collapse

www.cognitomoto.com

www.dimecitycycles.com

https://www.townmoto.com/collections/vanson-leathers


www.restocycle.com

www.CITYLIMITMOTO.com

www.jadusmotorcycleparts.com

www.bisonmotorsports.com

www.speedmotoco.com

www.lostapostlejewelry.com

www.sparckmoto.com

www.pistonsociety.com

www.steeltowngarage.com


Author Topic: 74 Cb360 Engine Noise  (Read 1255 times)

Offline tj10packers

  • Posts: 17
74 Cb360 Engine Noise
« on: Jan 24, 2017, 18:24:23 »
Was wondering if any 360 owners could help me identify what a healthy engine should sound like.


Background:
Bought this thing as a basket case and cleaned it up over the past few months. Trying to get it put back together so I can learn how to ride on it and get a feel for how much time and $$$ a cafe/brat project will take.  Haven't made really any big mods just yet but it's been fun learning how these bikes were built and I'm chompin at the bits to have it ready for this upcoming season.  Would eventually like to tear it down again and do a proper engine rebuild,  and give the bike a nice brat tracker touch. 

Here's how she sounds now.  Not sure if the cam chain needs to be loosened... the original cam chain tensioner set bolt was broken so I've got a large 8mm screw and some washers to manually adjust the tension.  The end of the video is me figuring out that the missing kickstarter return spring is causing the grinding noise.



-T.J.

Online irk miller

  • DTT SUPPORTER
  • *
  • DTT BOTM WINNER
  • *
  • Posts: 8226
  • You've been mostly-dead all day.
Re: 74 Cb360 Engine Noise
« Reply #1 on: Jan 24, 2017, 18:36:09 »
That cam chain is loose as hell.  This is not a bike to skimping on the tensioner mechanism. Have you run through the procedure in the FSM?

Offline tj10packers

  • Posts: 17
Re: 74 Cb360 Engine Noise
« Reply #2 on: Jan 24, 2017, 18:46:42 »
That cam chain is loose as hell.  This is not a bike to skimping on the tensioner mechanism. Have you run through the procedure in the FSM?
Yes I've attempted to do it but I believe the PO either broke the bolt or ruined the threads in the case.  When you go to tighten it down there's just a little resistance then it starts to spin freely. 



This bolt should have a smaller diameter portion at the very end right?  The part that sits in the groove of the tensioner push bar, at least that's how it looks in the parts illustration.

Sent from my SM-G900V using Tapatalk


Offline tj10packers

  • Posts: 17
Re: 74 Cb360 Engine Noise
« Reply #3 on: Jan 24, 2017, 18:51:42 »
What ive done instead is use a long 8mm screw in place of the oil check bolt-which I heard of a few people doing on the forums.   So now I can manually position the pushbar but I'm not sure how loud the valves and chain are normally.

Sent from my SM-G900V using Tapatalk


Online irk miller

  • DTT SUPPORTER
  • *
  • DTT BOTM WINNER
  • *
  • Posts: 8226
  • You've been mostly-dead all day.
Re: 74 Cb360 Engine Noise
« Reply #4 on: Jan 24, 2017, 19:15:39 »
That's definitely a loose cam chain.   You can tell by the noise changing pitch with revs. 

Offline tj10packers

  • Posts: 17
Re: 74 Cb360 Engine Noise
« Reply #5 on: Jan 24, 2017, 19:20:09 »
Thanks Irk.  I'll tighten it up a bit and post another video of it running after I find a kickstarter return spring. 

Sent from my SM-G900V using Tapatalk


Online advCo

  • DTT BOTM WINNER
  • *
  • Posts: 2738
  • Nick Ol' Eye
    • adventur Studios
Re: 74 Cb360 Engine Noise
« Reply #6 on: Jan 24, 2017, 19:39:36 »
You need to make sure you have the engine at the correct position, I believe the LT mark when the left cylinder is on the compression stroke, and then you loosen that locking bolt. The tensioner plunger is spring loaded and should automatically adjust. If that isn't doing it, then you either have a stretched cam chain, bad springs or a bad tensioner. Does this engine have the two punch marks on the engine no. plate?
"He broke the mirrors off his Cadillac, 'cause he doesn't like it looking like he looks back."

