R60/6 Ignition conundrum...

Post your post 1970 technical queries here

Moderator: Moderators

User avatar
Rob Frankhamr
Club Member 14
Posts: 4121
Joined: Mon Jul 25, 2005 6:33 pm
Country of Residence: Scotland
Location: Kinloch Rannoch, Perthshire

R60/6 Ignition conundrum...

Postby Rob Frankhamr » Sun Mar 15, 2020 11:05 am

Still 'playing' with the R60/6 (1976) ...

The bike is fitted with a Piranha/Newtronic electronic ignition system but that isn't really relevant to this.

On checking the ignition timing and advance mechanism, I have discovered that the rear part, the bit with the cam that rotates on the nose of the camshaft, can move well over 5mm axially (yes that's 5mm not 0.5 mm). At first, I thought there must be a bush or spacer missing that would prevent the movement but, looking at exploded diagrams, I can't see anything that would do the job.

The Newtronic system uses the OEM advance mechanism with a plastic shield press fitted onto the cam so that has absoultely no effect on this issue, the only relevance is that, if the advance moves back or forwards, the shield can contact the trigger head and there is evidence that this has been happening.

My instinct is to make and fit a bush behind the advance cam to prvent excessive movement and, therefore, contact between the two parts, but it would be nice to know whether this movement is normal for this type of ignition set up.

If anyone happens to be working on an early type ignition setup, I'd very grateful if they could check and see if this axial movement is normal and, if not, what prevents it. Don't need accurate measurements but if there are any 'extra' parts, I'd appreciate a photo...

Rob
Robin Frankham
ImageImageImage

Frankhams retirement home for elderly Boxers.

Mjolinor
Forum User
Posts: 2416
Joined: Tue Jun 12, 2018 9:38 pm
Country of Residence: United Kingdom
Location: Burnley

Re: R60/6 Ignition conundrum...

Postby Mjolinor » Sun Mar 15, 2020 11:21 am

I think 5 is excessive. I looked at this on mine and I seem to remember it is about 3 mm.

At full advance it doesn't move as much because the springs are more stretched. I don't think that my cam piece could move 5 mm, the pins that the springs hook over are not 5 mm from groove to plate and you have to subtract half the spring diameter from that figure to get the maximum lateral movement distance. I can't check it at the moment as the whole mechanical bit is in Preston on another engine.

All it needs is a couple of plastic washers on each of the pins I think.

User avatar
stevehiles
Club Member 14
Posts: 25
Joined: Sat Feb 21, 2015 6:41 pm
Country of Residence: UK
Location: East Yorks

Re: R60/6 Ignition conundrum...

Postby stevehiles » Mon Mar 16, 2020 10:42 pm

I have the same set up, 76 R60/6 with Piranha ignition. No idea how much axial movement mine has so I'll have a look tomorrow and report back.
R60/6, F800ST, Triumph Trophy 900, Yamaha XS500, 650 Bandit

User avatar
Rob Frankhamr
Club Member 14
Posts: 4121
Joined: Mon Jul 25, 2005 6:33 pm
Country of Residence: Scotland
Location: Kinloch Rannoch, Perthshire

Re: R60/6 Ignition conundrum...

Postby Rob Frankhamr » Mon Mar 16, 2020 11:14 pm

I have the same set up, 76 R60/6 with Piranha ignition. No idea how much axial movement mine has so I'll have a look tomorrow and report back.
Thanks Steve.
Robin Frankham
ImageImageImage

Frankhams retirement home for elderly Boxers.

User avatar
stevehiles
Club Member 14
Posts: 25
Joined: Sat Feb 21, 2015 6:41 pm
Country of Residence: UK
Location: East Yorks

Re: R60/6 Ignition conundrum...

Postby stevehiles » Tue Mar 17, 2020 6:28 pm

IMG_2547 (4).JPG
On removing the front cover the 'as found' condition is that the front face of the plastic shield (timing disc) is almost touching the trigger head, there is just a few thou clearance yet there is no evidence that the disc has been rubbing on the trigger head.

From the 'as found' position the disc can be pushed aft by 1mm, it looks more but I've measured it with feelers and it is only 1mm.

From the 'as found' position the disc can be pulled forward very slightly until the few thou clearance is taken up and the disc appears to contact the trigger head. I cannot be certain that it actually touches the trigger head as it could be something within the A/R mechanism that limits forward movement.

The natural at rest or 'as found' position is when the A/R springs are at their shortest i.e. not being stretched fore or aft by the axial movement of the disc.

Hope this helps.
You do not have the required permissions to view the files attached to this post.
R60/6, F800ST, Triumph Trophy 900, Yamaha XS500, 650 Bandit

User avatar
Rob Frankhamr
Club Member 14
Posts: 4121
Joined: Mon Jul 25, 2005 6:33 pm
Country of Residence: Scotland
Location: Kinloch Rannoch, Perthshire

Re: R60/6 Ignition conundrum...

Postby Rob Frankhamr » Tue Mar 17, 2020 8:35 pm

Thanks Steve,

When I actually cam to examine the bits apart, I found that the axial play was more like 3.6mm. there is a very slight step in the camshaft nose that stops the cam piece from moving right back but the springs still come into contact with the plate when it's as far back as it can go and the shield was coming into contact with the sensor when it was right forward (as witnessed by a worn ring in the shield). It doesn't seem to have affected the function of either but I wasn't comfortable with it and I've made up a bush to fit behind the cam piece so that there is now a lot less axial play (around 0.5mm). I also pushed the plastic shield back on the cam so that it is about midway in the gap. No matter whether it actually makes any difference, I'm happier with it and I can't for the life of me see any way it could be detrimental.

I'll see how it goes...

Thanks again for looking...

Rob
Robin Frankham
ImageImageImage

Frankhams retirement home for elderly Boxers.


Return to “Airhead Q&A's”

Who is online

Users browsing this forum: No registered users and 7 guests