Took a plunge... trying a PP LXR250 EFI

[ChondaChondaChonda]

[ChondaChondaChonda]

Compression valve assy




Base Valve:



34 shims in the compression stack!!

[BlackBike]

Is it about what you expected as far as wear? You have put some pretty heavy duty on it this last year.

[ChondaChondaChonda]

Originally Posted by BlackBike

Is it about what you expected as far as wear? You have put some pretty heavy duty on it this last year.

Everything looks to be in good order. I'm going to make a few adjustments to the shim stack and replace the seals, fresh oil and it should be good for another year or two.

The oil I poured out of these forks looked quite dark. When I take the other side apart I plan to get a good measurement on the fluid capacity.

[Megadan]

Are those Showa Forks? If not, they could be a dead nuts ringer for them. I would almost bet that valving and springs from the aftermarket would drop right in and work on those things.

[ChondaChondaChonda]

Originally Posted by Megadan

Are those Showa Forks? If not, they could be a dead nuts ringer for them. I would almost bet that valving and springs from the aftermarket would drop right in and work on those things.

Not Showa. FastAce is the brand. They aren't exactly like the Showas but close. I'm sure springs and seals for 47mm forks would work.

[ChondaChondaChonda]

Ran down to the local moto shop this morning to get some fork oil and a tool. They had this KTM Freeride out front and I like the idea so I asked how much. $6500 for a used bike. Nah.



So I tore the other fork off. This side has never leaked so I used a Ride-Rite measuring cup to record the stock fills.






The outer chamber only had about 200cc in it!! This might explain why they feel so plush. (Similar Honda forks call for 318-380cc depending on what bike you look at.)



Sunlight helps:

[ChondaChondaChonda]

Also opened up the inner chamber and poured the oil into a measure cup; after stroking the fork and letting it drip upside for about 20 minutes it looks to hold about 160cc.



So now I'm left with a few decisions. I've been reading as much as I can absorb about shim stacks and how they affect performance. In general, I quite like the way the forks work with the exception of how it handles sharp edge bumps; it's not bad. Just wonder if it could be better.

My mess:

[Megadan]

Originally Posted by ChondaChondaChonda

[SIZE=4]
So now I'm left with a few decisions. I've been reading as much as I can absorb about shim stacks and how they affect performance. In general, I quite like the way the forks work with the exception of how it handles sharp edge bumps; it's not bad. Just wonder if it could be better.

Shim stack tuning can make your head hurt. Trying to find the right combination of thickness, size, count, so that the low speed won't change, but they will deflect enough to soften the high speed dampening is going to take a little trial and error to get the result you are after. Those square edge bumps are the high speed dampening. With such a large shim stack, you may be able to simply remove one or two of the larger shims and see how it behaves.

[ChondaChondaChonda]

LXR250 Shim stacks- FastAce ARX01RC forks

Base Valve Compression Stack (as found stock)
12mm Inside Diameter shims x 34

18 - 31.90 x 0.12mm shims
1 - 20.0 x 0.16mm shim - (Crossover) -*Interactive stack
1 - 31.90 x 0.12mm
2 - 29.90 x 0.16mm
2 - 27.88 x 0.15mm
2 - 25.90 x 0.15mm
2 - 23.88 x 0.16mm
2 - 21.90 x 0.15mm
2 - 20.0 x 0.15mm
2 - 17.96 x 0.15mm

Single 31.90 x 0.12mm check plate and spring on back side of valve

Rebound stack (on Mid Valve)

2 - 19.9 x 0.10mm
1 - 13.9 x 0.10mm
1 - 19.9 x 0.10mm
1 - 15.96 x 0.10mm
1 - 13.92 x 0.10mm
1 - 11.85 x 0.49mm

Single 19.9 x 0.10mm check plate against a bellville washer spring.


Main spring is progressive 42mm Outside Diameter x 545mm long (free standing) with a 32.1mm Inside Diameter

*-Interactive crossovers have a shim diameter larger than the stack clamp. That allows force transfer directly through the crossover shim into the high speed stack before the crossover closes. Direct force transfer makes the stiffness of the low speed stack a function of high speed stack stiffness. Under those conditions changes to the high speed stack or clamp end up effecting low speed damping as well. -by Clicked author of ReStackor software

[ChondaChondaChonda]

Just about had the first fork all re-assembled tonight. Had to quit when I realized that the new seals were too small.

Had a good flow going too.




So I will post a few pictures and comments.

All of the teflon slide surfaces in the fork looked to still be in excellent condition despite my best efforts at abuse and neglect.


I added these cool cats to my tool collection:


The *one* anomoly that I found between the two forks;

14 coils at 27.5mm OD and 4mm wire *calculated rate 1.41kg/mm
Not sure why one is longer than the other.

[Megadan]

You would have to try a lot harder to start to wear those teflon seals down. Teflon is a fairly tough substance when it comes to abrasion wear.

The two springs being so different is definitely interesting. Same wire diameter and same number of coils. The coil spacing looks different, so either one sagged, or was made in a different batch. I think it is just a little evidence that while these forks are definitely a cut above what comes on most of these bikes, there are still areas where material quality or manufacturing consistency still needs to catch up a little bit.

Lots of great info as well, you are definitely providing a great service to others that may get one of these bikes in the future.

[BlackBike]

Gread workup. So are you going to stretch that spring and make it equal? Drop a bar steel in among those coils and put your feet on either side, put your back into it and ...perfect length.


response to above post , this is great that you can find replacement parts !!!

[ChondaChondaChonda]

Originally Posted by BlackBike

Gread workup. So are you going to stretch that spring and make it equal? Drop a bar steel in among those coils and put your feet on either side, put your back into it and ...perfect length.

Probably not.

I wonder if it was caused by running it with the leaking seal? On the last ride I bottomed hard on a big G-out that the bike normally would have shook off. It's feasible that not having enough fluid in the outer chamber allowed the inner to see pressures way above design and over compressed the spring on that fork.

Just ordered a set of 1.61kg/mm pressure springs on ebay. Factory Connection brand for $27; I'll definitely try to figure out a way to measure the rate on the stock FastAce springs. (found to be 1.41kg/mm after this was originally posted) I used the Racetech chart recommendations that are based on rider weight to pick the 1.61 - oddly they only have 1.4 and 1.8 and I fall right in the middle of both.

[ChondaChondaChonda]

Ok, so it turns out that these Pitster Pro LXR 250 forks are fairly close cousins to the 47mm forks that have been coming on Japanese bikes since, well... 2000?? or so??

Anyways, I took a chance (Again) and ordered up a set SKF seal kits for a 2007 CRF250X. Picked them up early this morning:



Managed to get the forks reassembled and the new seals installed. Even started to put them on the bike before I realized that it was a good time to service the steering stem bearings.

Lots of good grease still in there. Thread sealant on everything...very impressive for any bike at this price point.











Bearing is 32906X with an FP on the other side. Fresh Waterproof grease packed into both upper and lower.

Took at test ride and it feels pretty good. Still very plush and predictable on the street. No leaks!!

No good place to test off-road locally (in winter) so I mostly just scootered around town. I need to spend some time with a screw driver playing with the clickers.

I'll install the new pressure springs when they get here. Nice thing about this design is that it will be fairly quick and easy to pull the base valve and make adjustments to the compression stack or swap pressure springs.