Alternative to colortune

Hey guys, I am having a hard time tuning my bike properly. I need to find a good way to tune the mixture screws without a colortune. I am trying to find one, but if anyone has a good way to do it without, that would be awesome. I have dial gauges to balance the carbs, and I was able to get the bike to stop surging, but now it is running rich and has no low end power. When I mess with the mixture screw, I don't see any reaction in the gauges, and I can't hear when each cylinder dies off, so I'm not sure which way to do with my adjustment. I feel like messing with it hoping to come across the correct combo is a crapshoot and I don't know if I would know it when I see it anyway. Anyone with some tips for me?

 

you should put what bike you have in your signature. it would help people diagnose your problem. a lot of these bikes start with the screws 2.5-3 turns out and tune in very small increments from there. you should look up on the forum how many turns out your bike is suggested to have. maybe start at 2.5 and see how it runs and do some plug chops to see if you are lean/rich?

 

Good Call. I fixed it. If its not up yet, 82 750 Seca. Everything I read says 2.5 turns. But when I do that, it runs real poor. Again, biggest problem is I don't know how its supposed to sound

 

Are you anywhere near nw ohio? I have one you could use if you are.

 

No, I'm in Florida... :/

 

So you said you "fixed it." What did you set the mixtures at?

Also, have you wet-verified your float levels? You can't "adjust out" a rich condition if its source isn't the mixture screws.

 

it should sound like a new Toyota
you could hire a piano tuner, they can hear those sorts of things.
can do it with a real sensitive tach, not the one on the bike. a digital one that reads +/- 100rpm will get you close.

 

The person I bought it from tore everything down and rebuilt it per the specs on the manual. The screws are currently set at 3 turns out. I think I found a colortune though. I'll keep you all posted

 

8O

Oh boy.

Some things you just have to do yourself, as you're finding out. Are your valves in spec, or is that another case of taking somebody's word?

 

I appreciate the help Fitz. Don't get me wrong, I want this done right. But if I don't have the right tools and know what I'm looking for, it's irrelevant how far into this I go. So, I want to get the necessary knowledge and told so that I can indeed get it right. That's why I want to know if there is an alternative to the colortune. Either way, I appreciate the insight.

 

So; are the valves in spec?

Because if they're not, you can tune the carbs until you're blue in the face and you're gonna get nowhere.

I'd strongly suggest you check the float levels and ensure your valves are in spec before trying to worry about fine-tuning.

Float levels: http://www.xj4ever.com/setting%20fuel%20levels.pdf

Valve clearances: http://xjbikes.com/Forums/viewtopic/t=14827.html

Part Deux: http://xjbikes.com/Forums/viewtopic/t=29209.html

The best way to "know what you're looking for" is to invest in a service manual. You're going to need it. Just assuming the guy you bought it from actually knew what he was doing won't do.

I'm assuming the knowledge thing is why you're here.

 

Yes sir, knowledge is why I'm here, asking questions. I do have the service manual. I have the full one, the haynes, and a cd version. Overkill I know. The guy I bought it from is a mechanic from my work who is known for his overly meticulous habits. Not saying it's Bible truth, but he knows better what he's doing then I do. I will have to borrow the tools from some guys at work. I went over ask this stuff with him. Valve clearance, float levels, bench sync, the whole spiel. I'm going to see what happens with the colortune and go from there. I might have to rebuild the carbs, but if there is a shot at not having to, I want to explore it. Don't take this as I'm rejecting your input, you have a while lot more knowledge then me. I just don't want to have to jump to a whole tear down if I don't have to.

 

+1 on Fitz's advise -

If you and your friend want to get it "less rich" for now,
Listen to the engine idle, and watch the tach, and turn a Pilot Screw in, slowly, until you see, hear, and feel a cylinder drop out.

Then go out between 1/8 and 3/8 turn. Write it down.

Do the other 3 the same, then, go thru all 4 again, because you get the "feel" for the technique, and the YICS shares some of the intake charge.

Most importantly, test ride for drivability - go a few miles, and then look at the plugs. If they are paper-white, you're too lean (no good!) Shoot for cardboard box brown. This takes multiple rides at slight throttle openings.

