Not running well

[Tkosanic]

I just bought a 1983 xvz12 and it is not running very well. When you rev it up the front carb on the left side...the "piston looking thing" on the top (when air cleaner is removed) is not moving and the back carb is back firing when you rev it up. The right side seems okay. I was told it has been sitting since 89 but the last year he was driving to and from his MC club. and help would be greatly appreciated.

[Tkosanic]

so I just went out and did a little test. I sprayed carb clean around the carbs while running to check for a vacuum leak and found out if i hit the exhaust on the left side it burns right off and the right side it wont. thought this may help. Again any help would be greatly appreciated

Edited July 29, 2012 by Tkosanic

[jasonm.]

the carb slide that is not moving....get a thin screwdriver or your finger in where you should see the "taper" and see if it CAN move...is it stuck due old gas? Having a bad slide assy/diaphragm is not uncommon. There are aftermarket diaphragms listed on this site. Or get the slide assy. The assy. I think is close to $100 now for ONE. Maybe remove the ridged carb top too. If it's stuck and you have been running it. The diaphragm can be torn or "holed". Remove the top with a GOOD #2 phillips...not a 10 year old worn out screwdriver. I use replacable BOSCH tips from Lowes. They grip!

[Squidley]

Tom,

 

What I am going to mention is what I do everytime I get a used 1st gen. Start with a complete tune up, plugs, wires, fuel filter. It sounds like the carbs are in need of some serious cleaning, the slider diaphragm sounds like it might have holes in it and need to be replaced. A quick fix for holes in the diaphragm is black RTV and let it set up.

 

Drain the bowls of all fuel and make sure that they are filling with gas. Also while it's running tap on the bowls of each of the carbs, there is probably crud in them. There is a ton of info here on the site about getting into the carbs and such. If you fairly handy with a wrench and not afraid to get dirty, you can get it rolling again. If you have any questions my # is in my profile.

[jasonm.]

Tom,

 

 

 

What I am going to mention is what I do everytime I get a used 1st gen. Start with a complete tune up, plugs, wires, fuel filter. It sounds like the carbs are in need of some serious cleaning, the slider diaphragm sounds like it might have holes in it and need to be replaced. A quick fix for holes in the diaphragm is black RTV and let it set up.

 

Drain the bowls of all fuel and make sure that they are filling with gas. Also while it's running tap on the bowls of each of the carbs, there is probably crud in them. There is a ton of info here on the site about getting into the carbs and such. If you fairly handy with a wrench and not afraid to get dirty, you can get it rolling again. If you have any questions my # is in my profile.

Squidley...please...RTV is not to used in a gas environment. Now matter how lonng it sets, it will come off. :no-no-no:There are other things that are out there that are better. Yamabond 4 is a step up from RTV in a gas environment...but still not great. I suggest doing a search. Maybe sealers for "holed gas tanks"

[Flyinfool]

Seafoam is your friend.

Add a full can of Seafoam to about a quarter tank of gas. and get it running for 10-15 minutes, shut it off for 24 hours to soak and start it up the next day and once a day till it is drivable take it for a good hard ride till it needs gas.

This is the cheap and easy attempt at a fix. If the carbs are really plugged up you will have to pull them and rebuild.

 

Check the diaphragms for pin holes, in the process of checking the diaphragms you can also verify that the sliders are not stuck.

 

If this really sat for 23 years with out being ridden, it will take a lot of TLC to get everything good. You may really want new tires before trying a ride.

[Squidley]

Squidley...please...RTV is not to used in a gas environment. Now matter how lonng it sets, it will come off. :no-no-no:There are other things that are out there that are better. Yamabond 4 is a step up from RTV in a gas environment...but still not great. I suggest doing a search. Maybe sealers for "holed gas tanks"

 

 

I can appreciate your insight, and the RTV is just a temporary thing. If there are holes in the diaphragms, they need to be replaced with new ones. My thing is the RTV will last long enough to get whats needed for replacement and installed. It will also help along with the troubleshooting process. Thanks for the clarification and trying to help Tom along

[Tkosanic]

Okay so I went and got the one slide free. no holes in the diaphragms. Still running the same. Back firing and the left side is not heating up. Ran a can of carb clean thru it already. not really much of a change

[Flyinfool]

I have seen liquid electrical tape used successfully as a a temporary repair for a diaphragm if the holes weren't to big.

 

Seafoam and carb clean will not help a small passage that is totally blocked. Only removal and a rebuild will help that. Seafoam is not the same thing as carb clean. Seafoam contains a cleaner, a lubricant, and a gas drier.

 

Start at the beginning.

Are you getting gas into the carbs?

Open the drain screw to see if there is anything in the float bowl. With the drain open turn on the key, the fuel pump should run for about 2 seconds and gas should come out of the drains. The fuel pump makes a clicking noise when it runs. Mine is pretty quiet so you have to listen for it.

