Reed valve lift and flow

[Hart89]

I have a piston port/reed valve engine. What will the effects of removing some material so there is a larger "port" under the reed assemmbly? The reed valve assembly bolts on to the bottom of the cylinder i want to make the intake hole is flush with the cage so there is better flow. I would think it would be pretty much the same as making the intake manifold larger... which affects?

And what affects does changing the reed valve lift (by bending the stop out or in) have on power delivery?

Thanks for any help.
Daniel

 

[Bandit9]

I would think it would do the opposite of adding a torque spacer. Which would be hit harder and more abrupt? Unless you are not removing it uniformly around the entire surface. If you are just removing it some spots and not others, I have no idea how that would effect it.

 

[steve125]

What engine are we talking about here?

 

[Hart89]

Sorry this is the TS185 engine. It is more of a clean up then removing a heap. Can someone tell me what happens if u increase the lift of the valves? Is there a limit before things start splitting? They are fibre glass dual stage with only 2 pedals. Can anyone recomend any things that could give me some more mid/top power.

 

[rm_racer]

I dont know if I can help, but do you want to take off from the carb end or engine end of the reed? If you mean carb end, someone did that to my old reed cage before I had bought my bike. They took too much off and the result was this: A ruined cage, and huge loss of power, that I had not found out about until the new cage was installed. I suggest if this is your idea then do it properly. See below for pics.

 

[David Trustrum]

Ohh, TS185, nice. :ride:

Nah just kidding, I’ve spent time porting much worse.

Ok the drill; (sorry for reply to old thread, don’t come here often these days)

Anyway the reedblock of these old suzukis sits on the bottom of the inlet port of a piston port setup.

Period RMs had much flatter valves. Copying this works well (I race an old bike with same setup). Anyways if you put that reedblock on the mill in a vice & tilt it so the bottom front edge is sticking up & take off the angle on the bottom so it is, well, almost flat.

You can leave a wedge at the reed screw end (you’ll see what I mean when you take a few cuts). The retaining area for the screw will start to disappear until they are a thin wedge. There should be enough to hold the block in. Blend the inlet port for a smoother transition & add some Devcon to the back of the reedblock & port so there are no steps.

You will see where flow from the block now hits the bottom of the cylinder. Grind a couple of channels to allow clearer flow. Some devcon in the gap in between wouldn’t go amiss. Further if you are keen, extending the divider up to the port floor is a good idea. Basically making a wing on top of the divider from a piece off ally cut to shape. Drill a couple of small holes in each & make some short pins to dowel the 2 together then superglue them. Add devcon to smooth & join the ends.

Now the next bit will get people cringing. But bear in mind the TS is a farm bike & ported for the lowest engine speeds.

Having never seen a 185 you should arbitrarily be able to widen the piston port inlet a couple of mm & lower it the same amount. Make sure the piston skirt can still cover the ports when at TDC. Ideally you should raise the exhaust & transfers too, but it’s much safer to just raise the barrel & don’t touch the transfers & lower the inlet to negate the raise + skim the barrel the same amount to retain the compression. Really you need to measure the port size/durations & ask yourself what you are trying to achieve, but if you are just having a bit of fun playing then a TS will allow you to make big gains with amateur skills.

Kids don’t try this at home with your MX bike, they are much more complex to improve..