Tach cable help

[scaf77]

Hey guys I'm finishing up my 81 cafe build and ran into an issue.
the tach didnt work when I bought the bike, when I put the new gauges on it still didn't work. I took out the bolt that goes into the engine case and now it wont go back in all the way. Has anyone ran into this? Im thinking something isn't lining up right.
Also the cable came out without removing this bolt, was it not down far enough and thats why it didn't work?
Thanks in advance for any help

 

[fredintoon]

Hi scaf and welcome,
the tach cable comes off the drive by undoing the serrated nut on the cable's end using a pair of pliers.
The drive itself don't need to be removed to remove the cable.
Note that the tach drive is turned by a worm & wheel that's part of the oil pump.
Check out the manual to see what that looks like inside and make doubly sure that the oil pump is still working.
You don't want to drive the bike with a dead oil pump, eh?

 

[scaf77]

Good point.
Ill have to pull the side cover and see whats going on in there.

 

[yellowdog]

Try tapping the tach drive in a bit more ,it has to seat all the way in or the hole for the bolt is too high and it won't line up properly.

 

[scaf77]

Thanks I'll try that. I tried turning it with a screwdriver but it didn't move

 

[scaf77]

Update
So I took the side cover off and the oil pump is working properly.
The problem seems to be that the hole in the shaft were the tach cable goes is rounded, so it spins but won't spin the tach cable. Im wondering if there is a solution other than replacing the shaft.
Also once I knew the oil was pumping I put it back together and went for my first ride. Eventually I'll get around to doing a build thread.

 

[scaf77]

After her first test ride.

 

[fredintoon]

After her first test ride.

Hi scaf,
looks good. Alas that this old fat man couldn't reach the bars when sat on it.
Um, those pleated pods.
Even if they do say XS on the ends, the bike will run better with UNIpods.
And the not-so-square hole in the tach drive?
Mr Bodger sez try squidging the hole full of JB weld and shoving the cable in.
It may stand up until the replacement part shows up.

 

[XSLeo]

I don't think your hole is rounded much, it might just be full of crud. Making it look round. If it is then replacement is about the only option. I guess if you were a machinist you could weld the end full and recut the square or maybe drill it out and plug it then cut a new square. Either way it would be cheaper and easier to replace.
Check the ends of the cable core, they are more likely to be damaged. Poor maintenance of the cable damages them the most.
Pull the inner out of the casing. Inspect for rust on the inner The inner is made of many strands twisted together, rust gets in side and expands the cable. Even with proper cleaning you won't get all the rust. Proper lubing may get it to work for awhile.
If the inner cable is rusty the housing won't be any better.
Leo

 

[fredintoon]

Hi Leo,
if scaf's square hole is plugged rather than worn the cable wouldn't fit inside it and scaf implied that it does?
Whatever, crap can be cleaned out with patience, solvent and a small hooky thing but as you say, it's far more hassle to fix a rounded out square hole than it is to buy a new part.
And yeah, scaf should strip and inspect his tach cable too.
And should also check that his tach head spins free.
The test is to shove a Robertson screwdriver up it and twirl the screwdiver shaft, not the handle, to feel very little resistance.
Cost me another new drive cable to find that a speedo head was seized one time.

 

[scaf77]

Thanks for the replies
I haven't taken the cable apart but it spins freely by hand and goes into the shaft and can spin.
Its a new tach Maybe the old one was bad and thats what wiped out the shaft?
I found out about the uni pods after buying the mikes ones but it runs pretty good.
I went 2 up on the mains and 1 on the pilots.