Lost Spark and Tach at Low RPM

[sailing62]

Hello all, last fall I purchased a brand new used 1986 Venture Royale, I put about 500 miles on it before the weather forced me to put it away for the winter. As I was putting away for the winter, I fired it up and it was running very rough. Lots of backfires (inake and exhaust backfires) and chugging, as well as the tachometer was not working. I decided to worry about it in the spring because I had too many other projects to do. Well here I am in the spring and trying to figure this one out. The bike never had this problem before. When the engine is running below about 1500 RPM, the two cylinders on the left side have no spark and the tach does not work. when the engine revs up above 1500 the two left side cylinders jump back to life as does the tachometer and the bike runs well. I am stumped, I looked for any loose or corroded wires but could not find any, the coils checked out OK with my multi-meter. Does anyone have any incite on how to track down the problem or what it might be?

[videoarizona]

Mark,

I know there is a cure to your problem and the clue is no tach.... I just don't remember what! Suggest you do a search using no tach as part of your search terms....

I'm almost positive the answer is here on site. Guys and gals here are great and very knowledgeable!

Hope you join up.. Best bux you will ever spend!!

 

Update. Just had a thought. The TCI is the computer that fires the plugs via the coils. The TCI is located under the battery box. If it's corroded inside or the connections are corroded... You will lose a plug or two and no tach. Sometimes is a simple matter of moving TCI to above the airbox and cleaning up connectors. The wires are long enough to move unit. You may have to open computer and clean out gunk. Possible you will need to replace some old capacitors too. The TCI is fired by sensors.... That's a small possibility though. These bikes are reliable and easy to fix. All these issues can be found searching this forum. Also suggest you read up on the First generation tech area where members have posted notes, pictures and more on all types of repairs...

Edited March 15, 2015 by videoarizona
memory kicked in...

[dingy]

1st thing to check is a 6 pin connector that is located near the shock damping selector on left reaar side. I have seen several of these connectors cause ignition problems. There are 2 6 pin connectors in same area. One is for gear position indicator, it has all 6 pins used. Other is for pickup coils, it has 5 of the 6 pins used. The common (Black is on in position that has empty slot next to it. Other 4 pins are to each pickup coil. Use an OHM meter to check coils. Resistance should be 93~126 ohms on each of the 4 wires to the black one. There should also be infinite ohms from each of the 5 wires to ground. This is checked with connector disconnected and on side of connector with female pins.

 

#2 coil is where tach receives signal from.

 

If TCI is problem, I sell a replacement unit that is much better than stock TCI.

 

Gary

[sailing62]

Thank you guys for the very quick responses! I was outside just now, removed the TCI box, opened it up and there was a broken connection very similar to that causing the E4 error code! I re-soldered it, put it all back together and now the bike runs like a champ! I did not see any other issues on in the TCI that I could tell.