Hello. I have a '79 XS650SF. PO plugged the tach cable hole on engine and removed cable. Wondered if anyone has tried an XS750 or XS1100 electric tach on an XS650?. My XS650 has been upgraded to an electronic ignition I'm told, but not sure of the brand installed. Also, does the plug that the PO installed in engine tach cable hole need a hole in it for oil to flow or just a solid bolt. I'm new to the 650 world. Thanks.
-
Enjoy XS650.com? Consider making a donation to help support the site.
XS650.com receives a small share of sales from some links on this page, but direct donations have a much greater impact on keeping this site going.
Will an Electric Tach from XS750 or XS1100 work on a 1979 XS650SF?
- Thread starter tnbert
- Start date
angus67
Welder's penetrate deeper!!
Pic of how the po plugged the hole will help
Hi tnbert,
FYI the XS750/850 tach is mechanical, just like an XS650 tach, the only difference is the redline is at 9,000 Rpm instead of 7,500.
The XS11 tach is electrical, it counts the a/c pulses from the alternator. Dunno how to wire it to an XS650 though.
&BTW, the XS650 tach drive is an extension of the oil pump drive. Best you check exactly what the dreaded PO has done in there.
FYI the XS750/850 tach is mechanical, just like an XS650 tach, the only difference is the redline is at 9,000 Rpm instead of 7,500.
The XS11 tach is electrical, it counts the a/c pulses from the alternator. Dunno how to wire it to an XS650 though.
&BTW, the XS650 tach drive is an extension of the oil pump drive. Best you check exactly what the dreaded PO has done in there.
Also, the XS1100 had a 4 cylinder engine so depending on how it was wired, the instrument may read 2X the actual RPM.
Pete
Pete
Thanks for the responses. Yea, all I've ever had was XS11s since 1979. Just bought the 1979 650 last year and it's in the garage. No time yet to work on it, but it's very nice lookin! I didn't realize the 750/850 tach was mechanical too. Thought they were electric. I also considered the 4 cyl v. 2 cyl tach dilemma but thought some guru here had pulled it off! Anyway, thanks for the responses. I'll post if I learn more.
Yea Fred. You are right. Better check what the "dreaded" PO did with that plug. Believe me, he is more "dreaded" every time I talk to him. Did a real nice cosmetic job, but mechanical bothers me. Does oil flow through the bolt? In other words, does it need a hole drilled through the side? Thanks again.
Max. I have installed new tachs on dirt bikes and there was an option for # of cylinders. These are new bolt-on's I'm talking about, not XS1100 tachs. Now, I'm an idiot, but I know someone out there knows how to split a tach 4 into 2. Unfortunately, It's not me! However, it would be funny to show my friends that my XS650 redlined at 16000 rpm!
This bike could probably make the calendar nomination list at least, It's nice. New NOS tank and it shines everywhere. It rattles for 15 seconds when I start it, then gets quiet and no smoke. No rust, it's very nice Hope it's not the cam guide causing the noise. PO said he never adjusted anything. 11,000 miles showing.
Hi tnbert.
you are thinking about generic aftermarket tachs. They typically get their signal from a coil wrapped around a sparkplug wire and there's an instruction sheet to tell you how to hook it up to whatever bike it's going onto.
OTOH the XS11 tach gets triggered by a signal from the alternator. (You may have noticed that when your XS11 alternator quit the tach quit too because it also acts as a loss of charge warning device.)
So you won't get the 4 cyl vs 2 cyl thing or the '79 points vs the '80 lost spark thing.
What you'll need to find out is if the XS650 & XS11 alternators have the same number of coils.
And no, the stock XS650 tach drive is a solid shaft but you really should check to see what's been done in there.
Yea Fred, you are right about the aftermarket tachs. I've never had an XS11 alternator go bad, but that's good to know. Pretty sure the XS11's have 2 coil packs, but it's been a while since I've messed with the coils. I check in to that. Thanks again.
Well, that's a good point and I certainly don't think you're dumb - but it is something to watch out for.
