Okay so to start off I guess ill say that I own a 1995 savage. Motor has been bored out by the people at bore-tech in ohio when I decided to go to the 96 mm piston. I also change the stock carb to a VM36 mikuni with a 195 main and a 30 pilot jet. The rebuild only has about 300 miles max on it. Ran fine until the other day.


So the other day I am crusing about 70 mph down route one when all of the suddenly the engine just stops....rear wheel just starts sliding back and forth so I pull the clutch in as fast as I could and make my way to the shoulder.

A few days before I took the bike out I thought I was running a little rich so I figured I would change the pilot jet to something a little smaller so I went from the 30 to the only other one I had which was a 20. Yes I know that's a big jump in jet size but if I read on here correctly that is the starting point for a vm. My guess is that I leaned it out and over heated it. The engine starts up fine just smokes a lot from burning oil. Also I went ahead and did a compression check and is about 125 psi. Next I went ahead and took the engine apart and the piston skirts are all scratched up and the oil rings are completely stuck from the burr that came off the piston skirts. As far as the cylinder walls go there are a few scratches which don't look to bad and everything else looked fine.

Id like to hear some advice from people as far as what jet sizes they run in their carbs (vm carbs not the stock carbs)

What else could have caused this? Maybe over revving?
Ill take some pictures of the piston and cylinder walls when I get some free time.

Changing the Pilot Jet from a 30 to a 20 most likely had little to do with your problem.  The Pilot jet only controls the fuel mixture at idle to about 1/8th throttle.....at 70 mph you will be using the slide needle or main jet the majority of the time and that will be controlling the fuel mix.  When you set the idle (air) screw on the carb at idle.....how many turns in/out was the screw?  If the screw was less than 1 turn you should have tried a larger ......if you were around 1.5 turns the jet is the correct size....anything more than 2 turns and the pilot jet is too big.  (This is opposite the stock carb as the VM carb uses and air screw and not a fuel screw like the stock CV carb).

I really trust Bore Tech to do a good job and get the proper clearances, and until proven otherwise I would suspect the failure was either heat or lubrication related.  I have the 95mm in mine and I can't remember how many miles I was easy on the rpm and avoided sustained high rpm......but maybe you didn't give it enough break-in miles or as you suggested maybe the engine was running lean.

I have the 34mm VM carb on mine and feel that it is plenty of carb for the Savage - so my jetting numbers aren't going to be much use to you for comparing what jets to try.  What does your spark plug look like?  What color is the carbon on the piston and valves?

I believe that you should get your cylinder lightly honed, buy a new 96mm Wiseco and check the piston clearance, and then put it back together and go easy on it for a while......60 mph and below for the first 500 miles, and avoid any prolonged running at higher speeds.  When I had the Trailtech Vapor on my bike it had a cylinder head temperature gauge.  At back road speeds between 30-50 mph the head temperature was 250-270 degrees, at sustained 60 mph speeds it would climb to 280.....at 70 mph it would climb to nearly 300 degrees.

Where do you live.....what was the air temperature when the engine locked up?  What kind and weight of oil where you using?
   

Engine oil is Rotella T 15-40. I called bore tech this morning and told them what happened the lady said she will have the machinist give me a call sometime today. I think I could get away with using another 96 mm and just have him hone it out.

The wall clearance seems very tight Anyone have experiences with forged pistons as far as piston to wall clearance goes?

I don't think I was running lean the more I look at the top of the piston and the spark plug. Top of piston have plenty of carbon on it except where the oil hit it and took it off. The spark plug is black with no signs of detonation.

Bill Moeller at Boretech is the fellow who can tell you what the piston clearance should be.....he has been doing this for years and years and is the "Go To Guy" for this kind of work.  His only business is working on motorcycle cylinders and heads.....he "knows" his stuff and I believe he is the only one working at the shop.  He did the bore for my Wiseco and I have 6,000 miles on it....and I have ridden it pretty darn hard once I got 500 miles on it.  It runs great!

There area lot of possibilities about why this occurred....I have no problem with the oil you are using as I use the same oil.  It could be that it got too hot, maybe it was running too rich and the extra gas was washing the oil off the cylinder walls...dunno!  The weird thing in that photo is how the area between the holes in the ring grooves looks fine....while directly below the holes the scoring starts.  The top of the piston also looks like it has a lot of carbon for only having 300 miles on it.

You need to forward those photos to Bill at Boretech and get his comments....he really is the expert.

I'd agree...although this is for 2 stroke engines it sure looks like the multi-point seize.
http://www.smellofdeath.com/lloydy/piston_diag_guide.htm

Colxjon wrote on 06/24/15 at 21:11:33:


Can you give a bit more of the details about the ride?

Had you been riding for a while....engine fully warmed up and 20 miles into the ride, etc.  Or did this occur right at the beginning of the ride or right after a pause in the action?

Was the fuel tank nearly full......had some gas....or nearly to reserve?

How was the oil level after the bike stopped?

How did you get the bike home?  Did the engine become free once it cooled down and you rode it home?

In the time I have been on this forum I know of 2 other Wiseco piston failures.  One occurred as yours did, on the first ride where the bike was run up to 70 mph (not a Boretech job), and the other one occurred after the bike had a lot of miles on it and was started after being in storage for 3 years (was a Boretech job).  There have been a lot of stock piston failures when the owners just run them out of oil.

I searched around on the internet for Wiseco piston clearances...and evidently it is not a standard that they publish.  I believe I still have the sheet from Wiseco that came with my piston....I will try and find it and see if it lists any numbers.  

I believe you'll find the clearances printed on the outside of the box.