I have a 97MM7 with 1600 miles on it, put like 350 on it this past week, 400 for the season. The problem developed yesterday, at 35 F, it backfires and pops bad under 1/4 throttle to idle. It wont run at all at idle, it sputters and stalls, sounds bad. Like its not running on all 3 ! But if you go 1/2 to wide open throttle it runs and sounds perfect. Checked plugged they looked perfect on the belt side, like gray slightly wet, center looked a bit scary, slightly wet with metal flake or some flux looking crap 
, and the right side looked normal if a bit lean which doesnt make any sense, because the machine is running rich as it uses twice much oil as it should ( i have to take it to someone for a multitude of things) Uses like a gallon every 100 miles. I checked the linkage its at 20mm as it states in the manuel. I had the carbs cleaned at the end of the last season. Machine does overrev, it will turn 9400 w/o a problem. Running a dayco max2 on it, the machine shreaded the last 2 8dn's in the first 1000 miles i owned it. I have to max 3's on the way, they are supposed to be the best, and i got a deal on them, 42.99 each.... I am going to guess maybe the jets need to be cleaned, since it runs good under throttle.
This MM is my first modern snowmobile, prior to this i had a 79' John Deere 340 Trailfire that i had since new, i never did anything but the typical maintenance to that, change plugs, fresh gas, never cleaned the carbs, started a few times in the offseason, original track, never broke down, the clutch went two years, i sold it to a neighbor still runs fine for what it is. On the other hand this sled on 2 of the last 3 snows has failed. I hope this time, when they surface it, it will be right, cause i will write this one off as a lemon, and it might be the time to step up to an rx1, or a F7or6 (joke) nice red one not far from me, the efi is tempting, but i know AC will cause more problems than i am already looking at.....Thanks for reading...Sitting here, Watching the snow melt
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, and the right side looked normal if a bit lean which doesnt make any sense, because the machine is running rich as it uses twice much oil as it should ( i have to take it to someone for a multitude of things) Uses like a gallon every 100 miles. I checked the linkage its at 20mm as it states in the manuel. I had the carbs cleaned at the end of the last season. Machine does overrev, it will turn 9400 w/o a problem. Running a dayco max2 on it, the machine shreaded the last 2 8dn's in the first 1000 miles i owned it. I have to max 3's on the way, they are supposed to be the best, and i got a deal on them, 42.99 each.... I am going to guess maybe the jets need to be cleaned, since it runs good under throttle. This MM is my first modern snowmobile, prior to this i had a 79' John Deere 340 Trailfire that i had since new, i never did anything but the typical maintenance to that, change plugs, fresh gas, never cleaned the carbs, started a few times in the offseason, original track, never broke down, the clutch went two years, i sold it to a neighbor still runs fine for what it is. On the other hand this sled on 2 of the last 3 snows has failed. I hope this time, when they surface it, it will be right, cause i will write this one off as a lemon, and it might be the time to step up to an rx1, or a F7or6 (joke) nice red one not far from me, the efi is tempting, but i know AC will cause more problems than i am already looking at.....Thanks for reading...Sitting here, Watching the snow melt
...Mattf
New member
- Joined
- Jan 26, 2004
- Messages
- 10
Bad news. Sounds like you've got a burnt cylinder and piston. Get the compression guage out and check the cylinder that had the metal flakes. It's gone.
i dont have compression gauges but when i pull it over, its not any easier, or its not looser. It can be a cylinder down and run normal mid throttle and up? I have seen machines go down a cylinder while riding and either, wont start or run poorly back to a place to get towed. I havent owned a 3 cyl b4 so maybe thats why it seems normal under throttle. Anyway, i will load up and take it to get it looked at.
called 5 dealerships, based on my diagnosis i gave them, they all but 1 ( they said to break carbs apart) told me to put an additive in such as chevron techron or the related from yamaha, etc. I went and bought this at the local advanced auto. Ive put this (techron) in vehicles for i have found this to be the goto product for fuel related issues, over the other brands. Im going to go light on the additive, like 4oz to the mix as i heard these can make 2strokes run hot. Will see what happens next.
went with my own gut instinct, dont dump the fuel addictive on the (1) dealerships advice and chevrons advice whom i called too. Chevron told me not too drop it in, as it will or can raise temps too high in this type of application. So, i'll have someone professional look at it....
alright....so i take the sled in for an evaluation by a local shop. They quoted me $ 800 for the entire job. Being the entire left cylinder needs to be replaced, the piston is split in half,which in turn destroyed the cylinder, rings are melted and it cant be bored. The other cylinders look 'decent'. I cant bore a cylinder that hasnt been bored out before. Sounds like im getting beat to me. I could see if it was bored out a few times. But it wasnt. I dont know if im getting beat, but if you have an opinion post it!
