jwardjr
New member
Hello Everyone, new to your forum, new to Yamaha heck new to snowmobiling!
Well, I asked a few friends before I just jumped right in and a couple said Yamaha, I know Yamaha bikes and had great luck so why not?
I bought a 2002 600 MM, looked okay but needed some TLC, wouldn't run except giving a dribble down the plug whole. It was cheap and I like projects so I bought it!
Thought a basic carb cleaning and fresh fuel, change all the fluids and a once over and lets go ride. Not!
Took the pipes off just to have a look see. Oh man, two cylinders are scored and the pistons not so good either, one the skirts are cracked, no broken pieces though! Took it apart and I'm going to replace or redo cylinders, piston assy and crank seals. Any suggestions as to relining or replacing cylinders? Pistons I plan on going OEM. The Mechanic friend of mine that is helping is all into taking the oiler assembly off (top bike mechanic at a shop all his life, Yamaha, KTM, Honda etc). But as have read that system lubes the water pump bearing and the bearing on lower shaft output. Any suggestions there too? I would love to pre-mix the fuel, I trust it. We have a lot of equipment with oil injection and have had issues over time, (cold out side, oil is thick, Hot outside oil is thin)
Please give me a little guidance as to being reliable and fun for the long run! Not racing, just wanting to have my first experience with a snowmobile be a good one
Thanks!
John
And this is an awesome board!
Well, I asked a few friends before I just jumped right in and a couple said Yamaha, I know Yamaha bikes and had great luck so why not?
I bought a 2002 600 MM, looked okay but needed some TLC, wouldn't run except giving a dribble down the plug whole. It was cheap and I like projects so I bought it!
Thought a basic carb cleaning and fresh fuel, change all the fluids and a once over and lets go ride. Not!
Took the pipes off just to have a look see. Oh man, two cylinders are scored and the pistons not so good either, one the skirts are cracked, no broken pieces though! Took it apart and I'm going to replace or redo cylinders, piston assy and crank seals. Any suggestions as to relining or replacing cylinders? Pistons I plan on going OEM. The Mechanic friend of mine that is helping is all into taking the oiler assembly off (top bike mechanic at a shop all his life, Yamaha, KTM, Honda etc). But as have read that system lubes the water pump bearing and the bearing on lower shaft output. Any suggestions there too? I would love to pre-mix the fuel, I trust it. We have a lot of equipment with oil injection and have had issues over time, (cold out side, oil is thick, Hot outside oil is thin)
Please give me a little guidance as to being reliable and fun for the long run! Not racing, just wanting to have my first experience with a snowmobile be a good one
Thanks!
John
And this is an awesome board!
chris700readhead
Member
Welcome to the site and snowmobiling. Go with OEM parts as to they will yield the best reliability. I would leave the injection pump on. If it fails it will go wide open so u don't have to worry about it not getting oil.
Id fix to top end and run it. What it got for miles on it? Any thing less then 8k Id run the bottom end. As long your cylinders not scored new pistons rings and run it thats like a 2 hr job. Them sleds are vary easy to fix.
jwardjr
New member
One piston and cylinder was perfect other two were toast.
It has 4500mi. Bottom end feels tight. We think it sucked air and went lean. Can you replace crank seals without splitting the case?
Changing reeds, what works best for low elevation?
Thanks a lot for you input
Keep the oil pump unless you are strictly racing it. These pumps are designed to work in the cold and the variable mixture is a very good thing on a snowmobile engine that doesn't stay wide open all the time. The Yamaha oil injection system is the best there is.
Backwoods M Max
New member
The oil injection delete is popular for some reason on newer engines because the crank bearings are sealed and greased. It's how they are getting these crazy low oil consumption numbers. Research the rotax 800 ptek and etec. The ptek will pretty much grenade on cue if you don't disassemble the engine to rebuild the crank bearings. The oil injection delete is feasible on those sleds because you can flood the water pump drive shaft gear with a block off plate that will go up to a little bottle. It keeps the cavity flooded with oil and none really goes anywhere. All older oil injected sleds have a pass through oil system. The oil in the bottom end will ooze a little bit out and it gets mixed with the gas oil in the bottom end to be burned. Cut off the oil to those bearings and goodbye engine.
jwardjr
New member
I guess we will be re-installing the nipples and hoses on the bottom and re-installing the pump. I'm so glad I posted this thought. I was totally convinced by the Mechanic that was helping me removal was the only option. He has done it on all of the Yamaha's he has worked on but one difference, they were all bikes!
I guess I should split the case and check the bearings since the last guy started the premix idea but left the oil bottle on and hooked up but, no oil.
Thanks you all for helping with this
jwardjr
New member
I found out what happened to my engine, well at least I'm almost 99.9% sure of it. The petcock coming out of the fuel tank is plastic with a rubber bung seal. I noticed this glob of hard stuff like JB weld but white. I picked the stuff off and took the clamp off. The last guy tightened the clamp so hard trying to stop the fuel leak he collapsed the plastic nipple. Which restricted and cut off the fuel supply. Doing so he ran it lean, kept running it and toasted the pistons and cylinders.