[SlammedRanger]

Here is where i think you went wrong. Unless you are a professional machinist or took it to one and didnt say it. When you see scoring in the cylinder that is wear. Not just marks on the surface. At that point you take the cylinder to be measured for out of roundness and wear. The machine shop then tells you what you can do to fix it. Hone and rings 99.99999% of the time dosnt work. There are specific tolerances that have to be met here. This is why when you take it to a machine shop and they say i can bore it without the piston in hand you turn and run! They will taylor make that cylinder to the piston. They will measure for cylinder to wall clearance and account for heat expansion and contraction.

 

[SlammedRanger]

My best guess is the cylinder is in need of a over sized bore and piston. And did you measure after honeing? Cuz the hone does actually remove alittle bit of the metal and could have made your problem worse. I would bet the piston got wedged in a position when doing the compression test and caused those scores with mostlikely the piston skirt. With a piston to wall clearance to big it can do that or worse. Your lucky it didnt bust the skirt off while riding it and send a bomb into your bottom end. The noises you were hearing when you noticed all the smoke i would bet was piston slap. All caused by the same thing.

 

[SlammedRanger]

Best budget friendly build is a 416. Any engine machine shop can bore your stock sleeve from a 85mm to a 87mm. You will want to get gt thunder hd studs which means you will have to send you cylinder to snure interlocking or have your machine shop install them. The other option would be get the 87mm piston of your choice and send it all to snure and have them bore it to match and not have to worry about it being done wrong by a local machine shop. Unless of course you know a reputible one that is. If you look at my signature you will see a very low budget build. My quad sits right next to my brother kfx450 in a drag race. And will beat him on a track. Keep the questions coming and we will get you all fixed up.

 

[SlammedRanger]

Did you scrub the cylinder in hot, soapy water after honing it? Really work at it scrubbing and scrubbing...?

I cleaned it up in my parts cleaner....figured that would be just as good....?

Nope, not much difference than if you didn't clean it out at all. After machining and honing the bore is loaded with grit. The amount of grit in there that the bore holds can amaze you... You have to use HOT, Soapy water and scrub until you can't stand it anymore. Then rinse, dry with cloth and test your work with a clean white paper towel or cotton cloth with a bit of fresh motor oil on it. Rub the oil in really good then look at your wipe. If that wipe is not PERFECTLY clean you gotta mix up some more fresh HOT, Soapy water and scrub it some more! Oil it well once it is clean.

The amount of grit in there that the bore can hold after machining can truly amaze you... Failure to get it all out = early or immediate topend failure. This cannot be underestimated...

Neither me nor my family friend that has been an engine machinist for plane engines and race engines for 40+ years has ever done more then cleaning with a parts washer and then use atf on a no lint cloth through the bore. Probably 1000+ engines between the 2 of us. He has even built 1000+ hp engines and not done any of that.

 

[SlammedRanger]

I have too. Methanol fueled racing motors were my forte... My niche (and love) was design engineering. I thoroughly enjoyed beating up on my competition on the race tracks! I did the design and build of small, lightweight V-8s that would produce massive torque figures on the dyno. I was/am a humble and quiet pioneer. I put motors on the race tracks that made over 1000 ft lbs of torque at the crankshaft from as little as 441 cubes and a single 4-bbl carburetor, per sanctioning rules. As far as I know, today, some of my torque production figures still stand unmatched, per cube.

I explained the importance of cleaning out freshly machined bores and what can happen if you don't. If your wipe came out clean after washing, you got it all, so please disregard my warnings above. Being a forum environment here, it is difficult to assess one's skills and knowledge, so I always end up over-explaining things. I hope you'll forgive me.

Wasnt meant to offend at all. I completely understand and appreciate your knowledge! I talked to my engine guy and he said yep alot of people do wash in soapy water. We here do not because of the minrerals and crap in our water. He said his parts washer filters to microns and he has never had one come out dirty enough for it to be necessary. Again sorry if i came off like an A-hole as that was not what was intended!

 

[SlammedRanger]

Yikes! Those rocker arms dont look healthy! I think you topend isnt getting oiled properly. The cam bearing journals look completely normal. Could explain your topend seizure. I would be pulling that oil pump and measuring and inspecting everything!

 

[SlammedRanger]

Cam is rough also..........

 

[SlammedRanger]

I would still bet the piston caused the seizure. But lack of oil to the topend made all the problems worse. Those rocker arms and cam are in rough shape. I would be going over all the measurment of the oil pump that the fsm says to check. Any signs of wear i would change to be safe. We had to change the rotor on one of my buddies builds. I spec'ed out the oil pump on mine when i built it to be safe. Cuz lack of oil will wreck everything quick!

 

[SlammedRanger]

That would bring some clarity to some of this for sure lol!