sold separately with different part #'s .Also all the bearings are new, how can I remove them with out damaging them ??
nicko-31
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6/13/2016 4:19pm






This is the damage .
6/14/2016 5:34am
If your not fussy, you could probably get that ally welded. Then, either drill to correct dimension to accept the shaft, of get a small bush made up that would fit over the shaft and then interference fit to the new hole.
You can run separate covers. If they were sold in pairs then no, but as separate part numbers, no problem. I have several K and L engine case and i pick and choose between different ones. As the bearings are an interference fit, warm the case up in your oven and then gently tap out all your bearings.
Below is a pic of some cases i picked up. Have a look at the left hand case which is the same as yours. It has been welded where one of the gear shafts fits in.



nicko-31
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6/14/2016 6:00am
You continue to be very helpful to my little project Richard. Thank You. Grinning
nicko-31
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6/20/2016 6:17am
I have the Bike running , it's not pretty at the moment but that will be phase #2.Case's matched up properly and still minor jetting work to be done. Thanks to all that participated in getting me information. Especially my new friend Brian Fedigan at MX-Restorationhttp://www.mxrestoration.com.He was extremely helpful and gave me, "Yes" gave me most of the parts I needed for this bike and also work on the parts needing repair.





6/21/2016 5:23am
Well done. Looks OK in pics.. Not sure if your forks feel really spongy, but i highly recommend the Race Tech emulators and springs... amazing difference with those installed.
Cheers,
nicko-31
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6/21/2016 5:56am
Yes, actually they are soft and spongey. I was told that because there 43mm forks I can install cartridge in them. Thanks Dick.

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