HEADS UP!!!

Site upgrade in progress... Core site functions are working, but some non-critical features/functions will be temporarily unavailable while we work to restore them over the next couple of weeks.

Please post any bugs you encounter, but before you do, check to see if it's already listed.

Thanks for your patience while we work to improve the community.

Sign in to follow this  
Followers 0
Guest blatham489

Manual Decomp Start - Stupid Question?

4 posts in this topic

Just a thought, someone please analyze it. If the autodecomp works by keeping the exhaust valve open very slightly until the engine fires (reaching the required RPM to allow the valve to close) why couldn't you simply adjust the manual decomp lever to just barely open the valve the same amount as the auto device, and then manually hold the lever while kick-starting, releasing as soon as it fires off? :thumbsup:

Share this post


Link to post
Share on other sites

I'm pretty sure the auto decomp only opens an exhaust valve for a short duration, roughly around TDC. Similar to how the manual decomp is used-just to break over past TDC. This allows time for *some* compression when kicking, needed to fire the mixture. That's the scenario as I picture it in my head, anyway!

Share this post


Link to post
Share on other sites

When you pull in the decomp lever, you are holding open an exhaust valve so you can push the piston ever so slightly past tdc, then you let go, closing the valve. THEN you kick and the cylinder fires on the way down and starts. Doing what you said will burn the exhaust valve seat and ruin the valve/head. It probably wouldn't start either.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0