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Discussion Starter · #1 ·
hello, and thanks for letting me in.

just picked up a project 1981 cm400a a few days ago and have been getting acquainted with it. it runs on starting fluid so now it's time to move on to carb cleaning, etc., etc., etc.

located a service manual online and it says to use 10w40 oil for the engine. nowhere do i see mention of a separate oil change for the tranny, so ... am i correct in thinking that an engine oil change/tranny oil change are one and the same ?
 

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Yes, the oil is 'shared' and is pumped through transmission after it's lubricated all the power parts.
Don't use 'Car oil'
 

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Discussion Starter · #3 ·
got it, thanks !
while we are on the subject, i wonder how durable these automatics are. i searched the web specifically looking for people having trouble with these transmissions and problems seem to be non-existent. are they as bomb-proof as all that ?
 

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Yes they are, motor is very robust and difficult to damage with the auto trans.
The 6 speed can break but usually due to bad gearshift or deliberate downshifting at 'high' speed.
The manual trans models always needed clutch cover removed at 500 miles to re-adjust the balance chaintensioner quadrant, yours may be overdue for removal and re-setting?
Biggest issues I remember with them is oil leak from cam cover as the rubbers on hold down bolts are not changed frequently enough, few had base gasket leaks and maybe the special 'figure 8' 0-ring on cooler getting hard and leaking.
It was a good bike but Honda didn't get the market they expected and not a lot were actually sold. Motorcyclists wanted a foot change not an auto.
Honda were trying to entice car drivers who had never driven 'stick', it didn't work.
Oh, just remembered something, as they are all now pretty old, the valve guide seals may be very hard and start leaking, bike will smoke pretty bad if it happens.
If it's exhaust valve seals, the oil burns in the exhaust but plugs stay clean.
Just keep an eye on oil level and wait until you can't live with it any longer before fixing.
If intake seals go, plugs will get black very quickly and valve guide seals need to be changed
Head comes off pretty easy without needing to remove engine from frame, it's why 'top tube' has holes in, allows for long extension with 14mm socket.
 

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Discussion Starter · #5 ·
ok, thats a lot of good info. i have one question ... you said "The manual trans models always needed clutch cover removed at 500 miles to re-adjust the balance chaintensioner quadrant, yours may be overdue for removal and re-setting? " mine is an automatic ... does this still apply to my bike ?

thanks
joe
 

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To adjust the balance chain on the A model you have to drain the oil , remove both right side covers and pull the torque converter. If its not noisy I would leave it alone. When changing the oil also change the filter standard I know but very important on the A models . The torque converter needs all the pressure it can get. The oil filter is on the bottom of the motor .there are springs and seals in there so make sure you put it back the same as it came out. The filters are common and can be found on line. Use 10-40 standard motor cycle oil with wet clutch protection.

Bill H
 

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Discussion Starter · #7 ·
thanks, bill. i won't know if it's noisy until i get it running, so i'll just leave it. i didn't notice any unpleasant sounds during the few seconds that it was running on starting fluid. an extra oil change won't kill me if it does need doing.
 

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Just finished repairing a transmission problem in an automatic. The bike is a 1981 CM450A with about 17,000 miles. It would make a LOUD gear clash noise in low range and not move. Worked fine in high range.
The problem was caused because the shaft with the drive gears and drive dogs was moving axially and allowing the low range drive dogs to slip past each other. The plate that retains the shift drum shaft bearing was bent/bowed out and cracked. As a result, the shaft was able to slide axially about 3/16". In addition to the bent retaining plate, I found the roller that follows the track in the shift drum was cracked and out of round. My theory on how this happened: Someone must have tried "power shifting" from low range to high range and jammed things with enough force to cause the shift drum to slide and bend out the retainer plate.
The mechanism is fairly robust and the materials are good quality so it must have taken a real bozo move to do this damage. Hope this helps.
Dennis
 

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Discussion Starter · #9 ·
i dont have an owners manual and have never ridden one of these. i assume that it's ok to shift from low to high when riding as long as you back off the throttle a bit ?
 

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You shift the A model same as a standard. You can put it in 2nd sitting still and ride all day and never shift gears. A little slow from a traffic light but wont hurt anything. They are tuff as long as you dont abuse them.

Bill H
 
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