1980 XJ650 Carb Tuning

I think i actually do have some wire on a spool around. I also have metric feeler gauges but will need digital calipers and hemostats. Just gasket and sealant as well as those rubber donuts on the bolts that hold the cover down. There isn't a ton of space between the valve cover and the frame, I'm guessing I can still remove it but very carefully. Will be interesting to see how crispy the old gasket will be!

 

There is plenty of room to remove the valve cover with the engine in the frame. You might need to remove the horn from the frame (I did to make it easier to pull the cover off).

 

K-Moe exactly, I saw the horn on there and it's gonna have to come off. Alright i'll give the valve clearance reading a shot this weekend, just need the calipers and hemostats. Will report with the findings!

 

Curious what you need calipers for? Also you said you wanted to make all the mixture screws the same. You can't do that by aligning the slots because the threads in the holes will not be the same. The only way to make sure they are the same setting, as a start point, is to turn them in to a light bottom and then turning them out the same amount of turns.

 

I was told to remove the shims and measure them with calipers in the event the numbers are worn off. I did reset the screws, one was higher than the others so i spun them all in and turned 3.5 turns out.

 

It's not too likely the numbers will be worn off but calipers would not be the best choice for fine thickness measurement. You would be better off with micrometers.

 

Ill see if i can spot those at the hardware store this weekend should i find any shims missing numbers.

 

Either works. The shims don't wear in the middle.
You'd be surprised how many shims got installed with the ink-stamped numbers facing up.
About 10% of my personal stock have my handwritten numbers on them.

 

Baseline is 2.5 turns out, with most ending up between 2.75 and 3.00 turns out.

 

Thanks K-Moe, will correct them a turn in tomorrow. 3.5 was what some of them took to spin back in. I have wire and feeler gauges so at minimum i should be able to read the shims tomorrow and post results.

 

Calipers are harder to get a good measurement and are only accurate to .0005" or the metric equivalent. Mics are easier to get a good reading and can read to .0001". Convert the measurement to metric and will be more accurate than calipers. Same reason to use metric shims as opposed to standard.

 

All true, but the required resolution for shim changes is only to 0.05mm (0.002"). More resolution than required to read that isn't needed, and calipers are a more versatile tool. I do have both, but then I have need for a micrometer more often than most hobby mechanics.

 

Alright, so I've taken measurements and after seeing some other people's measurements I'm wondering if my gauges don't measure in fine enough increments. From 1-4 my measurements are:
1. I .08mm E .10mm
2. I .10mm E .13mm
3. I .10mm E .10mm
4. I .04mm E .10mm

Also if these measurements are too broad, could someone suggest a range I should be looking for in order to get better gauges?

 

If you're using metric feeler gauges then you're doing it right. A fair number of people use SAE feeler gauges, which works, but isn't ideal.

#1: Intake is tight, Exahust is very tight.
#2 Intake is tight, Exhaust is tight.
#3 Intake is tight, Exhaust is very tight.
#4 Intake is very tight, Exhaust is very tight.

Odds are that you will be able to swap at least some of the exhaust shims to the intake side.

Next step is to pull shims one at a time and make a chart of what's installed where.
Then figure our what can be swapped, and what shims you need.
Use the chart in the following thread. In-spec is In-spec. Use the size of shims that the chart calls for.
bigfitzs-airhead-valve-adjustment-with-pics-parts-i-ii.116006

 

Thanks K-moe, I'll pull them out after lunch and see about getting some numbers.

 

Ok got the shim numbers, luckily all were legible!

1. I Y280 E Y265
2. I Y275 E Y250
3. I Y275 E Y270
4. I Y285 E Y 280

So how i read the chart these would be the replacement numbers:

1. I 275 E 255
2. I 270 E 245
3. I 270 E 260
4. I 275 E 270

Meaning that after I swap the 3 I have on hand I will still require:
245
255
260
270 x2

 

Your spot-on. Start a conversation with @hogfiddles with a list of which shims you need.

 

Conversation started! Ill also see about getting replacement gaskets for the side and valve covers.

 

So the new gasket and shims should be arriving this Saturday and I'm looking forward to vacuum syncing the carbs afterwards. Once that's done i want to go through some safety items with you guys to make sure its not a better running death trap ie. brake lines/drum brake shoes.

 

Check the date codes on the brake lines. Replace if over 4 years old (unless they are teflon lined/steel braided).
Rebuid the master cylinder and calipers.
Replace the rear brake shoes (older shoes will delaminate from the backing plate, and make you go BOOM).

 

Where does this 4 yr old replacement of brake lines come from? Sounds like overkill to me, 8 or 10 yrs would sound more realistic?

