Alternative to colortune

That's a great idea. Seems like a good, easy process. I can't on mine though... My drain screws are all stripped from the PO. :/

 

If all the drain screws are stripped I think it's probably safe to assume that the float levels haven't been properly set.

You could also be dealing with plugged up pilot air/fuel passages.

 

I just ordered a bottom end rebuild kit. I have a bunch of spare pieces, hopefully I won't find anything too ugly in there. It sounds like they were never properly done to me too. I noticed with the ct that cylinder 1 has no ignition, the plug came out clean and dry after running it. I checked the plug it off the head and got no spark. I will investigaate that while I'm waiting on the parts. But I'm sure the no fuel is a big part of the problem. But that's one of the reasons I wanted to get the ct first, whether it fixed the problem or not. It at least showed me the problem.

Big thank you to fitz, you were spot on with the valves. Alllllll of them were out of spec. They are in for the most part now, need to find a few more to get some where I really want them.

 

What where the before and after clearances and what shims did you use to get the clearances back in spec?

 

Ok, here goes...

CYL 1;
Intake measured .000 YIKES!
Exhaust measured .006
CYL 2;
Intake measured .006
Exhaust measured .009
CYL 3;
Intake measured .006
Exhaust measured .000 YIKES!
CYL 4;
Intake measured .009
Exhaust measured .004

Here are the original shims followed by the replacements;

CYL 1;
I - 285 to 250
E - 290 to 260

CYL 2;
I - 280 to 260
E - 275 to 250

CYL 3;
I - 280 to 255
E - 285 to 240

CYL 4;
I - 270 to 250
E - 290 to 270

I ran out of the 265-250 range so i couldn't get them all done perfectly, but they are at least close until I can get the remaining shims.

 

hang on, I entered your information into the shim calculator I use, both in metric and sae, and the results show all your valves are still way out of spec.
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Did you use a metric feeler gauge or a sae that converts? Something is not right with the measurements. Did you recheck the clearances manually after the shim exchange? What where those readings? Do not attempt to start the motor with the clearances this far off....

If you current shim pad install listed on the chart is correct, retake all clearances in true metric and we can figure out what shims you will need to get them in spec.

 

I did recheck, but I was staring to get real tired by that time, so I may not have paid close enough attention.... I will recheck again today. But at least one of your entries is incorrect. Cylinder 3 ex is .000 not .009.

Oy vey. I hate it when I make simple mistakes like that.

 

If those are Imperial ("American") measurements, you're still going to be out of spec at the edges of the ranges. For instance, .004" = .1016mm (.10mm) which is out of spec.

Bruce B is right; you need to re-check and re-think here; and DO NOT run the motor until you've got it right.

 

I will recheck when I get off tonight. Sigh. I'll try to shoot some pics of what I'm using. Its a Metric and Imperial, one side standard, other side imperial. But it was after a rather aggravating day at work. I did think it was odd that I wasn't getting enough adjustment out of the suggested shims in the manual. But again, some of them had zero, or rather negative, clearance. Either way, I will remeasure and post the findings up here. Geez i feel tarded.

 

Don't. This really isn't that difficult.

Let's go with the original readings, convert 'em to metric and look at the originally installed shims to see what should be close to the answer:

#1 intake: 0 clearance with an installed 285. This would probably need a 270, and see how close to .15mm we get. Might only need a 275, but I doubt it.

#1 exhaust: .006" measured which is .15mm, with a 290 in it. One size smaller, a 285, would bring it to .20mm, in spec for the exhaust.

#2 intake: .006" measured, which is .15mm. That one was in spec with the original 280 shim and should have been left alone.

#2 exhaust: .009" measured which is .22mm on the original 275 shim and actually loose; a 280 would bring it to .17mm BUT WATCH THIS ONE! They should be getting tighter, not loosening up. Either you mis-measured or a valve may be starting to have problems closing fully.

#3 intake: .006" (.15mm) measured; this is in spec and the original 280 should have been left in there.

#3 exhaust: Measured at 0; this will probably need to go from the original 285 to a 265 to bring it to somewhere in the .16 ~.20mm range.

#4 intake: measured at .009" which is .22mm again way LOOSE. If this is true, you need to replace the original 270 with a 280 which would bring it to .12mm and in spec for an intake valve. Watch this one too, for the same reasons as #2 exhaust.

#4 exhaust: measured at .004" (.10mm) you would need to swap the original 290 for a 280 to get you to .20mm.

You're not doing the "shim math" correctly, made worse by using Imperial and not metric measurements. Generally speaking (except in extreme cases) you need one or maybe two sizes smaller shims; in some cases you went six sizes down.

Using metric numbers, one size smaller shim gains you .05mm in clearance; two sizes .10mm, etc. Since the specs are .11 ~.15mm intake and .16 ~.20mm exhaust, there is only one size shim that will put any given valve in spec.

Your #3 exhaust and #1 intake, being at zero, require an educated guess to get them in spec; go three sizes smaller (.15mm) than what was in there on the intake and four sizes smaller (.20mm) on the exhaust, and RE-check. That large of an adjustment might be too much, or it might be right.

Fix the rest of them too.

 

I will recheck tonight and see what the story is. I may have written .006 but meant .06. I'm sure I used the mm feelers. My derpy eyes see funny things with too many zeros. I work with part numbers (car parts) all day and my brain is like a scrambled egg when I get home. Doesn't help when my 2 year old is running around and my wife gives me the eyes...

 

Gotcha. Regardless of what measuring madness was taking place, you're never gonna swap a 290 down to a 260; that would mean a clearance increase of .30mm!

Like I said; in most cases you're looking at one, maybe two shim sizes smaller (or in rare instances, larger.) The only time it's going to be more is for the zero clearance valves.

 

Makes sense if you actually think about it

 

It gets easier every time you do it.

It's a 5000-mile maintenance item, and if you actually ride your XJ and put some miles on it, you'll be doing it more than a few times. Each time, there will be fewer valves needing adjustment, and it becomes a "check and record" thing with an occasional shim change.

Start and keep a log book. Date, mileage, work performed. I have one for all my bikes, including the '74 Norton.

Makes the whole thing easier. Riding truly old motorcycles takes a bit more involvement than a new bike. Kind of a "doctor-patient" relationship.

 

Can't agree more with this entire statement. Thanks Fitz for giving me and so many others great advice.

I'm sorry about messing up one of the numbers on the shim chart, was early and I was not going to be near a computer until tonight. Spent the day offshore about 70 miles doing some fishing.

Anyway, the message got through, the clearances are really that important.

Good luck with the rest!!

hope all this helped...

 

It all did help very much. Fitz was right, I was using Imperial without even knowing. Doh! He was right on all but 2 with what the adjustments should be, even the zero clearance ones. Amazing. You guys are great. I need to get 2 275s. Hoping my buddy has some. I'll recheck again tomorrow just to make sure I didn't make a stupid error again.

 

Well, valves are all in spec 100%. Still back to having a surging problem though. Carb kit comes tomorrow. I'll do what I can tomorrow night. Tried syncing and colortune, but I couldn't get the surging to stop and didn't see a whole lot of difference on the color of the burn at idle.

 

Now you need to ensure the float levels are accurate while you service the carbs.

 

On that note, I pulled the carbs off last night and pulled the bowls off... they all look to be cattywampus by eye. So, you appear to be right again. Go figure.