Need Help - Blown Engine!!!

filo_bedo said:
If the rings were installed incorrectly do you think this could have led directly to the problem? I dont ever recall my friend telling me to look for the T when we put them on so I am...... I just talked to him and he said he looked at them and could not find a difference so he assumed all the rings were the same. I am guessing it is highly unlikely that without looking for the "T" on the rings that all rings were installed correctly.
Do you think this could have directly led to this situation or not?
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I would say the rings had little or no contribution to your melt down, although they should obviously be installed correctly.

What were the weather conditions when your sled quit? What is your elevation above sea level[can get that from local airport if needed]
 

i really dont think it would cause what you have here you burned up (lean) you may have snagged a ring or had low compression from installing up side down!
 
lol let your friend live this time but if he doesnt know that theres an up side maybe you should do this work yourself with manual close by or find someone
 
Hi 9801 SRX.

Ok that makes sense but let me ask you this. All of last season I ran the same jets and lets assume fresher gas because it was not sitting all summer, despite the fresher gas at the time, I never had this issue. My question is would the greater compression combined with the leaner jets cause this as oppsed to lower compression with the leaner jets? In other words, the jets were the same last year but I had no porblems? I know there was some older gas in my tank this year but how much would the compression have played a roll in blowing up?

I appreciate everyones help. I am totally willing to put the money to rebuild this sled but I want to make sure I dont make the same mistakes twice and definetly not end up with the same result twice!
 
Hi Matty

In order to snag ring or have had the ring come around to a port, that would mean that the rings would have to be misaligned on the piston to begin with, correct?
 
filo_bedo said:
I will try and answer all questions as best I can

The main jets on the sled were 147.5 and 146.3. These jets match the stock settings in my SRX shop maual. Are they correct? Mr.Viper do you think I should use larger jets? I will need to look for the size of the pilots, I did not see any identification on them.

We did not measure the gap on the rings - I will do this on this install. I did use all Yamaha parts including rings assuming they would be quality parts within spec. My bad

Airbox is stock and not modified

Carbs appeared to be in overall good shape. There was no crap in the bowls, the only flaw we could see was the pilots somewhat plugged. The idle on the sled was always ok though.

Is there a way to test the base head gasket for air leaks?

All fuel lines were untouched from last season so no kinks and gas was topped and the tank was full although partially old gas from last season was still remaining. I will check the fuel line filter.
Could it be a bad fuel pump itself? The sled did run fine for 75kms with what seemed to be lots of power but could it still be a bad pump not pumping enough at higher RPM?
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Good morning Filo, well with your recent information, you have definitely found your problem, your jetted leaner then stock, those jet specs are from a 2000 srx manual, a 2001 used a richer setting and even yamaha sent out a service bulletin telling 2000 owners to use the newer 2001 richer main jet settings. This coupled with your old gas was the death sentence in such a short time of running. The reason it ran fine in the 75kn trail ride is you were never on the main jet circuit for long enough, all carb circuits overlap and you use the pilot and needle circuit almost 90% of the time, its not until its a very long stretch or heavy load do you get to the main jet circuit alone. The lake is the main jet circuit, hence burned pistons.

Its NOT the fuel pump, oilpump,ring end gap,carb boots, crankseal, tail light lens cracked, rings upside down,etc, its too lean of jetting and stale fuel combo.

for future referance if you look closely there is a "T" marked on the rings, this points up when installing them, the top and second ring are the same.

I stick to my first diagnosis.

Remedy: replace the main jets with the proper 2001 specs,drain out all the fuel and refill with known fresh fuel, put the old stuff in your truck or car. Repair/replace the topend as needed and you should be out riding again. If all you do is take 1 thing away from this bad situation its always clean the carbs and use new fuel every year BEFORE you start up the sled.
 
filo_bedo said:
Hi 9801 SRX.

Ok that makes sense but let me ask you this. All of last season I ran the same jets and lets assume fresher gas because it was not sitting all summer, despite the fresher gas at the time, I never had this issue. My question is would the greater compression combined with the leaner jets cause this as oppsed to lower compression with the leaner jets? In other words, the jets were the same last year but I had no porblems? I know there was some older gas in my tank this year but how much would the compression have played a roll in blowing up?