74 CB360 - Luna - http://www.dotheton.com/forum/index.php?topic=63294.0 - Sold
82 GS550L - Tracker-ish - http://www.dotheton.com/forum/index.php?topic=67229.0 - Sold
74 XL350 - The Turd - http://www.dotheton.com/forum/index.php?topic=70252.0 - Sold
Suzuki FA50 "No-Ped" - http://www.dotheton.com/forum/index.php?topic=71189.0
73 Suzuki RV125 -http://www.dotheton.com/forum/index.php?topic=73875.0
'97 BMW F650st - http://www.dotheton.com/forum/index.php?topic=75732.0

Offline tj10packers

  • Posts: 17
Re: 74 Cb360 Engine Noise
« Reply #7 on: Jan 24, 2017, 20:10:54 »
You need to make sure you have the engine at the correct position, I believe the LT mark when the left cylinder is on the compression stroke, and then you loosen that locking bolt. The tensioner plunger is spring loaded and should automatically adjust. If that isn't doing it, then you either have a stretched cam chain, bad springs or a bad tensioner. Does this engine have the two punch marks on the engine no. plate?
Yes the recall has been done,  it was stamped and had the new style tensioner holder.  I will go through that procedure again.  Even though I'm no longer using the set bolt which screwed in perpendicular to the push rod, but rather a screw that butts up against the end of the pushrod it serves the same function right?

I played with the tensioner mechanism when I had the top end apart to try and understand it better.  I applied some pressure on the bottom holder of the tensioner that is attached to the horse shoe. I could get it to move down in the engine and stay down,  and also measured to find the pushrod was moving towards the front of the case.   Then I would use a punch and lightly tap the pushrod into the case and watch the horse shoe push the tensioner up. At any position of the pushrod I could depress the lower tensioner holder about an inch or two and it would spring back into place without moving the push rod, which is normal right? 

With the pushrod pushed into the case, and the tensioner sitting in the engine on its holder, the top of the tensioner sat between half an inch and an inch above the mating surface, so I know that it was applying tension to the chain as I bolted the top holder in.

I just don't understand how you can loosen the set bolt with the engine in any configuration without the tension of the chain pushing the push rod to a point where you still have any tension left on the chain.


Thank you guys for your responses! Sorry for the short novel...

Sent from my SM-G900V using Tapatalk


Online irk miller

  • DTT SUPPORTER
  • *
  • DTT BOTM WINNER
  • *
  • Posts: 8226
  • You've been mostly-dead all day.
Re: 74 Cb360 Engine Noise
« Reply #8 on: Jan 24, 2017, 20:17:29 »
You need to make sure you have the engine at the correct position, I believe the LT mark when the left cylinder is on the compression stroke, and then you loosen that locking bolt. The tensioner plunger is spring loaded and should automatically adjust. If that isn't doing it, then you either have a stretched cam chain, bad springs or a bad tensioner. Does this engine have the two punch marks on the engine no. plate?
90 passed the LT mark

Online advCo

  • DTT BOTM WINNER
  • *
  • Posts: 2738
  • Nick Ol' Eye
    • adventur Studios
Re: 74 Cb360 Engine Noise
« Reply #9 on: Jan 24, 2017, 20:58:00 »
90 passed the LT mark

Yeah, that. The important thing when adjusting the cam chain is that all 4 of the valves are slack, which happens 90 degrees after LT. If you are saying you were able to easily push down the cam chain tensioner plunger then the springs might be out of spec, or only one of the two springs made it back in. It should take quite a lot of force to push it down.

"He broke the mirrors off his Cadillac, 'cause he doesn't like it looking like he looks back."

74 CB360 - Luna - http://www.dotheton.com/forum/index.php?topic=63294.0 - Sold
82 GS550L - Tracker-ish - http://www.dotheton.com/forum/index.php?topic=67229.0 - Sold
74 XL350 - The Turd - http://www.dotheton.com/forum/index.php?topic=70252.0 - Sold
Suzuki FA50 "No-Ped" - http://www.dotheton.com/forum/index.php?topic=71189.0
73 Suzuki RV125 -http://www.dotheton.com/forum/index.php?topic=73875.0
'97 BMW F650st - http://www.dotheton.com/forum/index.php?topic=75732.0

Offline tj10packers

  • Posts: 17
Re: 74 Cb360 Engine Noise
« Reply #10 on: Apr 03, 2017, 08:19:31 »
Still working out the cam chain tension issue. Got a new set bolt worked out but still getting some unwanted noise from the chain.

 Read thru some other posts to find that I'm missing the rubber damper that goes under the tensioner holder. P/n:14565-369-010

Does anyone know if there is supposed to be another damper at the bottom of the tensioner where it sits in the horse shoe?

Thanks, here's some pics of how she sits today.


Offline tj10packers

  • Posts: 17
Re: 74 Cb360 Engine Noise
« Reply #11 on: Apr 03, 2017, 09:32:39 »
Found the other damper on ebay, P/N: 141567-369-000 for anyone who's interested.  Got those two dampers and a cheapo endoscope ordered. Pretty certain that both those dampers were not installed, but I'll take a look down in there to ensure they're not floating around in the bottom of the case.

Seems like that's what kept the PO from messing with this bike.  The service bulletin was done but the dampers were missing and the original tensioner set bolt was screwed up so he must have said f$!# it.  I've been pretty close to throwing in the towel as well.

The cam chain tensioner and related components must be the wonkiest thing about these old twins..

Hopefully I can get it figured out before I go crazy. Thanks for all the help so far!


Sent from my SM-G900V using Tapatalk