Cylinder not firing?

I just got my carbs tuned using a home-made carb tuning tool, whic btw, was cheap and easy to make, and works friggin GREAT! However, I still have some running issues. After letting it idle for a while, it has a slight up-and-down movement, very subtle, but if you pay attention it's pretty easy to catch. So i drove it up and down the road by my house for a while, stopped, licked my finger, and hit each one of the pipes.

From the seated position, left to rigt, the first three sizzled, but not the last one. I suspect that the cylinder isn't firing properly, but I haven't taken this beast apart yet and am somewhat hesitant to do so until I know what I'm looking for. I don't have any compression gauges and was wondering if there is a better way to test if the cylinder is firing than spitting on it....Any and all ideas would be appreciated. The only other clue I have is while I was riding it I had it in second gear and slammed the throttle down, once it got to 6,000 rpms, it bogged down and wouldn't go any more...not sure what that means....

I live in a christian-based drug rehab, and the maintenance guy used to be a harley mechanic. He was helping me with my last bike, but it died, so I got this one. Even with only 3 out of 4 cylinders firing ( I think ) it's impressive. However, I was looking at getting a 2002 Harley sportster, 850cc, and made the mistake of telling him that. He was completely against me getting this bike, and insists on telling everyone I have no idea what I'm doing, it's never going to run properly, etc.

The people that had it before me by-passed the vacuum part of the petcock and installed a shutoff valve straight from the tank to the carbs. I forgot to turn it off the first night I had it here and it flooded the carbs and leaked out.

He insists that it was being modified to race and probably had some remote airplane jet fuel or some such put in it, which he says would make the rubber tip of the float valve swell, causing the flooding. I tried to tell him it was because its a gravity powered gas line now, and if you leave it on all night, of course it's going to flood the carbs and leak out.

I'd like to know if I'm right, if anyone has an opinion I'd be willing to hear it. I'd really really like to get this thing running perfect so I can show him the best bikes do NOT have to be Harleys, and I don't need his cranky old ass to fix this thing.

Oh, btw, he keeps telling everyone my bike is a fire hazard and will possibly explode....so I have to park it in the middle of our huge backyard at the moment.....f***ing asshole....

 

Run the "Simplified Test" for Spark.
Undo the Plug Cap and Plug-in a Spare Plug.
Ground the Spare Plug to the Head and look for the Spark during the Test with the Engine running.

If the Plug misfires with the 1/4 Coil plugged into the 1/4 Connection from the Wiring Harness ...
Swap the Coil Connections and see if the 4 Hole Fires and the 3 Hole misses.

(1/4 into 1/4 ::: 2/3 into 2/3 = 4 Hole missing .... Swap for test)
Test:
(1/4 into 2/3 ::: 2/3 into 1/4 for testing:
4 Hole fires 3 Hole misses: = Coil, Wire Cap related problem.
4 Hole miss 3 Hole fires: = Carb, Cyl or Valve related. Ck compression.

Compression Quick Test:
Thumb, Dowel, Heavily taped handle to block Spark Plug Hole
Crank Engine and see if finger / object is forced-off Plug Hole.
Yes = Incouraging
No = Bad news requiring further testing.

Good Luck.

 

What model bike do you have? You can put this info into your signature line, and use location feature so if anyone is close they can help you.

The gravity flow of fuel will only go to your carbs and 'normally' be stopped by the float valve when your float rises and seals it shut, but it's unlikely that 'airplane' fuel or any other such notion caused your problem. More likely you have a sticking float or your float needle valve isn't seating properly and this could be caused by multiple reasons-dirty carbs most likely or float valve assembly may have issues. Your going to need to pull them off and do a complete cleaning/inspection. If you can restore your petcock to working order (vacuum feed) I would do that as well.

Have you changed your oil/filter since it flooded? You probably have fuel in your oil from overflow going into the crankcase-change it ASAP. Best way of checking your cylinders is the heat check. Compression test is a good way to determine health ($20 at Auto store for tester), but if you had decent power on 3 it's likely that compression isn't the problem. From previous experience I'd say your float level is set wrong or your pilot circuit is clogged on your cold one (little or no fuel is reaching it). Carb mods can cause problems too like pod filters w/o rejetting.

Your 'maintenance guy' is wrong about these bikes-they run just fine and are more reliable than any Hog could ever be, although Hogs are silly simple so they require less intelligent mechanics. These older classic SJM's suffer from clueless previous owners who don't ask questions before they screw stuff up. So you're already ahead of the game and will prove him wrong in no time. You seem to have a good grasp of mechanics and just need to do the proper maintenance and your bike will be fine.

