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KZ650 H2 - Fork Seal Change - What else? 16 Sep 2013 00:18 #606633

  • isolatoi
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Hi,

I got my first bike - a 1982 KZ650 recently, and have been doing a bunch of general maintenance; I have to change my fork seals as they just started leaking badly and want to know if I should check out / change preemptively anything else while I'm changing the seals?



Thanks

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KZ650 H2 - Fork Seal Change - What else? 16 Sep 2013 00:23 #606634

  • 650ed
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If you pull the front forks off the bike in the process you may want to replace the original loose ball bearing steering stem bearings with tapered roller bearings. They really are an improvement and well worth changing. If you decide not to change them at least grease the old ones while you can get to them.

Also, I would definitely replace the dust shields that cover the fork seals while it's apart. If yours are original they probably have hairline cracks. Ed
1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)
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KZ650 H2 - Fork Seal Change - What else? 16 Sep 2013 01:57 #606639

  • TexasKZ
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change the fork oil, too. B)
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough

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KZ650 H2 - Fork Seal Change - What else? 16 Sep 2013 02:17 #606640

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Fork oil. I think the manual calls for 10W fork oil, but you could go with 15W.

Springs. The manual lists a service limit for the fork springs, so you could measure them to make sure they're within spec. Alternatively, you could get new Progressive springs.

Air pressure. The manual probably lists a standard pressure & a useable range ( ~7-14.5 psi)(not to be confused w the max pressure listed on the forks - ~35 psi which is too high - when you hit a bump, the pressure will go higher).





Or use an air impact wrench w a hardened 8mm allen socket (or brake caliper socket) -->> fork caps & springs installed.


Note: your inner fork cylinders (damper rods) may use a different size tool.
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KZ650 H2 - Fork Seal Change - What else? 17 Sep 2013 16:04 #606811

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Thanks for all the great replies!

I've got (on the way) fork seals, dust covers, bushings (just in case - a friend told be they might be going, and if they look coppery it can cause premature fork seal wear), tapered bearings, progressive shocks (for $58!), and I already have some 15w oil. Whew well hopefully after this I won't have to worry about front suspension for awhile - besides changing the oil :)

Being that I've never "applied heat" to bolts before - what is the procedure? Do I just blast them with a propane/MAPP torch? Or is it like hair dryer heat? Do I have to worry about heating the surrounding metal a bit to prevent cracking it? How hot does it needed to be heated potentially?

Daniel

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KZ650 H2 - Fork Seal Change - What else? 17 Sep 2013 20:50 #606848

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Hi,

I got my first bike - a 1982 KZ650 recently, and have been doing a bunch of general maintenance; I have to change my fork seals as they just started leaking badly and want to know if I should check out / change preemptively anything else while I'm changing the seals?



Thanks

Possibly the front wheel bearings, the brake pads, and the brake fluid. Maybe rebuild the brake caliper/s. Upgrade to stainless brake lines. Hows your front tire?
1982 KZ1000LTD K2 Vance & Hines 4-1 ACCEL COILS Added Vetter fairing & Bags. FOX Racing rear Shocks, Braced Swing-arm, Fork Brace, Progressive Fork Springs RT Gold Emulators, APE Valve Springs, 1166 Big Bore kit, RS34's, GPZ cams.
1980 KZ550LTD C1 Stock SOLD Miss it
1979 MAZDA RX7 in the works, 13B...
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KZ650 H2 - Fork Seal Change - What else? 17 Sep 2013 21:06 #606854

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[/quote]
Possibly the front wheel bearings, the brake pads, and the brake fluid. Maybe rebuild the brake caliper/s. Upgrade to stainless brake lines. Hows your front tire?[/quote]

Front tire is good, PO got new ones very recently before I bought the bike and got new pads (I saw the receipts), was a big +. I just did the brake fluid though, it's strange they got pads but didn't change the fluid IMO. It needed it so badly, it was silty gray/black. I had to run 300ml of new fluid through the system after draining before it came out perfectly clean looking - not including the air bleed. What in the caliper might need replacing (sorry for being lazy, my service manual is still in the mail) ?

Is there a way to check wheel bearings with the wheel on? Such as blocking the engine and spinning the wheel by hand? I ask because this is my only vehicle at the moment and I'd rather have everything I need so I can knock it all out at once. I'll price them out, if they're cheap I'll grab some in case I think.

Thanks a ton, by the way!

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KZ650 H2 - Fork Seal Change - What else? 17 Sep 2013 21:14 #606855

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The front caliper has an outer dust seal that you see. But the internal seal is what holds the pressure, and also helps to ease back the piston so the brakes don't drag. Did the PO lube the Slide pins where the caliper bracket and piston housing move on the guide pins? These often get over looked, especially if they didn't change the fluid.
The wheel bearings can be felt when you have the wheel off, and the axle out, you can feel each for dryness and roughness. But the bearing/ seal kit is cheap, like $25. I'd replace them if they look old.
1982 KZ1000LTD K2 Vance & Hines 4-1 ACCEL COILS Added Vetter fairing & Bags. FOX Racing rear Shocks, Braced Swing-arm, Fork Brace, Progressive Fork Springs RT Gold Emulators, APE Valve Springs, 1166 Big Bore kit, RS34's, GPZ cams.
1980 KZ550LTD C1 Stock SOLD Miss it
1979 MAZDA RX7 in the works, 13B...

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KZ650 H2 - Fork Seal Change - What else? 17 Sep 2013 21:17 #606856

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......and I already have some 15w oil.....?

Daniel


I hope you are talking about Fork Oil not motor oil. Ed
1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)

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KZ650 H2 - Fork Seal Change - What else? 26 Sep 2013 17:56 #607916

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Front fork seals and dust covers were easy and the change went great. I didn't get to the wheel bearings yet but they're in the mail and is east enough to get to. I couldn't get the steering stem nut off so the tapered roller bearings are on hold until I get a tool for that but now that I've pulled the forks off I'm not too nervous about that job.

Ed, I definitely used fork oil lol.

Motor Head, I'm assuming the slide pins have not been lubed. I'm not familiar with our kz calipers enough to know 100% what the slide pins are. Attached is the diagram from my service, are they the "caliper holder shafts" (no. 4 and 14)? In a few weeks once I have some more money I'll rebuild the calipers and replace the fluid seal (12) and dust covers (5) to prevent any water getting in and causing corrosion.

PS the forks had almost 3/4" of sludge in the bottom! Wow. This makes me wonder what else is badly in need of some TLC.

Thanks again for all the help guys!
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Last edit: by isolatoi. Reason: Tried to attach pdf instead of image format

KZ650 H2 - Fork Seal Change - What else? 26 Sep 2013 18:29 #607919

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Glad to read that it went well and that you found and removed the sludge. I suspect a lot of bikes are sold that have that problem. The sad part is that it can be so easily prevented just by changing fork oil every two years, and that is a very easy task. Ed
1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)

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KZ650 H2 - Fork Seal Change - What else? 16 Nov 2021 03:39 #857978

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Hi can I change the seals on the forks without removing the fork tubes ? 
re Samantha

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