UH OH! I broke my FJ

bugboy · January 30, 2012, 01:06:05 PM

I did my first valve adjustment and everything seemed to go smoothly. I replaced spark plugs and valve cover gasket, cleaned the K&N's, put a spin on oil filter adapter on and changed oil while I was at it. I did have the middle throttle cable connection apart in order to get the valve cover off and lubed the cables while I had them apart. I also had the front fairing off for painting, lubing speedo cable and new instrument bulbs.

So this a.m. I put the battery back in and the gas tank back on to see what it was running like with the vavles adjusted. SHIT!!! It appears to only be running on cylinders #1 and #3. The exhaust headers for #2 and #4 are touchable (i.e. didn't burn me like #1 and #3 did). Poor throttle response (as can be expected on a 4 cylinder running on 2) and I'm getting backfires.

I've re-checked the spark plug boot connection and re-checked the spark plug gaps and to make sure they are tight (without stripping out the head).

I'm assuming that I made some kind of rookie mistake, but being a rookie I don't know what it was.

Any ideas I what I did to my poor bike? My next step was going to be to sync the carbs, but I guess I can't do that until it is running on all 4.

I'd appreciate any pointers. AND, be gentle,,,,,,,, this is my first time.

Pat Conlon · January 30, 2012, 01:40:17 PM

Hmmm. If your dead cylinders are #2 and #4 you can rule out coils. 1 coil powers #1 and #4 and the second coil powers #2 and #3.

It still sounds like a spark problem to me.

Take the plugs out of #2 and #4 connect them to the plug wires and ground the plug bodies to the head, and crank the starter.
Do you see them sparking? and good strong spark?

Me thinks you might have damaged the plug wires or plug connectors. It is hard to damage the Yamaha oem steel core plug wires and resistor cap, but easy to do with aftermarket carbon core resistor wires.

Let us know what you find.

Dads_FJ · January 30, 2012, 01:45:12 PM

I agree with Pat, sounds like fire or lack of... check the order of the spark plug leads, they should have white bands indicating which cylinder to go to. How did the adjustment go, did you have to swap any shims? If you have a valve staying open you could have these symptoms.

John

bugboy · January 30, 2012, 02:02:16 PM

I've got what appears to be good spark from all 4 spark plug wires.

The wires are not labeled and I thought I got them back where they came from but now I'm not so sure.

There are 2 coils under/behind the steering head with 2 wire coming out of each. Looking at Pat's post, the left coil should be going to #1 and #4 and the right coil should be going to #2 and #3,,,,, is that right?

bugboy · January 30, 2012, 02:05:05 PM

I did have to move around and/or replace quite a few shims. I went back through afterwards and rechecked all valve clearances.

Dads_FJ · January 30, 2012, 02:20:53 PM

Quote from: bugboy on January 30, 2012, 02:02:16 PM
I've got what appears to be good spark from all 4 spark plug wires.

The wires are not labeled and I thought I got them back where they came from but now I'm not so sure.

There are 2 coils under/behind the steering head with 2 wire coming out of each. Looking at Pat's post, the left coil should be going to #1 and #4 and the right coil should be going to #2 and #3,,,,, is that right?

Not sure w/o looking at my manual (or my bike). But the coil with the orange wire goes is for 1,4 and the coil with the grey wire is for 2,3.

racerrad8 · January 30, 2012, 03:11:31 PM

Since you know 1 & 3 are firing, trace the coils wires that are firing, 1 & 3 back, then reposition the other two that are hooked up backwards.

The wire(s) coming from the coil going to cylinder 1 also go to cylinder 4, and the other wire already firing on the coil for cylinder 3 goes to cylinder 2.

Randy - RPM

Travis398 · January 30, 2012, 04:12:59 PM

It's an easy mistake to cross a couple of plug wires, but the good news is...........it's an easy fix.

bugboy · January 30, 2012, 04:34:29 PM

The plot deepens,,,,, or like Uncle Leo "I'm old, I'm confused"!

I didn't see the markings on the spark plug wires on the first go around (one was unlabeled, 2-3-4 are marked), but I've got them going to the correct cylinders now. It appears that now cylinder #2 may not be firing. I come to this conclusion as the headers for #1, #3 and #4 get damn hot and the header for #2 doesn't.

This is what I did wrong and what I have going on now.

I only run the bike briefly as I don't want to dick anything up. On the last check it seems that #3 and #4 pipe get damn hot quickly and #1 pipe took a little longer to get hot and #2 pipe didn't get hot at all.

I've put a spark plug on the plug wires one at a time and grounded to the head. The spark looks the same as far as i can tell and it does jump the 1/4" or so that the Haynes manual talks about. Sometimes when I'm to close to the problem I can't see "the forest for all of the trees",,,,,, but I can't see where I have a problem with a wire or a coil.

I know it will end up being something stupid as I'm known for that. Years ago I was at a big game hunting guide school and we were living in tents in the farmyard. After a couple of weeks I was laying in the cot trying to go to sleep but it was still pretty bright in the tent. I made the comment "why doesn't it ever get dark in Montana?!" to which one of my classmates responded "because there is a yard light directly above the tent you idiot". I've never let my problem bother me much though.

racerrad8 · January 30, 2012, 05:08:53 PM

Quote from: bugboy on January 30, 2012, 04:34:29 PM
I didn't see the markings on the spark plug wires on the first go around (one was unlabeled, 2-3-4 are marked), but I've got them going to the correct cylinders now. It appears that now cylinder #2 may not be firing. I come to this conclusion as the headers for #1, #3 and #4 get damn hot and the header for #2 doesn't.

Okay, so if #3 gets hot then you know you have spark. You then have an issue with the spark plug, carb or valve adjustment for that cylinder.

Have you sync'ed the carbs yet? If the #3 carb throttle plate is completely closed then it will not draw fuel and will remain cold.

If you give it a little throttle does it pickup the #3 cylinder?

Randy - RPM

bugboy · January 31, 2012, 02:35:28 PM

Got all 4 cylinders firing!! Thanks to all that helped with pointers (and those that silently wished me luck).

It kind of magically started working. I started dicking with it today and it was kind of just working.

I'm now gathering stuff to do the carb sync. I made the tool like Marsh recommended and am going to go buy some locking hemostats to cut off the vacuum while switching from one pair of carbs to the next. Got to get my fans in place and figure out how I'm going to supply fuel while sync'ing.

Thanks again to all those with recommendations and pointers. To quote the Terminator ----- "I'll be back"

Kurt

markmartin · January 31, 2012, 05:01:38 PM

Quote from: bugboy on January 31, 2012, 02:35:28 PM

>>> Got to get my fans in place and figure out how I'm going to supply fuel while sync'ing. <<<

Kurt

You can set the tank facing the rear like the photo below. I'm using a longer section of fuel line to reach the pump.. If you've still got the tail section / tail light off the rear fender, ( I think you had this off for repair in an earlier post) you can bolt the tank right down where it usually bolts down when its facing front. This way (bolted down) it won't get knocked off and damaged. I've got the tail off in this photo for some repair and polish.

bugboy · January 31, 2012, 05:14:30 PM

I bought some extra fuel line to do just that. I hadn't thought about bolting it down though,,,,,, nice tip, thanks.

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UH OH! I broke my FJ