89 VR Left 2 Cylinders Not 100%

[GolfVenture]

My 89 VR, last year, ran fine. I normally run an ounce of SeaFoam in each gas tank, and at the end of the year on a full tank I put in about 4 or 5 ounces of Seafoam, then ran it about 30 minute ride, then top of the tank. Now it is ready for the winter lay up

Sometime in Jan of 2012 during a nice day I took it out for a mid winter warm up. Just to make sure everything was running ok. It ran perfect until the last 5 minutes. All of a sudden I could tell that I was not getting the normal throttle response. At a stop light I noticed that it was idling at less than 500 rpms and I could hear what might sound like not firing on all 4s.

Got it home and let it sit. See I was too busy putting accessories on my 91 VR. But all the time been thinking about how to attack the 89 VR issue.

So I finally got to it this morning. As I turned the key on the fuel pump did it click click thing like a machine gun. Hit the choke and with in about the 2nd hit of the starter it started right up. During warm up I could tell that the symptom was still there. When I took the choke off, yep it is idling below 500 rpm, and not sounding good.

From cold start up I hit each cylinder with the laser temp run and all 4 cylinders seem to be warming up fairly evenly, temp wise. I will start it up tomorrow morning when cold and be more attentive with the temp on the left banks. The left banks temp may have been a bit behind the right banks. I just wasn’t paying too closely

So this morning I did the following:

I sniped off 1/8 to 1/4 inch of the spark plug wire. Started it up - Same symptoms.

Facing in the forward riding position

While running I pulled the right back cylinder plug - the engine died.

While running I pulled the right front cylinder plug - the engine died.

While running I pulled the left back cylinder plug - engine kept running. tiny bit less rpm.

While running I pulled the left front cylinder plug - engine kept running. tiny bit less rpm.

So it is my 2 left cylinder bank.

I pulled the plug cap of each left cylinders and put a spare plug in it to test for spark.

Both have good spark.

I then unscrewed each plug and then tested the two original spark plug for spark.

Both have good spark. Infact the plugs almost look band new. Well they should be for very little miles were put on them last year.

Also when I pulled the original plugs they were not wet with fuel. They were very dry, meaning they aren't getting any fuel or what fuel it was getting was being burnt off.

It was running initially with the choke but later I took the choke off.

So with good spark and the cylinder temp seemed to be going up some what normal would indicate that the 2 left cylinders were getting proper spark and fuel.

I'm suspicious it still is a fuel issue.

I’m going start it up tomorrow morning, cold, and record the cylinder temps.

Meanwhile any suggestion for me to think and plan would be appreciated.

I’d like to start with the less expensive and simpler solutions.

Thanks

[Yammer Dan]

Sounds like not enough fuel!! Take it out and run the crap out of it? Sometimes works. Why would those two be short on fuel? Tap with something. Floats might be hanging but strange two at a time on same side?

[bkuhr]

From cold start up I hit each cylinder with the laser temp run

My first thought is maybe you cracked or blew off a vacum cap, or some other vacum leak. Many items sprayed under carbs and around manifolds listening for change in rpm. I prefer start fluid-but have fire ext handy.

 

Second, water cooled engine will warm all CYLINDERS evenly. Need to test exhaust pipes 2-3 in from cylinders

[GolfVenture]

My first thought is maybe you cracked or blew off a vacum cap, or some other vacum leak. Many items sprayed under carbs and around manifolds listening for change in rpm. I prefer start fluid-but have fire ext handy.

 

Second, water cooled engine will warm all CYLINDERS evenly. Need to test exhaust pipes 2-3 in from cylinders

 

I kind of always wondered where one hits the laser with and why. Exhaust pipe, got it.

[Power Trippin]

Sounds to me like dirty carbs. If it runs halfways decent with the choke on, then it is for

sure, not getting enough fuel. Time to clean the carbs, replace the fuel filter, thats my best guess.

[PBJ]

If its two cylinders down could there be a blockage of gas on that one side??? or maybe a hung up choke cable causing an improper mixture?

[GeorgeS]

The main fuel line from pump runs to top of Carb bank, then the lines split off to Each side, left and right.

Possible the line going to the left side is blocked. ( but I doubt this, but its possible )

 

Open the Bowl drain, on each of the left side carbs. Turn on fuel pump, make sure you are getting fuel thru the bowl Drains.

 

If you can not find any other reason for the problem, I would Re Do the Carb Sync Proceedure !!!

 

Might be Moisture Inside of the TCI Unit.

 

Check the Wireing cable from the Ignition Pick Up Unit running up to the TCI. 5 wire cable, there is a Plug about half way up to the TCI, Open that plug, clean the Connectors, Check the wires , make sure not loose Crimps on the male and female pins. ( Plug located about under your left knee, as you sit on the bike )

 

I would also, completly drain your fuel tank, and start with fresh fuel.