Honda-SOHC
SOHC.co.uk Forums => CB500/550 => Topic started by: CB-500 on July 16, 2023, 02:29:19 PM
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Hi everyone
I have a 1971 CB500K0(USA) of which I have totally rebuilt including the engine - The bike itself is currently back to a mid state of rebuild - The engine is fully rebuilt and fitted in the frame however not in a runnable state as no electrics are installed - No clutch lever or cable fitted
The issue I'm faced with is the kick start and clutch actuations - So I thought it was time to reach out to you knowledgeable and experienced folk.
I'll start with the kick start problem - I'm unable to turn the engine over using the kick start - the kick start lever is solid but only once the clutch is fully installed- On one occasion I managed to turn the engine over via the kick start but I had to really jump on it - Remove the clutch pressure plate and all clutch plates the kick start can then be operated.
Breaking the kick start operation down everything appears to be working as it should - Operate the kick start lever the pinion gear engages turns the countershaft gear which then turns the main shaft and in turn the clutch centre hub spins - Release the kick start lever which returns to rest under spring force.
Turn the engine via the crankshaft which turns the primary shaft drive gear which in turn spins the clutch outer housing.
Reinstall the clutch plates and pressure plate - the kick start lever is again solid
With the clutch fully installed the engine still turns and the complete clutch assembly spins via the primary shaft drive gear.
Also when the clutch is fully installed the clutch actuating rod is solid - I'm unable to get the pressure plate to even slightly move.
The clutch has been assembled as per the parts fiche and the parts are within their wear limits - however all parts are originals including old friction discs and plates - The engine is after number 1021198 so part items 4 & 8 are not installed
Friction discs each measure from 3.26mm-3.3mm
Plates each measure from 1.14mm-1.2mm and don't appear to be warped
Clutch springs each measure 32.2mm
The engine has no oil in it apart from what was used for assembly but the clutch was assembled wet using new engine oil - However the clutch assembly was stored in plastic bag for quite some time whilst the engine was being stripped and rebuilt
I'm thinking it is probably a good idea to replace the clutch plates which could be the answer for the clutch actuation problem but surely even if the clutch was locked up you should still be able to turn the engine over via the kick start.
Any help greatly appreciated
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I would look at the gearbox, the symptoms look to be a misalignment between the 2 shafts. Fitting the clutch means these 2 shafts now have to move together and that appears to be a problem.
Are you able to engage all gears?
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Yes all gears can be engaged - however engaging gears is best when the shafts are spun
Is that normally the case?
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I'm not at your stage yet if the kick start turns the shaft with no clutch fitted & the gears shift that sounds good. If you fit the clutch basket without the rod etc assuming you are in neutral does it work then?
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Yes all gears can be engaged - however engaging gears is best when the shafts are spun
Is that normally the case?
Yes that's normal
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With the clutch plates and pressure plate fitted without springs and screws the kick start turns the clutch centre hub - the plates are heard to slip as there is no pressure upon them to turn as one unit - once the clutch springs and screws are fitted the kick start is solid.
There is no drive chain fitted to rear wheel so out of interest I have attempted to work the kick start in each gear- kick start solid
Also with the clutch fully fitted and the kick start in a locked state I have manually turned the engine over - if you put pressure on the kick start lever whilst turning the engine the lever moves downward - I’m assuming this is another indication that everything is engaged
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It comes to me that you do not have the thrust washer and thecollar the basket spins on assembled correctly, check against pictures in parts book and HONDA manual(available in Ashs dropbox).
Also how are yoy trying to move the clutch pushrod, you wont do it by hand
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It comes to me that you do not have the thrust washer and thecollar the basket spins on assembled correctly, check against pictures in parts book and HONDA manual(available in Ashs dropbox).
Also how are yoy trying to move the clutch pushrod, you wont do it by hand
Thanks that clears up the clutch pushrod not moving - been trying to push by hand as have no lever or cable connected
I’ve been using the parts book downloaded from manuals.sohc4.net
I have the clutch assembled as follows - clutch outer housing (part #1) on mainshaft followed by clutch centre hub (part #2) followed by spacer (part#12) followed by circlip (part #16) clutch lifter (part #9) then inserted into the end of the mainshaft and pressure plate fitted on top
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You can not push a the clutch by hand. Just because the plates measure within spec, it does not mean they will work. Old clutch plates go hard over time ;)
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The washer under the circlip is a "selective" fit and there should be some in and out movement on the outer basket.