 

I third fitz's suggestion... I kept trying to colortune last summer and had no luck getting consistent results. I had wet-set my floats but didn't take the time to do it properly, so when I pulled them to check at the end of last season I realized that they were only 1-2mm off. That was enough to make me waste WEEKS checking plugs, attempting to colortune, etc, eventually giving up. In the end I had to re-do it anyway, and all it would have taken was a half-days work and I would have saved me the headache.

I know how it feels to want to get everything together and go riding, but float levels are definitely not something to skimp out on. Plus, you could make all sorts of stands from stuff you have lying around. My first one I made by putting holes in a thin wooden slat, and screwing it into the bottom of the carbs. However, I would recommend spending $20 and making a PVC stand, it'll last you forever and it makes float setting a hell-of-a-lot easier. It really isn't that bad once you have the process down, but I recommend you do it outside so the fumes don't get to you.

Good luck buddy, I believe!

 

Here we go again; checking your valve clearances is NOT a "whole tear down." It is a simple maintenance procedure that must be performed every 5000 miles.

And it's step 1.




The use of the ColorTune is the final step. In between are float levels and a good solid running vacuum sync; BEFORE you try to adjust the mixtures.

If you're going to try to start at the end rather than the beginning, on the basis of somebody's word, then you're going to find this very frustrating.

 

These bikes are really built great and are fun to ride, when they are acting right. Fitz, many others, and myself would encourage you to do the maintenance and tuning in the order specified. Can't build a house with out first doing the foundation. It is that critical with these bikes. Most of us (me included) who took shortcuts at first only found that we had to go back and do all the things necessary to properly bring all maintenance items into spec and the fine tune. Where in Florida are you?

also to answer almost any question about tuning the carbs...

http://www.xjbikes.com/Forums/viewtopic/t=44642.html

and a great how to...

http://xjbikes.com/Forums/viewtopic/t=2 ... aning.html

 

Fitz, you were right. All the calves were way out of spec. However, I didn't doubt that you knew what you knew your stuff. You obviously do. You have a lot of insight to give. I never said sing the floats is a while teardown. Nor did I intend to imply. I guess what I meant without saying so is that if I was pulling the carbs, it would be to do the whole rebuild. And based on what you keep telling me, should be your suggested starting point too. I mean what's to say they weren't done correctly? If it's silly to take someone's word on properly song the floats, then it's silly to believe the carbs were done correctly from the start. This is supported by your last statement. That's why I wanted to try what was easy and quick to rule out something simple rather then doing, as I started, a full teardown. It seems absolutely absurd to pull the carbs of and spend the time to set the floats, only to put it back together and find out I didn't done the problem. That is the singular reason I wanted to sync and colortune before doing the rebuild.

Either way, valve clearances are in spec now, yet I still have a problem. But without the use of the colortune, I wouldn't have known what the problem was. It seems like I'm facing multiple problems, not the least of which is that the mixture screws don't change anything at all when adjusted, whether turned all the way in or out. Color doesn't change at all, unless I'm not giving it enough time to burn the excess fuel or for the midge to become more rich. I can't imagine that is just the float levels, but I may be wrong.

 

I'm in the Tampa area.

I appreciate everyone's input. I just wanted to find out as best I could what the actual problem was. Is wet setting the floats REALLY the best place to start? I mean if I'm silly for assuming the floats are done right, then I'm more so for not starting with the TRUE foundation. Fitz was right about needing to do the valves, but at the time I asked these questions, all I had were the vacuum gauges, so I wanted to do what I could with what I had. But now that I hit the feeler gauges, actuality had the ability to use the advice I was given.

 

If this hasn't been done do it. 8O

 

you don't want to do something that you might not need to do, i don't blame you a bit.
so here ya go, get a clear hose that fits the carb drains and loosen the screw and drain the carbs one at a time into a nice clean glass jar. if anything comes out that's not gas, your carbs need cleaned.

 

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.

 

Your getting there. It is all by the steps...valves, carb clean and rebuild, dry-set floats, then wet set floats to spec, then bench sync, then running vacuum sync, then colortune the a/f pilot and puff....a great running Yamaha XJ... easy peasy as untangling a cattywumpus with one eye closed.....

 

What will I be looking for with the colortune? I can kill off each cylinder with the af screw and that's the only time I see a difference in the ct at idle.