2 and 3 cylinders not firing?

Hello guys. After pulling my carbs and giving them a through cleaning, I have noticed that my bike has very little power? By power I mean "get up and go power". After a 15 mile ride I tested the header pipes with my hand and found that the number 2 and 3 pipes were not hot. My question is where should I start troubleshooting the problem? I am thinking it is probably carb related? I will pull the plugs today and try to take pictures to post and maybe see if they are fouled.

Thanks for all the help guys!

 

Don't quote me on this because I really have no idea..but I believe 2 and 3 fire off the same coil, so could be something with that. I'm sure the guys that know what they're talking about will be along shortly to help you out, and more than likely they'll find something carb related.

 

When I first started working on cars and the like, my dad gave me the best piece of advice: if anything goes wrong with something you're working on, double-check the last thing you did to it, because you probably did it wrong. That's pure wisdom, there, and it's saved my bacon on more than one occasion.

That said, why not help us out with a little history. Why did you pull the carbs in the first place? What did you do to them while you had them off. Did you find anything unusual inside the carbs? Did you bench synch them? Did you synch them after reinstalling them. Did you accidentally unplug one of the coils when you had the tank off? Did you remember to reinstall all the boot clamps? Stuff like that.

Good luck,

 

I removed the carbs due to the bike not wanting to start cold. I found a bit of tarnish in the float bowls, and cleaned out the enrichment circuits which were clogged shut. I did remove the floats and float needles, but these parts were replaced and seemed to move freely. I also did the clunk test on the pistons, they clunk down good. None of the coil wires were removed when the tank was off. Like I said Ill pull the plugs today and get a few pics.

I also have pod filters, I know thats important.

 

Could be carb related, but where it is Cylinder 2 & 3 giving you the problem, I would check the coil, they are fairly easy to test

 

Were the 2 and 3 pipes at least warm? If its the coil (electrical) then you would probably get no spark at all and the bike would be unrideable on only 2 cylinders, and pipes 2 and 3 would be cool, if its fuel related then you would likely have some combustion if the fuel is starved, and the pipes would be warm. Check the obvious like float levels - easy to do with short clear pipe.

 

The pipes were warm, but nowhere near as HOT as 1 and 4. Ill be checking the spark tomorrow after work, couldnt get to it today. Hopefully I can make it to MiCarl's shop this week.

 

Heck, if Carl's on the case you're in good hands. He'll have that thing fixed up in no time at all.

 

He is literally like 3 miles from my house so Im gonna swing in this week.

 

Sounds like you've got bigger fish to fry than a sync and Colortune.

Weather looks good tomorrow PM. Bring it over and we'll see what's up. Them maybe we can tear up Hines Dr.

 

Swap the Coils Plug-in's to the wiring harness.
If the problem shifts to 1 & 4 not firing ... you have an Ignition related issue.

I hate to keep playing the same music ... but, the Old, original Fuse Panel is probably dead ... so, get a New one and do the Upgrade Mod of your Fuse Panel when you two guys get together to solve the mystery.

A MoTown Tune-up at MiCarl's is probably just what the Doctor ordered!

 

Let me know what is happening because my bike is doing the same now... 2 and 3 not firing

 

Ok guys heres the latest:

Went to the garage today and tested my plugs, all 4 are good. Ok so now I test both coils. Coil 1 is good ( spark to 1 and 4 cylinder). Coil 2 gets no spark at all to # 2 and 3 cylinder, so I switch coils and find that when I plug wires from coil 1 into coil 2 I then will get spark to cylinder 2 and 3. So coils are good. I then plugged the coils back in to harness and coil 2 has no spark again.

I think i might start smoking again if I cant get this bike figured out.

 

Sounds like a bad pick up (if I'm following your test description correctly :?).

 

I'll add that to test the pick-up coils, here's what the service manual says:

To test the pick-ups, locate the plug at the TCI which is located under the left-hand side cover. The TCI will have two pigtails. The one you're interested in will have four wires: black, orange, gray, and brown (should be the lower of the two pigtails). You'll want to Ohm them out and see if you get the specified resistance between them. I don't have my meter handy, so I'm not sure if brown is paired with orange or gray. You'll just have to test between them.

Hope that helps,

 

Do I gather these readings with the key turned on? Turning over?

 

I'd be cleaning the Pick-up's with Q-Tips and Alcohol
Checking the resistance of the Pick-Up Coils
Cleaning the Plug-In of the Pick-Up's to the Harness
Cleaning the Contacts of the Harness to the Ignitor
Cleaning the Contacts from the Harness to the Coils
Ordering the new Coils from Dyna.
Installing the New Coils for this Summer!

Why not ... they're 25 Years Old.
Get rid of the Fuse Panel; too.
That's dead!

Am I right?
Have some fun ... fix the Bike right!

 

Rick

I have the upgraded fuses installed

I guess I start checking the pickups now.

 

Any suggestions on a decent multimeter?

 

Radio Shack or Sears. You can get one for under 20-Bucks.

 

NEVER OHM SOMETHING OUT WHILE POWER IS APPLIED.. Unless it's a relay that simply clicks over and no power is on the line.. You're meter will act like a short and probably blow the meter or short through ur heart if you happen to touch the leads and kill you... or you'll arc weld the leads to the item you're checking...

Looking at the schematic with the bike OFF... brown from the coil is tied to a black wire (shared ground prob).. my tci has 2 blacks (one with a white stripe - tied directly to the kickstand relay), an orange, and a grey... i ohmed from the solid black to orange and got 632 ohm.. from black to grey and got 1232... so my pick up coil is most likely shot on one side?.. bad brushes? . either way.. I ordered a used one on ebay (guaranteed good shape)... I wish i had a schematic of the TCI so I could take it into work and check it..

