ALWAYS Do THIS on Old Honda Motorcycles - 1968 Honda CT90 Centrifigual Filter and Oil Change

This footage of Brock cleaning out the centrifigual oil filter on his beater 1968 Honda CT90 has been sitting on a hard drive since this summer, so we figured we'd finally make use of it and spend way too much time putting a video together! While these aren't always that dirty, if they've never been checked or cleaned in the bike's history it's a good idea to tear into them and be on the safe side! While this procedure was performed on a CT90, the basics of these filter types on old Honda's and the disassembly/cleaning procedure are generally the same.
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[@HayabusaGSXR-cv6ig]

Excellent video and a well explained procedure to those who seam to think 🤔 there isnt an oil filter and its peace of mind that you know your filter system is cleaned its probably a good idea to change your oil more regularly to limit the amount of times its necessary to remove the side case and having the gaskets instock when putting it back together. Thank you for this guide 😉 😜

[@retro_grade]

Sure thing! I'm not sure that changing the oil out more frequently is really THAT necessary. Cleaning that centrifugal filter out is more of a 1 time deal on many of these bikes. (I'm trying to remember - but I think the new Trail 125 specs its to be cleaned at 6,000 miles?). They really don't get that gunked up that fast. So, it is a bit of a pain to do with removing the clutch, but not really something that's done often. Most old bikes I've had, I do it one time to make sure it's done and then possibly never again, because I don't put enough miles on them.

[@Robinsbro17]

Great video..Thank you for posting as this is a task I need to perform this Spring. Thanks again.

[@retro_grade]

No problem, glad we could help out! It's honestly one of those 'Peice of Mind' jobs....most times it doesn't need done, but you feel alot better knowing it's clean. And, on the occasion that the area gets full and starts restricting oil flow, the results are not good LOL.

[@BradenMcCandless-bs7tc]

Thanks for the how to. I'll do that when I get the gaskets. though I was unable to find it on Google until I searched clutch outer cover gasket on the small one.

[@retro_grade]

Sure thing, hopefully it was helpful! Try CSMNL for the gaskets (and other parts). They stock most stuff or at the very minimum, have all the part numbers you need to search Ebay and other sources for it. www.cmsnl.com/ (Not sponsored by them, just a good resource).

[@RobertHatfull-df4ch]

I used to take the engine out and lay it on its side to do this aint done a cub since the 80s kinda took me back .

[@retro_grade]

Yeah I suppose one could lay the bike on its side as well to not have to drail the oil out, but it's not hard to drain and not very much to refill. Other than that, I guess it would help the clutch components go back together easier and not fall off when trying to slide the cover back on?

[@SSOMMERHOFF]

Nice video! Just a suggestion: to properly measure the oil level, don't screw the dipstick.

[@retro_grade]

Thanks! You are correct on that one. I measured oil level incorrectly on old Honda's for years doing that, and for some reason still find myself forgetting to do it the proper way. Most times when I fill, I end up right at or slightly on full which I guess is good for those occasions LOL.

[@tauncfester3022]

Just to add: Most of the Honda twins of this era also used a centrifugal filter, as do a lot of presently made Chinese clones including the CG125 based upright singles. Also note that loosening the right side footpeg's bolts requires you loosen the left side while removing the right side's. Trail 90/110's also benefit from removal of the skidplate.

[@retro_grade]

Yep, you're correct! Some of the earlier models (like the CB160 and CB77) are much easier to access the filter, as there is a seperate round cover to get it it, rather than having to remove the entire clutch cover. One one hand, I'm not sure why Honda didn't make it easier but on the other, it's not like it has to be done very often in a bike's lifespan. I actually had a statement in my initial voiceover about that filter system being used on many old Honda models, but later cut it because I thought I was rambling on too much. The whole job probaly would have been easier to just remove the skid plate and foot pegs entirely, but that's how it goes.....spend more time being lazy and trying to do it the 'easier' way.

[@donsoule6411]

Worth mentioning… the original 7-pcs Pan Head Screws are not Standard Philips Head as they may appear. Most will have a small dimple punched into the head, indicating they are JIS (Japaneses Industrial Standard) as mentioned. Use of a Standard Philips tool to remove them has the real potential of tearing up the head along with the inclusive aggravation. JIS tools are worth every bit of the investment and actually work good on Standard Philips Head Screws as-well.

[@lancenorton1117]

My 1975 CB 125s has a centrifugal oil filter and it is accessed via removing the right side crank cover.

[@lancenorton1117]

@@donsoule6411 YEP, IF they were put on tight and you use a phillip's head screw driver you may be screwed.

[@donsoule6411]

@@lancenorton1117 LOL… “screwed”, but not un-screwed!! Even with an impact-driver JIS, I recently had to use a 4-lb. “beater” to remove the clutch cover screws from a 1974 Trail 90. As rough as that sounds, the screw heads weren’t deformed much by using the appropriate size JIS tool.

[@mikes-mz5xb]

I have the same bike, and the same johnson seahorse. Both great machines

[@retro_grade]

Nice! They are both fantastic machines, this is correct LOL. And 1957 is my favorite of the Johnson outboard years :)

[@bewilderment9268]

At the end, when you went into gear, it looks as if you need the rear hub rubber shock dissapaters replaced.

[@retro_grade]

Would not surprise me. This 90 is definteily more of a "beater" one. I've had the wheel off but probably never checked or noticed.

