Bucket development: A few questions for the wise ones

[jasonu]

[QUOTE=F5 Dave;1129769481]Hi

. . .well I'll let someone deviantly filthy (like Jason) complete the analogy.

What are you trying to say???

[speedpro]

:slap:

33.5 huh? Well it was a 'production' bike & no one ever cheated on those. . .

which planet are you living on?

[F5 Dave]

It's called sarcasm. All the TZR carbs I've had have had a idlejet stuffed in the powerjet rubber hose connecting with float bowl. Don't think that is std & gets around the 5% jetting rule.

[TZ350]

As you are using long plugs, mill the plug recess down by 2-3 mm. Then you can use standard plugs rather than special ones for the life of the motor. If you remove the thermocouple later, replace it with a 2 mm aly washer. Cheers

You can get standard plugs at bargin prices if you buy in bulk from ebay, we got 70, after paying for shipping they worked out at a $1 each.

[F5 Dave]

Some engines like specialised plugs & flash ignitions (timing aside) & some don't seem to give a donkeys, I have some fairly simplistic theories but it comes down to test & test again.

[Bert]

Some engines like specialised plugs & flash ignitions (timing aside) & some don't seem to give a donkeys, I have some fairly simplistic theories but it comes down to test & test again.

I'm hoping this one is a donkey... I've just about finished building my own ignition (with lots of help), The sparkplug discussion is more about dealing with the shape of the current TZR combustion chamber design and the fact that is doesn't suit the requirements now with a smaller bore.

So the head is going to be welded up and reshaped; but I'd like to set the sparkplug further down. so I was looking for the easiest option first (being longer plug as it is going to be welded up anyway). but it looks like machining the top of the plug surface down and running a standard plug is a better option; then run the old fav B9evg's... at lease will reduce one point of potential issue....

[speedpro]

I've reshaped an RGV combustion chamber and got immediate horsepower gains on the dyno. Compression was exactly the same and there were no other modifications. It was close to 10% improvement and improved the spread. Ended up with a nice squish area then a nice radius into an eliptical shaped bowl. Bit of welding involved but well worth it. The EGV plugs are a waste of time in my experience.

[F5 Dave]

Be careful who you get to weld combustion chambers, older cheaper welders just seem to create porosity, something about not being sinusoidal wave, or maybe square, I forget, but the modern ones are the other type from older cheaper ones & have half a chance. The ally used is casting ally with a lot of zinc & it bubbles easily.

EGVs gave no improvement in my H100. But they certainly liked the 50. (Mike think you are talking about the ones that are supposed to melt before detonation & they are EGs I think). But either way I've seen a $150 racing plug give almost a 1 hp on a 50. Big numbers. Tried in my bike it was no better, possibly worse. Glad I didn't have to buy it to find out.

If you can run a cheaper commonly available plug all the better.

[speedpro]

The only bike i ever had a power increase when changing plugs was an old (new then) XS1100 which gained 2hp when i fitted basically standard plugs with a "J" gap. The earth electrode was cut back so it only extended to the centre of the centre electrode.

[speedpro]

I think if a plug change causes a power increase it's probably because the ignition is marginal. The only other possibility is something mechanical like the gap being in the wrong place in the chamber.

[jasonu]

I've reshaped an RGV combustion chamber and got immediate horsepower gains on the dyno. Compression was exactly the same and there were no other modifications. It was close to 10% improvement and improved the spread. Ended up with a nice squish area then a nice radius into an eliptical shaped bowl. Bit of welding involved but well worth it. The EGV plugs are a waste of time in my experience.

I had similar results when fiddleing with dome shapes, squish widths and clearences.

[gatch]

Is there any sense in machining the head right out and pressing in a piece off a suitable grade ally, rather than welding on old castings ? No distortion with heat, no risk of porous welds etc..

I've heard of interchangeable combustion chambers for varying squish etc. Though this may be with water cooled motors only ?

With a pressed in insert, maybe heat exchange between 2 parts would be a problem ?

[F5 Dave]

Is there any sense in machining the head right out and pressing in a piece off a suitable grade ally, rather than welding on old castings ? No distortion with heat, no risk of porous welds etc..

I've heard of interchangeable combustion chambers for varying squish etc. Though this may be with water cooled motors only ?

With a pressed in insert, maybe heat exchange between 2 parts would be a problem ?

I have a head like this on my 500, works fine for watercooled as water flows over insert (& o-ringed). Wouldn't try it for aircooled.

[F5 Dave]

I think if a plug change causes a power increase it's probably because the ignition is marginal. The only other possibility is something mechanical like the gap being in the wrong place in the chamber.

Or the chamber is so shallow it shrouds the spark (sort of your option 2), that is where racing side projection type plugs come into their own.

I've had improvements with EGV plugs where the ignition wasn't marginal, or at least was a good ignition, just it liked the EGVs.

[Bert]

Is there any sense in machining the head right out and pressing in a piece off a suitable grade ally, rather than welding on old castings ? No distortion with heat, no risk of porous welds etc..

I've heard of interchangeable combustion chambers for varying squish etc. Though this may be with water cooled motors only ?

With a pressed in insert, maybe heat exchange between 2 parts would be a problem ?

something like these:

http://www.rscycles.com/images/vhm_p.../vhm_heads.htm

yes, wouldn't that be nice; but I don't really have access to the required tools to make something like this.