Fouled Plugs! Calling All Gurus! What Carbs do i Have?

[browntown]

hello! It appears i am in a dysfunction relationship with a 39 year old yamaha. i have a TX650A.... i think. (It appears it was laid down at some point and some parts must have been damaged and replaced...ie. gas tank is from a special maybe???) anyway, to the matter at hand. my plugs are fouling. here they are: now i have been searching and reading a ton to figure out what i am doing wrong. so here is my theory. i am running rich. i need to change settings in my carbs. especially the right one. so i ordered a rebuild kit from mikes. i got the one for the tx650A. i should have done more research.... because these two pieces were not like the ones in my current carbs. the gasket wasnt quite the same shape, and the metering needle was a few millimeters shorter than what i have

so i figured i dont have the carbs i think i have. so i have been scouring the carb guide and the german translation bs38 carb identifier (i am sooo confused) but here they are. i cant find any markings on them, i have looked, but i figure i must be missing something.

it seems to me from my reading of the carb guide that i need to have the correct settings of the carbs i have, and not necessarily the model year of the bike.
was my carb rebuild kit wrong? do i have the original carbs? are these for the tx65A?

when i have new plugs the bike runs like a dream for about 10 miles and then it starts getting funny. it starts to idle high and then the right side starts sputtering and soft backfires (not a crazy loud backfire, but a backfire nonetheless). it then dies and i have to push it home. sometimes with the chock on i can get it to sorta run and limp home. (i stay close cuz i have been having this trouble, so i am usually only a block or two from home)

is this a carb setting issue?
is my ignition system not supplying enough spark after it warms up?
is the right side fouling from oil getting past the rings?

this is the stuff keeping me up at night for the last year

please help. i need to know where to start i have eliminated other problems that were getting in the way. replaced leaking vacuum petcocks with manual. took off loose airboxes that werent sealing (between or on carbs) with pod filters.

 

[gggGary]

What pods did you put on? Lots of cheesy pods MAKE carb problems. Then...look at the charging system. Get a volt meter on it, should be 12.5ish off 12.7ish idling and upper 13s to 14 when you rev it. There are some great bought an XS now what? threads in the tech section, and lots of specific how to trouble shoot fix X threads, do some basic troubleshooting, feel free to post back with your results and advice on what to look at, fix next.

Welcome to the forum!

 

[browntown]

The same problem was there, and the same before the pods. It actually seemed to last longer before fouling out with the new pods. Got about 8 miles before. They are mikes xs 53mm pods (15-0033)

It really does run sooooo good( IMO, but I am new at this) for about 10 miles before it all goes to poo and fouls out so bad it won't run.

I don't have a volt meter so I guess I'll make a trip to HF and then scour and scout how to use it. I figure that info is on here too.

And thanks for the welcome, I'm here a few times a day for the last year. I really need to figure out how to search better, cuz I'm sure my answers are here, I just can't figure this out.

Can you tell which carbs I have? Do you know what I should look for?

 

[gggGary]

Also in tech is the charging system thread.

Probably the the correct carbs for the year, they are early anyways. Gotta go see what year "solex" was last stamped on the lids. My 73 carbs still say solex on them.

You might work backwards from the brass that's in them.

 

[gggGary]

what's your vin? what color was some of the original tin?

 

[browntown]

I'm pretty sure the tins are not original. It didn't have side covers when I got it. Bought some on eBay, one fits. The fenders are black. The gas tank is black but it only has one petcock (left side) and an right offset gas cap (need a new one, it's worn out and I have to use a bottle cap opener to open it) the vin is 447000838. That's what's on the title anyway. Can't read it on the bike, it's painted over. I'll go look again.

 

[browntown]

here is a pic of the painted over info.

 

[gggGary]

Then it should be what you said; a 74 tx650A

wouldn't hurt to check the engine number, it would have matched the VIN from the factory. It's stamped vertically on the upper case behind the tach drive, by the front engine mount.

Follow the chart above for the 74-75 carbs and see if that matches up to the brass in the carbs.

Stock color would have been a kind of reddish brown though I have only seen pictures of that color.

 

[browntown]

Yep. Stamp says same 447000838

 

[browntown]

Looks like comparing the box I got from mikes and that chart, I must have some of the wrong stuff. Know a good supplier?

 

[jkocr2]

Check your float height on the right side?

