Please help figure out what's wrong?

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KrashKrieg

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Can't start it up...Thought I had leaky head gasket.


Pulled Cylinder and this is what head looked like...yeow...Is this real bad?


Head gasket was leaking...I cleaned off the head (pic shown) and put back together with new gasket but still won't start...


I get spark, compression, pulls cleanly, all other gaskets are good, bolts are tight...ring seemed OK but in the first pic you can see it's opened a little wide so I had to bend back in slightly & re-install..should I replace ring?


Is the Head Dead?... :confused: ..
 
If you get good compression, I doubt you would have to replace the ring. Maybe bad gas? Is there any sign of damage to the head?
 
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What did you have to bend back? And what head do you have? And it looks a little rich. You may try new plug even if yours is getting spark.
 
Hey Krash, hows the inside of the cylinder look? No major marks or scoring? Try a new plug, reset the needles to factory, double check your fuel lines are on correctly, and check your coil gap. If she wont fire after that try dropping a few drops of oil premix down the plug hole and seeing if she will fire then. If it does then its not good.
 
are you sure about the compression? buy the looks of that first pic you have serous "blow by".. where as oil is being pushed up thru the ring. it might feel ok, but if your getting absolutly no fire, it might be compression. now if you had to bend back the ring i would dought it will get a perfect compression seal. to check try putting a teaspoon of 2stroke oil in the head, (thru the spark plug port). it will be tuff to pull but it will give you a temporary compression seal to get it fired up. you'll only have a couple of pulls as the oil will shoot straight into the pipe, but it should fire on the second yank.
 
Obeast44 said:
Hey Krash, hows the inside of the cylinder look? No major marks or scoring? Try a new plug, reset the needles to factory, double check your fuel lines are on correctly, and check your coil gap. If she wont fire after that try dropping a few drops of oil premix down the plug hole and seeing if she will fire then. If it does then its not good.
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That is some sound advice right there. Oil in the plug hole will also help start a flooded engine. In a warm engine that won't start, adding oil then it does start is a sure sign of low compression.


I also have a Tech page on my site with some info on engine starting troubles. It's a work in progress but most of it is done.


http://www.dogpileracing.com/scripts/openExtra.asp?extra=11
 
Thank You Everyone ! This forum rules!...


It’s fixed!...Let me run through a bit of the feedback for others to learn from as well…


First off, it was definitely the head gasket first….


it didn’t look like it was leaking bad, just some darker looking dirt than other areas around the gasket.


When I first took the head off I knew that was it…


I’ve never pulled the head on one of these engines,


so when pulling the head I thought the ring bent a little,


when I pulled it off, it liked slightly caddywompus..and wouldn’t slide back into the cylinder


so I bent it slightly in and it looked good/ flat…


I reinstalled and it didn’t start, but it seemed like I was getting good compression?>>


No head damage (stock 26cc) Cylinder looks smooth, spark good (new plug as well),


all other gaskets good, primed right, Had just reset coil gap when changing gasket.


Thanks for the great tips on compression checking, it’s real good to know for future troubleshooting…


But in this case, I pulled it apart again, changed the Piston Ring and it worked!!!


Sooo to sum up it seems like the head gasket leaking was causing the ‘blow by’ and the ring was damaged on removal,


unless they were both an issue…I have less than 4 gallons on this engine though, can a ring blow out when this young?


Thanks again to all that replied, great stuff to keep an eye out for.
 
krashkrieg said:
I have less than 4 gallons on this engine though, can a ring blow out when this young?
Thanks again to all that replied, great stuff to keep an eye out for.
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You bet ya it can. The air filter and how you take care of it has alot to do with it. My personal race engines get a new ring about every two races and a new piston about every 4 races. $6 ring and $2 gasket and a chance to do some wrenching is money well spent. Glad to see you got her fired up again.
 
Underdog said:
You bet ya it can. The air filter and how you take care of it has alot to do with it. My personal race engines get a new ring about every two races and a new piston about every 4 races. $6 ring and $2 gasket and a chance to do some wrenching is money well spent. Glad to see you got her fired up again.
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Thanks for that...Didn't now and they are pretty easy to change.


I think you meant new head gasket (you said new piston every 4 races)..


Since I don't race; How many tanks would your approxiamate 'a race' to be?


For more future knowledge; Could just a blown head gasket cause the burn marks I had (see pic #1 above) if I knew the ring was very new let's say?...
 
krashkrieg said:
Thanks for that...Didn't now and they are pretty easy to change.
I think you meant new head gasket (you said new piston every 4 races)..


Since I don't race; How many tanks would your approxiamate 'a race' to be?


For more future knowledge; Could just a blown head gasket cause the burn marks I had (see pic #1 above) if I knew the ring was very new let's say?...
Click to expand...
I ment new piston.LOL Keep in mind I race oval and being an engine builder offering services I have to be at the top of my game when I race. It is what sells engines for me as well as customer support. When I race my engines are at thier peak. They are also wide open throttle for 20 minutes at a time. This kind of maintenence is not required for bashing. General bashing with good a good air filter set up I would estimate a new ring about every 15-18 tanks and a new piston every other ring until the cylinder shows signs of wear. results may vary depending on conditions. Black discoloration below the ring is caused by blowby/ loss of sealing by the ring. A bad base gasket will not cause this directly. It will however let dirt into the motor causing the ring to wear very fast. Allso keep in mind that I race only Zenoah engines and different brand engines will vary depending on the quality.
 
Thanks again for the excellent info...


I use the HPI filter setup with an Outwears over it and clean it /re-oil every gallon or sooner if running in lots dirt..


So the dirty head was caused by the gasket but always change the ring at the same time as head gasket because dirt wears the ring faster.


Great lesson!
 
Agreed in racing where a failure is not an option its a good a idea to frequently change the rings and or pistons. And agreed there is no set time frame for any of these parts to fail because we all drive differently, under different conditions, different fuel mixtures, and with different setups.


With that said Krash I think theere is 3 tanks in a half a gallon. So (assuming Im remebering correctly) so 4 gallons is about 24 tanks. If your engine is not ported/lightened/storked/etc. Id say it might be a slightly little premature. Id expect 30-50 to be in the normal range if the engine is stock. Rings and gaskets are so cheap though its really preventative maintence any way.
 
ya, so it was a compression issue. 4 gallons seems a little shy, but its kinda hit or miss. depends on how ya run though. they are so cheap it certanly don't hurt to have some on hand... i personely have gone way past the 8gallon range on a beater rig. glad its up-n-run'in
 
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