INVADER 340 OVER OILING

[rminier]

 

Hi Rick

I am doing fine.  A few months back I bought an older dirt bike to start riding motocross again to get in shape. I rode MX as kid for a long time and haven't rode in 13 years so I got a bug up my A$$ to start riding again and in a couple years I am going to get a bike for my son so we can ride together. I rode yesterday and this morning I feel like I got hit by a semi lol. I am deff not 15 anymore, I used to be able to ride for hours as a kid only stoping for gas, food and drinks not because I was all worn out. Now I know why my dad would ride for a half hour and then crack open a beer. Getting old sucks lol. You made a valid point with the air screws on the carb and the hot weather outside. From day one the sled would idle fine even after the whole hill climb ordeal that started this issue once it got it started again it would idle fine. I think since I set the air screw to factory settings in this 80 weather that messed it up. Once I chop the throttle and play with it I can get the sled to run great wide open with the track suspended in the air. I believe I have the seals, they are made by Winderosa and the part # is GS1149. Im just worried about fighting 40 years of rusted bolts lol.

Getting old sucks lol?   WAIT until your 61 like me!
 The Company I work for had the annual golf outing yesterday...I played with my youngest son and 2 other guys from work....'bout killed me to play 18 holes....the old back muscles tend to tighten up quite a bit any more...
  I doubt that you need to change the idle SPEED screws when you play with it during summer weather....just the air screws probably need opened up to 2 or 2 /1/2 turns open to compensate for the thinner, hot air.

[rminier]

 I failed to mention...as if you need any more reminding. ..a very common symptom of a leaking crank seal is a sled doesn't want to idle as smoothly as it should, even with everything else correct.. Once it revs up, it will often sound and run great, until you are flying across a frozen lake and pistons start melting.
 I fear that the seals, particularly the MAG end, hidden behind the recoil and the flywheel, probably looks like 35 year old, petrified, piece of burned toast.
 Many good comments on here previously, also, to check thru on the carbs to make sure you have them dialed in.
 I don't think you will have much trouble with rusted nuts and bolts when you go to remove the engine....The drive clutch and flywheel will be the pain.
 

[rminier]

 A picture is worth a thousand words....I thought I may have saved this crank seal from a parts sled (79 440 Invader) I picked up in 2010...that had probably sat in a barn for 20 years.
 The outward facing part of the seal doesn't look too terrible...this one was on the MAG end...but check out the inner portion facing in toward the center of the motor!!
 It was bad enough that moisture had pitted the seal mating surface of the crank and slightly affected the end bearing of the crank, which isn't a terrible deal....but one reason I am closely following mswyka's thread about the Speedi sleeve on here to address the pitting on the crank without spending a small fortune on machine work.
 Pics taken in my garage on the seat of my fairly new to me Blizzard 9500, which has been getting an end to end clean up and check of everything this summer....gettin' close to finished with it...May have to post some pics under the "what have you been working on?" topic, soon..

[rminier]

Whoops, could only post 1 at a time?

Inner view.

[rminier]

Outward facing view of original seal.

[IraqvetUSMC]

Man that crank seal sure looks nasty and I can definitely see where the pitting on the crank came from, I really hope mine does not look like that but I am sure they are close to that. I just don't think i will have the time this winter to tear apart the engine which really isn't a smart idea if I want to ride lol.  I will maybe make that a spring project that way I have all summer long to work on it. Realistically I probably won't ride it to much this winter and I need to cover that seat, I am dreading it haha. After the sled died on me and I was finally able to get it to start again it would sit there and idle perfectly but when i decided to take it back out to see if it miraculously fixed it self it died out after about 3 minutes or so under a load on the snow  on the ice. Im still thinking the right carb bowel plug came loose and caused the initial problem ( i hope). If the air screw adjustment doesn't work then its either the carbs which i have cleaned out or those seals and I may not get any riding time this winter . I do appreciate all your guidance and yes getting old really blows lol. Im still sore from riding on Saturday lol.

[IraqvetUSMC]

Update. I have adjusted the idle stop screw about 1.5 turns off the seat and the air screw about 2.5 turns off the seat and the sled seems to idle now without dieing out. It will idle much better but every once in awhile you have to blip the throttle. I am wondering if these old 2 stroke sleds tend to load up much faster with the oil injection system vs a new 2 stroke sled with newer carbs and technology. The sled fires now on the first pull without using the choke.

[jimvw57]

Crank seals are not too expensive, I would never use a salvaged seal!!  Balancing the carbs makes a huge difference in power and speed. There is a simple balancing tool you can make from some clear tubing a scrap of wood, and a ruler that makes balancing super easy without spending a bunch of money on a fancy tool.

http://snowmobile.off-road.com/snowmobile/tech/round-slide-carburetor-synchronization-how-to-20201.html

But i'd say to replace those seals and then you don't have to worry about hem any more. While you are in there, grease up the lower steering post bushing.The motor has to be out to get to it so it is a good time to take care of it when you do the crank seals.

[IraqvetUSMC]

Thanks for the advice Jim. I will have to check that out and get them crank seals changed. I have new ones still in the packaging just not enough time right now lol.

[jimvw57]

How many times have I said that!! I spent almost a year messing with an Invader that I got and the previous owner swore up and down that he just put crank seals in. eventually I pulled the motor and found the flywheel crank seal ripped apart. He put them in on a dry crankshaft and they tore right away.  Lesson learned, pack them with grease, and only trust your own work. (grease also helps protect them if the motor gets flooded)

[IraqvetUSMC]

I "know" everyone has mentioned crank seals and yes its a big issue but when you have a 1 year old and work 50 hrs plus a week while trying to get other stuff done its a little hard and it will be a spring summer project next year. I will ride my sled a little bit with the crank seals the way they are and worry about it next year. Even if it snows I may not even have much time to ride it which is why I haven't jumped all over doing these seals. However I am glad you mentioned grease otherwise I may not have used grease on the shaft and would be in the same boat as your invader.

[gixxer6]

Riding a 30+ year old sled without changing the seals is a risk, but it is your risk to take.  I hope it works out for the best.  Good luck! 

[mswyka]

Don't do it.  It is a long, sad walk home in the cold when the engine blows a piston.  Been there, done that, won't ever do it again.  Better not to ride than to suffer the shame of being towed home by a (choose one) [skidoo, arctic cat, polaris, yamaha, boaski, bolens, john deere, ariens, gilson, ford, chevy, dodge, porsche, kia, yugo, other...]  Remember, friends don't let friends blow pistons.

[IraqvetUSMC]

Haha yes its a big risk and thats why I don't plan on going very far. I have a small field across the street that I could ride in so atleast I wont be miles away from my house lol.