gx390 springs too hard

ruicunha

Member
Hi all.

First time on forum.

I have a gx390 on my kart, with alumminium flywheel from nracing, a bored genuine crab, big airfilter and installed 50lbs springs.

What happens is that to start the engine is almost impossible, the starter rope is very stiff, sometimes the rope pulls to the engine so fast that you end up hurting your hands, it seems dangerous.

This happens because of the springs or am i missing something?

Thanks.

ps. srry for my english, im from portugal.
 
Any number of things , valve lash too loose , ignition timing .
With the big springs , my understanding is the compression release fails .
This is highly likely .
 
Yes, same issue, the only person that can get the engine to start is the mechanic form the track, everyone else fails. after it starts engine runs ok, The ignition timming is set 6 degree with recomended key from site where i bought the flywheel.
I asked for them to install the older springs with less strenght.
 
If the springs don't fix it .
The compression release is broken .
Learning to slowly pull it through the compression stroke , before giving it a pull to start .
That gets you 2 free revolution's before compression again .
 
What is the compression release? After mechanic gets engine running (by pulling chord with lots of strenght) engine runs fine, but something is wrong, it shouldnt make that mutch strenght. I also noticed that when he installed new engine flywheel, when i tried to start engine, the chord was so hard that it could lift the kart.

ps. managed to find what compression release is, my question what is coild bind? i know how to set the space between the rockers and the spring, but i cant find what coil bind is.

Thanks.
 
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Coil bind is when the valve springs collapse so far that they literally bind the valve from going further open due to the spring being fully compressed and is physically touching it's self during the valve attempting to open.

If the cam is trying to open the valve further than the spring will allow, it creates coil bind. OR like having a solid object where the spring would be.
 
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