 

I got a replacement brake lever and master cylinder already but will check it again. I have new OEM brake lines and rear brake shoes coming from Len. I also forgot to order the cam-end plugs so I cant put it all back together today. This may be a sign from divine powers as by the time I get the plugs ill also have the new brake lines/rear drum shoes. No big deal I almost have my other bike up and running. Todays objective is to replace the shims!

 

From Yamaha.




It's truly scary how many motorcycles still have their original rubber brake lines after 20, or 30+ years.
Why You NEED TO REPLACE Original brake lines w/pics

 

I kind of guessed that, but it was written 40 years ago, surely the material spec has improved many times since then? What do yamaha specify for more modern times? Allways assuming (that word again) that the lines you can buy now are more modern?

 

i would think if you looked in a newer factory repair manual for a newer bike you would find that answer.

 

Again...it's scary how many motorcycles still have the original brake lines on them after 20 or 30 years.
They may be more often overlooked than valve clearances.
My son's 2003 Honda Shadow also called for brake lines to be replaced after less than 10 years (The service manual is still in a box somewhere or I'd quote the actual interval).

 

Steel brake lines that are corroded should be picked up at the MOT test here on older cars in the UK. Motorcycles because they don't have steel lines that can corrode pass if they are not leaking. Sometimes it is easy to overlook the fact that lines are old on our bikes.

 

New shims are in the bike! Looks like brake lines and rear drum shoes will get here just before I put the valve cover back on.

 

Update: I got the valve cover back on the bike, replaced the front brake lines, and also replaced the rear shoes. They were bad however I simply didn't want to chance something bad happening. I tried to start the bike in order to get it synced and the battery was so low it wouldn't crank. No big deal, so I bought a new one because I didn't trust the previous owners work after seeing some of the stuff he did while fixing it. Put the new battery in, and now the main fuse pops every single time I try to reconnect the negative side. Perhaps the fuses I'm buying aren't the correct type.. they are 20A AGC Fuses but they look different than the one I pulled out of the bike. That one has fat ends with a thinner middle. The new ones are thin all the way across. I would be lying if I said this didn't completely ruin my day. I finally get it all together and now some unknown electrical issue has stopped be right before getting it back on the road.

 

Retrace all your steps to find what you did to cause this. Start with battery polarity -ve to earth....

 

So I looked at the battery closely, the one that the parts place said fit my bike has the positive on the right. I'm an idiot, no wonder the fuses were popping. SO I got one with the correct terminal placement. There is still an issue even before I switched the batteries which I'm hoping is solved by charging the new one I got. The bike would barely turn over to the point the motor would stop moving and you could hear liquid, presumably fuel being squirt in the carbs or around that area. I will try again when the new battery is charged and installed but i hope nothing else has died on this thing.

 

Yes you are an idiot, but the consequences of your actions may not yet have shown themselves yet. The tci is transistor - the "t" in tci. I suspect it won't have enjoyed being reverse polarity'd.
And to go back up to your comment on " "you could hear liquid.....". This was NOT liquid, there is nothing to squirt it, it was your starter crying in distress, either from not having enough current to drive it, or not getting the available current into the rotor. Most likely due to low battery, but maybe it needs looking at?

 

I'm charging the new battery right now so I'm hoping it was simply the low battery. Luckily the fuses were popping instantly when I was hooking it up backwards so any damage, if any, was minimal. I rode this thing around right before I took the top end apart and replaced the brake stuff and even then it would sound lazy when starting so I'm hoping it was simply a low battery. We shall see tomorrow... Idiot, out.

 

To be fair your parts supplier tee'd you up to make this mistake, but it was still a fundamental error, hope you haven't fried your tci...
Good luck with it.

 

Alright, so I charged the battery, mounted it and tried to start the bike. It was still majorly sluggish, and ultimately the engine stopped turning, now all that happens is the neutral and oil level light come on. This behavior was visible BEFORE I even switched the polarities like a dumb. So at this point its got to be electrical right? OH also new development, I tried to use a rubber mallet to tap the back end of the fuel tank to seat it onto those rubber studs and now there's a pinhole in the back corner of the tank leaking fuel. Hidden rust in the bottom of the tank perhaps. If so is that even fixable or would it be easier to get a new fuel tank as a whole?

Edit: I don't think this is fixable nor would I want to put some sort of temporary fix on the tank just to have it come apart later or worse, clog all the fuel systems I just replaced/cleaned. At this point I'm at a decision to get a new tank and hope the work I've done to it thus far makes it run or abandon the project and sell the bike. I'm just unsure now.