I would spend .50 (home improvement store) and get a acid brush with isopropyl alcohol (walmart)... q tips tend to fall apart and leave cotton everywhere and can't get inbetween things

 

So do I test Ohms with the key on or off? Sorry for the noob questions, I know nothing about all this electrical stuff.

 

OFF! My bushings were rusted and there was a screw missing off the cap from the previous owner.. resulting in a glob of oil in the bottom of the cap.. I cleaned it with alcohol and sand paper... but no spark on 2 and 3.. I think the bushings are worn down to nothing.. they are flush with a plastic holder.. I just switched the coil wires and I still get spark on 1 and 4... so I'm thinking it might be the TCI.......... unless the 1200 ohms is too much resistance to provide voltage to the TCI... either way.. I just tore out my TCI... going to bring it into work to check the diodes, caps and transistors... The only way I could get to the inside of it is with a dremmel destroying the case (no big deal... i got plexi glass to make a new one).. yamaha really doesn't want anyone in there.. they seal up the heatsink screws



Weird part of today is it's training day in the Navy... and I have to give a lecture about Anger Management.... lol...

 

Keep up the good info dustball. I just got the multimeter and will post all results tomorrow after I test.

 

Anybody got a spare NON working TCI that I can have?? I'll pay shipping

 

Ok so after the Ohm test I have found that both readings wer right around 628 Ohms. I removed the TCI box and found that if I shook it, it rattled.

New TCI ordered. Hope thats the problem.

On a side note......I also had my carbs off drilling out stuck drain bolts. Ended up sticking the drill bit into my thumb!!!!! :x I broke the drill bit and the easy out bit twice. Time for a new float bowl.

 

You broke the easy out pulling the drill bit from your thumb? :wink:

If you haven't got all your screws out, try heat. Works wonders.

 

Ya I tried my torch but no luck at all, this thing is in there. I got 1 but no luck with the second. MAy need a new bowl from chacal.

 

I have always used a good amount of heat and my SEARS Craftsman Hand-held Impact Tool and have managed to get those stuck Drain Screws out 90% of the time without too much trouble.

I did lose one, one time ... when I applied a little too much Impact and fractured the Bowl.

 

That is key. Aluminum pulls heat away from the area very fast.

 

I replaced the pick up coil.. so it ohms out to 632 on both sides.. but, it turned out to be a bad coil pack ... #2... I tried to twist the boot all the way on where it meets the spark plug... it kept twistin.. so I tugged on it and it just came right off... got a used one on ebay and bike fired right up on all 4..

 

Awesome! Does this mean we can meet for a ride (if it ever quits snowing)?

 

hell yeah... lets go to canada and get some cuban cigars

 

Just wondering what happened to this thread, just kind of stopped with no result. I bought a 83 XJ750 Maxim to do a bit of work on and resell. My neighbor saw it and wants it so there goes the profit.
Anyway, I was having trouble with the bike sporadically. When I first got it #1 cylinder was dead. I checked the spark and it was firing, but not very well. I pulled the seat and someone had cut all but one fuse out of the system and tied the wires together. The other one had aluminum foil around it and the wire was very warm. I plan to replace the fuse box.
In my efforts to determine what I was facing, all of a sudden I lost #1 and #4 cylinders, noticing that they were on the same coil I figured the coil was probably bad. I fooled with it a bit more and then lost #2 and #3 cylinders and 1 & 4 was firing. :?:
I checked it a bit more by pulling the plugs and switched them to different cylinders. Back to #1 dead and the other 3 firing. When I first bought the bike I was told that the carbs needed cleaning so I just took them off and have them cleaned except for one of the fuel bowl has a passage way that I can't get loose so far. I have a carb kit on the way.
I just went out to check on the pickup coils as was recommend on this thread. I did not find a brown wire but did find a black, black/white, orange and gray. I checked the resistance and got 647 on between the black and gray, and 650 between the black and orange. Nothing on the black/white. So, I am assuming that my pickups are good. I will have to wait until I get the carbs back on before I can switch the coil harness wires to see if anything changes.

Ed

 

The brown wire is tied to the black... so that is why you didn't find it by looking up top


Sounds right... 647 is a good number.. 700 ohms +/- 10%.. Sounds like you have some make shift wiring going on though.. I recently replaced one of my coils due to it being "rigged" from the last owner... The spark plug boot just fell off after tugging on it (should twist on).. I got a set off ebay and it fired right up on all four..... it's the same coils for the 550/650/750... because of this I ordered a used TCI and now I have a TCI and an extra coil for future troubleshooting if need be

 

Hi dustball,
Yes, my plug wire end for the #1 cylinder fell in the floor when I pulled it off the plug. I will check to see if I can get an new set. Does anyone know who has them? After I get the carbs back on I will check the coils. I took all the plugs out, hooked the wires to them and they all were firing, but seemed to me that they were kind of weak. Although, the plugs look like they are fairly new but were kind of fouled a bit from not firing. Could be that is why they looked weak.

Ed

 

For an update on my situation, I tested pickup coils and found that they are good. I am still awaiting the damn TCI, as soon as I get it (Wed-Thurs) I will update.

 

hurst.. recharge your battery... I've learned that these bikes don't like a non-full charge.. if you are unsure of the plugs.. just replace them.. they cost $2... also, you should put your bike model in your "sig".. so people can help bro...



Philbrewer...I feel your pain

 

Good news, the new TCI works great! Heres a quick update:

Cleaned carbs, bench sync carbs. New TCI, starts right up and idles anywhere from 800rpm to 1200rpm depending on how i set the idle screw. This bike really has some power now, wow! I am sure I need to sync with a manometer now as I get a few pops and soft backfires now and again.

Still canno get that damn brake light figured out tho!