[@garygullikson6349]

We have feral cats that sneak into our garage. BTW, other UY'ers suggest checking/replacing clutch disks while in there. I think I may have a defective shift star stopper gizmo making shifting sticky. Getting up courage to rip into engine, find parts, '68 KO parts are scarce.

[@retro_grade]

Hah! Yeah, the normal thing we typically are dealing with are neighborhood dogs that always sound like they're fighting it out. Literally every day. Always something! Replacing clutch plates would be a good idea as well, I was running out of time in this case as I was doing this in a 'rush job' before taking the bike on a trip. And, I hadn't had any issues with slippling clutch plates on this one so I figured they were fine. You could also check on your shift indexer (star) to make sure the bolt is still tight - I have seen several old Honda's where that bolt loosens up and then the indexer gets bound up because it's no longer sitting flat on the shift drum. Apparently, on some of the 90 and 110 models the spring loaded indexer arm also breaks? Have you tried CSMNL for parts? Between that and Ebay it seems like I can still find some of the early 90 parts. The PO also bought parts lot with some carburetor parts and extras, so maybe they are getting more rare! Guess I didn't' realize that.

[@thevwdude]

Typically the screw that holds the gear selector plate to the shift drum comes loose / breaks off and gives you false neutrals / bad shifts does require a special tool to remove the clutch drum, but other than that it’s super straightforward.

[@megastick9324]

The side cover has the oil grade stamped into it. 20 below a certain temp and 30 above. Though running multi grade won’t hurt anything really, I prefer to follow the OE instructions on lubes and fluids, it’s what they were designed to run.

[@retro_grade]

Yeah, they typically do have the grade stamped. I used to run straight 30 weight in my Z50 but then after further thought, it's harder to find straight 30 oil that doesn't have detergents and things in it potetially harmful to wet plate clutch assemblies. And 20 weight? I have zero idea where one would even purchase that at. So, I opt for the Honda GN4 10W40 used in most larger vintage Honda motorcycles, or a similar motorcycle type oil safe for wet plate clutches.

[@pujabelgian]

I bought a ct90, spent 2 weeks dismantling the top end, adjusting valves, messing with points, timing, disassembling the carb trying to get it to run right, took the clutch cover off, cleaned the screen, had a helluva time getting it back together, then it spit the plug out so I needed to take the head off again for a helicoil, back together and thought, why did I buy this thing? I obviously hate riding. 😄

[@retro_grade]

I know how it goes! Once they're sorted decently they run really well but it can be alot of work getting them to that point. I just finished putting my CT110 top end back together and I see a dowel/alignment pin left in the Cool Whip container of bolts - guess what that means I get to do?! 🤣

[@CharlieRice-eq5hb]

I just brought home a 1981 Honda Passport 70. I imagine the same thing needs to be done to my bike. Same procedure?

[@retro_grade]

Yep, the procedure should be basically the same as far as pulling the clutch cover off and cleaning it out! You may have a few different things in front of it to pull off in order to access the cover, but it shouldn't be too hard to figure out. Just get everything out of your way in order to slide it off - if it's easy to remove, pull it. It takes less time to pull things like foot pegs, plastics, brake cables, etc....than fighting with trying to slide the clutch cover on while holding everything out of the way. I could have benefited from doing more of that on this job (rear brake cable and dropping foot pegs and skid plate entirely, for instance).

[@Me0wkerz]

I have the same bike, it sat for a long time in my grandpa's barn. I think the electrical's are broken. Anywhere that I can take it to get fixed?

[@retro_grade]

There arent' a ton of places that will work on these old bikes, which is why alot of people end up doing it themselves. New motorcycle dealers typically won't touch anything over 10 years old. In Louisville, however, we do have one shop called Retro Wrench that works on old motorcycles. That's literally all they do. I'd try to find a comparable shop that works on old bikes in your area. They are around at times.

[@Me0wkerz]

Thank you for the reply! My bike actually has a brother but it's beyond repair I think. I'll probably refer to your video when I can't find anywhere most likely 😆

[@pujabelgian]

If you can't fix it yourself, forget it! Buy a newer bike, have fun and enjoy the ride.

[@AvinashThakar-l9y]

Will it be available in India? At what price?

[@retro_grade]

@@AvinashThakar-l9y we aren't selling this one for now

[@cerealtiller]

The original Screws were not Phillips type..they were JIS

[@retro_grade]

Ok technically, sure, I suppose they wouldn't be called "Phillips" - but I believe that I mention to use "JIS" bit inserts the next second in that statement.

[@phebelle04]

Get JIS #2 and #3 screwdrivers.

[@retro_grade]

I have two JIS sets made by Vessel.....one with oil resistant brown handles (shown in the video) and one set with thru tangs so they can be struck on the head with a hammer/mallet. The bits that I was using in the Milwaukee impact are JIS bits, also made by Vessel....and I do have #2 and #3 sizes of them. I just checked and I did say to use a JIS screwdriver at 9:49. I maybe should have mentioned it earlier for removing the screws.

[@lukekresek3480]

Where do you order parts from?

[@retro_grade]

I've been using CSMNL quite a bit, they have pretty much everything - and if they don't, you can pull the Honda part number from there and try to find it NOS on Ebay.

[@Philip-hv2kc]

You just had to include that music or whatever.

[@retro_grade]

Well, yeah - we're shelling out like $15 per month to be able to use that royalty free music! All the big time successful KZbin channels have trendy music on them, and we're aimed straight to the sky!!! 🤣