Your bike would only be a fire hazard if his 'cranky old ass' goes over and smokes nearby! You could always drain and remove the tank so he couldn't bitch and get it back where it belongs while you work on your carbs.

There will be more advice to follow and it's tried and true-if you follow it your bike will be up and running and you can ride past his old ass and smile! Keep asking any questions you might have and use this site to research what you need to do. You can use the 'search' tool and read through tutorials about maintenance and carb cleaning. Enjoy!

PS - sounds like the rehab needs to work on the old cranky one and give him some Christian values. He should be encouraging you-not shooting you down-I.M.H.O.

 

What you'll read, here, in the posts to follow will all be good advice,, but can be a bit discouraging.

You've got some work to do!
You'll need to set your priorities and find a place to work, indoors.

I'll give you: Job-1!
Before you start doing anything which you'll read needs to be done to get you up-and-running, ... GET A MANUAL!

Preferably, a Genuine Yamaha Workshop Manual --> specific <-- to your bike.
Other Manuals will do but cover material you don't need that might make things confusing.

The Manual will have a schedule of Maintenance you need to perform.
All the items on the list will need to get done.
Having the BOOK will guide you through the process.
Plus:
Teach you how.
Show you how.
Answer every question which may arise.

Get your Signature Section filled-out with Thumbs on the bike.
Those who are here to help you need the following information as your signature.

<>Year<>Model<>Total Miles<>Stock or list Mods<>Location<>

Also use the Location feature.
You might find a Member is your neighbor and can offer to help.

 

Fix the carb thats flooding when the taps left on first, as there is a chance that may also fix your running problem.

There are also some recommended maintenance and safety items that should be checked before riding, but i'm sure you will find them on here, they seem to be repeated every 11th post.

 

Some basic intelligent logical troubleshooting might help, as would knowing what bike you're working on; I couldn't find it.

First off, a cylinder requires compressed fuel air mixture and spark to run.

Compression testers are cheap; you can pick up a nice kit at AutoZone or Sears for under $30; or borrow/rent one from the auto parts.

Start with a compression test, so we know what's going on with the motor itself.

Then investigate your plug wire, plug CAP, etc. Since each coil fires two cylinders, only one being dead narrows it down.

If fuel leaked out or leaked anywhere, you do need to check the crankcase for gasoline. Take the oil filler cap off and smell it; it should smell like toasty oil NOT reek of gasoline.

Finally; the advice you've been given to get a manual is solid; you're going to need one. If all of your carbs' float valves were functioning correctly, accidentally leaving the fuel supply on overnight should NOT cause any sort of fuel leakage. While not a good idea, if the whole system is working correctly it won't cause a problem.

You DO have carb issues; but without some further diagnosis, it's impossible to say if the cold cylinder is necessarily directly carb-related. It could be anything from ignition to carbs to a dead tight or sticking valve.

Guessing will get you nowhere.

 

[quote="backlash1818]Just got a 85 maxim 700 for 500 bucks.[/quote]



This quote is from his other post about an electrical problem.

 

changed my signature.....took a ride today, starts bogging down hard around 4k rpms....starting to think the float valve could be the issue, although my fourth pipe still doesn't get hot. hopefully i'll get some more time later to do some checks, but thank you all for your advice, its extremely useful!

 

PODS......

First thing I would do is pull the carbs and see what jets are in there, if you haven't already.

 

You really need to check the valves and get a compression test; if that's a "neglected motor" it could explain your problem. If you KNOW it's only running on 3 cylinders, quit riding it; all you're going to do is hurt it, it won't "heal itself."

 

I guess Harley boys will never learn that there are other good machines out there. I started with a Harley as a young man-loved it, but later on I moved on to better machines. I personally think that the biggest problem with the Harley boys is that after they put all those $$$$$$$$ into their Harleys they are afraid that if the don't brag them as the best that they just may depreciate in value??? All kidding aside the Harley is a nice machine but I definitely would not say the best. Years ago I gained a great respect for the BMW's but if I ever get the time to dive into my XJ 750 Seca I can see the potential of a very fine machine there also.
You put your Sweat into a bike and it becomes a part of you-how can a guy hate himself? grunt007, 81 Yamaha 750 SecaR

 

well, I did a compression test today. Never done one before so I'm not entirely sure I did it right....

