New addition to the garage

[gggGary]

Hoos Racing for front guides. http://www.hoosracing.com/new650750engineparts.html
When he restocked a few years ago we did a group buy and there were no negative reports. Been all good news since as well

 

[MaxPete]

Superb - there ya go!

 

[jetmechmarty]

This is mine. Rubber gone from cam chain guide.

I have 1,000 miles or more on a Hoos guide. It's good!

 

[MaxPete]

Yup - that’s the sound alright.

 

[bosco659]

ThX Pete.

 

[bosco659]

Hoos Racing for front guides. http://www.hoosracing.com/new650750engineparts.html
When he restocked a few years ago we did a group buy and there were no negative reports. Been all good news since as well

Thx Gary. I’ll get one ordered today. If I’m lucky and it’s not needed, I don’t mind having it the parts bin.

 

[bosco659]

This is mine. Rubber gone from cam chain guide.

I have 1,000 miles or more on a Hoos guide. It's good!

Thx Marty. For the short moment I had it running it may have sounded like that. Plan today is to adjust cam chain tension; set valve clearance; check sump for guide plastic bits; fire it up and have a good listen. On my bike the noise is quite apparent, even when turning the motor over with the kick starter (fairly slowly). Well I bought it as a project so I got what I paid for lol.

My ‘76 is on the lift now for a bit if winter maintenance. I should probably get that done before tearing into the ‘79. I‘ll keep everyone posted.

 

[jetmechmarty]

check sump for guide plastic bits

The last engine I opened had nothing in the sump. The plastic had come free of the guide all in one piece, nice and neat. The adhesive had failed.

 

[5twins]

Check and adjust your cam chain as the engine sits there idling. If a loose cam chain is responsible for the noise, it will go away as you tighten the adjuster.

 

[MaxPete]

True - and if the guide has come adrift, I’d guess that the slapping noise would become more of a scraping whirrrr.

One thing though - even if the noice largely disappears, the valve and ignition timing would be way off if the timing chain guide has fallen apart.

 

[5twins]

To answer an earlier question - the head stud washers are 10mm and pretty thick, about 2mm at least.

 

[5twins]

And when you get around to changing the handlebars, if you plan on still using the original angled Special master cylinder, I recommend you get Euro bars. The way they droop down slightly on the ends, besides being very comfortable, allows that angled master cylinder to mount up quite nicely, sitting almost level .....

 

[bosco659]

So I messed around with the bike mist of the afternoon and here’s what I did and found:

1. Adjusted chain tensioner - didn’t seem to be too far off.
2. Checked valve clearances. Left exhaust .006”; Left intake .006”!; Right exhaust .008”; Right intake .005”. Adjusted to .006” & .0025”
3. Checked advance mechanism - ok
4. Removed sump plate - clean as a whistle (a bit of sediment on plate but no “bits”).
5. Checked side case oil strainer - clean (note all oil was vey clean too.

Noise still there with kickstart (no electric start). Strapped on my stethoscope and with the probe on the front guide mount bolts, it sounded like the noise was coming from this area and not the valve train area. I thought this confirmed the failed guide but it bothered me that I couldn’t find any shrapnel. Tried listening again. I found the noise is coming from the chain tensioner side. With my stethoscope probe on the threaded part of the adjuster, it was clearly coming from that area. I noticed the little plunger that goes back and forth in the treaded part of the tensioner is in sync with the noise. At it moves to the furthest point outwards and returns back in, that’s when I get the metallic clicking.

Does this make any sense to anyone?

 

[bosco659]

Here’s the video.

Turning over kickstarter by hand. Whooshing noise is from open spark plug hole. Tensioner nut off. Tensioner not adjusted properly in this video. Increasing or decreasing tension doesn’t affect noise very much at all.

 

[Jim]

5twins is the tensioner guru here, so he'll likely be more accurate than me, but it looks like you've got some missing/mismatched parts in the tensioner. Correctly set up, that rod shouldn't be jumping out that far. It shouldn't move out much past flush.

 

[5twins]

Yes, I think you're simply missing the copper damper washer that should be on the plunger rod .....

As Jim said, the plunger shouldn't be popping out so far past the end of the adjuster screw. With the damper washer in place, it simply can't .....

So, pull the adjuster screw, plunger, and spring out of the housing and check to see if the damper washer is missing. I'll bet it is. You can remove these parts without anything falling into the engine.

The damper washer pads the head on the tensioner rod when it strikes the back of the adjuster screw so it doesn't "tick" (like yours is doing, lol).

 

[bosco659]

5twins is the tensioner guru here, so he'll likely be more accurate than me, but it looks like you've got some missing/mismatched parts in the tensioner. Correctly set up, that rod shouldn't be jumping out that far. It shouldn't move out much past flush.

Jim the tensioner isn't adjusted for this video. I had it adjusted do it was flush with the end of the threaded piece. Still the same noise. I’m hoping 5T will be able to suggest something.

Picture of tensioner. Missing washer? Would that make a difference?

 

[gggGary]

can we see it with the movement down to the 1mm spec?

Photo ctsy 5twins

 

[5twins]

Yes, the damper washer is missing. Easy "fix" and should cure the noise.

 

[bosco659]

Yes, the damper washer is missing. Easy "fix" and should cure the noise.

Copper or rubber 5T? Just make one up or can I buy something? Not really understanding the movement of that rod. Can someone enlighten me? Thx!