Expert advise!!

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xs650dude63

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OK all you experts, I have a 1980 xs650 special, with the 34 carbs, the bike has new plugs, wires and the carbs were rebuilt, fresh gas, when I start it, it will only start with the choke all the way out, once it starts it revs to about 3000 rpm's then drops down, it pops a little out of the exhaust, if I push in the choke it dies, if I give it gas it dies. any suggestions??? How do I time a bike like this, it doesn't have points, please, experts I need all your wisdom and knowledge on this one!!! Make me proud! Thanks!!!:banghead:
 
1980 TCI ignition the timing is not adjustable (from the factory) never hurts to check but it's almost certainly fine..
Have you checked for strong blue spark? Never crank a TCI without grounded spark plugs.
Define rebuilt carbs.... There are few good rebuilders out in the wild.

Would suggest you check idle, pilot and choke circuits again. Sounds like it's only pulling off the needle and mains.
 
Hi, what do you mean by grounded spark plugs? I do know how to check for spark. I took the carbs apart and thoroughly cleaned, blew out, ran a little wire through all the jet holes, made sure everything was spotless, used a basic rebuild kit from mikexs. What do you mean by choke circuit? and I don't understand what you mean by "pulling off the needle and mains".

One of my carbs backfired and the bike stalled.

Are their adjustment screws on these carbs?
 
I would suggest replacing the TCI ignition Box, I have a 1981 XS650 Special and it had the same symptoms, I had the carbs off cleaned and back on more times then I could count, check spark (good), check rotor and brushes (good) check compression (good) I check everything I could think to check from fuse box to ground wires, then decided to bought a TCI Box, that fixed it, runs good now.
 
Did the bike start and run before you worked on it ??
more information would be helpful
 
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TCI box, that's interesting, when I bought this bike it was blowing the main fuse over and over, opened up the stator cover and one of those tiny screws came out and was lodged between the cover and the stator, replaced the screw, no more blown main fuses. I wonder if that could have fried the TCI.
Where can I get one? How much is it? Is it easy to install?
Thanks!
 
The TCI Box is located under the battery box, and connected on the left side of the bike up aside the air box. they are screwed (at least mine is under the battery box and can be rusted) go to the classified section and place a wanted ad there, now my was the 6 pin or wire one, if you unplug it you will see the one you need, should be a six pin, the 7 pin ones were for the softy switch to the kick stand.

PS. if you can't get it off, you could relocated the TCI box somewhere else.
 
here is what your looking for:
 

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To answer Peanut, the bike would start when I bought it but continiously blew the main fuse, thats the reason the person sold it to me, upon further investigation I discovered a small screw came loose on the stator and was arking off the stator cover and that was causing the main fuse to blow, which makes me wonder if my TCI was fried at that time also, the previous owner told me the bike ran fine until it started blowing the main fuse.
 
I found me a used TCI unit on Ebay, hopefully it will do the trick, if not it is returnable. I opened up my old one and took a look inside, it looks brand new in there, it looks like nothing is wrong with it, maybe its hard to tell, hopefully that is my problem and the new one will work.
Does anyone know of anybody that refurbs, these things? Thanks!
 
:agree:

trouble shooting is a methodical process of elimination. Eliminate items that don't require spending lots of money first. Buying a random used TCI off ebay is unlikely to fix anything. Then you will be head scratching, did I get another bad TCI or is the problem elsewhere, You will just be poorer, a week down the road with no bike to ride and no better off.
 
Hey gggGary, when you say recheck pilot, idol and choke circuits, do you mean take them apart and reclean them. I'm telling you dude these carbs looked spotless, brand new, I wish I took a picture of them and posted it. So you think the holes in the jets may be clogged, tell me exactly what you would do, remember this is all new to me. And what did you mean by pulling off the needle and mains.
 
I think first you need to do one thing at a time and cross it off the list. You are jumping around like a jumping bean.
Gary is giving you good advise on checking carbs and I would just go over them again.
TCI box is 30 yrs old and why would you go out and spend money on another 30 yr old box?
If you plan on keeping bike now's the time to upgrade to good NEW parts that you know works and is a upgrade.
STOCK USED TCI can go as high as $100
PAMCO or a BOYER ignition may sound like a lot but your done.....CHECK IGNITION off list.
Week spark can cause the problem but if you keep throwing USED parts after used parts you are not going to be sure you fixed the problem.
SO I TELL EVERYONE are you keeping bike or just a fad?
Spend the right money and the value of bike goes up.
You have any private questions you can always get me at DADDYGCYCLES@YAHOO.COM
 
All in trying to help.
pulling off needles and mains...

Idle, pilot circuits are plugged somewhere, the choke or a leaking float valve lets it start, and if you get lucky it grabs enough air to lift the slides a bit so gas can flow though the main jet, taper needle, then it revs, try to idle back, no fuel, it dies. Have you read the carb guide? look up in the tech section read the guide till your eyes bleed THEN go back to your carbs. I smell that maybe someone did a dip type cleaning of the carbs but never really pulled cleaned all the jet passages etc. You ask if the carbs have any adjustment screws??????
BS34s have an idle fuel screw top front, from the factory it's covered with a brass plug. If the plug is still in, the carbs have NOT been "cleaned".

Here's a bit of a riff; you are asking for expert advise (sic) but you haven't done leg work 101, search and read threads containing BS34 every conceivable issue with a BS34 has been detailed to death on here with super detailed pics with arrows, pointers and a detailed description (Alice) . You get familiar with the basics, do the recommended fixes, then if you still are having issues start asking questions detailing what you have done so far, so we don't have to play 64 questions.

One of these days we should do a BS34 specific overhaul thread. It would help the newbies (IF they read, follow it, LOL).
possible BS34 carb issues.
plugged; idle, pilot, choke orifice.
Leaking float valve, or it's oring. plugged float valve screen, mis-set float. leaking vacuum line, intake manifold(s)
bad petcock diaphram,
Usually it's several of these. Fix one issue and the other problems make it run worse, the leaking float valve lets it run with a plugged idle circuit, fun ensues till everything is right. LOL.
Get that all fixed and you still need to do the washer mod to get rid of hte off idle flat spot.
Then there's throttle shaft seals.
I have been through at least 10 sets of BS34's I budget about 5 hours to get a set right, I know all the tricks and short cuts, have a dedicated carb bench and a bunch of special tools made. All that said I am no carb expert there are others on here that are lot sharper than me. You CAN do good job on your carbs, BS34's work great when they are right, but it's not a quickie thing
 
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