I took all the sparkplugs out, checked the gap while I was at it. They look new and not dirty at all

I hooked my compression tester up to each one and hit the start, got 120 psi, give or take a few, on each cyclinder, although number 2 was about about 116 or so.

What I noticed as I took the plugs out was that there was some gas on the rim of the hole as I took it out, so I'm assuming that my carbs are indeed severely flooding.

I've been trying to avoid taking the carbs apart, as its a fairly complicated maneuver, and there are a pretty decent amount of small parts to loose and things to mess up if your not careful.

That being said, I'd like to check one more thing before I go that route. While I may have a float needle issue, I'm wondering if perhaps my air-fuel mixture is badly off....I have individually aspirated carbs, and my petcock has been converted to a gravity-fed hose, with a shutoff valve in-between the petcock and the carbs...I'm thinking the petcock stopped working so they did that, or they were going to convert it into a race bike but never finished

So with the gravity-fed gas line and individually aspirated carbs, is there a chance my air/fuel level is out of wack? Or should they still not flood even if that mixture is very off?

 

Oh, and thank you all for the support and help. This forum is much better than the one for my vulcan =)

 

120 for the comp numbers is on the low side, but not terrible.

However, I suspect you have fuel in the oil, which will:
A, thin the oil and make your numbers low do to the fact that the rings aren't sealing properly.
B, not provide adequate lubrication to run the motor, causing major engine damage.

The fact that the plugs "look new and aren't dirty at all" leads me to think you have a lean condition, caused by, PODS which is why I suggested taking a peek at your jets inside the carbs (you will see this is a recurring theme)

I think we have already established that you do have a float needle issue.

The in-line fuel shut off will have no effect on your carbs IF you shut it off every time the bike is off. If fuel flows to the carbs while the bike is off, AND you have a needle valve issue inside the carbs, then yes, it will flood the carbs, engine, and crankcase.

You have multiple issues going on. It would be best to start from square one and clean/rebuild the carbs.

Then you need to check the valve shims, set fuel level, make sure it's running on all four cylinders, re=sync the carbs.

Then you can start getting them jetted properly to run on those pods.

The carbs are really not that bad.

And you definitely need a manual.

EDIT: oh, and if the oil has fuel in it, get it out of that crankcase before you cause more damage.

 

100% SOLID advise on all counts
just my opinion-but if I was going to add anything it would be ditch the pods and get an air box or get a big bottle of aspirin
Regardless either way, pods or no the advise above is dead on

 

So I got some oil and a new filter today, should be able to change it tomorrow sometime. I think I definitely have gas in the oil, was riding it to the store to get the oil (she's my only transportation) and went to change to 4th gear, didn't catch and revved the engine nicely. I grabbed the clutch and eased it back into 4th and she took it no problem.

I got an extra two quarts of oil so I can do the change, let it idle for a while, then drain it and refill it again, hopefully with the idea of getting the gas out completely.

After the oil change I'll be pulling the carbs and checking the jets and float valve. I met a guy today who is currently in school for motorcycle mechanics (MMI) and he's worked on several xj700's.

He was going to test my generator, but the quick connect plug thing has a melted pin, so he couldn't get a connection. I'm hoping thats the problem with my battery not being charged as I ride,but I'm not sure.

So after i change the oil and check my carbs, set the float level, ect...how do you check the valves? I've never checked valves for anything...my last bike (vn750) had HLAs (Hydraulic Lash Adjusters) which automatically adjusted your valves for you. I'm assuming I'll need some gauges of thin pieces of plastic (shims?) to check the settings properly. Also assuming that a local bike shop would have those. Although I hate doing all this assuming.

Also, getting the carbs jetted properly for the pods was mentioned.....Does this mean I need a jet kit or something? I was kinda hoping that since the pods were already on the bike that the person who installed them hadre-jetted the carbs....then again, it looks like a half-finished,half-assed project bike anyway, so I could be wrong.

Thanks again for all the help guys!

P.S. No more riding till I fix the carbissue and change the oil, don't want to damage the bike any more than it already is.

 

When you pull the carbs to clean them, write down the number on each jet in each carb. Reference these to the manual to see if they are the stock jets for your bike, and keep them in a safe place for future reference.

You can never assume that a PO knew what they were doing when the touched the bike.

 

And for the valve clearances you will need some basic tools, a metric feeler gauge set, and a new gasket.

I don't have a book for the 700, but check out this post will give you a basic idea of what is involved. Your manual will give you all of the specifics.

 

I'll take PO's jack s**t up for 400 alex