 

[browntown]

Float height checked, rechecked, thought maybe it moved on me somehow so I rechecked and then I checked for leaks in the float and then I rechecked again. Checkedy check check

 

[5twins]

You are exhibiting the classic symptoms of a weak spark. Test the voltage at the battery and then at one of the red or red/white wires that feed power to your coils. They should be very close to the same. If the reading at the coils is a few volts lower, you may have found the problem.

 

[browntown]

Got a multimeter tonight. Free. Love them HF coupons. I know, i know, get a good one... but it was free and is doing fine for now. I took out the battery, and it seems as tho this is a toy battery. I tested it and it read 13.2v. I hooked a tail light up to it (that I took off earlier) and ran it for about 10 minutes and then tested it again and it was at 12.1 v and then started climbing back up. Now I gotta clean some plugs so the bike will run and figure out how to check the coils.

 

[browntown]

Is this battery possibly my problem? Do I need a real motorcycle battery? It seems to me like it should do the job, but what do I know. I'm new at this.

 

[gggGary]

check voltage when it's running. lets some a pics of the bike? With that battery it's anyone's guess what all the rest of the charging system is. not using the electric start that battery MIGHT work but the stock charging system rather likes a bigger battery. The early mechanical voltage regulators are kind of meat axe about voltage control, a bigger battery absorbs and smooths some of that fluctuation. Well that's a theory of mine anyways.

 

[browntown]

i think it has an electric start, but there is no button for it to hook up to and i am use to kick starting anyway. it kicks nice and easy, when the plugs arent fouled. the rest of the electrics are a mess. it seems as tho it was all "re-done" at some point. i use quotes because its pretty sloppy. like i said earlier, it looks like this bike was down at some point and got a bit of a resurrection. it might behoove me to start from the ground up on the electrical system. but first i want to know that i have a good running engine. this is tougher when you arent a mechanically minded person, but i am learning.

 

[gggGary]

OK, fine, don't attempt E-start with THAT battery .

Do get it running and check battery voltage at idle and revved to 3K for a bit. it helps to use some alligator clips or an assistant while doing this. With a tiny battery like that you need a battery minder, many now come with leads that you attach to +12 and ground bolts so you can just plug the bike onto the charger, that plug is a very handy spot to check your voltage.....

you should see high 12s low 13's at idle, up around 14 at 3K RPM. Report back with what you find. I still want to see pics. Bikes that have been "fixed up" by PO's often have the strangest collection of charging system components and wiring "schemes" and only rarely do is it all working the way it should be....

 

[retiredgentleman]

Toss out that wimpy minature battery and buy yourself a real man-sized battery. Get a 14 amp-hour lead acid battery. They last 7 to 10 years and will give you instant starts.

Its important to do things in order:

First, repair the electrical system.............all connections/switches checked and cleaned...............a good battery...............alternator/charging system producing 14.1 volts at 3000+ rpm.

Secondly, ignition must be checked that it gives a strong blue spark. Don't try to use really old ignition coils/plug leads/points etc.

Third, only after the first 2 steps are done, its time to focus on a complete check over of the carbs.

 

[XSLeo]

On your carbs you won't find any ID markings. You have to go by the way the enricheners work and by the way the carbs look. By comparing your carb to the BS38Carb ID you will discover you have the either the 306/366 carbs or the 447 carbs. In your pics I can't see if your carbs have the raised floor or not.
If you look into your carbs does the floor of the carb go straight back to the slide and leave a gap under the slide or does the floor raise up so there is very little gap under the slide?
The 306/366 carbs have the raised floor and have different specs because of this.
On carb kits, Mike's or anyone's, Mikuni built many versions of these carbs to be used on many bikes. The kits come with generic parts that fit your carbs but not your application.
The best way to determine if you need parts is to tear down, clean and inspect what you have. Only get the parts you actually need. Saves buying parts you can't use.
Out of the kit the float bowl gasket is about all that can be used.
The needles and jets are not usable.
You follow the steps in the carb guide to tear down, clean and inspect what you have. Once you determine if what's in there needs replacement, then get the exact parts you need.
The 306/366 carbs and the 447 carbs both use a Z-6 needle jet but the 306/366 is longer than the 447 Z-6 needle jet. Won't interchange.
I would put all the stock parts back in your carbs. Then following the tuning steps in the carb guide. Test what you have, the tuning guide will tell you what to change or adjust to fix the problems you find testing.
Make one change, test, make a change test. It takes awhile but it's the only way to get it right.
Leo