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| World traveler H2B rebuild http://www.kawi2strokes.com/forum/viewtopic.php?f=13&t=12577 |
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| Author: | Ja-Moo [ Sun Jan 21, 2018 11:16 am ] |
| Post subject: | Re: World traveler H2B rebuild |
Yeah, it's a strange set up. But just think about it a bit, and it will come to you. It is actually simply elegant the way the factory did the rebound damping. |
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| Author: | DGA [ Sun Jan 21, 2018 7:22 pm ] |
| Post subject: | Re: World traveler H2B rebuild |
I figured out that the light spring and shuttle inside the steel sleeve is a one way valve, it bypasses for bump and you get zero bump damping, but shuts off for rebound so you get the small side hole 'controlling' that. Pretty antiquated. So I cut the top off the aluminium spring seat and machined it while it was still on the main center tube. Had to also bore it to accept the snout on the XS650 valve. But then the roll pin was in the way of the nut on that valve, so it had to go. I tapped the roll pin holes 6/32 and loctited some short stainless button head screws in it, then filed the heads down a little to clear the inside of the fork tube. The piston rings were either worn out, or more likely, never did seal on the inside of the fork upper tube, so I machined some bronze ones, with a .020" bigger OD and gapped them to fit. Bit tricky to get the lower damping assembly in the upper leg with these new large rings, but it does go in if you hold your tongue just right.... |
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| Author: | H2RTuner [ Sun Jan 21, 2018 7:53 pm ] |
| Post subject: | Re: World traveler H2B rebuild |
One thing to remember about the times these stock parts and systems were used, the factory recommendations for fork "oils" weren't fork oils, but, 4 stroke motor oils. For the times, that worked OK, but, we really didn't know any better. When the sophisticated fork oils came along in the mid-1970's, they were far past helping a system that really didn't work that great in the first place. This is why I still use straight weight 4 stroke motor oils in stock and lightly modified front forks, and not specialty fork oils. On my street hot rod H2, I used Z1 dampeners, different holes in the dampers, different feel, better, but, still scary in a fast turn. Emulators should be so much better, it won't be funny, the changes. We also didn't have Progressive fork springs back then, either, it was modify the top spacer, or, different stock springs, modified to work. Another thing to remember is, with a straight wound fork spring, shortening it increases the spring pressure, a progressive spring usually has one closed wound end, which can be shortened without changing the spring rate, and the open wound end, which does when cut. Front ends are so much better these days. |
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| Author: | H-nube [ Tue Jan 23, 2018 10:12 pm ] |
| Post subject: | Re: World traveler H2B rebuild |
Wasn't there a mod to weld up the holes on the rod itself then redrill them a different size? |
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| Author: | Ja-Moo [ Tue Jan 23, 2018 10:25 pm ] |
| Post subject: | Re: World traveler H2B rebuild |
That's a real shade tree mod, with a lot of trial and error. Plus that was also used for the tiny rebound oil hole also. |
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| Author: | H2RTuner [ Wed Jan 24, 2018 5:15 am ] |
| Post subject: | Re: World traveler H2B rebuild |
Another way was to block the holes with a roll pin inserted in them. The early Z series bikes already had less holes drilled in them in the first place. They did work somewhat better, but still not very good when compared to today's suspension systems​. |
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| Author: | DGA [ Wed Jan 24, 2018 8:47 am ] |
| Post subject: | Re: World traveler H2B rebuild |
Honestly, without actually trying it, I would say the best bang for the buck might be to make and fit new piston rings that actually seal off, so that little rebound hole actually has a chance of doing something. Mine had at least .020" ring to upper tube bore clearance, the rings will just bypass and I bet there is as much oil flow around that as the little rebound hole has. I see new rings on Ebay for around $50 a set (!) but I will bet those aren't an improvement. Think about it, when have you ever had a problem inserting the damping tube into the fork upper leg? You never do because the rings don't seal, and slide right past the shoulder in the leg without catching. Mine I had to leave the parts off the damping tube and hold it on an angle to get the ring started, then slowly roll it up to get the ring to go in, and that worked good, no issues. I'll get oil in them tonight and let you know how they feel by hand off the bike. |
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| Author: | DGA [ Wed Jan 24, 2018 9:48 am ] |
| Post subject: | Re: World traveler H2B rebuild |
Here's an excellent page from Racetech about fork damping and their emulator valve. http://racetech.com/html_files/dampingrodforks.html |
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| Author: | Ja-Moo [ Wed Jan 24, 2018 12:07 pm ] |
| Post subject: | Re: World traveler H2B rebuild |
I thought you bypassed all of it, and the emulator did all the damping? |
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| Author: | DGA [ Wed Jan 24, 2018 12:56 pm ] |
| Post subject: | Re: World traveler H2B rebuild |
The emulator only damps the bump, not the rebound. There is another spring loaded valve in the emulator that works on rebound but it's not a control valve, only a check valve. Have a read of the Racetech page I linked, it's good at explaining it, and they say why it's better to control the bump, and the rebound is't as big a problem. But at least with the piston ring actually working as designed, the rebound might have a chance at working now, my rebound was almost non existent as it was. |
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