 

Ok. I am going to attempt to remove the rust on the inside of the tank and seal it with stuff that says it seals pinholes. Its cheap and hopefully it works. I also found a new starter solenoid for 10$ I will try when it comes in. I'm going to work on my other bike next week, this maxim is an emotional rollercoaster.

 

Pull your starter motor and clean it. Checking your carbon brushes and your insulating washers. This may be the cause of the previously sluggish turnover of the bike and the not starting but have neutral and oil light issue you have now.

 

Only one fuse is 20 amps (the main). All others are 10 amp.

What brand of tank liner are you using? Kreem is total crap. Don't waste your money on anything other than Caswell or Red Kote. Use masking tape on the hole so the liner doesn't leak out.

 

So I used a small patch on the outside and put a bit into the hole, forgive me it was JB Fuel Tank weld. Its cured over 24 hours now and appears solid, its also ugly but its at the back corner of the tank where you really wont see it. The cleaner, rust remover and sealer all came together from KBS. I went with that because everyone has their own stuff they use and process and I figured id have less of a chance to screw something up if I went with a package system.

 

I'm working on the tank right now, I got some Red-Kote since it seems well liked. Otherwise I installed the new starter solenoid and now the bike clicks audibly when the ignition is turned but just the Oil light comes on. So I cleaned the side stand switch, bike is in neutral, clutch is pulled out of habit and still just a click. I'm putting the battery on a charger right now just to make sure it didn't die in a week of inactivity but that seems unlikely. Before I did anything electronic the bike barely turned over and ultimately stopped altogether. New solenoid happily clicks away but nothing happens afterwards.

Edit: Solenoid bypass does nothing, perhaps the starter motor being gummed up is why it gradually stopped starting over time.

 

Pull the starter motor and check the brushes.
Replacing your starter motor brushes w/ pics

 

Already pulled and rebuild kit ordered going to seal the tank once it dries out hopefully tomorrow.

 

Awesome news, rebuilt the starter motor with the kit I bought. The copper was completely black along with the rest of the armature and upon cleaning I saw the copper was in pretty rough condition. I sanded it the best I could to make it smooth and replaced the brushes as the old ones were reduced to slivers. Put it back together and assembled to the bike, turned it on and with a bit of praying... pressed the ignition. It turned over at least twice as fast as it used and sounded 10x better! Absolute victory for the night, gas tank is dry and ill be putting some Red Kote in it tomorrow, there is a tad bit of surface rust left after the acid bath in some spots but it says you should be able to put it over some rust and it will seal it.

 

Next you should pull the plug on the outside (one or four), set it against the head and crank it over to check for spark. If by some miracle you still have one, do the same on cyl 2 or 3. THEN put the tank back on. If you don't have sparks you should check fuses, power to coils and tci before condemning anything.

 

Bike is back together and starts strong! No more waiting for the battery to die while starting. I made sure the spark is good as well. Now it's on to tuning! It doesn't seem to idle without choke right now but I only got about 30 minutes to work with it before I had to go to work. I tried vacuum tuning it and I'm unsure if I was lucky or if it simply wasn't set up right but all 4 needles were vibrating in the same direction. I do also have a colortuner that may help me determine if I need to adjust the mixture screws which are out 2 3/4 turns. Adventures for tomorrow!

 

thats a known issue and yamaha makes a fix for it

 

I was able to figure it out with the assistance of another member. The starter motor was in desperate need of a rebuild and afterwards it worked just fine.

 

if you look at the battery schmatic you will see adaptor bars because the original batterys have a different set up on the battery posts then replacments (reversed)
so you end up with extensions on batterys to fit them instead of a proper length battery cable to fit directly. just one of the quirks of yamaha. they could have just offered longer cables for when you replaced the battery

 

Yes the store I got it from was able to give me the same battery but with the terminals swapped. Convenient, although I would have rather gotten the correct terminal setup before I potentially fried my electronics. Its also tight fit but I can still get the covers over it. So a new battery, starter solenoid, coils, wires, plug caps, plugs and rebuilt starter now means the bike starts very quickly which is awesome. It still has the old fuse box which aside from the dust that was on it seems to be working just fine.

 

Update: So I was able to ride it without any issues for the first time today. It takes a bit to warm up but I can ride it with a bit of choke on until its warm and then it does ok. There still must be some kind of issue as I can get it to idle at 1500-2000 rpm no problem but if it falls below that it will slowly die. Aside from that I pulled the spark plugs and they're all very close to being the same condition which is also great! It pulls strong and no longer backfires on deceleration as well! I ordered new tires to put on, Dunlop 404's as the ones on it are from 2007. Overall extremely happy that its come this far. I cant thank all of you enough for the assistance and will be coming back if there are any more issues. For now I'm just going to deal with its little quirks and enjoy the rides.