Author Topic: Cheap shock curious.  (Read 893 times)

0 Members and 1 Guest are viewing this topic.

Offline John Orchard

  • Legend
  • *****
  • Posts: 2863
  • ^^^ Jan 1984
    • View Profile
Cheap shock curious.
« on: January 16, 2020, 01:37:06 PM »
I've always been curious to see inside Cheap Chinese shocks, they look pretty cool on the outside (the ones fitted to the newer Chinese bikes), I wonder if they can be made to work with a bit of 'home maintenance'?

I have a pretty recent Chinese made Atomik 250 here, upside down forks, rear shock with adjustable Comp & rebound; I'll take the suspension apart when I don't have any vintage stuff to work on (hope I live that long ha ha).

I recently bought a pair of $100 new Chinese rear shocks off ebay, listed as Honda CR125M fitment (I needed 365mm length) , yes before you bag me out, I was not expecting much, but as the Little River Band says "Curiosity killed the cat".

These shocks didn't look too bad quality/build wise, probably much like what might have come stock on my DT1, BUT the spring rate is too strong for a 4" travel bike, I'm guessing the rate might suit the CR125M2 with the shocks mounted further forward?

Damping wise; almost no compression damping, the rebound is about 4 times what is needed; not knowing if the internals utilize any shim washer style valving, as these are not rebuildable. These are not gas filled, so I drilled a hole in the bottom of them, drained out what looks like about 10wt cooking oil. I then braised a steel schrader valve in.

While flushing the shocks with diesel fuel, before the final oil fill, I noticed the damping weren't much better, diesel fuel has an ISO (International Standards Organization) viscosity of about 2 Cst (about 1wt), I had some ISO 8 Cst (about 2.5wt) shock oil on the shelf, so I mixed it 50/50 with some diesel to thin it out.

So, the 50/50 mix is in the shock, the air pressure that I felt best (only going by a push test in the vice) was 75 psi on the guage, which is about 60psi once the air pump is removed (I refitted the air gauge and added half of what the loss showed).

And so, yep still no compression damping (as expected), maybe the stiff springs might help keep it off the bump-stop? Still about twice as much rebound damping that is needed, maybe the stiff springs might help fire the shock back?

Anyways, These will lay in the spares box, as my second choice 'last resort' should I need them one day ;-)

Sure I will do it again, while I have a dollar in my pocket, the curiosity will always eat me up.
« Last Edit: January 18, 2020, 12:04:15 PM by John Orchard »
Johnny O - Tahition_Red factory rider.

Offline pokey

  • Legend
  • *****
  • Posts: 1375
  • Arse .. Elbow. Know the difference
    • View Profile
    • FB
Re: Cheap shock curious.
« Reply #1 on: January 17, 2020, 12:22:36 AM »
No dampning  and over rated springs does not surprise me at all.

If it looks right and they can make a profit and sadly its not limited to after market parts from no name companies.

I have a job where I get paid to do burn outs on your lawn for a government run delivery company ;) We are issued with the new fuel injected electric start NBC110 Honda supercub that while faster and more torque than the super reliable CT110, the NBC is absolute rubbish in the reliability stakes.

The shocks from new were as you describe, Super strong springs and no dampening. Poor design and low grade metals see the engine oil pump bush wear prematurely so pressure is pushed through the bushing which leaves the top end starved and two top end and two clutch rebuilds in 15000Ks. Fork stanchions are half the length and stop at the lower triple, The bar clamps have cracked and the frames crack on the rear mount and centre stand mount.

I have ridden maybe 30 different NBC's and only two actually had reasonable suspension even for a scooter.
 Is it not surprising to find a sticker on the swingarm fof the maker. A Chinese company Sundiro who are partly owned by Honda.

I wouldnt buy a used one..

Offline Curtis

  • Legend
  • *****
  • Posts: 522
    • View Profile
    • japspec.com.au
Re: Cheap shock curious.
« Reply #2 on: January 17, 2020, 09:18:39 AM »
If you need something to hold the rear end up and look cool they will do the job but if you want to ride faster than 20kmh then they will be pure punishment..curiosity got to me as well  ;)

Offline David Lahey

  • Legend
  • *****
  • Posts: 954
  • Gladstone, Queensland Australia
    • View Profile
Re: Cheap shock curious.
« Reply #3 on: January 17, 2020, 12:20:30 PM »
About 20 years ago, I bought a 1970s Japanese trials bike that already had a set on. One ride on my practice sections and my curiosity was cured. Not even as good as the Japanese originals which were pretty crap. Same issues. Huge springs and ridiculously heavy rebound damping. May have worked OK on a 200kg road bike.
previous pseudonym feetupfun

Offline LWC82PE

  • Superstar
  • ******
  • Posts: 5931
    • View Profile
    • PE motorcycles & SuzukiTS.com
Re: Cheap shock curious.
« Reply #4 on: January 18, 2020, 10:17:34 AM »
Quote
the NBC is absolute rubbish in the reliability stakes.

Cant agree with you more there. I sevice the things.

Theres been many recalls/revisions that had to be done. Fuel pumps always playing up.

They used to get rid of them at 30000km but now i am told 'we are keeping them past that' A few around here are well past 35000 and more parts are wearing out.
« Last Edit: January 18, 2020, 10:20:03 AM by LWC82PE »
Wanted - 1978 TS185 frame or frame&motor. Frame # TS1852-24007 up to TS1852-39022