Neil86

If you still have the airbox off...verify the carb bowl vents are clear on the right side... they share a common hose so check it too. They will cause a very rich mixture if plugged as the carb will pressure up.

On my 86, I went from bottom. Already had side grills and lowers off for valve clearance checks. Removed the heat shields atop front valve cover. If your 84 still has the YICS chamber it has to be removed. You will then see 2 JIS (Japanese philips) screws facing down. I used a socket with that bit on and air ratchet and out they came.

Are the turn signals self cancelling if you leave them flashing? If they do not, there may be an issue with the speed sensor mounted at the speedometer that the cruise and signal canceller both utilize. The cruise interlocks (r/brake, f/brake, clutch) can be tested easily by removing headlight since they are wired in series. Send me a PM if you need more info.

Is there any change using the front brake or the light is definitely full brightness. You can test at the unhooked yellow wire for the voltage (vs a good ground) in the brake light circuit. As mentioned disconnecting front switch eliminates the switches then if still getting voltage you can focus on other stuff...CMS issue, antidive relay, ground issue on one tail light socket etc.

If the pump didn't click at all during the 5 secs, inspect the hoses for pump inlet and outlet. Sometimes an aftermarket hose thats too long is used creating a kink, and stalling the pump.

Its normal to only have 5 seconds of power to pump, without engine rotation.Its a safety feature in case of a fuel leak. If the pump was clicking away for the 5 secs, just flip the kill switch off and back on to restart the 5 secs. Once carbs are filled then try the cranking. With the airbox is off, it will be hard to start cold....might want to reinstall.

One thing you might check are the vent hoses for the carbs....you will have one for left carbs, one for right carbs and they run forward past air intakes and down into lowers. If there is a blockage in the vent either in the carb or hose the carb will pressure up and run rich. Sometimes insects will plug the hose. You might also pull spark plugs and see how they look.....might show one or two cylinders running rich etc.

The UNI filters...made of foam I guess? They were oiled before installation, correct?

Are the slides clean....wondering if some stuck open when it detonated and finally worked free?

I believe the Uni is designed to come apart (the springs) so you can wash the foam and re oil.

One thing to keep in mind....if the replacement TCI is an 83 (with a 26H model on the sticker) the pressure sensor hose can left connected to the #2 carb body. If its a 84-89 TCI (with a 41R model on the sticker) the carb port needs to be capped and the pressure sensor hose connected to the #2 cyl synch port so the timing advance under load is correct.

An engine starts out with standard bore piston and rings. (STD) As wear occurs it gets to the point where the engine is rebored to true up the cylinder.....the Venture has 2 oversizes (0.25 MM & 0.50 MM). The pistons and ring sizes must match...ie Std piston/std rings etc So without history on the engine, basically you would have to diassemble and determine whether it still had standard pistons in it or not and whether the cylinder bore was worn to the point requiring a rebore. If you rebore you need larger pistons and rings.

Perhaps someone will offer to try your unit in their bike to see if it operates okay or gets the misfire. So your tachometer is totally dead when running or it won't even start?

Good ground connection at starter?

Actually Mike, the 2nd gen front calipers only have pistons on one side.

heres a ebay pic...showing the ridges that would be outside filter http://i.ebayimg.com/00/s/MzAwWDQwMA==/z/4VUAAOxydB1SjTPv/$_12.JPG

Theres also locating ridges on floor of airbox....not sitting atop one?

If you still have the stock filter, compare the heights of removed filter....I'd be surprised if they weren't the same. If ok....check over the gasket of element bottom....maybe its misformed and the element is hanging up and not fully seating in the airbox.

Since you reported elsewhere a fuel leak issue with key on, you might consider unplugging fuel pump electrical connector so you can rotate starter for the compression test without fuel dumping on the ground.

Do the turn signals still operate?

A multimeter would be handy.....test voltage with key ON right at battery posts, then battery cables....if normal, follow positive cable down to starter relay/main fuse holder....test there and check for a poor connection.

Is the YICS system still in service? A vacuum leak on one of the chambers can easily cause a cylinder to go dead at low throttle.

Typically Yamaha uses the strategy start in neutral start in gear only if sidestand up and clutch in. I would check and test the starting circuit cutoff relay. If its in neutral and the neutral light works, it suggests the neutral switch is functioning. It would be helpful to view the wiring diagram for that model.

Yamaha wouldn't fib to us would they...

Kevin you have a 90-93....