snow guy
New member
I've got 5K on a 99MM 600. It runs great with no issues. Am I pushing the life of the engine and at what point should I look to rebuild and what constitues a rebuild, just the top end meaning hone the cylinders and put in new rings or should I do more?
T.S.U.Filmz
Member
Not at all i have 7000 on my 99SX 600 and i have herd of maney SX and SX-R 600 and 700 with 10,000 or more. still on stock motor I think you should be good.
Jeff
Jeff
03viper159
Member
a good way to tell would be to run a compression test, if you are still around 120lbs then you will prolly be ok, generally a worn out motor will lose compression and be hard to start due to lack of cylinder pressure.
a compression test does not tell you everything you need to know. A leakdown test is what will tell you the shape of the internal componets, as you may have compression but for how long??, a piston traveling fast may build pressure quickly to show you on a guage but may not hold the pressure for any length of time. A 2 stroke engine will benefit from at least fresh piston rings about every 2500 miles to stay in tip top running shape. I know there is people who run them for 10,000 miles and never do anything to them, but the motor doesnt make the same amount of power it did when it was new either. Blow by from the rings will contaminate the fresh fuel/air charge in the case and this means less power.The rings are a big factor in the performance of a 2 stroke engine, they go thru hundreds of cycles of opening/closing as they follow the taper and runout of the cylinder up and down, so they do wear out about 2 to 1 ratio of the piston, and when the ring wears it contributes to the piston losing stability in the bore, this leads to rocking back and forth and then broken skirts, not to mention the loss of sealing capability's. Its your call but youd be surprised as to the amount of topend jobs that are done and the owner thinks he got extra power from it, sled will pull more clutch weight,more response, when in reality he was just used to the sled being slowed down from the lack of power over a period of time, when freshend back up its running at its potential again.
pistons
Can you repeat that?LOL
Mrviper is right on the money.Running piston's high milage can lead to other problems.
Can you repeat that?LOL
Mrviper is right on the money.Running piston's high milage can lead to other problems.
snow guy
New member
Makes sense. What about my MM700 with about 3400 on it, I know the tripples run smoother, less vibration, does the same apply to them? Also in looking through the catalogs for rebuild kits what gasket set is the best/ cheapest, or can I reuse my gaskets? A complete gasket set is more expensive than the darn rings!
nailsandrails
VIP Member
MRViper - If just throwing in a set of rings.. Would you normally need to re-hone the cylinder? I have a 99 SRX with 9000 miles and orig. rings. (125 PSI on all three) I am thinking of changing them, but wanted to know if I needed to do anything else. Thanks!!
The gaskets are reuseable with a dusting of permatex hi tack sparay on them, they are a steel gasket,head and base gaskets on a sx/mm/sxr engine.
To answer the second guys question: yes, this applies to ALL 2 stroke engines regardless of 2, 3 or 4 cylinders.
the nicasil on the cylinders is very hard and usually you cant do anything to it by honing it, they usually will have the cross hatch still in them, so no you dont have to hone them, its not that critical on plated cylinders.
To answer the second guys question: yes, this applies to ALL 2 stroke engines regardless of 2, 3 or 4 cylinders.
the nicasil on the cylinders is very hard and usually you cant do anything to it by honing it, they usually will have the cross hatch still in them, so no you dont have to hone them, its not that critical on plated cylinders.
01sxr700
VIP Member
The manual recomends xhatching the cyl with 600 grit paper.
bolin22
New member
if it has been fogged every summer and shows no obvious signs of problems.....ride it.......
its not uncommon for 15,000miles on a tripple with nothing replaced......after that i would say not to push it.....
3-5thousand miles......your wasting your time.......
..........when you do get it apart and see how perfect it is, just replace the seals and be thankful you own a yamaha
i pulled my motor last year for a bad crank seal.......11,000 miles on a '02 viper and everything was within spec and looked fabulous.
yamalube since new
its not uncommon for 15,000miles on a tripple with nothing replaced......after that i would say not to push it.....
3-5thousand miles......your wasting your time.......
..........when you do get it apart and see how perfect it is, just replace the seals and be thankful you own a yamaha
i pulled my motor last year for a bad crank seal.......11,000 miles on a '02 viper and everything was within spec and looked fabulous.
yamalube since new
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See,... theres people who will run them till they break, then they know they need something done because it went boom, or you can keep them fresh. Sorry, but rings and pistons in a 2 stroke snowmobile of any brand will not be within spec at 11,000 miles no matter what oil you run!! It may still run fine to you the same owner of it since new, I dont argue that, these yamahas are great about giving you trouble free service but its not running the way it did when it was new! I would be willing to bet you the sides of your pistons were very dark brown and black all the way to the bottom of the side of the skirt, this is blow by!! this cant be done with a compression tester, see you can build compression, but how long can you hold onto the compression is the real task in a 2 stroke.
I fixed a srx last year that was the cleanest sled you could ever possibly find, I think the guy kept it in his living room..., anyways, at 6600 miles all 3 pistons were way under spec, yamalube used its whole life. Sure it started and ran fine, but it wasnt making all the power it used to!! The thing is if it would have had the piston rings changed just 1 time in the 6600 miles, it wouldnt have gotten to the point of letting the piston rock back and forth and wear the skirt from instability. The stock yamaha srx/viper pistons are about the best out there, a powder forged unit that runs a nice tight skirt to wall clearance, this improves sealing and stability, but once the rings get tired, it lets it rock back and forth and this leads to skirt wear and blowby. I dont think people understand what it is that drives a 2 stroke engine, its the piston/rings!! Theres no camshaft, valves, oilpump,etc. Ring seal and piston stability is crucial in a 2 stroke, its how all the power is moved around in the engine, and it is what the deciding factor is on how quickly and efficently it can be moved, sloppy rings and pistons contaminate the fresh fuel/air mix in the crankcase with burnt fuel/air charge that seeps by the rings into the crankcase below instead of being evacuated out of the engine, this in turn heats up your fresh mixture and this makes less power. heat is the number one enemy of a 2 stroke sled, the warmer the engine, the richer it is, the power drops off!
