all valves WAY tight - affects?

14 months, hundreds of bucks on carbs, ingnition, wiring & still can't get it running stable enough to sync the carbs. I bought the bike not running (started w/ starting fluid only) and assumed the PO had tried to get it running since the motor was freshly painted black and the red RTV was squeezed out of the mating surfaces.

ANYWAY, it was the absolute last thing for me Personally to do before I hire someone and this is what I found:
Exhaust Intake
1 .006 .015
2 .003 .003
3 .003 .015
4 .002 .015

should be
.16-.20 .11-.15

Ok, they're WAY tight

My # 2 hole isn't firing, using the hand on exhaust test during cold startup & i don't hear it fire by turning the mixture screw

What are some characteristics of tight valves?

After knowing the carbs inside and out, everything memorized, acid bath and complete rebuild, I don't think the non-fire is the carb.

Just wanted to see some thoughts, Thanks ya'll

 

#2 probably won't run with valves that tight and you may have a burnt valve by now.

Adjust the valve clearances, and then do a compression test. Then you'll know if the head's gotta come off for a valve job.

At that mileage it's a crapshoot if they were never touched, you may be lucky-- there's only one way to find out.

 

Double check your numbers.
I'm guessing you are meaning .0015" instead of .015"
and remember that the specs are probably listed in mm

Keep your fingers crossed you don't need to pull the head, BUT that might give you more insight into why it's not firing.

As fitz said >compression test will tell you the way.

 

thanks guys, Mike you're right, the feeler gauge says:
.0015
.038
mm

& the specs ARE in mm
So what is my guage saying, .038mm?

I have the same exact feeler gauge set in Fitz's thread here:
http://xjbikes.com/Forums/viewtopic/t=1 ... art=0.html

 

That's what it sez.

 

hahaha thanks MiCarl :lol: so I guess the top # is inches. got a little thrown off there. I"m glad cause they're not as tight as i thought :wink:

So I have my shim #'s recorded and one shim had no #, of course it's on the 2 hole. if no one has any ideas in this situation i'll ask Len his advice when I order the shims I need

it's XJ Donation time!

 

A "Tight" Valve ... even tighter than this fellows numbers ... does not mean the Valve's NOT closed.
It's tight.
Needing to be Shimmed to a value LESS tight.

If the Compression is good ... the Hole should fire.
No matter how tight the Valve Clearance is.
The operative word being ... Clearance.
The operative word ... being ... Clearance. Some clearance!
It's when tight become open that causes you problems.

 

You can use a caliper to figure out the number that should be on your blank shim, as the number refers to the size (mm). If you dont have a caliper, a Jap dealer will measure it and label it for you for free.

Also (if you haven't realized), figure out the size shims you will need for each valve and make a chart, along with a list of the size shims you have. You'll find a few of the shims will fit in other valve positions, if you're lucky that is

 

Thanks. Well after making my chart and preparing to order my shims it looks like I have a hung up valve or something since 2 of the gaps are the slightest bit too large (would have been the very next column/value on the chart). When I get home tonight I'm going to check the clearences again to see if the valves fall in the same spot or if the gap values are consistent.

Worst case, since we can't let this happen again, the next question is - How did this happen. I can't rule out it could have been improper reassembly by the PO because when I bought the bike it has a nice coat of black paint on the engine and headers and fresh red RTV squeezed out of the head and cyclinder mating surfaces...

 

Good eye on the RTV.
Maybe the PO burned a valve and did a funky repair on it.

Don't sweat Shims that aren't on the Chart. You can get Over-sized Shims.

Just get the Math right and be sure you order the right size Shim for the Hole.

 

Just a thought, have you checked the fire to #2 plug. I just had the same thing happen and pulled the plug wire from the coil,it was green with gunk. Cleaned and put back in coil ,worked great.

 

PROGRESS PROGRESS.
BikerEd - thanks, it's a new ignition
Rick and all - my conversion from inches to mm was wrong for that one gap (which was on 2 holes) I got it right now, the real gap is .038, not .381. And for the blank shim, i took Len's advice and put a shim w/ a known value in the hole the blank one Used to be in, then checked the clearence, know I know what I need.

Yes the 2 hole was tight for intake & exhaust but my gut is telling me this isn't the reason for not firing, since There Is Clearence.

For those of you who remember all my posts regarding my first and only XJ purchased 1/09, yes it's the same bike and I'm still trying to get it right - still haven't ridden it more than a few miles back in 4/09

 

well, all 8 shims were ordered and installed. 6 worked, 2 spaced it too much, but my math was right. 2 more shims ordered and expected to be installed tomorrow