ESE's works engine tuner

[Michael Moore]

FWIW, Jeff Henise and I spent the afternoon machining two TZ350 heads to convert them to replaceable combustion chamber inserts for his Bonneville LSR project.

I did a simple program at the mill and machined the first head and everything went along fine -- not as fast as possible (no flood coolant on my mill) but no excitement either.

The second head was a different story. It either at some point got hot enough in use to completely anneal it or that batch of heads was from a different alloy or HT spec from the first. Nasty gummy aluminum, building up on the cutter to the point of making the head extremely hot from rubbing as well as pushing it out of position (4 clamps, the first head had no problem) 2/3 of the way through the cycle.

It would be interesting to know what was going on. The same end mill that worked a treat on the first one immediately went into "I'm not happy" mode on the second one so we're pretty sure it was the head casting and not anything we were doing (same program as the first head). Slowing the feeds and RPM down by about 2/3 took some of the "why is the coolant smoking so much?" heat out of the head but even with that the EM was clearly pushing metal around instead of cutting it.

I guess it is just part of the mystique of old race bikes.

cheers,
Michael

[wobbly]

Seen that before when the head has been weld repaired.
This kills the heat treat and weld materiel is usually different ( wrong ) as well.

[WilDun]

Let's switch to four-strokes, they said.
Oil on the track? Nah, won't happen....

Now look here Frits, how often do I have to tell you not to watch a "four stroke" race?

FWIW, Jeff Henise and I spent the afternoon machining two TZ350 heads to convert them to replaceable combustion chamber inserts for his Bonneville LSR project............. The second head was a different story.......... or that batch of heads was from a different alloy or HT spec from the first. Nasty gummy aluminum, building up on the cutter to the point of making the head extremely hot from rubbing as well as pushing it out of position (4 clamps, the first head had no problem) 2/3 of the way through the cycle. ......................was clearly pushing metal around instead of cutting it...........
cheers,
Michael

Not trying to be an expert of course, but it would seem to me that it was cast from a high silicon content ally (good for fluidity in castings), but which is well known for blunting cutting tools and sticking to them (as I have experienced many times over the years!).

[SwePatrick]

nice job there. will you be using standard Kawasaki ign box ? if so can you report back if the best results require the timing plate under the flywheel to be advanced or not ?

Hello.

Sorry, but i'm using either PVL or Ignitech.

TZ350, glad you like it =)

And,,, no problems in dyno. i built my own

[Michael Moore]

WilDun, the first head machined fine, the second was horrible from the start and I'd be surprised if Yamaha had made a big change in alloy between them. The first one seemed pretty normal to machine for a Japanese casting.

wobbly, I didn't notice any obvious weld repairs on the second one but then I didn't have a reason to go looking for them. Both heads had been nibbled on around the edge of the chambers, perhaps the second head had already been repaired a time or three. Both chambers were like that all the way through, it wasn't a localized spot.

The second head will be the back up that hopefully doesn't get used, but it should be OK as a water jacket with the chamber inserts to the spec you sent Jeff.

It was another typical day in the shop with Mr. Murphy.

cheers,
Michael

[WilDun]

...........I'd be surprised if Yamaha had made a big change in alloy between them. The first one seemed pretty normal to machine for a Japanese casting.
wobbly, I didn't notice any obvious weld repairs on the second one but then I didn't have a reason to go looking for them.
cheers,
Michael

Yes, I don't think Yamaha would have changed materials much and probably aren't responsible - Wobbly could be right, but could it be that someone has made a copy in the past? (we know that lots of people do this type of thing! ).

[jonny quest]

https://www.facebook.com/TwoStrokePe...c_ref=NEWSFEED

YZ125 with fuel injection.

Regarding head machining, did you use same bit for second head? HSS works better on aluminum than carbide, preferably 2 flute. Wd40 makes an excellent cutting fluid to spray on while cutting.

[Michael Moore]

Yes, the same .5" HSS cutter with air blast to clear chips and lubricant went from "that was good, let's get the next one done" to "WTF?" straight away on the second head. RPM was set right and the feed and WOC/DOC were conservative. The head being annealed is the most likely culprit. When he gets a chance Jeff will try a test cut in some scrap 6061-T6 with the EM on his manual machine to confirm that it is still sharp.

[Norman]

Did these "powervalves" actually work? Does anybody knows more about them?

[husaberg]

Did these "powervalves" actually work? Does anybody knows more about them?

Looks like an atac valve.
They are just a chamber about the same size as the engines cylinder, and a butterfly valve.
They do work on increasing low end power as long as they are mounted close to the exhaust port.
They have been used in various incariations on Honda CR NS and MVX as well as the BSL500 and Cagivas.


Suzuki and Kawasaki have also used more compicated variations of exhaust chambers.

the this is how they work
note the butterfly is mounted 90' away from how it is pictured here

This was Farmakens DIY effort (maybe not its a twin lol)

[Flettner]

I think I might have seen those before

How did they go in the end?

[husaberg]

I think I might have seen those before
How did they go in the end?

not sure I just emailed KTM though they seem keen

Here is the farmaken
DIY verson he did a spool one as well
https://www.kiwibiker.co.nz/forums/s...post1130357926

[wobbly]

The ATAC idea is ideal for an MX type application, where extra power is needed well under the natural powerband the pipe is capable of.
In the two cases I have used this, the BSL and the 1090cc SeaDoo World Champ winning ski, it added nearly 30% power under the pipe.
But it is severely limited in that it only works up to a very set defined rpm, and then the valve must be shut instantly, or you then loose 30% above that rpm very quickly.
A PV working correctly is useful in shaping the powerband well under the pipe and right up to peak torque rpm as well.
Using both adds huge power everywhere if they are both digitally controlled correctly.

[husaberg]

The ATAC idea is ideal for an MX type application, where extra power is needed well under the natural powerband the pipe is capable of.
In the two cases I have used this, the BSL and the 1090cc SeaDoo World Champ winning ski, it added nearly 30% power under the pipe.
But it is severely limited in that it only works up to a very set defined rpm, and then the valve must be shut instantly, or you then loose 30% above that rpm very quickly.
A PV working correctly is useful in shaping the powerband well under the pipe and right up to peak torque rpm as well.
Using both adds huge power everywhere if they are both digitally controlled correctly.

Sounds like a job for a Solenoid like the Aprilia RS125 road bike had.

or if you are cheap almost all starter motors.

[chrisc]

Can someone with way more experience with high performance carbs please recommend me one. Freetech 50 engine, reed valve, with hopes to end up 16-18hp in the long run. Would like a TPS to run a 3D ignition map and wouldn't mind a powervalve to get the most out of it too.