KDXRIDER.NET

Hi
For those that like to tinker could I suggest next time you have your barrel off consider crankcase stuffing

It's one of those things that you can argue for or against. Thing is, it has a place. For me the area after the reeds is generous in its openness. All the better for access to the crank. Now if I can concentrate that energy and not have it dilooted, why not.

I estimate 18 to 20cc gain and it's free, reversible and explained.

Anyone with itchy fingers?!


Half way down page 25' on my signature.

So what is crankcase stuffing? I looked at page 25 and couldn't figure it out.

Also, I see how you were adding aluminum putty to the flow passage for the reed block. Aren't you afraid that the added material will cause inference issues with the reed petals? Looks like they would hit the sides when they are buzzing? I would also be pretty scared that the putty will start coming off eventually. I don't know what the temp limits or oil/fuel resistance is like. One little spec of that putty passing into the cylinder wouldn't be good. Did you really notice any difference after you did all of this?

Ty13r, if we ever go for a walk together you can go in front and do the worring for me. All good points for sure.

Crankcase stuffing is about taking volume out of the crankcase area. Theory is by reducing the area you increase the pumping efficiency. Bigger piston is another way to it.

I've run Devcon in transfer ports on air cooled motors next to the exhaust port and it's held, changed colour, yes but held. Used it to reconfigure motors, hold reed cages, replace cut out sections of cases, fill, shape and mate.
Simple rules:
Clean the area with detergent,
Leach clean with thinners
Rough up all over,
Clean with detergent
Leach again
When you apply it rub the first smear coat in
After set and shaped clean with detergent
Then don't ask it to do anything else other than sit there

I spent a lot of effort in making sure they couldent touch unless opened further than it did in the 200 motor, then just the tips and I dident change that area.

Does it work - for me, yes.

Ive seen people raise their intake runners/ports 3 or 4mm higher for a more direct flow of air into the cylinder on 4-cylinder sport bike motors, they epoxied the bottom of the runners in place of the unneeded extra space. those engines run much hotter than ours and the epoxy/putty seems to hold up well. Id be interested to see how this would work

It would be super cool if you had some way of measuring the actual increase in efficiency that you gained based on fuel consumption and power output. I'm a nerd and like trying to get all that you can out of something by fine tuning the crap out of it, so I can appreciate what you are doing there. I work with air pumps and compressors everyday and I won't allow for weld repairs or patching material on any of our castings. The risk associated with the repair material pulling away from the substrate is far too high for the business we deal in, so I cant help but be skeptical! lol We mainly deal with sand cast iron though, that's a lot different that aluminum investment castings. Just had to satisfy my curiosity!

I have done this alot when working on outboards for drag racing. The way I like to explain it is crankcase compression. The tighter you can "stuff" a crankcase the quicker it will accelerate. Another thing I would do is to deck the intake surface to set the reeds and carb closer to the crank. Next time I have my cylinder off I will look into this. It will make a considerable gain in acceleration.

Dam ecojbr I wish you would have reminded me about decking the reed cage months ago when I had the barrel laying around befor plating and painting. Missed opportunity, oh well.

It does accelerate fast now. Best way to discribe it is it doesn't matter if you are in gear or not for first and second. There is a different sound under load or not but it's going to rev the same speed with out lag.

Now you've kicked my memory into gear. There was a builder who swore by running Reed stops on fiber reeds. The "theory" was if a fiber Reed opened faster but against a stop, there would be more velocity or vacuum of the fuel/air mixture. How one would ever determine this as fact or theory I do not know. But he did for sure epoxy between the sides of the Reed cage and barrel. Some models of outboards actually had rubber "stuffers" to fill the excess gaps, similar to the nylon on a crankshaft

In 2001, kawasaki milled 4mm from the mounting surface of the kx125 to move the reeds closer to the piston. I'm very curious to see how this affects throttle response. Interesting topic!

It will make it quicker. How much I can't say.

Makes sense to me. As the space behind the reeds is the only space behind the reeds it has to go vacume before the reeds open, then suck on and have a delay in filling the minimum gap between the two.

I did not fin the return bottom passage into the crank area so when it goes positive preasure it's discouraged from going back easily. The hole in the piston is small. The side ports are squaring to the transfer ports so will have a leniency to suck. All in all I'm trying to extend the duration as long as possible. As a package with the other subtle touches it working.

It's like a dog or fly chasing a scent.

Make sure the hole in the piston is the same size as the boost port also

You know indirectly it is. Because I had to move the rear boost port back 3 mm to fit the 220 piston I reshape it nicer than our squairish castings. Then made it slightly shallower and slightly different angle.

At its heart this is a 200 barrel with a desert pipe. I was never in danger of loosing the 200 topend as I prodded and poked where that lived on my 200. I just want to add some 220 ness to the mix

Thank you for the info, that is a very interesting thread you have over there at trials.com.au. One of these days I am going to make it through the entire thing, rather than just a few posts at a time when you post specific references.

Thanks Julian D as a administrator I appreciate that. It troubles me that I'm doing it in a trials forum but they don't seem to mind and I'm to far into it now.