possible cause of meltdown? mrviper?

cylinders arent ported. cant check squish cuz the whole motor is in pieces waiting on parts to rebuild. i will hang on to them, but unfortunately one is destroyed
 

I bet you could sell the 2 good ones. I can also almost guarantee the head has been cut down. Swirl cutting the combustion chamber is very old technology and most believe it does nothing. What what your compression at before?
 
good luck on the rebuild. I hope you can get it all back to stock specs and ride it again.

Would check the jetting too. stock 01 jetting was spot on.
 
You can tell the heads were cut pretty good by looking at where they connect to the water rail. I had a set a long time ago that were cut .030 that looked just like that... minus the goofy swirls LOL
 
are you going to re-use the 2 good cylinders and salvage another good one from somewhere? A fresh top end to boot and you'll be riding.
 
just looked on ebay at heads and you are right, the blue paint should be there. so with cut heads, dont you need higher octane gas? and thus using 91 would have caused my meltdown?
ya i need a cylinder, 3 heads, all new pistons rings and needle bearings, complete gasket set.
have the whole motor polished now, pvs cleaned, everything nice and shiny. just waiting for the $1200 for parts! should have them ordered this week
 
Just thinkin out load here...If you cut the heads, you are decreasing the head cc's for higher compression. In doing so you get more power but need better fuel to resist detonation.

I would think that the swirl cut would somewhat counteract the cut head by adding the volume back in the combustion chamber, but the sharp edges of the swirl, I would think would create extremely hot edges and cause detonation.

I almost want to call photoshop LOL!!!

Hopefully someone around here can tell us the actual meaning?
 
Call CB performance parts in Illinois or Port Yamaha in wisconsin for your OEM Yamaha parts. I know CB will ship USPS and give you a much better deal on parts then you will ever find in Canada. Many on here would agree with that.

Bruce @ CB is a vendor here on the site. Yea there is always Ebay and craigs list to find the heads and cylinder. I recommend posting a wanted AD in the classifieds for a set of 2000-2002 stock heads and a stock 2000-2002 cylinder.

There is no way you should pay that much to rebuild your motor. You looking at more around $700 to $750 for the used cylinder, stock used heads and new top end parts by the time you have bought everything you need. If your looking to save even more, there is nothing wrong with a good set of used OEM pistons that are within specs if you can find them. Just buy new rings and wrist bearings
 
that was my initial thought. the weird grooves help get back the displacement lost with the cut heads. but that would cancel each other out and be a complete waste of time. no photoshop, this is real, and real weird...but theyre definatly cut so i think ive found my problem as to why it melted. i keep refreshi g this page hoping someone figures it out lol
 
im not getting anything from ebay. but i priced the parts at a yammie dealer here in canada:

3 pistons, rings, circlips, bearings
3 exhaust donuts
complete gasket set
895 plus tax. an extra 60$ if i want it within 7 business days.

plus now the cost of a cylinder and 3 heads, used of course
 
Call bruce at CB performance in Illinois on Monday. Tell him you are on here needing new top end rebuild for 01 SRX. No tax either I don't expect.

(847) 662-5916
 
awesome buddy thanks a lot. hopefully someone on her can tell me if those heads may have blown my motor, cuz if not them then i still dont know the cause, and am skeptical on putting it back together without knowing
 
The heads are the old "turbo" design deal, supposed to swirl the mixture for more complete burn. They also did that to crankshafts saying it moved more air thru the case to make more power.

The heads were definitely cut and likely remachined but "to what" is anybodys guess. I wont say thats the cause of a burndown because I cant see the rest of engine nor do I have any specs to work off of other then 135lbs of compression. If the squish is set tight, then with a mere 91 octane I can see you getting some detonation, depending on jetting also but as for saying thats what caused it would be jumping the gun in my opinion.
 
ok thanks mrviper. jetting is stock, 9801srx measured ports and theyre at stock specs. he is going to give me some old gaskets to check squish when i get the bottom end back together, hopefully can find out more then

i dont know how much material is supposed to be left there where the base of the head meets the combustion chamber,but there is next to none, maybe half a millimetre. but i guess were talkin thous when it comes to that stuff
 
matt, if you want you could put the crank back in the case without seals or sealer on the halves ,one piston on with bearing and pin (don't need the clips). i found a good used cyl gasket so we could check the squish before you get your parts . just going by our crude measure last night i think the heads are flat cut about .015" compared to the damaged stock one i have here . i could bring down some measuring tools to see if the squish angle has been changed and to get the squish clearence so maybe don could give some more informed input to weather these heads are suitable for pump gas or not.
 
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