Rear shock shim stack

[kdxdazz]

The rear shock on my Kdx220 is really harsh on the compression over faster terrain. I have the Yz125 spring which is perfect for my puny 60kg frame. Trying to gather all the information I can on the shim stack and how to modify it in preparation for a full rebuild. It will be my first time rebuilding a rear shock. There seems to be very little information on softening up the kdx shock/shim stack
All help appreciated

[kdxsully]

The reason there’s very little information, is because we often leave that to the professionals. Otherwise it’s trial and error. I myself wouldn’t want to be rebuilding my shock over and over.

[bufftester]

If my notes are correct (IF) the stock shim stack was
Compression ----------- Rebound
(8).20x38 ---------------- (7) .20x34
.10x30 ------------------- .12x24
.12x25 ------------------- .30x34
.30x36 ------------------- .30x32
.30x34 ------------------- .30x30
.30x32 ------------------- .30x28
.30x30 ------------------- .30x26
.30x28 ------------------- .30x24
.30x25 ------------------- .30x21
.30x22 ------------------- 3.2x26
.30x19
4.5x41 plate
.8X15.5

Easiest change would be go to a lighter oil. To soften up the compression side a bit you could go to thinner shims in the high speed portion. But as KDX Sully points out, it becomes a real PITA to continually tear your shock apart to do it, and puts a lot of wear and tear on it as well. Being in a part of the world where parts are harder to come by you might be better off looking for a different shock (say a KDX125 or YZ 125). There are other folks on here who are much more versed in suspension than I am, so hopefully they come by and save you from my advice.

[KDXGarage]

SR KDX220R, correct??

[kdxdazz]

Yes Kdx220sr and as already pointed out in my part of the world there are no professionals. I can find somebody to do a basic rebuild but then I can do that myself. Doing it myself is the only option. Will a Yz125 shock fit? I have one back in Australia I could try post.

[KDXGarage]

My measurements were the same as bufftester.

Buy some thinner shims or remove a few are options.

[ericr]

I wanted a little softer high-speed compression too when I rebuilt my shock. I added one, 16x0.30 pivot shim between the last shim and base washer. It's not a dramatic change, but I'm quite happy with the results.

[kdxdazz]

If I were to remove shims which ones would I use, if the shock has never been rebuilt is it possible the oil inside has become thicker over time and that is causing the harshness. Rode my friends xr250 yesterday with ohlins rear shock and it felt super plush in comparison even though the spring rate is heavier

[KDXGarage]

As oil wears out, it tins out.

How many years and miles have been put on the shock since the last oil change? Has it ever been changed?? Forgive me, but I assume you have a shock many years and thousands of miles on it, then you are on here and TT, elsewhere asking about your SUPER worn out shock feeling harsh. The nitrogen charge is not as high as it is supposed to be either.

If you had a fresh stock shock with standard charge, it might be different.

99+ % of people on here have never seen an SR model, so we have no clue as to what shock we are giving advice on.

Put fresh oil, seals, bushing, etc. and 150 psi nitrogen then ride it.

I hope you can understand that you are asking people to guess how a shock they may have never seen is going to react to fresh oil, full charge, AND a shim shuffle on your bike they have spent zero seconds on a test ride.

Thanks.

Sorry if that sounds harsh.

[kdxdazz]

Does sound a tad harsh, I also posted on TT as kdxrider just doesn't have enough people on it posting.
As I don't live in America or the rest of the world I don't know what countries had the SR model. Remember that WWW at the top of the page stands for world wide Web not American wide Web.
My shock is worn out and most likely has never been serviced hence I am going to rebuild it, my question is in regard to shim stack mod, not asking anyone to diagnose a problem on a bike they have never Rode but even so experienced guys are good at problem solving.
As it is my first time rebuilding a rear shock I am just trying to draw on people's knowledge, primarily changing the shim stack.
Does increasing the nitrogen charge make the shock more plush? I thought it was the opposite. As stated I weigh 60kg so I know just about every dirt bike I buy will need a spring change and a revalve
In Thailand there are very few good mechanics and I have to look at the rest of the world for help