The reason there isnt 2 stroke cars out there is because although a 2 stroke engine makes more power then a 4 stroke does with less weight, it cant be made to give suitable service life without piston /ring service!!
Like I said, some people will run them till they break, thats fine its a free world, you have to make your own decisions, but if you want your machine to stay in tip top running shape, you cant ignore the rings and pistons...its like not ever changing the oil in your car till 50,000 miles! sure it will run fine, but its not going to make the power it should from the contaminates in the oil which in turn effect the way the engine makes power overall. Its your engine and what and how you maintain it is entirely up to you, I am just trying to explain why you should maintain it, at least you have the facts and other differning opinions...........what you do is your decision.
I fixed a srx last year that was the cleanest sled you could ever possibly find, I think the guy kept it in his living room..., anyways, at 6600 miles all 3 pistons were way under spec, yamalube used its whole life. Sure it started and ran fine, but it wasnt making all the power it used to!! The thing is if it would have had the piston rings changed just 1 time in the 6600 miles, it wouldnt have gotten to the point of letting the piston rock back and forth and wear the skirt from instability. The stock yamaha srx/viper pistons are about the best out there, a powder forged unit that runs a nice tight skirt to wall clearance, this improves sealing and stability, but once the rings get tired, it lets it rock back and forth and this leads to skirt wear and blowby. I dont think people understand what it is that drives a 2 stroke engine, its the piston/rings!! Theres no camshaft, valves, oilpump,etc. Ring seal and piston stability is crucial in a 2 stroke, its how all the power is moved around in the engine, and it is what the deciding factor is on how quickly and efficently it can be moved, sloppy rings and pistons contaminate the fresh fuel/air mix in the crankcase with burnt fuel/air charge that seeps by the rings into the crankcase below instead of being evacuated out of the engine, this in turn heats up your fresh mixture and this makes less power. heat is the number one enemy of a 2 stroke sled, the warmer the engine, the richer it is, the power drops off!
The reason there isnt 2 stroke cars out there is because although a 2 stroke engine makes more power then a 4 stroke does with less weight, it cant be made to give suitable service life without piston /ring service!!
Like I said, some people will run them till they break, thats fine its a free world, you have to make your own decisions, but if you want your machine to stay in tip top running shape, you cant ignore the rings and pistons...its like not ever changing the oil in your car till 50,000 miles! sure it will run fine, but its not going to make the power it should from the contaminates in the oil which in turn effect the way the engine makes power overall. Its your engine and what and how you maintain it is entirely up to you, I am just trying to explain why you should maintain it, at least you have the facts and other differning opinions...........what you do is your decision.
ExpertXViper
New member
MrViper700, great info. What mileage is best to change rings? I'm at 2000miles on my stock top end on my Vip and its getting pipe this year and have new rings sitting here. Should I just change them out since everythings apart? and do I have to have the cylinders honed first before I put the new rings in?
daman
New member
ExpertXViper said:
1. yes i would
2. and;
mrviper700 said:
ExpertXViper
New member
Thanks daman.
daman
New member
ExpertXViper said:
keep us posted...
ExpertXViper
New member
Will do. Ive been taking pics of my process of getting the pipes on. So I'll post them all when I have a finished product.
daman
New member
Pics are always good.....LOL 
I finally tore mine down this summer, at 3600 miles, ( I probably should have did it last year) While it was running "fine", I could tell it was loosing power compared to when it was new. By having to go down one jet size and run less weight in the primary to get it to hold the proper rpms.
Sure enough the piston to bore clearance is at the max spec, and the piston's show signs of blow by. No abnormal scuffing, just normal wear.
Mountain sleds are usually gonna wear a little faster then a trail sled, due to the WOT hill climb pulls, etc.
Sure enough the piston to bore clearance is at the max spec, and the piston's show signs of blow by. No abnormal scuffing, just normal wear.
Mountain sleds are usually gonna wear a little faster then a trail sled, due to the WOT hill climb pulls, etc.
daman
New member
I know it doesn't realy matter but what oil did you run in that 3,600???
Yama-lube, however the sled hasn't seen typical use. I started it out by glass dragging it when it was new. Grass raced it for 3 seasons, still snow dragging it, and it's my mountain rider, piped the past 3 seasons. So it's what you might call heavy duty use! Through it all, its always performed well! A tribute to Yammy reliabilty!
I always go through it every pre-season, pull the skid, check/replace bearings, service the clutches, chain case, suspension, clean the power valves, carbs, check piston wash, run a compression check. Last pre-season I ran a leak down test, it was at 7-8% which is "ok". I decided to run it another year, but in retrospect I should have gave it a set of rings last year. That would have prevented some of the blow by gasses from entering the crankcase and causing some piston wear.
A friend is an Amsoil dealer, so I thought I would try sythetic oil when I get'er all back together.
I always go through it every pre-season, pull the skid, check/replace bearings, service the clutches, chain case, suspension, clean the power valves, carbs, check piston wash, run a compression check. Last pre-season I ran a leak down test, it was at 7-8% which is "ok". I decided to run it another year, but in retrospect I should have gave it a set of rings last year. That would have prevented some of the blow by gasses from entering the crankcase and causing some piston wear.
A friend is an Amsoil dealer, so I thought I would try sythetic oil when I get'er all back together.