whats your diagnosis based on these pics?

tank_tech

Member
Jan 2, 2010
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whats your diagnosis based on these pics? NEW DETAILS!

so i started rippin apart the bike i bought this winter(rml85), i knew the motor was toast when i bought it, but i wasnt sure what it was. now that snowmobilingi s over and ive had some time to wrench on the bike i think its a little worse then i anticipated. i took some pics for you to look at and tell me what you think, sorry about the quality, but if you squint your eyes, and turn your head you can... the cylinder is scored right over the exhaust valves, with one gouge thats noticeably deeper then the rest. there was also a bit of scoring on the intake side as well(maybe 3/8" wide). what do you think caused this? what do you guys think needs to be done to fix it?

to me it it looks like ill obviously need new piston and rings, and either the cylinder bored/honed, or re sleeved. i dont know for sure, because im new to all this, but i think these suzuki motors just need to be resleeved if you cant hone it out? there it one gouge that's noticeably deeper then the rest of the scoring. what do i need to do?
 

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IndyMX

Crash Test Dummy
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Jul 18, 2006
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You might as well box it all up and send it to Eric Gorr..

I believe that's a plated cylinder, so it's going to need to be replated.. And while you're at it, you might as well have him do his magic on the ports.

I'm no expert, but I'd guess it was run pretty lean.

Something got that exhaust port awful hot.
 

whenfoxforks-ruled

Old MX Racer
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Oct 19, 2006
8,129
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Merrillville,Indiana
Detonation killed that engine, that is the exhaust side missing? Some ruff pics is an understatement! What Indy said, and rebuild the bottom end also. Ask if Eric can get you a good deal on a complete engine kit, and send the piston with the top end. Vintage Bob
 

jayhedrick

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Mar 10, 2009
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Yup yup very hot!!! Guessing the ring caugt the tip of the exhaust port and broke that part of the piston?
 

tank_tech

Member
Jan 2, 2010
22
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yes the pistons is missing pieces on the exhaust side.

so this isnt going to be a simple rebuild then...? how much am i looking at roughly?
 

whenfoxforks-ruled

Old MX Racer
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Oct 19, 2006
8,129
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Merrillville,Indiana
Or, a really lean condition up top, like a head gasket leak, or advanced timing? Can you take a pic of the plug, a clear one? The ring did not make the top of the piston come off. In its last minutes it was blowing parts of the piston off, either through the exhaust or a head leak. Vintage Bob
 

tank_tech

Member
Jan 2, 2010
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0
heres a pic of the head with the plug in it. it doesnt look super lean to me, what do you think?
 

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whenfoxforks-ruled

Old MX Racer
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Oct 19, 2006
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Head gasket leak. The plug/pic does not confirm detonation, or the advanced timing. Did it ingest sand, is the skirt scratched up and down? Could have over heated and then the head gasket went. Vintage Bob
 

tank_tech

Member
Jan 2, 2010
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how can you tell its a head gasket and not the other problems? not questioning your judgment, just want to know. thanks for all the knowledge btw.
 

whenfoxforks-ruled

Old MX Racer
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Oct 19, 2006
8,129
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Merrillville,Indiana
The first 2 pics kinda stunk like a tincture of coolant was in the mix, the head pic to me, confirmed it had been burning a small amount of coolant, got worse, and or overheated to the point the stupid p&$ Suzuki o ring head gaskets failed, and air helped finish her off, by a hotter than required flame front, not unlike a plasma cutter(except premix and coolant with a little extra kicker of fresh air) blowing, almost entirely the exhaust side of the piston crown off. Besides, I am pretty sure if that was just hard core detonation, that colored goo on the roof of the combustion chamber, would have fell off, there would have been no discolorations on the head and cylinder top, (bet the dis-colored area matches?), and the plug looked intact, you could have changed it before it died, but that much damage if it was detonation, would have destroyed that plug. IMO, and rusty remembrance of the mid to late 90's. And, the rant about the 85 being a less than great bike, I had one, the head gasket issues made cr's seem like child's play, sorry. It will probably get better, hope you call Eric and send him all the stuff. He likes looking at what happened also! He does not require the long story, just fix it and how fast you want it to go, till he sees the damage himself, rough call on the price. Be real about your needs though! How is the bottom end while you are at it? It got hot also, maybe not as intense, but? Wiseco and quality parts for the whole motor. Best of luck, Vintage Bob
 

tank_tech

Member
Jan 2, 2010
22
0
i had a big long explination of what i found, what i thought, the plan now... blah blah blah, but then i accidently closed the window, and now im too pissed to retype it all. maybe later.

short version. i found that the exhaust valves had malfunctioned, stuck in the idle position all the time. this is what it did. what do you think? i guess ill be taring the hole motor apart now to clean out all the aluminum that is no doubt in the crank case.
 

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ellandoh

dismount art student
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Wow
 

_JOE_

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May 10, 2007
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Suzuki at it's finest, lol. I've seen this happen to others, even big bikes. Worn/broken power valve parts are usually the culprit. Keeping them clean seems to prevent these failures as it's not a large amount of bikes that do it. Have you started pulling the power valve assembly out?
 

tank_tech

Member
Jan 2, 2010
22
0
I havent started taking them apart yet, but im pretty sure i dont have to, because its pretty obvious why they didnt work. a bolt that holds the a control leaver, on the main shaft that controls the valves came loose, or wasnt tightened properly in the last rebuild(about 2 hrs run time before this failure), so there was essentially a spot in the control arm system that didnt allow the valves to open.
 

whenfoxforks-ruled

Old MX Racer
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Oct 19, 2006
8,129
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Merrillville,Indiana
Thats how a leak can look a little like detonation, and blow iddy biddy pieces of piston everywhere you have been. And yet the engine still started. Top end a little past the hour mark? Vintage Bob
 

tank_tech

Member
Jan 2, 2010
22
0
yes, the motor had just been rebuilt a dealership, that was before i bought it, right after the rebuild the previous owner, who i bought it from, slapped a FMF pipe on it, didnt change any jetting, didnt do much of a motor break in, he just started riding it again. he says it was about 2 hrs after he started it for the first time after the rebuild that this happend. I know that previous owner personally, and i know how he rides the crap outta everything, so he probably didnt break the motor in at all really. just jumped on and started riding like usual(workin it hard) because he was excited to have his bike back.
 
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