[Squidley]

I have a feeling that those carbs will have to come off and be properly cleaned. Seafoam is good stuff, but if a jet is plugged, Seafoam wont unblock it. Like mentioned, do a tuneup 1st, if your not getting spark, having fuel there is useless....

[Tkosanic]

okay with the carbs exposed...when i spray carb clean down the left side it bogs down. the right side absolutely nothing. no change. i am going to test the fuel now

[Tkosanic]

All the carbs have fuel coming out of the bottom drain.

[Black wing]

ya the left bank if bad is always really bad due to the lean on the kick stand, it looks like a full clean ahead of you. its fairly easy do do but you are looking at about 100 in gaskets to do the four of them.

[Tkosanic]

just checked the spark and it is very week on the right side

[Yammer Dan]

Running carb cleaner thru it will not do the same as a Sea-Foam soak. As stated if completely blocked you will be pulling them but Sea-Foam can work wonders if used as Jeff said. When I do a real strong soak I mix about 2/3s Sea-Foam and 1/3 fresh gas in a container. Close off and remove the fuel line going into the rear of the fuel pump. I use a small set of vise grips here. Most of those old petcocks will break if turned much. If it is set on reserve leave it alone.Using a extra piece of line hook it to rear of fuel pump and put other end in container of mixture. Start bike and run til you are sure all carbs are full of this mixture.Shut off and leave sit overnight or longer. Draining carbs with drain screws will help before you start to add mixture.Expect a lot of crud to come out of the exhaust when you restart. Some Carb Cleaners are very harsh and not good for these carbs. A new set of Autolite 1163s I think the number is will do fine in it til you get it running right. If you foul them it don't cost a lot.Check those Tires!!! If they are that old DON'T RIDE ON THEM!!

[dvuch1]

theres a set of 4 rebuilt carbs for 125 on either this or the other venture forum..check it out before you do your own or have them done

[Tkosanic]

Tire are new. thanks for the concern. it show people on this site really care. i will give the soak a try i appreciate it.

[Venturous Randy]

Check your spark plug caps, they have a built in resistor that can corrode. Just unscrew it from the wire and with a screw diver you can take it apart. Also, these bikes run poorly with the air box off.

Also, welcome to the site and this will be the best $12 you will ever spend on your bike.

RandyA

[Tkosanic]

It has brand new ngk's and ngk wires with new caps

[KIC]

I will tell you how I soaked my 87 after it was parked with gas in it for 2 years by the previous owner. I disconnected the gas line to the fuel pump. added a line to the fuel pump and using a small funnel I poured a very rich SeaFoam/gas mixture into it and let the gas pump, pump it in.

 

But first I drained the bowls using the connected drain lines. Then I drained it again to make sure the Seafoam mixture was in. Let it set for 48 hours. It will run like crap when you first (finally) get it started but a fresher gas/SeaFoam mixture from the gas tank will help.

 

Good luck.

[jasonm.]

I can appreciate your insight, and the RTV is just a temporary thing. If there are holes in the diaphragms, they need to be replaced with new ones. My thing is the RTV will last long enough to get whats needed for replacement and installed. It will also help along with the troubleshooting process. Thanks for the clarification and trying to help Tom along

 

RTV scares me only because I have seen someone leave it in "there too long". It can let go at any time and clog stuff. OK just temporary as a running test...wish I had seen you state that before...cheers

[van avery]

You said something about the right rear backfiring in the original post. I would clean the terminals on the TCI. It's the black box in front of the intake air box on the right side of the bike. (Down under)Clean the terminals on both sides of the connection. That really helped out my 83.

The other thing would be to check the valve clearance.

It gets too tight and can leave the intake valve open too long.

You might also check the vacuum line that comes off of the left front carb and runs up to a small box to the left of the TCI. It like the vacuum advance for the timing. You might have a leak in that line, mine did.

Assuming that the bike has been setting that long the YICS system is most likely still there. It is a cause of vacuum loss too. Most people have already removed that from the system and plugged the vacuum ports on each cylinder.

Good luck and welcome to the site, best $ 12 I spent. Lots of very helpfull people.

[Tkosanic]

Alright I really want to thank all of you for your help. I have narrowed it down to my front right cylinder with no spark. Pulled the plug and it is as clean as when it went in. Where do I go from here

[Power Trippin]

If that spark plug is clean, (not wet or black or white, just looks like new) then that cylinder is not getting gas. You will need to remove the carbs and take them apart and clean them. Or, buy the carbs that are for sale, that someone else mentioned. If you have never cleaned carbs before, I recommend to have someone do it for you, or at least have someone help you do it. Also, if the gas in the tank has sat in the bike as long as the bike has been sitting, you are going to want to get that gas out and add fresh gas. If the gas has a turpen tine smell, it is no good and will only cause you more headaches, even after your carb problem is fixed. Good luck and welcome to the site.

[Rickaroo]

I second the recommendation to give the SeaFoam a try. It did wonders for my old sweetie when I got her from the previous owner (who didn't really do much in the recent past to keep her up)