Bent connecting rod?

Yes, that!


Sent from my iPhone using Tapatalk

 

I doubt you would be able to measure accurately enough to pick a bent rod, for you to be able to find a difference the rod would need to be bent quite a bit to a point the motor would not rotate or the piston would jam in the bore

 

The skeptic in me says the analysis of a bent rod by the "mechanic" was a way to make some pesos off an unknowing customer.

 

I always check in with my skeptic first, then my pessimist, then my naysayer, before letting my optimist get a word in edgewise...

Norm - I think you're right. I was doing the geometry on it, and if it's turning, it's either not bent, or not bent badly enough to measure by piston depth/height.

 

**On to the task at hand: I reinstalled the plugs, connected the coils and their connectors, put fresh 91 octane in*the tank, took the battery off the tender and installed it. waited for a lightning storm to help bring the creature to life, and cranked it over. The engine tried to catch, but wouldn't. Some combination of cylinders was not firing. I then tested spark at plugs, and #1, #3, and #4 have no spark. #2 [the cylinder whose plug had fuel-fouled*black sooty deposits] was firing and valiantly attempting to turn the entire engine. The FI warning indicator did not illuminate or flash.

I am now studying the ignition schematic in section 19-2 of the manual, and it is not immediately apparent where a broken wire or connector could stop spark from reaching cylinders 1, 3, and 4, but deliver spark to 2. Visual inspection did not reveal any broken connectors or wires, the engine shutoff relay housing was fine, ECU looks good from the outside [Like so many women].

 

Before all that I check oot the mechanic.

 

I have been following this thread but I can't recall, does the bike currently run? I think you can safely rule out the bent rod. Even if it had bent rod it would still run unless you had a bent value which you don't because you have compression. If it were me I would pull the injectors for cleaning. It won't hurt and it would be a great place to start.

 

Hi Jim - no, it seems that with no spark at three cylinders, the last one can't get it to run, though the lonely #2 cylinder has spark and is trying. I'll go through and clean the injectors while I'm at it. It seems getting spark to all four cylinders will be task #1. Thanks for your reply.

 

Have you put in 4 brand new plugs yet ? I generally work on if I'm going to pull them out they get replaced. Then cleaned and gapped as emergency spares.

 

Excellent. Don't touch the injectors yet. This is really good news. You have a working cylinder and three dead ones. I believe that if you start with what you know (one plug firing) and work your way back through the system, testing each function, you will soon have an answer. Since you have a known good plug and coil you can start there. The first thing I would do is swap the good plug and coil for a bad one and see it it still fires. This will tell you if you have a bad coil/plug combo or maybe just a bad plug as has been suggested. If you still have no fire then you can start tracing the fault back from what you know.

 

Well one thing that all the coils share is an earth connection. So if your earth connector is corroded/melted, that might explain the sudden demise and subsequent unwillingness to function as Soichiro intended. I'm not familiar with the 6th gen but recall there is a common earth bundle somewhere under the top fairing.

 

Cool. Thanks for the guidance. I've labelled all the plugs and coils so I can keep track of them, and I'll start switching them out with working #2 plug and coil to see if the problem follows any particular plug or coil, or if #2 plug or coil correct the problem in another cylinder. If the fault stays with the same cylinders after moving the plugs and coils around, I'll work my way back in the wiring, starting with the earth connection.

 

That would be my plan. Good luck and keep us posted.

 

On to the 'bent rod'. I apologize for the long silence. I reached a satisfactory solution last Thursday, then spent a way-too-large chunk of today learning how to get a brief video of the VFR into a shape and format to post - it's 1:26am and the video is just now ready to attach. I won't bore anyone with the tedious details of a close encounter of the Microsoft kind.

I swapped the plugs and coils around among the cylinders with no spark, and the lack of fire stayed with 1,3, and 4. So I moved up into the wiring harness and found a broken wire - the black/white one in the diagram in section 19-2 of the manual. The manual's diagram does not indicate that there is a point in the wiring where a break in a wire would disable 1,3, and 4. I didn't want to get too far into the harness or replace it, so I installed a jumper bypass around the break in the wire. This brought the three miscreant cylinders to life. Actually, I shouldn't disparage the cylinders, as they were standing by and now that they have spark, they run great. See attached video. Note - the video is called 'rightside up' because I held the phone incorrectly when filming and had to rotate the video.

So I let it idle for 45 minutes to make sure everything remained stable, and it did. Temp stable, fan turned on, FI malfunction indicator and all other warning lights remained off. The beast sounds gnarly-snarly with the airbox open and no mufflers!

As for the plugs, I replaced the fouled plug and one other with the recommended NGK iridium plugs. All four now have the type of tip electrode that threads on and off, but I thought the OEM Honda plugs had built-in, non-threaded tips, don't they?

I also purchased a set of Brisk AOR10LGS plugs but have not installed them. The Brisk units were reported by several VFR owners as producing a noticeable improvement in power delivery. Does anyone have experience with or knowledge of the Brisk plugs?

Thanks to everyone for their assistance and support.

https://www.youtube.com/watch?v=GRqF3g71jPM

 

Haha, congratulations!

Bent rod, eh???

 

From the start the thing least likely to be the cause was a bent con rod

 

Man that's awesome! Good job

You must be stoked

 

Congratulations I love stories with a happy ending. That black and white wire is the common link through all the firing circuit with a yellow (I think from memory) coming into #2. This make sense as to why the three plugs would be dead.

Once again I am very happy for you.

 

Great detective work, when a wire breaks like that it is from fatigue from constant movement, check harness for possible causes.

 

That's awesome, maybe you can still get NG to buy that off of you, even though he just got the Triumph!