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smiths tacho
Posted: Sat Nov 05, 2011 5:22 pm
by Wags
Hi
Can anyone answer whether a smiths tacho from a British bike will work on my 860? what ratio 4.1?
Re: smiths tacho
Posted: Sun Sep 21, 2014 8:51 am
by Mayor08
Wags- the ratio is for an 18" front wheel is 20/10 (speedo drive) and the Smiths speedometer should have the number 1600 on the face. I believe the 1600 refers to revolutions per mile but cannot comment on 4.1 as stated in your post.
This is what is on my 860GT here is a link to the ratio for other size front wheels
http://www.bevelheaven.com/speedOdrive.htm
Re: smiths tacho
Posted: Wed Oct 01, 2014 4:20 pm
by jockduck
The question was on a tacho not a speedo, yes tacho should work assuming the direction of rotation is the same, smiths and veglia tachos use a 2:1 gearbox in the cylinder head which is driven off the camshaft which is driven at 1/2 engine speed therefore 2X2 = 4 (4:1) drive to the tacho is 1/4 crankshaft speed.
Jockduck
Smiths Speedometer
Posted: Sun Jul 19, 2015 4:08 pm
by herbg
Further to the thread on the Smiths tachometer ...
My 1978 900SS (blue/silver, Borrani's) was originally purchased in Europe as a US/CDN model. I've just got the bike back on the road after 27 years of dis-assembly and restoration. Back in the 1980's, I noticed that speedo was never accurate ... seemed to be indicating Km/h even though the speedo was in MPH.
Back to 2015, I've now got brand-new, rebuilt SMITHS guages (not the same set) and I've notice that this problem still persists. So, if it's not the Speedo, or the cable, I'm concluding that I must have a defective speedometer drive installed.
Before I order a new speedo drive, is there some way to verify that the drive unit is ok? It should be a 20/10 drive so is there some way to check this.
After fixing or replacing just about everything on this bike, it's annoying that this problem still persists. I'm actually in the process of rigging up a discrete RAM mount so I can install a GARMIN Edge 25 bicycle GPS computer to verify speed and distance accuracy of the SMITHS gauge.
Looking for suggestions.
Cheers,
Herb...
Re: smiths tacho
Posted: Mon Jul 20, 2015 8:25 pm
by BevHevSteve
Sure - take the front wheel off, look at your speed-o-drive and verify 20/10 is stamped into the body and/or the correct part # for it (refer to list via link above).
I just took the front end off a 7300 mile 1980 900SS and it had a 23/11 speed-o drive. Those knuckleheads put whatever they had on the shelf back then....... Yes it's supposed to have a 20/10 same as your bike.