Cant for the life of me remember whether the 500 is primary or secondary kick
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You can not push a the clutch by hand. Just because the plates measure within spec, it does not mean they will work. Old clutch plates go hard over time ;)
Looks like replacing the plates is something that will have to be done - would you recommend just friction plates or all plates including metal discs?
Would hard friction plates cause the kick start to lock?
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I'm confused here if the clutch is assembled and the bike is in neutral how does that affect the kick start becoming solid ?
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You can not push a the clutch by hand. Just because the plates measure within spec, it does not mean they will work. Old clutch plates go hard over time ;)
Looks like replacing the plates is something that will have to be done - would you recommend just friction plates or all plates including metal discs?
Would hard friction plates cause the kick start to lock?
The kick start would lock if not assembled correctly or the circlip has come off the end. Look in the sump for any parts that have come off. Always replace the end circlip on the kick shaft with a new one.
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Are the spark plugs fitted - might be worth seeing if removing them changes anything?
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You can not push a the clutch by hand. Just because the plates measure within spec, it does not mean they will work. Old clutch plates go hard over time ;)
Looks like replacing the plates is something that will have to be done - would you recommend just friction plates or all plates including metal discs?
Would hard friction plates cause the kick start to lock?
The kick start would lock if not assembled correctly or the circlip has come off the end. Look in the sump for any parts that have come off. Always replace the end circlip on the kick shaft with a new one.
Agreed it would lock if not assembled correctly - However the kick start mechanism engages turns the gearbox which spins the centre clutch hub without issue and at the other end the engine turns the outer clutch housing
Once the clutch plates and pressure plate are bolted on then the kick start can’t turn the engine over - You can feel the kick start engage it’s as if there is something further down the line which the kick start is struggling to overcome
The kick start worked before the engine was stripped so obviously something has gone a miss somewhere - But struggling to work out what - As far as I’m aware all gone back together correctly at least that’s how it appears until the clutch is fully assembled
Later on with clutch plates and pressure plate removed I’ll try and wrench just the clutch outer housing round to see if I’m able to turn the engine over in the way the kick start would
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So with the clutch pressure plate, friction plates/discs and clutch centre hub removed this leaves just the clutch outer housing on the main shaft
Turn the engine over via the crank - this turns the primary drive gear clockwise which turns the clutch outer housing anti-clockwise
Being careful with two long screwdrivers I’m unable to turn just the outer clutch housing on its own the same way (anti-clockwise) in an effort to turn the engine over like the kick start would
Am I missing something?
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I'm mystified, be interesting to read the fix when it pops up.
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I'm mystified, be interesting to read the fix when it pops up.
Hahahaha me too!
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So when you rotate the crank the primary drive chain is rotating the primary drive shaft as it should.
However rotating the primary drive shaft results in such a load that the crank will not turn either via the kick start when the clutch is in place or by hand using screwdriver levers when the clutch is removed.
Could this be connected in any way with the starter clutch hub as I can't see what else could be causing the issue?
You should have a glimpse of this mechanism when the sump is removed.
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I was thinking down the same lines at first - but the idler gear for the starter motor in the top crankcase locks in the correct rotation and free wheels in other - So it appears the starter clutch hub is working as should
Never the less trying to turn the outer clutch housing anti-clockwise isn’t asking the drivetrain to do anything different then what it is already doing when I turn it at the crank
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In the pic it looks like the bearing behind the primary gear is not fully in, is it and the retaining plate tight?
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I know what you mean about the photo
Have double checked - The bearing is fully in and retaining plate is tight against the crankcase
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Just to satisfy my curiosity can you count the number of teeth on both the primary drive sprocket and the back of the clutch, just to check they are compatible. The 500 and the 550 both use different number of teeth and I'm wondering if there is a mix and match going on.
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That sounds a promising idea from Ken.
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Just to satisfy my curiosity can you count the number of teeth on both the primary drive sprocket and the back of the clutch, just to check they are compatible. The 500 and the 550 both use different number of teeth and I'm wondering if there is a mix and match going on.