[kdxsully]

Rebuild it and see how it feels first. Play with the clickers a bit. Then mess with your shims

[bufftester]

I would tend to agree with a rebuild, fresh N charge and ride a bit with the proper springs for your weight. The KDX shock in stock trim is on the soft side, generally you have high speed compression issues when folks switch to a KX front end or hybrid rear because the MX suspensions are geared for that kind of stuff. Don't underestimate the impact of proper sag, fresh oil and full N. Especially inspect your rear cushion, and the O-rings/seals on the piston. give everything a good cleaning. You mentioned using a YZ spring, does the length of that match the OEM length?

[KDXGarage]

Does sound a tad harsh, I also posted on TT as kdxrider just doesn't have enough people on it posting.
As I don't live in America or the rest of the world I don't know what countries had the SR model. Remember that WWW at the top of the page stands for world wide Web not American wide Web.
My shock is worn out and most likely has never been serviced hence I am going to rebuild it, my question is in regard to shim stack mod, not asking anyone to diagnose a problem on a bike they have never Rode but even so experienced guys are good at problem solving.
As it is my first time rebuilding a rear shock I am just trying to draw on people's knowledge, primarily changing the shim stack.
Does increasing the nitrogen charge make the shock more plush? I thought it was the opposite. As stated I weigh 60kg so I know just about every dirt bike I buy will need a spring change and a revalve
In Thailand there are very few good mechanics and I have to look at the rest of the world for help

Hey, no one said stay on the Thai wide web.

fresh oil
full charge
If you must revalve before riding it in proper working condition, take out a 38 and the 32 and 28. That will soften it up.

I used to work on a few people's shocks on here 14 years ago. With just fresh oil an nitrogen charge, I got a couple of comments like "What did you do?" and "The clickers actually make changes I can feel now".

If you do fresh oil, seals, bushing, charge, etc., then ride it, I think you will be surprised how well it rides. You are only guessing at how much softer you want it to be.

[kdxdazz]

YZ spring is the exact same length as the kdx but wider internal diameter at the bottom so need to use the YZ cup.
Cheers guys. I will pull the shock out, do a full rebuild and drop down to a 2.5weight oil. The rebound is at 12 clicks out so plenty or room for movement.
Have bigger fish to fry now though as yesterday I was out riding. Cooked the motor. Water pump impeller has spun on the shaft, looked through the exhaust port and a broken left hand power valve and the bore doesn't look healthy either. It never ends. Getting drunk last night helped but still feel pissed off when I woke up

[KDXGarage]

OH WOW! Good luck on the rebuild.

[kdxsully]

Wow that blows. If you do go through with the rebuild, maybe invest in one of those radiator caps with the temperature gauge

[kdxdazz]

Wow that blows. If you do go through with the rebuild, maybe invest in one of those radiator caps with the temperature gauge

Might get one yes but don't think it would have helped, the impeller wasn't spinning so didn't pump water up to the radiator. Piston is 0.12mm undersize, piston to bore clearance is 0.25mm. Went to 3 engine shops and nobody has a bore gauge to measure the cylinder, . Its worn but not badly scored so will take a chance on it

[pumpguy]

".....and no-one has a bore gauge." IMO, not much of an engine shop.

If you really want to know your bore and piston measurements, go to a machine shop. I'm sure they will have a micrometer and telescope gauges. Even I have these tools and I just mess around in my garage.

[kdxdazz]

".....and no-one has a bore gauge." IMO, not much of an engine shop.

If you really want to know your bore and piston measurements, go to a machine shop. I'm sure they will have a micrometer and telescope gauges. Even I have these tools and I just mess around in my garage.

Agreed, I couldn't believe it either, sometimes life in Thailand is not easy.

[doakley]

My inclination would be to simple service the shock first with fresh everything. Then see how it felt. It’s like trying to tune a worn engine in need of service. You wind up chasing your tail if you start from a worn base.