Tachometer Acting Up

akpasta · Post by **akpasta** » Wed Mar 07, 2012 11:24 am

I've got a restored superhawk that has a 'rebuilt' early-style speedometer/tac unit. Don't really know what rebuilt means exactly, but I know that the seller sent it off to a guy for repair and had the mileage reset. It's got about 850 miles on it since the rebuild.

Earlier this week I noticed that when I'm riding and the rpms go above 5k, the unit will start buzzing and the needle will shoot up to 8k or 10k, then when I return to idle it will still buzz and the needle hovers around 4k.

Oddly enough, if I smack it on the top left of the unit, the buzzing stops and the needle drops back down to my idle speed of 1.5k.

I'm gonna pull the unit out and have a look, but wanted to ask some advice before I do. Is anyone familiar with this problem? Is there anything in particular I should watch out for when pulling the unit out?

One thing I'd like to mention is I don't think the inside is totally sealed off from the elements. The lens on top of the unit regularly acquires condensation on its underside, and this tach problem started to present itself on my way home from work on a day after having been parked in the rain for a couple hours. Perhaps moisture has affected something? Perhaps it needs lubrication somewhere?

Any advice would be appreciated. Thanks!

davomoto · Post by **davomoto** » Wed Mar 07, 2012 2:41 pm

Andy,

remove and lube the inner tach cable, and perhaps a couple small drops of light oil where the cable attaches to the tach head.

Davo

akpasta · Post by **akpasta** » Wed Mar 07, 2012 3:50 pm

davomoto wrote:Andy,

remove and lube the inner tach cable, and perhaps a couple small drops of light oil where the cable attaches to the tach head.

Davo

thanks for the tip Davo, I'll give that a shot.

teazer · Post by **teazer** » Wed Mar 07, 2012 11:12 pm

Sounds like condensation in the aluminum "bell" that the magnet drags around.

Or someone oiled the cable. That's a good way to kill an instrument if you get oil up there. That's why the previous poster said "a Little".

akpasta · Post by **akpasta** » Sat Mar 10, 2012 9:21 pm

Well I oiled the cable more. It wasn't dry when i pulled the housing off, but i put more on anyway. Before I read your post I actually lubed the entire thing. I used the kind of grease you use on your chain, so it's pretty heavy. However, I didn't run it for more than a second with the grease going into the tach itself so I (hope) there's no damage done. I cleaned it off today and ran it.

It made a slight improvement for a minute, but then it was back to normal.

It makes a crazy vibrating sound in the headlight when it gets stuck at high rpms, and then again, you can kinda swat it in a certain spot and it'll drop back down to idle rpm.

If i sorta unscrew the housing so it isn't on as tight, it goes away, but that's no real fix.

Looks like i'm gonna have to pull it apart and inspect? What do i do now?

LOUD MOUSE · Post by **LOUD MOUSE** » Sat Mar 10, 2012 10:50 pm

Remove the cable and wipe it clean.
Add White Grease to the cable as ya push it into the casing. ...............lm

akpasta wrote:Well I oiled the cable more. It wasn't dry when i pulled the housing off, but i put more on anyway. Before I read your post I actually lubed the entire thing. I used the kind of grease you use on your chain, so it's pretty heavy. However, I didn't run it for more than a second with the grease going into the tach itself so I (hope) there's no damage done. I cleaned it off today and ran it.

It made a slight improvement for a minute, but then it was back to normal.

It makes a crazy vibrating sound in the headlight when it gets stuck at high rpms, and then again, you can kinda swat it in a certain spot and it'll drop back down to idle rpm.

If i sorta unscrew the housing so it isn't on as tight, it goes away, but that's no real fix.

Looks like i'm gonna have to pull it apart and inspect? What do i do now?

akpasta · Post by **akpasta** » Mon Mar 12, 2012 12:37 pm

Well I got some white lithium grease and some light machine oil and pulled the cable-housing off again, cleaned all the oil off, and used the white grease beneath the housing. Then I dabbed two drops of machine oil on the tip of the cable and put it back together. Still bad. Seems worse in fact. Every time I put it in gear and go, it hits 3k and tears up to 8-10k, making an ugly whirring noise. It only goes back down (and only sometimes) when I click it into neutral.

What now?? Do i have to take the speedo unit apart and investigate? I keep reading about people 'sending them off' for repair; is this something worth attempting on one's own? What would cause a rebuilt unit to be damaged so soon? Could the problem be on the engine side?