improving Velocity!!?!!!
- Thread starter Triplecrown421
- Start date
There is a builders product for filling voids, it is an expanding foam.
Maybe a former for a mould could be made by covering the reeds and stops, injecting some foam and fitting up the reeds.
If one coated the surface of the jug, or applied a wrapping film the foam should release quite easily.
When the foam dries it is very workable.
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I Know the foam you are talking about. I like the film idea, Saran wrap or thin poly. Very sticky and rigid so I'd have to have a release agent and good draft angles to pull it out, but it would make a great mould for doing these cylinders repeatably. Good idea!
I just now noticed the link in Best's sig, missed it origanally due to no internet for 6+ months.
I wonder if part of the effectiveness of the vf3/4 is due to the fact that the cage itsself is stuffing the intake? And the CR cage automatically does because you have to grind the intake to even make it fit.
Any more feedback on this mod? Do the side spacers fill the gap completely or were they used more for convieniance? Or is there still a hair space on each side? Tho my cyl was done before this was posted, I'd have built up the divider to get a more gentle taper rather than just angling it off. I didn't narrow it much if any.
My thought is that the mixture "stalls" in velocity as it enters the big cave, so if the volume is smaller less area to expand into and stall. Seeing that my engine is still down
I'm going to do this before it goes back together.
I don't understand useing both JB and Liquid steel, do you mix both together or is the steel easier to use in certain spots as it might not be as runny and stringy ?
Not that I wouldn't like more peak power, but I wouldn't want it more peaky either. And if this adds more meat in the middle it would actually make it better. Doubt if I'll raise the ex any but might widen it a hair. Only got widened enough to eliminate any bumps. I:I
I wonder if part of the effectiveness of the vf3/4 is due to the fact that the cage itsself is stuffing the intake? And the CR cage automatically does because you have to grind the intake to even make it fit.
Any more feedback on this mod? Do the side spacers fill the gap completely or were they used more for convieniance? Or is there still a hair space on each side? Tho my cyl was done before this was posted, I'd have built up the divider to get a more gentle taper rather than just angling it off. I didn't narrow it much if any.
My thought is that the mixture "stalls" in velocity as it enters the big cave, so if the volume is smaller less area to expand into and stall. Seeing that my engine is still down
I'm going to do this before it goes back together.I don't understand useing both JB and Liquid steel, do you mix both together or is the steel easier to use in certain spots as it might not be as runny and stringy ?
Not that I wouldn't like more peak power, but I wouldn't want it more peaky either. And if this adds more meat in the middle it would actually make it better. Doubt if I'll raise the ex any but might widen it a hair. Only got widened enough to eliminate any bumps. I:I
Larry, Neil has been running this since the summer. We have had the cylinder off a few times, epoxy holding well. The power improvement was nice, more top end, more revs and broader powerband range. Very successful, large improvement.
About stuffed reeds, I have noticed that on my KTM's. They have stuffers on the carb side of the reeds. Take them out and power is lost. We notice the Boyesens and VF reeds are essentially stuffed. How it works? I am with your theory. Keep the fuel moving!
The side spacers fill the gap completely. It is a tight squeeze getting the reed cage back in. Not hard to do, the plates were glued and held in place with the reed cage so they form fitted. That is useless space, fill it.
This cutaway pict is from JoeAK47:
And here is where got filled:
The Liquid Steel is a thick putty. Doesn't stick to the aluminum too well and doesn't smooth easily.
We sandblasted the port to rough it up, coated it in JB weld, then built it up with the putty, then coated that with more JB Weld. The JB Weld can be smoothed with a wet finger. Reduces the sanding needed. The putty was to get volume and shape. The JB Weld tends to flow so you have to apply it to the bottom of the port, then allow it to cure, then flip the cylinder over and to the other side of the port.
Steve
About stuffed reeds, I have noticed that on my KTM's. They have stuffers on the carb side of the reeds. Take them out and power is lost. We notice the Boyesens and VF reeds are essentially stuffed. How it works? I am with your theory. Keep the fuel moving!
The side spacers fill the gap completely. It is a tight squeeze getting the reed cage back in. Not hard to do, the plates were glued and held in place with the reed cage so they form fitted. That is useless space, fill it.
This cutaway pict is from JoeAK47:
And here is where got filled:
The Liquid Steel is a thick putty. Doesn't stick to the aluminum too well and doesn't smooth easily.
We sandblasted the port to rough it up, coated it in JB weld, then built it up with the putty, then coated that with more JB Weld. The JB Weld can be smoothed with a wet finger. Reduces the sanding needed. The putty was to get volume and shape. The JB Weld tends to flow so you have to apply it to the bottom of the port, then allow it to cure, then flip the cylinder over and to the other side of the port.
Steve
So the triangle plates got glued to the cage? What kind of glue?
To bad there wasn't something like kids playdough, fill the voids, push in cage, perfect void fill.
To bad there wasn't something like kids playdough, fill the voids, push in cage, perfect void fill.
No, the triangle plates got glued to the port with JB Weld:
Blowing air thru the reeds showed there was a significant amount going sideways, so we opted for the extra side clearance of the "triangle" cut plates, rather than the full length stuffer plates. This was an educated choice, and not borne out of any testing.
(this plate NOT USED, but shows full length stuffer plate)
Full length stuffer plate compared with the "triangle" clearanced plates that were used:
The Liquid Steel is a playdough type putty that is much less sticky than JB Weld and does allow some form fitting.
This picture is the reedcage (minus reeds but with the reed screws spaced with washers) covered in tape, pressed into the epoxy putty to form fit for minimal clearance. Notice there is no gasket. This pushes the cage back far enough to give us some needed clearance for assembly:
The final result is not the beautiful artwork of a diegrinder on aluminum.
It can better be described as "THE BLOB"!
It still requires some filling and filing and fitting :
A big change from the stock port:
And a big change in performance. Powerband broadened out, coming in sooner and hanging on longer.
Power increased throughout the range with no losses anywhere. Idle and starting improved.
Very pleased with the result. We will be doing this again, probably after experimenting with Boyesen ported cylinder.
Filling in the carb side of the reed cage is another possibility:
Steve
correct me if i am wrong. the fastest way from one point to another is a strait line.(fuel/air) now with voids and sharp angles it only makes sense to fill the voids.. (so there is no little tornadoes ) thus the straighter the line. (considering twirling etc.etc..) the most efficient... from what i see above in red. that empty space just looks like trouble/ turbulence... And only makes sense to be filled in....specialy since we are talking about a2 strokes and how they work.... now what about a textured finish in the intake.. ?
This is pretty cool I am just getting into 2 strokes and was talking to a machine shop last night about this very thing. love this post.
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