I appreciate everyones help. I am totally willing to put the money to rebuild this sled but I want to make sure I dont make the same mistakes twice and definetly not end up with the same result twice!
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with your report of only 115 psi of compression, its likely the reason someone before you has jetted the sled down, and why you were able to ride it last year with no failure. Now this year you added compression(this makes more heat in a engine) and still had the lean jetting,and stale fuel combo, poof there goes the pistons.
 
WOW....Well thank you for everyones help. It was a painfull and expensive lesson well learned.
Never again will I not clean my carbs or change over fuel before the start of a new season.

When I rebuild this....
Should I add oil to the fuel for the first tank or not?
What is the easiest way to empty the fuel in the tank?

Thanks again for everyones help....especially viper and bob!
 
easiest way to get the old gas out is use a siphon, I have one with a shake/ball mecanism in it, you just shake the hoes up and down and this little ball mechanism on end of hose makes the vacum siphon and it will drain all the old gas into a gascan for you. I have seen them for sale at like tractor supply stores also.

no, you dont need to add oil to the gas.

good luck Fido, I know how painfull and expensive it is to repair your mistakes, but its a lesson you have taught yourself and will never forget. Its all just spilled milk now, just learn from it and repair and ride!

Have a safe riding season, and Happy New Year!
 
Hi Chevy.... I emptied my box. Sorry about that.

I can't take pics until later this week because the sled is disassembled at my friends shop a couple hours from here. I am heading there tomorrow night. What kind of pics are you looking for?
 
My second piston closed the plug cap as well. But not #3, its just looked melt. When this happened to you, what caused you to "eat your rings"? Piston no 2 has a huge score on the wall now and the jug will be replaced. Both heads are eaten up and will be replaced as well.

I am about to order the parts and rebuild this on the weekend, so any expeirience you have had first hand would be apprecaited. Your kind of describing what happened to me.... What did you do the second time you rebuilt it to prevent it from happening?
 
I found that if you install the rings the wrong way(upside down) they won't compress all the way in order to slide into cylinder.When I rebuilt my SRX about 2 months ago..the first ring I installed wouldn't compress to the stop.Then I turned the ring up and seen the "T" marking.Then the ring would compress to the stop pin.So even if you think the rings were upside down,you should of had a hell of a time trying to install piston into the cylinder..so you probably installed them right.But you must check ring gap prior to this also..GOOD LUCK!!!
 
Bluemonster....you are right. My buddy confirmed that all the rings were installed the correct way because when he tried to install them the "wrong" way, they were very difficult to install and even more difficult to install on the jug...so that makes sense.

Chevy I will check the pistons and see if the ring locating pin on the piston is still there or not. I am assuming you mean the little notch in the piston slot that the ring slides into which holds the ring in the right the location, correct?

Can someone please confirm the jugs I need are 8DN-10 for a 2001 SRX.
Also how can I confirm the pistons I buy are for a 2001 SRX and not another year of SRX or do the pistons not matter?
 
go to a Yamaha site and check the parts Fiche for your year and parts numbers.A lot of other parts sites also have these same parts Fiche.I would say the pistons should be the same..but check the right year of sled to make sure.
 
bluemonster1 said:
go to a Yamaha site and check the parts Fiche for your year and parts numbers.A lot of other parts sites also have these same parts Fiche.I would say the pistons should be the same..but check the right year of sled to make sure.
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i think 2000-up got a little extra coating on the skirt of the piston ;)!
 
yes 2000-up cylinder and jugs are the same ...98-99 got a little different porting
 
Do you know if there is a difference between pistons for SRX models? I would 2000 and 2001 are the same, but what about 98 and 99 year models?
In other words how do I know a piston is from a 2001 model or does it matter?
Maybe I will just buy new pistons from Yamaha
 
filo_bedo said:
Do you know if there is a difference between pistons for SRX models? I would 2000 and 2001 are the same, but what about 98 and 99 year models?
In other words how do I know a piston is from a 2001 model or does it matter?
Maybe I will just buy new pistons from Yamaha
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98-99 doesnt have coating on skirt but they work in every year ..
 
it was running lean ...burn the top till it hit the ring and then crunch crunch crunch
 
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