I was just wondering if anybody knew what the compression is suppose to be on a 09 800 dragon? My sled went from taching 8250 down to 7600-7800. Dont know if the temp is messing with me that bad or what is going on. Any help would be great.
09 800 dragon compression
- Thread starter WFO D8 09
- Start date
Check your belt, you may need to change it or re-adjust your secondary.
I just changed the belt 30 miles ago and it was sitting pretty good on the secondary. I am at 6300 in elevation
guys in the midwest elevation, are saying 135. If this helps
I tested at 5K ft and mine was 110 in both cylinders. What gauge brand where you using? Higher the elevation the lower the compression readings so it seems our sleds are about where they should be...
My ported and milled head 08 D8 is supposed to have around 145 psi. I checked it on Tuesday and I was at 120 on the mag side and 115 on the PTO side. Not good! Pistons are scored/scuffed based on looking at them through the power valve slots.
Make sure that you have the throttle wide open when you pull the rope. Otherwise, you will not get a true reading.
Make sure that you have the throttle wide open when you pull the rope. Otherwise, you will not get a true reading.
Update
I decided to check my d8 out the other day and this is what i found. First i checked the compression, cold and hot it was 105 cold and 100 psi hot. Then i was told to take my throttle body off and reeds. Took them off and they were filthy, I mean you would have thought that I threw a hand full of belt dust in there. So I cleaned them and then pulled the valves off to check pistons for scuffing and they looked good. Went for a ride the next day and it would tach 8000 to 8250. So I dont know if the reeds were choking it off or what but it seems to run better for now.
I decided to check my d8 out the other day and this is what i found. First i checked the compression, cold and hot it was 105 cold and 100 psi hot. Then i was told to take my throttle body off and reeds. Took them off and they were filthy, I mean you would have thought that I threw a hand full of belt dust in there. So I cleaned them and then pulled the valves off to check pistons for scuffing and they looked good. Went for a ride the next day and it would tach 8000 to 8250. So I dont know if the reeds were choking it off or what but it seems to run better for now.
800 compression
We were all curious how much compression you loose when going from flatlands to the mountains. Home (Nebraska) is about 1000 ft alt, and both cylinders were 120-125. At 10,000 ft in Wyoming, it pulled 90-95psi. Somewhere on snowest, somebody had a formula that stated what percentage you loose for every 1000 ft altitude, but I can't remember it. A sledder I know here had a mod sled that he could not hardly pull to start here, but he could when he got to mountains. So it depends on what altitude you test it. Hope that helped.
We were all curious how much compression you loose when going from flatlands to the mountains. Home (Nebraska) is about 1000 ft alt, and both cylinders were 120-125. At 10,000 ft in Wyoming, it pulled 90-95psi. Somewhere on snowest, somebody had a formula that stated what percentage you loose for every 1000 ft altitude, but I can't remember it. A sledder I know here had a mod sled that he could not hardly pull to start here, but he could when he got to mountains. So it depends on what altitude you test it. Hope that helped.
2 stroke rule of thumb for industrial engines is 1 % per 1000 ft elev.
T
towngrunt
Well-known member
My 08 Dragon 8 has been doing it all last year and this year as well. Finally phoned Rep. and informed him I was extremely upset and was going to sell both Dragon 8's, both RMK 7's, both Sportsman's, take the free advertisement off my trailer and vehicles, and get rid of all my Polaris clothes, and start riding green if he cant get this problem figured out. He came to my home and picked up my sled, left me his sled and told me he would get it fixed. Heard from him today and he stated it was being ridden today by one of the best and they would figure it out.
T
trench
Member
My slp ported and slightly milled head gave me 125/125 hot 129 deg.wot. pulled with both hands.
I thought was alittle low, so I tryed my o7 700 dragon it was 125/126 could I say the same. I'm about sea level.
Done on a K D compression tester.
Thought my 08 800 would be slightly higher...?
My dealer told me that I should have had 145 psi reading at 2700' elevation. That seems about right. My built big bore Yamaha Superjet (800 cc) is in the 160 psi range. It runs great on pump gas (91 octane). I wish that Yamaha still made two stroke snowmobile engines.
125 psi on both cylinders, my buddies is about 122 to 123 on both cylinders. Both checked at 700' elevation, needless to say I am running 87 octane fuel with no detonation. I ride 4500' to 7000'
