Early to Mid 80s Yamaha YZ 250 / 490 / IT 200 Rear Mono Shock Rebuild

BM
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BM
Edited Date/Time 5/3/2020 7:42pm
Hi is there any one with any past experience who has rebuilt one of these shocks. All the parts diagrams i have seen only show the exterior parts and not the inside of the shock as in the seal head etc. Also the procedure and the correct amount of shock oil required in the rebuilding. If so i can use your help

Thanks BM
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Bent206
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Bent206 3/18/2018 5:02pm
3/18/2018 5:02pm
Look on the Race Tech website. I’m pretty sure they have a “how to” article on rebuilding that style shock.
nicko-31
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nicko-31 3/18/2018 5:46pm
3/18/2018 5:46pm
I appreciate your help. I'm doing a 1985 shock right now and removing the double ring seal head is a bear with out the special tool required.

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nicko-31
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nicko-31 4/2/2018 5:11pm
4/2/2018 5:11pm
If you've ever wondered why Yamaha would make taking a mid 80'S YZ shock apart here's one reason why it's a beast. You can see that I had to grind the top clip in half and still have to press it down enough to get the clip out.





Cesar_Holguin
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Cesar_Holguin 3/21/2019 5:01pm
3/21/2019 5:01pm Edited Date/Time 3/21/2019 5:03pm
nicko-31 wrote:
If you've ever wondered why Yamaha would make taking a mid 80'S YZ shock apart here's one reason why it's a beast. You can see that...
If you've ever wondered why Yamaha would make taking a mid 80'S YZ shock apart here's one reason why it's a beast. You can see that I had to grind the top clip in half and still have to press it down enough to get the clip out.





Is the second clip in the middle.? or the lower part.? Do you have pictures of it.?
nicko-31
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nicko-31 3/22/2019 10:25am
3/22/2019 10:25am
Sorry ,I don't remember the original clip position on the stock set up .I just installed a new complete Race -Tech seal head on both of my 85 shock's.
450exc115
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450exc115 3/27/2019 11:50am
3/27/2019 11:50am
The seal head is pinned between two clips. I use a press to compress the seal head rubber enough to get at the outer clip. RaceTech makes the best seal head for it but you can use a All Balls or MSR 46mm/14mm seal head to save a few bucks.

A quart of shock oil is enough to do the job and make sure you bleed as much air out of the system as possible.

The Nitrogen fill is a rubber plug that you can either use a needle to fill or replace the plug with a 1/8 NPT schrader valve using a drill and tap.

1
Cesar_Holguin
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Cesar_Holguin 3/27/2019 1:45pm
3/27/2019 1:45pm Edited Date/Time 3/27/2019 1:48pm
450exc115 wrote:
The seal head is pinned between two clips. I use a press to compress the seal head rubber enough to get at the outer clip. RaceTech...
The seal head is pinned between two clips. I use a press to compress the seal head rubber enough to get at the outer clip. RaceTech makes the best seal head for it but you can use a All Balls or MSR 46mm/14mm seal head to save a few bucks.

A quart of shock oil is enough to do the job and make sure you bleed as much air out of the system as possible.

The Nitrogen fill is a rubber plug that you can either use a needle to fill or replace the plug with a 1/8 NPT schrader valve using a drill and tap.

Thank you very much for your help and information.... Last question :.... What oil should I use .20, 10...?
450exc115
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450exc115 3/27/2019 2:05pm
3/27/2019 2:05pm
5-7wt shock oil. Honda 7w works well and holds up. Most modern oil is 2-3wt and fork oils aren't as good for the high sheer shock oils see
Cesar_Holguin
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Cesar_Holguin 3/27/2019 2:11pm
3/27/2019 2:11pm
450exc115 wrote:
5-7wt shock oil. Honda 7w works well and holds up. Most modern oil is 2-3wt and fork oils aren't as good for the high sheer shock...
5-7wt shock oil. Honda 7w works well and holds up. Most modern oil is 2-3wt and fork oils aren't as good for the high sheer shock oils see
Wow I didn´t know that, so which one should I use on forks.?
450exc115
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450exc115 3/27/2019 2:19pm
3/27/2019 2:19pm
That's a loaded question. What springs , terrian and what's your riding skill level
Cesar_Holguin
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Cesar_Holguin 3/27/2019 2:25pm
3/27/2019 2:25pm
450exc115 wrote:
That's a loaded question. What springs , terrian and what's your riding skill level
Jajaja, a 50+ guy who wants to go back to do Enduro again just for recreation, so I considere my self a beginer again. So I say I prefere to stay with the standard settings.
450exc115
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450exc115 3/27/2019 3:20pm
3/27/2019 3:20pm
If you are not changing to a more modern spring rate I would start at 10w. If you go up in rate then I would bump up the oil weight as your only way to change the rebound is with oil weight.

Have fun and good luck!
Cesar_Holguin
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Cesar_Holguin 3/28/2019 9:16am
3/28/2019 9:16am
450exc115 wrote:
If you are not changing to a more modern spring rate I would start at 10w. If you go up in rate then I would bump...
If you are not changing to a more modern spring rate I would start at 10w. If you go up in rate then I would bump up the oil weight as your only way to change the rebound is with oil weight.

Have fun and good luck!
Thank you very much, !!
Yamaha353
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Yamaha353 5/1/2020 5:59pm
5/1/2020 5:59pm
Hey guys sorry to drag back up a dead thread here but I see nowhere else to ask. I'm trying to rebuild the shock on an 85 IT200 and of course it's a pain in the butt. I finally got the top clip off but I still can't get the shock shaft out or remove the seal head. I'm kind of banging my head against a wall here and since it seems a few of you have gone down this road before I'm hopeful one of you can help me out here. Tell me what I'm missing. I'd be most grateful!
450exc115
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450exc115 5/3/2020 7:42pm
5/3/2020 7:42pm
Use a hand pump to slowly put pressure in the reservoir and watch the seal head slowly work its way out. Be careful not to go to fast as it might pop out and make a mess! Then remove the inner clip and pull the valve body out.
Yamaha353
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Yamaha353 5/3/2020 8:12pm
5/3/2020 8:12pm
I actually had to apply some air pressure and work it in and out with PB Blaster before it finally came out as crazy as that is.

Thank you so much for replying 450exc115! Just waiting on the new bumper to rebuild it. Fill it up with oil, bleed it, and pressurize it. These remotr resevoir old shocks are a pain the butt 😫 😅😂

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