Liquifire looses power rpm when warm

[1982LiquFire440]

Have a 1980 Liquifire, live at 1300ft "NW iowa" and have been running sled in 20-30 degree temps. I have removed the tank and cleaned out very good, rinsed several times. Have brand new 91 fuel mixed with avgas in the tank, nearly full.
Installed all new fuel lines in the tank with a new check valve screen from new breed parts. I installed a brand new fuel pump from new breed parts, as well as all new fuel lines to the carbs and power jets. Also replaced the pulse line from pump to engine. Have two brand new BR9ES spark plugs installed. The drive belt in in really good shape, clutches seem to be working correctly. Have the airbox with hose installed.
The problem... The sled will start and run really really good for the first 10 minutes or so, after that it seems like it looses power on the top end. The bottom end seems the same, however when you try to get on it, 7000 rpms is all that you get, and seems to not want to pull. The sled will start with one pull when warm and sit and idle for days no problems.
When the sled is cool it rips, runs just like it should I will, just looses power when it gets warm. I have cleaned the carbs a couple times now, I have the chokes set "I think", it is jetted exactly how the Fine Tune manual tells me too for 80-81 liquifires. Everything is set just how it should be. The only thing I know is wrong is the primary has a yellow spring it it, not a purple like it is suppose to have. I have a new purple spring, i just need to find a clutch puller so i can fix it.
Any help or suggestions would be great!!! need help!!

[ihengineer76]

I can't remember the spring rates off the top of my head, but if the spring you have in is too light, you may be overshifting. Do you know what weights you have inthe primary? This won't let the engine get to 8000 rpm. I would start there first. Also, is the av gas you are using 100 low lead? What ratio are you mixing? Too high of octane will loose power especially at higher rpm without adding timing to take advantage of the longer burn time/resistance to ignition.

Tom

[1982LiquFire440]

If it were the fuel or the clutch it would act the same when the sled was warm or cold. I know that I probably have too much octane. I use a 1 gal avgas to 5 gal 91, just like I do in my 880 SHR mountain sled engine. I understand that I may be loosing a little performance in the Liquifire using this, but avgas always seems to keep the gas fresher and keep the water out of it.

Like I stated the sled runs great, rips 8000 8200 rpm and pulls good for the first 10-15 minutes when cool. Then when the sled warms up it looses power and won't pull over 7000 Rpms. The yellow spring that is in the primary is for high altitude, which should let the motor rev higher and put less load in it then the purple. So that should be helping the situation not hindering.
The rev limiter is unhooked, I did try that. The airbox isn't plugged, I just checked that as well

[1982LiquFire440]

Should also mention that I also installed a brand new temp gauge from new breed parts. The sled shortly after being warmed up goes right to 140 degrees and stays right there maybe a touch under

[Sprailfire340]

Check your stator. See post #5 from Scott @ HewTech here:
http://vintagesleds.com/bs/index.php?PH ... ode=mobile;



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[1982LiquFire440]

Little update.
The last few times I have ridden the sled I have not experienced the top end power loss that I was experiencing before when the sled got warm. Can not for the life of me figure out what was causing that for sure. I am convinced it is a stator Cdi or coil issue that will probably come and go. Right now it's working good, so don't fix what isn't broken

On a different note, I received my new secondary helix "sportfire dual slope" in the mail from joe, and installed it. As well as gearing down the sled with a 18 tooth top gear. Let me tell you TOTALLY different snowmobile. The acceleration and performance in deeper snow it right on now. Sled wants to pull skies off the ground when it hooks up and pulls. Don't know how much the top end my be effected, I don't have a long smooth enough run to see. But I know for where I drive it is much much better. Def recommend!

[1982LiquFire440]

My youngest son can not get enough of the liquifire!

[AirborneX4Special]

Nice looking sled.

[sledhead16]

I'd bet it's the ignition coil needing replacement