Plug reading what is wrong and what to do? pics here

i would not run it anymore , 110 and deposits on the plug , it could be rounding off the piston,, on the exaust side , once it sneaks under the ring then cylinder damage will occur , maybe the crank seal did not seat well on that side ? wont cost you anything to pull the y pipe off and have a look . hope its something simple Bud !!!!
 
yea if he suspects theres engine problems i would too,we need to know whats going on here,engine truble or just fuel issue???
 
I would clean and double check all of the circuits in the carbs and blow them out with compressed air. Were the needles settings changed at all from last year? If so put them back "IF" the needles were set richer before. Your fuel issues may be linked to clutching and not jetting. We ALL may be overlooking something here are the carbs synced or out of sync? and the cylinder with the low compression NEEDS to come apart before you completely burn a hole in the piston and contaminate the crankcase bearings with shrapnel that will destroy the crank bearings.
 
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dude do not run that motor any more, right now, you may only need a piston,pin,rings, if you run it you will need way more once it grenades, please prove me wrong pull ypipe and look in cylinder and at piston, did you run double oil? did you use stock cast pistons,or after market forged? was it total rebuild or just top end?
 
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UPDATE.....pics

Ok it is apart. I am not sure what is going on here..... one good and one bad.
I would love to know what did this with only 100 miles on the rebuild..

What do you think to it out. also if you have time and want to talk about this you can call me on my cell anytime at 717 629 7237.

Here are the pics....

To many to list here is the link.....

http://s689.photobucket.com/albums/vv254/j_k_auto/97 YAMAHA VMAX 600 PLUGS CYLINDERS/
 
Yep that's ugly. 100 miles huh? Total rebuild or just the top end? If you only did the top end I'd suspect the crank seal assuming that you had been through the carbs and such already.

What was the reason for the rebuild 100 miles ago and if it was due to a burn down did you find the issue or just slap a new piston in it?
 
Yeah, some major heat happening there I would say. More than just a slight lean condition. The intake side is very damaged as well indicating the entire piston was hot. Crank seal or posibbly cooling issue.
 
Ryan B said:
Yep that's ugly. 100 miles huh? Total rebuild or just the top end? If you only did the top end I'd suspect the crank seal assuming that you had been through the carbs and such already.

What was the reason for the rebuild 100 miles ago and if it was due to a burn down did you find the issue or just slap a new piston in it?
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The reason I rebuilt the top end only was that both pistons melted down on the front and took the cylinders out. I thought is was due to the needles being leaned out by one clip.


Well if this is a crank seal how will you know if it is bad. What marks will you see?
 
ouch ! i would guess that the top ring failed, judging from chips on ports top-bottom, it was not a fuel failier this is a mechanical failier how is crank bearing/rod bearing? if you look real hard you can see the wash on blown piston was the same as good cylinder
 
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When I bought my phazer it ran and idled just fine but used lots of fuel. The floats were set way off. I doubled my fuel economy by resetting them correctly.
 
j_k_auto said:
The reason I rebuilt the top end only was that both pistons melted down on the front and took the cylinders out. I thought is was due to the needles being leaned out by one clip.


Well if this is a crank seal how will you know if it is bad. What marks will you see?
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A way to check the crank seal is to have the motor running and spray carb cleaner by the seals (mag and pto) and the motor will noticably change tune if the seal is bad.
There is alot of detonation going on in that cylinder. Whenever you tear a motor down it is EXTREMELY important to make sure that ALL of the gasket surfaces are spotlessly clean (base, intake and Head) when re-assembling. I even take a fine flat file and double check that the machined surfaces are free of burrs and nicks. If you had an air leak on the base gasket you will run lean, also if you had an air leak on the intake you will also run lean, also The twin motors have a notorious mid range lean spot. Plus if you are trying to make a twin as efficient as a triple on fuel you will never achieve this task as the twins are naturally hard on fuel. What is your jetting set at?(please post)
Which side of the motor is the port for the fuel pump?
 
When my crank seal was bad I had already torn the engine apart so I couldnt run it to test for a leak. I found that tearing a motor apart is not as hard as we make it out to be. Take your time and recount you steps and youll be all set. Judging by your name you must have som automotive backround so split the case replace seals and replace piston with rings. That would be my advice. Good luck!
P.s. When I removed the crank seal on clutch side voila! The crank seal has a spring that holds tight against the crank and the seal had a rip about 12mm long. It was very easy to tell that was my problem. Ill tell ya I felt a lot better my next trip out after the rebuild.
 
Thanks guys for the help so far. I am going to rip it apart and see the seal and go from there. I am going to take pics and post them in the same file where the cylinder pics are........ ;)!
 
Same one

Joe, is this the same sled that blew up last year that you were thinking about parting out? I know you must be frustrated after recently rebuilding the top end and I'm not trying to be a prick here but you really need to consider the most reasonable solution. DON'T FIX IT. PART IT OUT. Yamaha twins of this vintage are underpowered gas hogs and prone to detonation. Cut your losses sell off the parts and buy somthing else.

Madmatt
 
Madmatt said:
Yamaha twins of this vintage are underpowered gas hogs and prone to detonation.
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When.........not tuned in properly,,mine are living a looong healthy life and getting respectable gas/oil mileage.
 
I expected this

When.........not tuned in properly,,mine are living a looong healthy life and getting respectable gas/oil mileage.

How do you guys do that quote thing?...never figured that out. I don't really want to get into a big argument on this but you HAVE to admit that these twins are not the best thing that Yamaha ever built to say the least. "Not tuned in properly"??? Take a look at the wash on the good piston.....a blind man could tell you it's plenty rich. I don't care what the plug says, look at the piston. Assuming that Joe didn't screw up the carbs there is obviously somthing else going wrong with this thing for it to detonate like that when it's pig rich. I've been through it myself....I had a 500 then a 600 twin. Once I got a tripple I never looked back. OK Daman YOURS might be "living a looong healthy life" but this one is blown up for the second time in 100 miles. Now you guys are playing the guessing game...."maybe it's a seal, split the cases, it's not that difficult" blah blah blah.....all on a 13 year old sled that might be worth $1,200 if it were in perfect condition. All I'm trying to say is that if it were me I'd say its time to pull the plug. Just curious...but what do you consider "respectable" mileage? 8-9mpg???

Madmatt
 
wash looks good now but how did it look the other day or last year? things change temps change.

i had two big paragraphs typed out but deleted them this isn't about what's better twin or trip(should have never been brought up Matt ;) ),he has problems that hasn't been found yet and he needs to or part it out like he said.

no arguments here just discussions. ;)!
 
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I agree....no arguments, just discussions. I was just trying to offer a different discussion....my opinion on what to do with the sled.....what I would consider if I was in his shoes. Not one person mentioned my perspective which I feel is valuable in this case. I don't think I'd roll the dice again unless I found somthing difinitive like a totally screwed up crank seal. It's too bad he didn't do the ether crank seal test the first time he rebuilt it....might have saved himself a few $$.....or several $$. That motor is hurt bad. He needs a cylinder, head, piston, rings and he still doesn't even know what caused the burn down.

Madmatt
 
How do you guys do that quote thing?...
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after you paste what you want quoted in the reply box, highlight it and click the quote tag next to the B I U
as far as your problem jkauto, you seem to be in good hands here, with some good leads to check into, and it's up to you to decide when enough is enough, i'm stubborn and dont like to throw in the towel but that's just me
 
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