1989 yamaha venture royal

My bike just started loosing power while ridding. Also the tach drops to 0 when this happens. It still runs but like on one or two cylinders and gradually will increase power but not till the tach starts to register correct rpm will it run correctly.What is the connection between tach and engine performance. Any thoughts out there.

I believe the tach runs off of the number 2 coil. That is where I would start.

Gunk and corrosion tend to accumulate where the HT leads plug into the coils. Also have a look at the spark plug caps. There is a writeup on that and testing pickup coils and ignition coils in the first gen tech section. I would also inspect all the grounds and electrical connections, faulty grounds can show all sorts of strange symptoms. Keep us posted.

I have had those exact symptons two times on my 1st Gens thru the years and both times I ended up having to swap out their TCI's to get em to run right. Others have made some GREAT suggestions here IMHO but it might not be a bad idea to at least clean the pin connector(s) on the TCI while in the process of fulfilling their admonitions. If doing all the above does not help though, do a search on "cooking" or "heating" the TCI (put the TCI in an oven and get it hot to dry it out) and also on opening it up (maybe "TCI Repair" = there may even be something in the tech section on doing what needs to be IF what I am thinking holds any merit = I'm a geezer wanna be fixer ) and cleaning it and replacing diodes if needed. I did have an extra TCI that may have worked on your scoot but already gave it away. If you find out you need one, I would make a post stating that as these are old bikes and there seems to be a few of them around waiting in parts status..

Puc

By the way,,, , glad you found our club!!

Moving this thread to the 1sy gen forum.

Welcome! And we always enjoy photos of owner's bikes! Hint! Hint!

You have an electrical problem that is affecting the #2 cylinder. The tach is driven from the primary side of the #2 coil. The tach going to zero is the clue as to where to start. It means that there is no signal to the #2 wiring.

My guess is the TCI crapping out! Do a search here and find out about replacing diodes in them, as well as removing the cover and baking them in an oven at 200 - 250 degrees for an hour or two to remove moisture in them...

My bike just started loosing power while ridding.

 

Also the tach drops to 0 when this happens. This, in this case would suggest it can't ground

It still runs but like on one or two cylinders and gradually will increase power but not till the tach starts to register correct rpm will it run correctly.

 

What is the connection between tach and engine performance. Any thoughts out there.

So this is the kicker and why I might add an area to the inspection schedule:

"It still runs but like on one or two cylinders and gradually will increase power but not till the tach starts to register correct rpm will it run correctly."

Th control module will only switch when commanded by the pickup coils! This adds up in this scenario to me at least. Check impedance.