Hello all. I've encountered a puzzle that I need some assistance solving. My bike is a 1997 VLX 600. No mods or custom pipes or anything; everything is stock as far as I know, with the exception of the chain and sprockets which were changed shortly after purchase about five years ago.
I will attempt to be brief and succinct:
I recently cleaned and lined the tank (POR-15 kit followed to the letter)
replaced the fuel petcock (brand new OEM part)
replaced the fuel filter (glass transparent filter from O'Reilly's)
cleaned the carburetor
replaced all spark plugs with brand new manual-specified plugs
Battery is practically brand-new; less than a year old and kept on the tender when not riding
The issue I've encountered is thus: fuel is getting to the carburetor but does not seem to be getting to the spark plugs.
I've checked the fuel line all the way to the carb and it flows great, no issues or leaks, and the fuel pump pumps away very well.
Fuel appears to be flowing well to the carbs because I drained the float chambers by loosening the drain screws and plenty of gas comes out.
Spark plugs all have good strong healthy spark. After trying to start the bike I pulled them out and they appear to be dry and just a little dirty.
I've tried starting the bike with a spark plug out to see if air is reaching it, and I can indeed feel air coming out of the chamber.
I've made sure to check the little things i;e kill switch is on "Run", kickstand is up, bike is in neutral, battery terminals are clean, fuel filter is pointing the right direction, petcock flows cleanly and smoothly
For some reason fuel does not seem to be leaving the carburetor and reaching the spark plug
Mine acts the same way if I do work on the fuel system or carbs. It's almost like the carb bowl isn't full enough. What I do is put just a small amount of gas directly into the carbs, and I mean verry small amount as little as possible. And try to start the bike. It works every time for me. IV just come to think of it at priming the bike. I don't understand why the bike does it but it does.
Negative, bike had sat for quite awhile before all this work was done.
Checked all four spark plugs; they all have good clean strong spark
bigolepit: I haven't tried that priming trick but I have read about it in other threads. If I'm clear on the process it involves spraying/pouring a small amount of gasoline directly into the throat of the carbs?
That is correct. As little as possible though so you don't flood it and you might get a backfire if you put too much fuel into the carbs. I wouldn't say it's a correct thing to do but I don't see the harm in it and it works
When you say you cleaned the carburetor did you remove the jets and make sure they were clear? Squirting carb cleaner won't necessarily clean them. Nothing is worse on jets than a bike just sitting "for quite a while". Just had to rebuild mine after sitting for a few months. Also possible your accelerator pump is bad on the carb. Looking into the carb throat and twisting the accelerator you should see a pretty healthy squirt of gas. If it will start by squirting gas in the carb throat then the carb is surely the problem. I'm unfamiliar with your bikes carb but some have an adjustable float needle valve. The fact you are getting gas to the bowl doesn't mean the gas level is okay
I'd go back and look at your A/F screw passages. If you have fuel to the bowl, you've got enough to reach the A/F passages even with an improper float level setting, which is what you're starting on at no throttle. Also verify you have no air leaks either before the carbs or between the carbs and cylinders.
You can use a little spray of carb cleaner or better yet some starting fluid. A small amount sprayed into the carb.
You seem to have all the right ingredients. And as well as timing, compression needs to be good. You might actually test compression since it sat for years the rings may not be sealing well. Shoot about a teaspoon of motor oil into the plug hole to help seal the rings. If the compression is low the vacuum will be also, and that could effect how much fuel is drawn in. But not a very common problem.
Best thing is to have a jumper battery while you test and try starting so you can be sure there is plenty of crank amps.
Swifty is spot on. Starter fluid is a "tell-all" tool. By spraying some directly into the air box and turning the motor through with the starter button your actually simultaneously checking compression and valve train, spark as well as carb condition in the most basic way possible. If its fires quickly than more than likely you issue still lays inside the carburetor(s). Try it out and get back to us!
You're absolutely right! It's confusing (and lazy) to use technically incorrect and inconsistent terms when discussing very technical issues. Henceforth "carbs" it shall be.
I will try the starter fluid method and the carbs priming method.
I'm also considering pulling the carbs off and cleaning them again. Since the carbs are going on 20 years old, would ya'll recommend doing a rebuild kit on them?
Most simple rebuild kits are needle and seat, O rings and bowl gasket. Or you can get the complete kits with new jets. Depends on the condition of the jets and how much you want to spend. And if you want different jet sizes.
I just tried the starter fluid method: I removed the air filter and sprayed the starter fluid into the airbox
This video captured the results of one of the attempts to start the bike:
Another attempt, after the first and with much more starter fluid sprayed into the airbox:
After the second video, I sprayed quite a large amount of starter fluid into the airbox, and the results were very similar to the second video except a lot more "firing up",and it actually responded to increased throttle like it was about to roar to life, but did not. Unfortunately I didn't capture it on video... My bike battery is now recharging, getting ready for another try tomorrow.