Wilson
New member
If you are getting some one to do all the work and that includes parts I
don't think you are getting screwed . seems to me i hear people paying $1100.00 for an over haul . Do You know this guy is good ? If you don't trust him go some where else .
don't think you are getting screwed . seems to me i hear people paying $1100.00 for an over haul . Do You know this guy is good ? If you don't trust him go some where else .
I understand now after doing more research that its fair for that repair. I just dont understand how i cant bore it since its never been opened up. I guess i could get a second opinion but i trust these people so as far as getting a second opinion goes i doubt i will seek a second opinion. Also if it was that shot where it needed a complete overhaul, wouldnt it be leaking oil, smoke, or coolant through the cylinder? One last thing, when i checked my plugs it was the center plug with the metal on it, not that left which is what went down. Is that typical, sorry for the amateur ?'s, but thats what this msg board is all about....
grinder
New member
Backfiring Etc
Your Cylinder cannot be bored because it is a nickasil cylinder, the cylinder can be re nickasiled for approximately half the price of a new one
grinder
Your Cylinder cannot be bored because it is a nickasil cylinder, the cylinder can be re nickasiled for approximately half the price of a new one
grinder
Wilson
New member
He is probably getting a rebuilt one how else could they do it that cheap .
I am also confused why the cyl with the aluminum on the plug is not the one that needs to be replaced .I don't think that metal can transfer from one cylinder to the other as they are separated by the labarith seal . Why is that cylinder scored ? What does the over haul guy say .
I am also confused why the cyl with the aluminum on the plug is not the one that needs to be replaced .I don't think that metal can transfer from one cylinder to the other as they are separated by the labarith seal . Why is that cylinder scored ? What does the over haul guy say .
I have been offerd 1600 for the MM sight unseen from a nearby dealer, for what i have to put into it i would be almost as much as i paid for it. (3K) Thats fair for a 97 in that condition I still might get it fixed as thats 1000's cheaper than the alternative (trade)....Due to work i havent had the time to go to the shop where the sled is at to get a chance to look it over myself. So on the other hand if i decide to keep it I want it torn down to inspect the crank and a complete detox if i do decide to keep it. I am weighing the options currently.
fwiw i can get a new o4 viper er for 5400 thats with the trade or a new 04 rx1 warrior for 6600...or i can wait and ride a 05 3cyl as i wouldnt get one of them w/o riding plus i would want a Y.E.S. thrown in on a first year model! Oh well, i should just look for a replacement track for the 79' Polaris Cobra, so i can at least ride now, id be well ahead of the game $ wise....
fwiw i can get a new o4 viper er for 5400 thats with the trade or a new 04 rx1 warrior for 6600...or i can wait and ride a 05 3cyl as i wouldnt get one of them w/o riding plus i would want a Y.E.S. thrown in on a first year model! Oh well, i should just look for a replacement track for the 79' Polaris Cobra, so i can at least ride now, id be well ahead of the game $ wise....
Wilson
New member
Get an o4 rx1 or warrior and forget these 2 stroke problems .My riding partner has an o3 RX1 he has not had one problem in 2 years 4000 miles .
Juat a matter of time for me .
Juat a matter of time for me .
i have opted to rebuild, its cheaper and more realistic for me now, which is better for me. I think the fact that it is nonrebuildable makes me kind of laugh, the nickasil must be more durable in most scenarios i guess. The other manufactuers use this material as well? I have to look into what that is all about, interested in what its made from,etc.... Heading down to make a visual on it tommorow and to order the parts. But yeah, the next up will be a 4Stroke, im pretty sure of that.
red devil
New member
You just bought someones junk. I have a two stroke that has 4000miles on it whith pipes and it runs good and just like everyone else I will knock on wood for that statement. Fourstroke is the future and I will get one but I am sick and tired of our own brand guy's bashing the smoothest two strokes ever made. (yamaha!!!) and only getting better. I hope to get 10,000 miles on my sled and let my son take it over without any problems with motor. I think it,s possible but not the way I run it we will see. Wilson
New member
I am not bassing Yamaha . I have just had enough of two strokesafter riding beside a four stroke Yamaha for two winters I know what I want .
yeah i kind of feel i bought someone's neglected machine. The fact is 'supposedly' it was the dealers own sled. It had only 214 miles on it when i got it and it appears that way, the exhaust manifold and the pipe where still factory black and the rest of the machine included track has or had definitely that amount of miles on it. I think what hurt it was the fact that they didnt ride the machine much for the 7 yrs prior to me. I was told when i bought it last november that it was completely prepped and ready, and they gave me a 90 day warranty which is fair for a 7 yr old machine i think. But, I do know one thing, that Montgomeryville Motorcyle in Hatfield, PA is sort of sketchy, (place i bought the sled) as they dont sell or work on sleds now this year. They only sold yamaha.