Primary Chain Question

[cbRider]

Hello,
I would like to get some insite into the primary chain tensioner operation.
I am a retired certified master technition but have never seen the inside of one of those twin cam CB 750 engines.
The Clymer manual is very vague on the suject. An explodet view would help.

Questions: Can the chain tensioner be serviced with the engine in the frame?
               Will the pan come down in the frame? It looks like it should.
               It seems to be hydroulic, will an additive in the oil help clean the tensioner?
               Can the tensioner be servised when the pan is off?
My problem is, as much as I can tell, a loose chain. A rapping noise when the engine RPM go obove 4 grand.
The bike is a 1981 CB 750 F Super Sport with 30,000 miles on it.

Thanks for any info on the subject
Karl


             

[Re-run]

I have not had the dohc bikes apart but the sohc750 allows you to remove the pan and so aside from needing a jack to raise the bike some to work easier, I would think you should be able to drop the pan.

[cbRider]

It is hard to belive that there isn't anyone on this forum that can help me out on this one.

Karl

[Re-run]

To be honest, people do not seem to stay around much. This is a very basic forum. No stickies, not faq section. no way to even section years off for the bikes or anything.

I am almost 100% sure you can drop the pan though.

[CB750Winger]

  Karl, I'm not familiar with the DOHC models either but if you go to hdlparts.com and go to the diagrams for your model and year, it will show what is inside and may help you. Sorry no more help than that right now.

[OTTODOCTOR]

Karl , try the DOHC site for info on these bikes -- WWW.CB750.COM -- Primary chain is spring over hydraulic type . -- The noise you have may not be the primary chain . -- Could be rubber cushions in the final drive . -- See you on the other site . -- Mark -- aka -- Otto

[Rick V]

 To answer your question the engine cases have to be split to service the primary chain tensioner, which means that the engine has to come out of the frame and be turned up side down and disassembled. These chains are usually very reliable which makes me think your problem may be somewhere else, most likely cam chain tension.
Good luck,
Rick

[cbRider]

Thanks Rick,
I'll take down the oil pan and go after the oil pickup screen, check to make sure it's clean and check on the pressure relieve valve.
I hope I will find a problem there.

Karl

[surfish95747]

Hey OP, sorry to reply to such an old thread. Do you remember what the solution was? Or what was the cause of that noise? What did you see when you dropped the oil pan? Thanks man!