Question: Would it be possible/safe/a good idea to connect the bike's battery cables to a running truck's battery via jumper cables in order to increase the time of trying to start the bike? In other words, to have a truck supply a steady source of juice directly to the bike (just bypass the bike battery) while figuring out what the issue is, not having to keep removing the bike battery and recharge it
Yes you can jump it with a truck battery but you don't need it running , you just need more crank amps for a few starts.
I looks like you are right that fuel is not getting into the cylinders even with fuel in the bowls. So either the floats are too low or the jets are plugged. Are the mixture screws out a few turns at least?
"After the second video, I sprayed quite a large amount of starter fluid into the airbox, and the results were very similar to the second video except a lot more "firing up",and it actually responded to increased throttle like it was about to roar to life, but did not. Unfortunately I didn't capture it on video..."
There is your answer! Don't over think this.
I know you "cleaned the carbs" but there is still something plugged up or still not right internally. The test you just did verified this.
I checked the float valve and it was pretty cruddy. I cleaned it with a stiff wire brush and it looked nice and shiny after. I checked the float level with a standard ruler and it seemed to be level. There's a crack in one of the carbs' throat, caused by using a flathead screwdriver to help "drive" it down into the boot. It still seats in the boot just fine, and appears to seal with no air leaks.
The float valve was pretty cruddy, so I used a stiff wire brush to clean it and it came out nice and shiny. I checked the float levels with a standard ruler and they seemed to be level. There's a crack in one of the carbs' throat, caused by using a flathead screwdriver to "drive" it down into the boot. It still seats in the boot fine and appears to seal without any air leaks.
I put the carbs back together and back on the bike. I sprayed some starter fluid into the air intake and tried to fire her up:
I also gave it a little bit of throttle when pressing the starter. After many tries that drained the battery, I hooked it up to my truck battery. No additional starter fluid, just a little bit of throttle when pressing the starter:
You can hear me pressing the starter without throttle, then the difference when I do apply a little bit of throttle
I pulled the plugs after to see if they were getting wet at least; two seemed dry, one seemed damp, and one was wet with some dirty gas or oil on it
When you had the jets out did you run small diameter wire through all the holes? That makes sure they are fully open to flow fuel. Also it may be that the old dried up fuel sediment has clogged up the passages that the jets screw into, so the fuel isn't going into the carb body to get into the venturi. It does look very cruddy on the jets and the passages can be restricted too. You will need to "rotor rooter" all the openings and drillings in the carb body. But do it gently so as not to change the size of the factory drillings and ports.With the jets out you can spray carb cleaner through each passage to see the flow. Protect your eyes though.
I used a piece of electrical wire to clean all the jets .Add or subtract strands to get a size that fits. carbs and passages plug up when they sit a long time.Pull the needle and seats out to check the screens .
I used a very small-diameter sewing needle to clean the jets' pinholes until I could see daylight through them.
I cleaned the length of the jets with carb cleaner and a pipe cleaner until I could see daylight through the far end. Sidenote: I'm not sure if the slow jets are plugged up real bad or not, but they both have some sort of obstruction inside the "tube" that prevents my pipe cleaner or my needle from passing through the entire length. The obstruction is at the exact same depth in both slow jets and prevents visible light even after squirting carb cleaner and poking at it with my needle. Maybe some kind of Honda-designed bottleneck to restrict fuel flow through the slow jet?
In the meantime, I'll perform the recommended cleanings and inspections. I'll be back with an update soon
I just cleaned my carbs completely. What I did was tear them completely down (one at a time so I didn't cross parts) and soaked them in chemdip for about 30 minutes. You can get it at any auto parts store in a gallon bucket. Scrubbed it all with a nylon bristle brush after I took it out and blew it all off with my compressor including in all pathways and through the jets aswell. I'm not a big fan of putting anything inside the jets that could scar the inside walls and disrupt fuel flow. If you go that route and seperate the carbs you will have to sync the carbs once there back on the bike and that's a easy job if you have the gauges to do that.
As Swifty said make sure all the openings on the jets are open especially the low speed jet. Double check your diaphragms for pin hole leaks. I always replace the float valve when I open up a carb. Depending on where the crack in your carb is it could cause problems, if you can seal it up with something like JB weld with out affecting any of the carb components I would, you don't want air being pulled into the carb from somewhere it shouldn't or fuel leaking out.
I separated the carbs and broke them completely down. I then soaked each carb in chemdip for a few hours. I inspected all diaphragms against light for pinholes and did not see any. Both vacuum pistons have some faint scratching and wear on them. Not sure if they should be replaced yet.
I bought two kits and replaced the float valves, valve seats and filters in each float chamber. I also replaced each float chamber O-ring.
The carbs are now back together; I plan on reinstalling tomorrow and if all goes well then I will construct a carb sync tool and sync these carbs together.
I'll check into the JB weld thing tomorrow as well.
Question: to my knowledge the pilot screws have never been adjusted or messed with in any way from the factory settings (plugs still intact). Is it necessary to adjust them now after cleaning and replacing parts?
Thanks for the advice
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