wet clutch question NGC

[lucian]

I recently picked up a Honda ct trail90 for a winter project . It had not been run for the past 20 years and needs some tinkering. The compression is good at 140 lbs and the leak down only at 8 1/2 percent. After cleaning out the carb and replacing the fuel lines ,adjusting the valves and timing, installing new points and a battery she fired right up. So next on the list is inspecting the clutch pack as the kick starter has some slip to it. I ordered a socket to remove the castle nut and should have it in a day or two.  I have never dealt with a wet clutch and have read that it may need only to be de glazed . I am envisioning friction disks soaked with motor oil and am wondering the best way to accomplish the de glazing. Should I first remove as much oil as possible with a solvent ? Or just have at them with some wet or dry sand paper?  I don't think a replacement pack is too expensive, but if the disks have some meat left I thought I would try de glazing them first. Appreciate any thoughts.  Dave

[pete roper]

Have you tried just adjusting the throw of the ramping mechanism? On the RH engine cover there is a lock nut with flat bladed adjuster in the middle. Loosen the lock nut and wind out the screw 1/2 a turn.

Also don't forget to tension the camchain. If you don't know the procedure pm me and I'll walk you through it.

Pete

[nc43bsa]

After sitting for 20 years, you're lucky the clutch plates are not stuck together.

[Huzo]

I was a postie for 35 years on CT 90 and later CT 110's
I can tell you that 90's were harder on their clutches than the later 110's.
I think it's more of a function of the less robust design, but will be corrected if necessary.
The average postie would root up a set of plates in about 8,000 k of Postie work on a 90 yet the later 110's would almost see out the life of the bike if not flogged.
A set of plates is 3/5th's of 5/8th's of SFA in $ terms.
If adjustment to Pete's specs. does not completely fix your issue, just shout her a set..




Noice...!

[Two Checks]

I would bin the plates and buy new ones. Many times the linings after sitting will delaminate and circulate the material through the engine.
I know, we are cheap...er, frugal. Do it once and be done with it.

[lucian]

Thank's men,   When the socket arrives we'll have a look.
 
 Pete, I did adjust the clutch per the manual I got with the bike. Thank's for the heads up on the cam chain. The tension er is hydro, No? I did prime the oil pump by pushing it around in fourth gear, with spark plug removed, until oil spit out the domed head bolt . Motor seems to run good with no rattles or smoking. Perhaps wrong engine oil?  I put dino 10/30 in it though the book calls for straight 30.  I was told to avoid synth in the old girl.

[Rick in WNY]

Make sure the engine oil you used is JASO spec motorcycle oil.

Automotive oils have "friction modifiers" in them which, while beneficial in a car or truck motor, are too "slippery" for a wet clutch. That would cause it to slip sure as anything.

BTW, the numbers on motor oil... yours specified 30 weight... which is fine if you could find it. Single grade oils are difficult to find because multi-grade oils are just flat out better. Short course on oil "weight" which is really a viscosity number. Higher number = thicker oil. A viscosity of 0 means it literally flows like water, because that is the baseline it's measured against.

Multi-grade oils give two weight numbers, the first, the one with a W (for Winter), is the cold viscosity. The second number is the warm viscosity. So running a 10w-30 oil will be fine as long as it's cleared for a wet clutch. It will flow like a thin 10 weight oil when cold, yet still flow with the correct 30 weight viscosity when warm. That's a very short and simple course on oil weight numbers. The point is, if that engine was designed to run 30 weight, 10w-30 will be just fine in it.

If in doubt, buy some oil that is branded as "motorcycle oil" It will be more expensive, but in a postie bike, you're not talking gallons of the stuff. And if you're really worried about it, go OEM.

https://www.amazon.com/Pro-Honda-4-Stroke-Motor-10W-30/dp/B0039LFALQ/ref=sr_1_3?ie=UTF8&qid=1548334853&sr=8-3&keywords=honda+motorcycle+oil+30

[Two Checks]

Automotive oils with the energy conserving "starburst" on the label have friction modifiers. Rule of thumb is 10-30 and thinner. Most-I repeat most 10-40 and thicker do not contain the added moly to try and make up for less zinc.

[fotoguzzi]

I changed out the rectifier on my '72 added new AGM batteries and she now starts first kick.



When I was a kid I burned up 3 clutches in the first summer trying to wheelie it, finally the shop told my dad no more warranty coverage and I was banned from riding it till I "grew up".

[lrutt]

My CT90 was used for farm work and was worked very hard. No clutch issues at all. The adjustment is key, try that first.

[Fontain25]

Does the clutch slip during operation or when kick starting? Your leg produces a lot more torque while kick starting than the engine does. "Almost" "normal" to slip clutch during kick starting although you can replace clutch springs with more robust ones to help eliminate it.

[Muzz]

Years ago I bought my wife a C90 with a ruined clutch, needed a new body.  Still slipped but fortunately it came with a genuine Honda shop manual which listed all the tolerances.  Measured the plates and found all bar one were well and truly within spec.  You could not really tell the worn one with the naked eye.  Replaced the one and problem solved.  Cheaper than replacing the whole lot!  (Guzzi content )

[lucian]

Thank's Muzz, I downloaded the shop manual and have all the clutch plates tolerances. Plan on tearing it down for inspection and measuring this weekend. I got the castle socket and may have to make a clutch holding tool if my chain wrench wont do it. Maybe try a rattle gun first. If the friction disks are within spec and drive plates are also I will deglaze them and try it again. If it still slips I will order some new springs, as I have no real way to gauge the spring rate.  I'll post up a pic or two tomorrow. Thanks for chiming in. 

[lucian]

Update, Shaved ape suspected.
First thing I find when removing the right case is the wrong gasket which is completely blocking the oil passage that runs through the oil screen  and  through a passage in the case and up through the center of the crank .   And next the lock washer for the clutch nut is not staked, so someone has definitely been here.








Friction disks  were within spec and had obviously been replace as the plates were worn well under spec. None of the springs measured up either so new parts are on order. I just hope there is no damage from oil starvation from the blocked gallery.






 The trouble you can find when you go looking!

[Muzz]

The little Hondas are built like a brick outhouse.  The main bearings in the 90 were at least as big as my Matchy 350. 

I would strongly recommend checking the oil pump drive.  The cam chain does not actually wrap around it but just skims across the top.  The early 90's had an hydraulic cam chain tensioner.  Slight hiccup and the chain would lose tension, which would then jump the oil pump drive which would then..... you get the picture.   The later ones went to spring loaded, a much better system.  However, the oil pump drive can still lose it's teeth very quickly.

The good thing is, because they are so robust it is amazing how little oil can still keep the bottom end functioning.

[normzone]

Years ago I bought my wife a C90 with a ruined clutch, needed a new body.

You think you can make it up to your wife for talking about her body like that with a used motorcycle? You're far bolder than I am ...   

[Muzz]

You think you can make it up to your wife for talking about her body like that with a used motorcycle? You're far bolder than I am ...