Hi guys can anyone help me with this issue, can I replaced the valve springs without removing the heads or is the frame in the way, I want to upgrade the springs to a higher lift.

Any help appreciated.
Thanks

 

No. You have to hold the other end of the valve. And springs won't change the height of the lift.

 

On cars there is a way to change springs w/o removing the head by using air to fill the cylinder. Don't know if anyone has done that on a bike, or if th eframe would be in the way.

 

I doubt you could get the spring compressor under the frame...

As stated above, there is a fitting you can use compressed air to hold the valve up while removing the spring, but the spring compressor used for this method is turned by hand like opening/closing a plumbing valve. Not a lot of room, especially on the rear cylinder to get that spring compressor in there.

Also, just thought of this.. there isn't much room for the spring compressor arms to get beside the spring and under the spring seat to compress them.

Give it a try, and let us all know for sure!

 

I watched a friend do this years ago. He pulled the spark plug then pushed about 5 ft of thin rope into the cylinder. Then put the cylinder close to TDC. This keeps the valve from falling into the cylinder. He then made a compressor from a piece of flat stock. Drilled a couple of holes where he could secure it, and a bigger hole to get the valve keepers out. He said the problem with using stock springs is they bind when using a high lift cam. He got springs that would allow the valve to open slightly more then the stock ones, and would behave like the stock ones, but not need added pressure to open the valves. It ran good when he was done, so I guess it's been done before.,,

 

You don't say what bike you have, but space for doing this is real limited. I don't know of anybody who makes a tool to do this, and I think there's a good reason. And you can't necessarily increase the lift capability just by installing new springs.

What do you have? What are you trying to do?

 

How much lift you have is determined by the cam profile not by the valve springs. Putting heavier stiffer valve springs will help the valves not "float" at high rpms though...and the heads need to come off to do this job.