I’ll try and count the number of teeth laters
The kick start worked before the engine was stripped so obviously something has gone a miss somewhere - But struggling to work out what
With the outer clutch housing fitted on the main shaft as per the previous photo - The transmission can be discounted as the outer clutch housing freely spins on the shaft (the inner clutch hub fits onto the main shaft splines to turn the transmission) - So trying to turn the outer clutch housing should just spin the primary gear drive and crank
This operation works when turning the crank and results in the outer clutch housing spinning anti-clockwise - but I can’t turn just the clutch housing the same direction (anticlockwise) to turn the primary gear and crank
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With the pitch of the gears being different it would most likely jam solid when trying to rotate them.
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Ok I’ll get the teeth counted and update
The clutch and drive gears are all the originals from when the kick start did work
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If its the same pair of gears you have re-fitted then wtf.
I assume you have the plugs out - that there is plenty of oil down the bores so no danger of the con rods not being able to work due to dry piston side wall friction with the forces being reversed?
Just my twaddle mode.
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Plugs out to ease compression
Bores oiled - Engine turns over nice
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So with the clutch pressure plate, friction plates/discs and clutch centre hub removed this leaves just the clutch outer housing on the main shaft
Turn the engine over via the crank - this turns the primary drive gear clockwise which turns the clutch outer housing anti-clockwise
Being careful with two long screwdrivers I’m unable to turn just the outer clutch housing on its own the same way (anti-clockwise) in an effort to turn the engine over like the kick start would
Am I missing something?
Although the clutch outer is a big diameter it will be difficult to turn the engine over using it because of the gearing.
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I see what your saying - When turning the engine over at the crank you also have the aid of the crank throwing weight
But with the issue I’ve found do you reckon I’m looking down the rights lines?
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I'm a few months away from your level of assembly so am not able to offer a comparison.
Sorry to ask but is there any possibility you have the con rods the wrong way round ?
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Ted, that is an interesting point you raise.....
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Shouldnt make any difference to the engine rotating, if it rotates by hand it should rotate with kickstart
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So with the clutch pressure plate, friction plates/discs and clutch centre hub removed this leaves just the clutch outer housing on the main shaft
Turn the engine over via the crank - this turns the primary drive gear clockwise which turns the clutch outer housing anti-clockwise
Being careful with two long screwdrivers I’m unable to turn just the outer clutch housing on its own the same way (anti-clockwise) in an effort to turn the engine over like the kick start would
Am I missing something?
Although the clutch outer is a big diameter it will be difficult to turn the engine over using it because of the gearing.
Looking at the clutch basket when trying to rotate the engine by hand you are trying to turn a large gear - think cycle front chainwheel to turn a much smaller gear in my head that should work.
If I grip that small bottom gear I can move my crank pretty easily.
Not got my block in place yet so can't try my basket.
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After quite a few google searches by accident I came across a few posts on the sister forum where people have experienced the exact same problem with their 500 kick start - they also had the problem after a rebuild or if the engine had been sat on the bench partially stripped/built for a extended time
One post explained that they also were convinced everything was assembled correctly and decided to forget about the kickstart and just continue with the project - They found once their project was up and running they randomly decided to re-look at the kick start issue - However the kick start was working with no explanation
I looked at my engine again - concluded that everything was assembled correctly - So with the clutch fully fitted started lightly jolting the kick start - after quite a while I noticed the primary gear drive started jolting along with the clutch - at the same time as jolting the kick start I started manually turning the engine over - after quite a few turns everything appeared to free up and the kick start is now working as it should
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That’s good news. Sounds like the whole system has to rotate a few times to self align. Hard not to worry about these things when you’re not rebuilding engines every week!
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That is weird.
I did wonder if lack of oil everywhere might be part of the issue hence why I kept on thinking friction in the bores was causing it.
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If you go back to the kick start a while later it is again stuck - However it appears to free off easier each time
A mate of a mate who builds race/competition engines mentioned that the engine assembly lube I have used is fine for my normal engine build but can be known for causing slight drag on components during the build process - All should be good once up and running with normal engine oil circulating
Thanks everyone for your help on trying to resolve
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Out of interest before I fitted my pistons I could rock the crank by hand using the bottom gear on the primary drive - now with the pistons in place - no chance. I put that down to the friction from the new pistons.