Hello all currently building a engine for the mini bike my current project is a predator 420cc I hade removed the governor and am currently am working on the valve springs my main concern is I hade purchased 50lb valve springs as an upgrade from the stock springs is 50lbs too much? Should I of went with a lower lbs? Thanks for the advice I greatly appreciate anything anyone has to say
Predator 420cc
- Thread starter SquareCup
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Denny
Canned Monster
Why do you want heavier springs? No need unless you plan on reving the guts out of it.
Since I removed the governor from the internals the valves like to float at higher RPMs I am trying to avoid the floating .
Denny
Canned Monster
They don’t float until about 5,000 rpm. Acts as a governor, all the stock pieces can take that.
but they still end up floating and I’m trying to avoid that . Would 50lb spring be too much for stock parts or would 35lb be better ? It’s hard to find 35lb springs for a gx390 -predator 420cc lots of 50lbs but is that too much for stock parts or will everything be fine?
panchothedog
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50 lb. Springs are the 1st upgrade over the stock ones. The stock ones are 29 or 30 lbs. I have never heard of 35 lb. springs for a big block. Doesn't mean they don't exist. Completley foolish to go through the labor and expense for a 5 lb. difference. Wouldn't make a bit of difference in the way it runs.
I might upgrade the cam / flywheel just not sure if it’s necessary for what I’m doing