Post-valve adjustment issues resolved

[soderstromk]

I adjusted valve clearance on my 2007 a few weeks back. I had't had much chance to ride since but enough to know something wasn't right. Symptoms were occasional low idle to the point of stalling and a hint of hitch in the giddyup. It did start using less gas - I got 43 mpg on the first tank through it. Typically I get 38 - 39.

I thought it was probably either the iridium plugs I put in, or problems w/throttle sync. The stock NGKs I pulled out of it looked great, but I got a set of Autolite iridiums on sale for less than 1 NGK plug cost. This may have been false economy.

The second thing I thought it might have been is the throttle sync that didn't seem to go right. It didn't seem like adjusting the screws did anything much so I backed them out one turn and left it.

So today I replaced the plugs with stock NGKs and tried without not much more success to sync the throttle bodies. They all seem about on with unadjustable cylinder 3. Cylinders 1 and 4 seemed to have some adjustment, but cylinder 2 didn't change much screwed all the way in to 1.5 turns out. I didn't want to turn it out any further not knowing how far I could go before it came completely out.

While in there I discovered that I didn't have the little bracket that the cylinder identification sensor screw is supposed to go through buttoned-down - it was just dangling off the wire. Not sure if grounding it it somehow important or not. So I fixed that issue.

It seems to run as well as it ever did with no hesitation, steady idle and is back to 38.5 mpg.

As I changed three things: plugs back to stock, throttle sync a bit more regulated and cylinder ID sensor bracketed down - I don't know what the fix really was. I suspect I need to throw the cheap Chinese vacuum guage set I bought away and get something reliable to sync throttle bodies.

 

[RossKean]

I use a simple four channel manometer filled with ATF.



The throttle body synch has a significant effect on idle smoothness but not so much effect on overall performance. A good place to start with the TBS is to lightly seat all four valves and then open each half to three quarters of a turn. Balance them from there - If they are way out, it will be difficult to set idle speed (for a Gen II).

38.5 mpg is lower than what I would normally see, but it obviously depends on how aggressive you are with the throttle.

Are you very sure you didn't skip a tooth during the valve adjustment? Creates issues with idle, acceleration and power. If more than a couple of teeth out, you can run into serious damage to valves/pistons...

 

[Constant Mesh]

What air flow orifices do you use with your manometer? With that setup I'd be nervous that one of the hoses might disconnect from its TB and the fluid would be vacuumed into the other TBs.

 

[RossKean]

What air flow orifices do you use with your manometer? With that setup I'd be nervous that one of the hoses might disconnect from its TB and the fluid would be vacuumed into the other TBs.

I have narrow orifices in the ends of the tubes (not sure of the size, but less than 1mm ID) to reduce fluctuation which isn't as good as having a large enough air gap to prevent fluid from potentially entering the engine. There are better designs out there but this works OK, didn't cost much and took just a couple of hours to build. I also have pinch clamps on each of the hoses so they can be opened sequentially and slowly. Worst case scenario is that a small amount of fluid (ATF) gets sucked into one of the ports - I doubt it would do any damage. I only do a TBS after engine work such as a valve adjustment and rarely find that it is off by very much.

 

[saread]

I can say that it wasn't the iridium plugs. I ran them a few times and no noticeable difference in my '08. The don't last any longer than normal plugs due to the lost spark ignition the FJR uses.

 

[mcatrophy]

I use engine oil in mine. Self damping, and not the end of the world if a little (I emphasise "a little") does get into the cylinder. I also have screw clamps on all four tubes that I only release when I am sure all is stable. In reality these are variable sized orifices, so I suppose did act as dampers, though I did have them pretty much fully open when I last used this.
(Click on image for larger view)

 

[soderstromk]

Rode it 300 miles Sunday and all seems back to normal. If the sync doesn't make that much of a difference it was either the iridium plugs (Autolite Xtreme Sport Iridium, XS4303) or something to do with the cylinder ID sensor.

Maybe I had a bad iridium plug? Or maybe my particular ignition system doesn't get along with them?

The gas mileage issue might have been due to laying off the throttle because something wasn't quite right.

The manometers you guys have built are beautiful - but more than I'm up to assembling myself. I think muddling through I may have it close enough for general service. This was a new procedure and I wasn't sure how close to perfect I should have been able to get it.

 

[MotoMike]

This is what I use. Simple and works great. Just re-read the instructions for use each time you go to use it.