Here's the thing: many 4 cylinder bikes (1970's SOHC Hondas for sure) had two coils (each with two plug wires) and some others had four coils (each sparking one plug). The two coil bikes produced a "waste" spark on the exhaust stroke of the "other" cylinder. It didn't cause any harm and it made the wiring and under-fuel tank area simpler. I'm afraid I don't know which setup was used on the XS1100.
Anyhow, the 650 has two coils (one plug for each) and so if your tach senses on the coils and the XS1100 also had two coils - then you should be fine, while if the 1100 had four coils, you'll get an incorrect RPM reading.
One way to check is to simply start the bike and once it's idling, stare at the tach. If it reads somewhere around 1000 RPM, then you're fine while if it reads around 2000 RPM - then "Houston, we've got a problem"
Pete
PS - an XS650 turning at 16,000 RPM would probably be airborne!!
Hi Pete,
only up to '79. The '80 & newer XS650s have one dual plug-wire coil and a wasted spark ignition.
But that's only important if you are fitting an aftermarket electric tach that counts the ignition pulses.
The XS11's electric tach counts the pulses from the bike's alternator NOT it's plug wire.
And I dunno whether it reads just one of the alternator coil's pulses or all of them.
But you are correct, if you overtake highway traffic at an indicated 2,000 rpm or if your revs peak at an indicated 15,000,
you ain't done it right.
only up to '79. The '80 & newer XS650s have one dual plug-wire coil and a wasted spark ignition.
But that's only important if you are fitting an aftermarket electric tach that counts the ignition pulses.
The XS11's electric tach counts the pulses from the bike's alternator NOT it's plug wire.
And I dunno whether it reads just one of the alternator coil's pulses or all of them.
But you are correct, if you overtake highway traffic at an indicated 2,000 rpm or if your revs peak at an indicated 15,000,
you ain't done it right.
Indeed Fred!
BTW - winter has arrived here: -3C today and a trace of snow. Everyone is sliding around like they're having a freak snowstorm in South Carolina ...
BTW - winter has arrived here: -3C today and a trace of snow. Everyone is sliding around like they're having a freak snowstorm in South Carolina ...
Hi Pete,
it must be winter denial syndrome.
Just because the roads got slick with ice every winter since you got off the boat don't mean it'll happen again this year, eh?
And I swear the born Canadians are worse than the immigrants! Wear a tuque, jackass, perhaps it'll keep your brain warm?
minus 3ºC, eh? If you get an inch of snow will the military come and clear it away for you again?
Apart from the since melted 4" of too wet to be moved with my snowblower slushfall of 3 weeks ago Saskatoon is snow free
but we are seeing minus 30ºC with the windchill temperatures tonight.
-30 = yike! The army thing was Toronto...
Its winter in Canada, so lets all enjoy it! Its -24C this morning, and will be warming up to -19C later today. I don't even think about wind chill factor, but I think its in the -30s C range. My solution....................avoid going out side at all costs.
Max....................I've spent some time in Windsor area, and its a great place to live. The banana belt of Canada
Max....................I've spent some time in Windsor area, and its a great place to live. The banana belt of Canada
Hi Pete,
alas that the prairies concept of Ontarians is that they all live in Toronto and that Torontonians think the world if flat, rotates about the CN tower and that the edge is just outside the 401.
Or like I saw a CBC interviewer a while back doing street interviews asking Calgarians (or perhaps it was Winnipeggers) if they thought that Canada had any Nuclear weapons.
"You mean, we don't?"
"No we don't. What would we do with one if we did?"
"Drop it on Toronto!"
Thanks for the input Pete and Fred. The XS11s have the two-coil pack/4 plug wire setup. I'm ok with most repairs, but electric is my weakness. The XS11 tach reading from alternator pulses as Fred discussed is way over my head. Not sure how I would wire the XS11 tach to a '79 XS650? Maybe I should just try to reinstall the stock mechanical tach on my XS650 and not worry about it. Are there any drawbacks to using the stock XS650 mechanic tach? My 650 is very close to stock anyway. If it's only performance related, then I don't care. I'm too old to race, and when I need a big rush, and can always hop on the XS11 for 5 minutes! Going down into the teens F tonight in Music City. That's cold enough for me. Thanks again.
