So, I got a dead #4 cylinder. checked spark, and its good. my compression tester does not fit and the rubber plug is no good to me, so i had a bright idea. I will test to see if the compression is good with my good ole mercury sync sticks before i start tearing down the carbs. so, i hooked it up to the dead cylinder and its pulling a solid 18 hg, which is great. what I was thinking is, this should be a bona fide check on if the cylinder has compression because it needs to be sealed to pull vacuum... I think. anyone want to weigh in on this one. Although i am praying that the carbs are fouled, I really do not want to tear them down again. they were just put back together from a few weeks ago when they were rebuilt and jetted. keep in mind, that this bike had all 4 cylinders running until a few days ago. any vets that want to either agree with my logic or give me a sanity check are welcome to chime in here.

 

Sounds like you are overthinking this.Don't fret,we've all done it.On these bikes,the best way to diagnose a problem is go after the simple things first.It's RARE, I mean RARE,that anything catastrophic happens to these motors/carbs.

What, exactly, is your bike doing?

Don't 'tear down' your carbs.Use Yamaha carb dip if you want to clean them.

 

bro, im a bike mechanic, trust me i know the troubleshooting process. i am not asking someone to help me troubleshoot, im just trying to get a sanity check on my idea about checking for good compression by seeing if the engine makes vacuum. oh, and by the way, if you are troubleshooting a dead cylinder and you dont check for spark, and then compression... then you are missing steps. I know i am getting fuel to the carbs, and it has nothing to do with the petcock, because im using a remote fuel tank. my pump is verified good, and the bike runs like a top on 3 cylinders. so, since i have a spark, once i verify compression, it can only be the carbs. (the whole fuel, spark, compressed air thing.) dont be so presumptuous with people.

 

Re-read my post.

You're the one being presumptuous,all I'm doing is trying to help you.If diagnosing a 'dead cylinder' has you going nuts "trying to get a sanity check",on a public forum no less,then imo you're not much of a mechanic.

Good luck.

 

Please explain to me how Running simple Spark/Ignition/Compression/Vacuum/Fuel checks is over thinking it. the last time I checked my books, those were all of the factors involved in getting an internal gas combustion engine to fire off and run correctly.

Please do tell, what simple things would you suggest? is there some secret way to troubleshoot an engine that is misfiring without checking those things first that i havent stumbles upon in the last 10 years? If there is, please feel free to share with the class.

define catastrophic... If you are assuming that a catastrophic failure would be wear and tear on 15 year old piston rings causing bad compression? or perhaps, you would have me believe that an out of adjustment valve would also be catastrophic? possibly, you could consider that for a 15 year old bike, it would not be insane to presume that before you wasted your time troubleshooting a bike to death that you verify the three factors in combustion would be present is a waste of time? help me out here, because your logic is escaping me.

WRONG! First, if you are going to properly troubleshoot a lack of fuel that is not readily apparent, removal and inspection of the carbs, and jets is most certainly in order. second, if i were an amateur, and i took your advice about cold soaking the entire carb assembly without first completely disassembling it, not only would i have just bought myself a whole new set of gaskets and o-rings, but i would have damaged the hoses and small plastic parts of the deceleration circuit, as well as the choke circuit parts and a host of other plastic/rubber pieces of the carb assembly.

I wasnt going to call you out or blast you, until you called me a ****ty mechanic. people like you **** me off in the worst way. first, you are condescending to other people on the forum. you assume that everyone on here that posts a question is a rookie that needs to be spoonfed information, and have their troubleshooting techniques dissected.

Secondly, you have offered bad/misinformed/assanine information, that could have cost me a lot of money if i had followed it.

Third, this is a public forum, of like minded individuals that like to have a place to vent frustration, and compare ideas as well as a place for veterans to offer a little piece of their knowledge to someone that may be looking for help.

No one knows everything, and it does not make you incompetent to seek advice from your trusted peers on a site that you frequent to offer your own two cents and bounce around ideas. Please, in the future, if you are showing your ***, and someone calls you on it, do not immediately respond like a *****, or you may get schooled. now, if you would like to continue this, you can feel free to either PM me if you would like to move this conversation into a private arena, or you can continue to air out your dirty laundry for everyone to see. Please do not take away from this that i will not be cordial to you in the future, but for this instance, you have incited me, and i felt as if i had to defend myself.

All the best,
Josh

 

quote from above^

"now, if you would like to continue this, you can feel free to either PM me if you would like to move this conversation into a private arena, or you can continue to air out your dirty laundry for everyone to see. Please do not take away from this that i will not be cordial to you in the future, but for this instance, you have incited me, and i felt as if i had to defend myself.

All the best,
Josh"

Nooo keep it public,i'll be watching for sure

 

Switch to decaf,you're wrapped a little too tight.

 

nah, I completely agree with him, and I believe many others will too.

 

thanks kerosene. to KJ, sorry that i was a dick, but i felt as if it had to be said.

 

All I did was ask you a question.

And Yamaha carb dip rules.