Sofa

[csrc]

Just got my 80G back on the road again after sitting for 5 years. Runs great now due to performing upgrades recommended on this forum. Everything works as it should save for tach erratic above 6 grand.. Tested voltages on white wire going into tach-7v dc, 9v ac, has good ground on black wire. tried a couple used tachs off ebay and same condition. Also bought OEM oil cooler used off ebay complete save for union bolt that secures adapter plate to block and bracket that cooler cover mounts to and can't find them anywhere. Could probably fab a bracket, Does anybody know if the SOFA is still available as that would solve my dilemma. I have messaged Topcat but no reply. Any advise welcome

[DEEBS11]

https://www.ebay.com/itm/125259668768?itmmeta=01HY45R1E5DKF6QRRY8AHP5W7K&hash=item1d2a0edd20:g:t60AAOSwPPViWCUo&itmprp=enc%3AAQAJAAAAwG%2BKGyHrTfHyHBesE5QNmdmamo4p1OwFTyn0J21tKGdAFO7bo89dlfi9DJXSJ6HVOOr7PiNT%2F5%2FcipN1zWFz1ilUe3FuowLMbtgZAl59GLzoRRoOvpNgZgcrvryrukpue7gjmA4W047FJVlGgDusFcn01jFx%2F7P%2Bkc48%2FY%2FqQ1Dt%2Fa5l8Ais3gBA%2Fkqnr24hiZBq8TLUGCDg6NNeWTA4FHdZLfRGcK%2BQ7kEefYgnZgfgsmocJv7Y4cT3zyxOlcORpg%3D%3D%7Ctkp%3ABk9SR5SX4IXxYw

[DEEBS11]

https://www.ebay.com/itm/261045385834?itmmeta=01HY460ZR790BD28DCZM1V3TZM&hash=item3cc7847a6a:g:faMAAOxygo9Q52wb&itmprp=enc%3AAQAJAAAA0EUb2GqoDtsUUxEmovuATT2iRY%2BaBfpgisMdDnsQoAj0j2aX7a0vwJU25ZbAzLEHHBPyuYJ9pjBTGMkMjMfpHw9xB5WVy0TiYIuZ7I6ryE%2FoEFSwhlzsNYignjCEYoKWNzzgeC%2FjOsYpAQo25v9HztddZOKEbWNAdanNhMUuETaovwyTD5NamtmdVPcQmVfnygGZuvhQyYbQZG4q9dsEuTmIQv9AD1noYBt%2FW9ixSK2xcZrttY%2Bs3sC40O9wA6vpiEt9npW4BH%2Fm1MKMfj3TVYY%3D%7Ctkp%3ABk9SR6L8g4bxYw

[DiverRay]

TC quit building the SOFA about ten years ago. You should be able to find adapters for oil coolers on Ebay, as DEEBS11 found. Remember, all the 750/850 and 1100's can use the same adapter.

[csrc]

Thanks DEEBS11 that solves my oil cooler issues. Now if only I could figure out the tach issue, think
I'll just try another used one

[csrc]

thanks Driver Ray

[DEEBS11]

Had to post this.

[DiverRay]

You know it's a Yamaha Sofa. One for a HD would have oil spots on it....

[Radioguylogs]

I have a similar problem with erratic tach in my SG. Mine is erratic on and off, but most erratic at 5k RPM.

I've tried 3 different tachs with the same result. I've fooled with the wiring behind the tach with no change.

Someday, I plan to rotate the 3 terminals in the stator-to-regulator connector. That will tell me if the stator is or is not the problem.

If it's not the stator, then there is a intermittent break in the wire harness, probabably at the steering head. I might just run a parallel wire if I can't find it easily.

[bikerphil]

I've tried 3 different tachs with the same result

Just a couple ideas...

If the wiring checks out, it could be a vibration from the engine causing this.

If you are running green Dyna coils without resistor plugs/caps, there may be some type of electrical interference. They do produce a lot of RF interference.

[csrc]

Of course I have dyna green coils without res caps but have resistor plugs as of 2 years ago, I can't remember if that's when my tach problems started. If possible I'd like to verify correct signal to tach before trying another used one. 3 white wires coming from stator. IIRC one to headlamp relay with latching diode, one to tach is supposed to be what value is the question, the third white wire IDK and don't really care right now since everything else good chg sys etc.

[DEEBS11]

[DEEBS11]

Just for reference, I run Dyna 3 ohm coils with non resistive caps and plugs. Tach is smooth.

[DEEBS11]

There is a ground strap in back of the transmission to the frame and one from the battery to the frame that should be looked at. Could be a floating ground.

[Radioguylogs]

Thanks for the ideas.

My bike is completely stock, so it shouldn't be related to the coil RFI.

I can look at the grounds, but doesn't it seem I would have other problems if those locations have weak grounds?