Trouble shooting. Engine starts but dies. Carbs? Piston rings? Charging system?

Prisondawg

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Ok. So I've added many parts from a 78 special to an 83 frame with an 82 engine. By adding a solid state reg rec a TCI box and a single coil I managed to get the bike to start, eventually I got the thing to drive, I was driving it around my neighborhood and it was pretty joyous. However , it died at some point. Now it will start (after many kicks) run for a few seconds at best and die. Initially we took the seat off and noticed the ground has come loose when the nut vibrated out. And was just sitting there. We added a new nut but still couldn't get it going. My next suspicion was the battery charge which was dipping below 11 so I charged it back to 12.5 still not will not stay running. It also was backfiring pretty loudly like a firecracker. Which prompted me to pull the carbs re clean everything, I also did my best to adjust the butterfly valve so no light peaked through when they are shut. One of them closed better than the other however and I couldn't get it any tighter, but it was better than it was before and it was running. I put it back on the bike (I adjusted the cam chain tension while I had the bolt off) but still couldn't get my bike to stay running. It starts runs and then dies.

I've recently added fresh oil and an oil filter

It has gas. And it's getting into the bowls.

I just cleaned the spark plugs with a wire brush and changed the wires and caps to the yellow performance wires and NGK resistance free caps from Mike's XS.

When cleaning the carbs, I noticed a lot of putting in the cast of one one of the carbs.

Looking into the clymer manual , it suggests that if the carb isnt the cause it may be the piston rings so I suppose a compression test is next in line for diagnostics.

It seems that there is a lot of backfiring happening and I've seen a few puffs of smoke shoot out the left carb.

Here are some pictures

Please help me get this thing on the road. Any advice is welcome IMG_20180821_164331.jpg
 

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you need to be absolutely meticulous in cleaning and setting up the carbs if its ever going to start and run reliably .
 
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Ok so you drove the bike so carbs do work. Now charging system probably not so much. Download the charging guide on here and go thru it step by step. If it worked and after a while it died and wouldnt start again thrn something is up for sure. Get a good charge on your battery cause the stock TCI system requires good voltage to run good then check off items one by one. If you dont thrn you will be running in circles and buying parts for no need. I just went thru it all.
 
Ok so you drove the bike so carbs do work. Now charging system probably not so much. Download the charging guide on here and go thru it step by step. If it worked and after a while it died and wouldnt start again thrn something is up for sure. Get a good charge on your battery cause the stock TCI system requires good voltage to run good then check off items one by one. If you dont thrn you will be running in circles and buying parts for no need. I just went thru it all.

I wonder, I think I think I need to replace my brushes, I haven't had time to take them out and check their length. If I charge the battery to 12.5 and try to start it, wouldn't it make sense that it would stay running until the battery charge depleats? Or does the charging system need to be intact? Because even at a charge if 12.5 it starts and dies quickly . It's leaking oil out the front base of the head. And when I kick it sometimes it feel like it has a ton of compression, other times it feels like it has much less. I'm going to do a compression test on it soon but I feel like it might be the piston rings . The carbs did work, it only stopped running after it was driven after sitting for God knows how long.
 
Yes, it should stay running until the battery charge depletes. To get both butterflies to completely close while doing a bench sync, first you must back off the idle adjustment screw on the left carb so it isn't touching the cable arm. One plate will always remain open if that adjustment screw is touching the cable arm.

The way it cuts out abruptly sounds like an electrical issue. You've added many "fresh" parts. I'd go back and check all the electrical connections for them, particularly the coil and TCI connections.
 
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Yes, it should stay running until the battery charge depletes. To get both butterflies to completely close while doing a bench sync, first you must back off the idle adjustment screw on the left carb so it isn't touching the cable arm. One plate will always remain open if that adjustment screw is touching the cable arm.
That's good advice, I had another carb on another bike, I cleaned it and put it on, the butterflies were closed, and it didn't have that gross pitting in it. Which did seem to help it start, but it still dies, could it be the piston rings ?
 
If the rings were bad and compression was too low as a result, I don't think it would start and die like it is, it probably would be very reluctant to start at all.
 
If the rings were bad and compression was too low as a result, I don't think it would start and die like it is, it probably would be very reluctant to start at all.

What do you think is the cause then? I've seen fire shoot out the tail pipe, smoke shoot out the carbs. Backfires as loud as a gunshot. It'll start to idle and if you try to rev it you hear the carbs sucking in air and then it just dies.
 
Sounds like you may have some bad air leaks. You said you swapped in different carbs, BS38s, but did you change the intake manifolds as well? The 38s use different ones than the 34s.

I assume you will be running pod filters? It also looks like you have a different exhaust, 2-1 maybe. Your carbs are going to need to be re-jetted for those mods.
 
Sounds like you may have some bad air leaks. You said you swapped in different carbs, BS38s, but did you change the intake manifolds as well? The 38s use different ones than the 34s.

The carbs are exactly the same. The bike hasn’t an 82 engine, but the p.o. had bs38s on it. And the ones I had from my parts bike are from a 78 , maybe the manifold on the 82 engine is wrong ?
 
I don't think the wrong carbs would even fit in the wrong manifolds. Let's assume they are correct because the bike was running for you, for a short time anyway, and probably ran like that for the last guy. But, the manifolds could be bad, cracked and leaking. Unfortunately, you have to get the bike running to test for that.
 
I don't think the wrong carbs would even fit in the wrong manifolds. Let's assume they are correct because the bike was running for you, for a short time anyway, and probably ran like that for the last guy. But, the manifolds could be bad, cracked and leaking. Unfortunately, you have to get the bike running to test for that.

I could swap the manifolds from my parts bike. I had idling pretty well before it apart to build the new one .
 
Yes, that's worth a try I guess. While the carbs are off, check/set the float levels if you haven't done so. These carbs are pretty particular about that setting. You should probably also check and record the jet sizes so you know if they have been changed. You can fix the sync too.
 
So
Yes, that's worth a try I guess. While the carbs are off, check/set the float levels if you haven't done so. These carbs are pretty particular about that setting. You should probably also check and record the jet sizes so you know if they have been changed. You can fix the sync too.
I swapped manifolds , and the noticed there wasn't any gaskets, after adding the gaskets it's running again. I was going to check the volt meter on the battery to see if it goes up when I rev it, but the volt meter was going crazy as soon as I turn off the bike the meter went back to normal, this bike must be putting out some kind of electric field all around the bike, but just not back into my battery where I need it.....
 
Not saying that this is your problem, just a few of my many experiences.:) I put two digital voltmeters on two identical bikes with the same type of alternators as the XS's. With the stock reg/rec's the meters would go whacko, flip to zero and blank screen, and then normal with decent voltages for the RPM's being revved, alternating whacko and normal. After doing the automotive reg and ebay rec mod described by Pamco Pete on this forum and others...……...those same voltmeters are rock steady now. I used the Fiat regulator and the cheapo rectifier from ebay.

Scott
 
Not saying that this is your problem, just a few of my many experiences.:) I put two digital voltmeters on two identical bikes with the same type of alternators as the XS's. With the stock reg/rec's the meters would go whacko, flip to zero and blank screen, and then normal with decent voltages for the RPM's being revved, alternating whacko and normal. After doing the automotive reg and ebay rec mod described by Pamco Pete on this forum and others...……...those same voltmeters are rock steady now. I used the Fiat regulator and the cheapo rectifier from ebay.

Scott
I've seen some talk about this in other posts, I'm interested in trying it out, I have to find solid instructions for the 1980 up reg/rec. Hopefully that and new brushes will cure my charging problems.
 
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