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Discussion Starter · #1 ·
I'm trying to get my 72 cb450 running again, I had it going 2 years ago and then it just sat. Never ran perfectly but would always turn over for me and had nice compression. Now when I try to kick it in neutral it will kick but the camshafts and alternator don't budge. In first gear with the clutch in when I kick it the bike lurches forward but the cams and flywheel still don't budge. putting a wrench on the alternator doesn't give me any kind of motion either, neither does putting it in 5th gear and rolling it...

Does this sound like the pistons are just seized or is there something in the clutch thats not working properly? Also theres no oil in it and am wondering if that's necessary for the clutch to funtion properly?

any suggestions or ideas would be greatly appreciated, i'm relatively inexperienced in engine diagnostics but was really hoping to get this puppy back on the road! thanks in advance!


josh
 

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Well, if you pull in the clutch and try to kickstart in neutral, you should feel no resistance at all.
If you kick it while in gear, it should indeed lurch forward.
The kickstart directly engages the tranny, but goes through the clutch to turn the crank.
So I guess the clutch is a good place to start........
 

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Discussion Starter · #3 ·
But it shouldn't lurch forward with the clutch pulled in and in first gear which it does, right? When I kick it in neutral i don't engage the clutch and I feel slight resistance yet the cams don't turn. Does that still sound like a clutch problem or something else?
 

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funk2eat said:
But it shouldn't lurch forward with the clutch pulled in and in first gear which it does, right? When I kick it in neutral i don't engage the clutch and I feel slight resistance yet the cams don't turn. Does that still sound like a clutch problem or something else?
If you are kicking it in neutral but the crank and cams are not turning then it sounds like the clutch could be engaged for some reason. Back out the clutch adjustment screw on the side cover and try it again. If the scenero I'm describing is true then if you put it in gear and try rolling the bike it should move (but probably with some resistance (before backing out the clutch adjustment scxrew).
 

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funk2eat said:
But it shouldn't lurch forward with the clutch pulled in and in first gear which it does, right? When I kick it in neutral i don't engage the clutch and I feel slight resistance yet the cams don't turn. Does that still sound like a clutch problem or something else?
Yes, that's my point - I don't think your clutch is working properly.
At least that's what I'd check first, it's cheap....
 

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Discussion Starter · #6 ·
what should i be looking for and how will i know if its the clutch thats the culprit? sorry this process is just new territory for me but i'm really eager to learn and excited about finally getting the time to tool around with this bike. would the lack of oil in the case and clutch cause it to malfunction? also a lot of the screws on the clutch side of the case are stripped and nearly impossible to get out even with an impact driver, is a screw extractor my best bet? and if so where can i get replacement bolts for these covers, are they a special threading or could i pick up similar replacements at a hardware store? sorry for all the questions but i really appreciate the time and advice people give!

josh
 

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Discussion Starter · #7 ·
also, if it's the clutch, shouldn't i at least be able to move the alternator a hair or wiggle it a bit? it's frozen completely solid and won't budge, as with the camshafts and chain.

just a thought, i could be completely wrong...trying to think through it as i fall asleep...
 

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It IS likely your pistons are "stuck".... This also prevents you from turning the crankshaft with the alternator bolt..... When you try to kickstart to rotate it over, the weakest link (the clutch) slips and allows the transmission to rotate, but does/can not transfer that motion to the "stuck" parts (crankshaft, pistons, cams, etc...) ...The effort you feel kicking it is the energy required to "slip" the clutch plates past each other against their springs..... You will eventually need to free the pistons, check rings, etc and check the clutch plates......... In the meantime, pull the sparkplugs and fill the cylinders with penetrant oil...... Hopefully, this will make the top end tear-down easier when the time comes......Allow to soak for a good while (days or weeks)....
It's rebuild time......
 

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funk2eat said:
also a lot of the screws on the clutch side of the case are stripped and nearly impossible to get out even with an impact driver, is a screw extractor my best bet? and if so where can i get replacement bolts for these covers, are they a special threading or could i pick up similar replacements at a hardware store? sorry for all the questions but i really appreciate the time and advice people give!

josh
I had this problem on some of the engine side cover screws on my CB450. I drilled the heads off the screws I couldn't remove from the cover. Then when I got the cover off enough of the screws was visible to screw out with pliers and they came off easy when there was no tension from the cover.
BUT, you have to be sure that you can get hold of new screws before you do that.
 

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"...would the lack of oil in the case and clutch cause it to malfunction..."

Josh,

For future reference, you really should not be trying to start that baby up without oil in the the sump! Or maybe I misinterpreted your post.

Mike V.
 

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Discussion Starter · #11 ·
thanks for the advice everyone. 66sprint that sounds about right, when i try to kick it in neutral theres a lot of resistance at first but then it just gives in and the kicker drops with ease. i've got the pistons soaking in PB blaster for the time being and will give it another try in a couple days, hoping thats enough to get her going!
 

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It might be enough to "free" it for disassembly, ...However, It is likely a tear-down (at least top end) will be required.........Plus, I think I'd check the clutch after all this.... ;)
 
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