Welding Reed Block to Cylinder

[stinkbait]

Anyone ever played around with welding a reed block to a piston ported chainsaw cylinder? I've been wanting to do this for a while with a modern saw as an experiment. Wanted to run it by the forum just to see if anyone had any prior experience with this. I did a bunch of searching and didn't really come up with anything. I really don't know what the exhaust and transfer durations should be on something like this either.

 

[ericm979]

You need enough metal (or epoxy) in the cylinder to lower the intake port significantly or add a boost port or both. Just adding a reed in a port sized and timed for piston port intake will lower performance.

 

[rupedoggy]

Just my opinion and others will disagree but that is OK. Welding on a reed block is not the way to go.
!. The welding will often times distort the cylinder and mess with the sealing/roundness.
2. The reed block is used to put the charge right into the crankcase in most instances. Why would you try to introduce it in front of a piston? Educate me.
Mike

 

[stinkbait]

You need enough metal (or epoxy) in the cylinder to lower the intake port significantly or add a boost port or both. Just adding a reed in a port sized and timed for piston port intake will lower performance.

I was planing to notch bottom of piston in combination of lowering intake, and adding windows to the piston inline with the intake. Would probably cut a single boost port from top of intake also.

 

[stinkbait]

Just my opinion and others will disagree but that is OK. Welding on a reed block is not the way to go.
!. The welding will often times distort the cylinder and mess with the sealing/roundness.

I've seen where larger intake blocks were welded on saws to be able to run bigger carbs for racing. Didn't think that it would be an issue.

2. The reed block is used to put the charge right into the crankcase in most instances. Why would you try to introduce it in front of a piston? Educate me.
Mike

Newer piston ported saw designs don't allow for and easy way to add an intake block to the crankcase from what I can tell.

 

[mdavlee]

I have a 62mm 088 jug with welded blocks. I’ve never got it running right though. Going to try a muffler instead of pipe on it one day.

 

[stinkbait]

I have a 62mm 088 jug with welded blocks. I’ve never got it running right though. Going to try a muffler instead of pipe on it one day.

That looks awesome! I'm planning on doing it to a spare 660 that I have.

 

[ericm979]

Just my opinion and others will disagree but that is OK. Welding on a reed block is not the way to go.
!. The welding will often times distort the cylinder and mess with the sealing/roundness.
2. The reed block is used to put the charge right into the crankcase in most instances. Why would you try to introduce it in front of a piston? Educate me.
Mike

Cylinder reed ports were common for quite a while in motorcycles. As I noted the porting has to change (see A. Gram Bell's Two Stroke Tuning book for details) but it works fine. The problem is that all the ports on the intake side result in faster piston and cylinder wear. In most applications the piston is pressing against the intake side during the power part of the stroke due to rod angle. Adding windows on the intake skirt of the piston also caused faster wear.

The case reed greatly reduces that problem as only the rear transfers are on tyhe intake side of the cylinder and no windows are needed in the piston.

 

[stinkbait]

Cylinder reed ports were common for quite a while in motorcycles. As I noted the porting has to change (see A. Gram Bell's Two Stroke Tuning book for details) but it works fine. The problem is that all the ports on the intake side result in faster piston and cylinder wear. In most applications the piston is pressing against the intake side during the power part of the stroke due to rod angle. Adding windows on the intake skirt of the piston also caused faster wear.

The case reed greatly reduces that problem as only the rear transfers are on tyhe intake side of the cylinder and no windows are needed in the piston.

Do you have any input on port timing that you would like to share? I don't want it to be piped because I want the saw to be usable. I've got a 6 petal reed block and a block to use already, and I plan on using a walbro wb carb that I already have as well.

 

[mdavlee]

That looks awesome! I'm planning on doing it to a spare 660 that I have.

My buddy that welded it up did awesome. It just doesn’t want to run right on the pipe that he had for it. Hard to get it leaned out enough.