Another Porting Question

[drf255]

Got into the jug last night. It's very difficult to get a pic of the cylinder ports on a clamshell. The angle makes it nearly impossible to get anything worth looking at. The jug is nearly 4" deep.

I used a piston ring as a guide. Scribed sharp lines with a sharpie and went to work.

I may have raised the exhaust a degree or 2 in error. The ports were widened by around 20%. Visually MUCH wider than stock. Plenty of meat left to keep the rings seated.

I blended the ports to the openings. After I was done, I took a small spherical stone and went around the port inside the cylinder. There was a definite ridge at first which I knocked down.

The combustion chamber on this Huztl jug appears smaller than on OEM. The OEM jug has a bit of opening coming back to the intake side, this has none.

I did notice that the piston height (from the top of the wrist pin to the top of the piston) was lower than OEM. I'm wondering if this is why compression runs generally lower on these AM P&C kits. Looks like it would be a safety issue for their parts.

I tried welding a dome on a burnt out piston. I think I did too much. The biggest problem was how dirty the old OEM casting was. Even after SS brushing and acetone, a lot of black soot. The cleaning action of the AC wave pitted the piston around the dome a bit.

I purchased the 4xxl tig cups.

I wish I could get some pics. I took a few, but so hard to appreciate anything.

 

[drf255]

So what's the opinion on reducing combustion chamber volume?

Should I just weld a small blob of aluminum to the piston top or try to just close off the dome of the chamber a bit opposite the spark plug?

I don't have a lathe.

The piston would be much easier, but much more likely to warp and will add reciprocating weight.

I think I'm gonna assemble my tig torch and see if I can just reduce chamber volume.

 

[drf255]

I tried.

Stock exhaust and intake



Ported.




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[Moparmyway]

Nice improovement on the ports !!!

 

[drf255]

Thanks. I'm trying.

Will post pics of piston or combustion chamer when I can.

I only have 1/16" aluminum filler rod in 5356, not 4043. Will ask on a WeldingWeb if acceptable. Generally 5356 cannot be used in any high heat applications.

 

[Moparmyway]

What was the balance set on when you welded the piston and blew through it ?

 

[drf255]

Machine set at

AC
60Hz
65% EN
Preflow .2
Postflow 6.0
150 amps
3/32 4043 filler
3/32 2% lanthated.
#8 cup
Gas lens
No preheat

Never blew through it. Need a lathe to make concentric. Started in the center and moved out too much. If I hit a piston again, I'm gonna turn the AC frequency up to max (150) and used less amps with smaller filler wire and preheat.



Embarrassing attempt on a junk piston. But an attempt nonetheless.


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[drf255]

I may try the next piston partially immersed in water. Will need higher amps, but heat will only concentrate at the crown.

Will weigh before and after. Will try to remorse material from under the dome to match.

 

[LegDeLimber]

For whatever happens, I'm just going to enjoy the show.
I have been wanting to see someone take a swing at this.

One of the main things I've wanted to see is someone weigh a piston first
and do that under dome reduction as best as you can.
And as I think you've said, get the stock buildup looking right and then dial in on the reshaping.
Thanks for chucking the money into it and then posting the results.

 

[drf255]

Measured the chamber on the modified cylinder. .785, so I should be fine at .750.

Marked piston and weighed with and without wrist pin and clips. The modified piston has the clips and pin installed.

I plan on welding in sitting in a water bath.





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[BBP]

How about drilling hole in the top of the cylinder, recess a piece of aluminum roundstock into the combustion chamber and weld it in place from the outside?

 

[drf255]

So with all that extra aluminum, much larger than the one I plan on, the OEM only 2.5 grams heavier than the Huztl replacement. An entire 3/32 filler rod weighs about 8 grams.

 

[drf255]

How about drilling hole in the top of the cylinder, recess a piece of aluminum roundstock into the combustion chamber and weld it in place from the outside?

Not a bad idea, but the area need to be off centered. The plug area need to be open for flame travel.

I have an idea to drill a 3/4" hole in copper plate I have and clamp it to the piston. The aluminum won't stick to the copper. It would effectively mold a 3/4" ring of aluminum and also wick heat away.

 

[LegDeLimber]

I've done the water tub thing for mounting brackets of a motorcycle tank.
Just wanting to save the paint job, was the reason.

Just for giggles, how about taking some measurements of the piston before starting any work or heating of it.
I think I would check in direct line , front to rear and as close to the "cut away"
in the side area of the skirt.
Try the middle section between the ring groves, maybe about 45 degree intervals.
Heck, could even stuff it into the cylinder with some paper strips in various positions
and see how it fits and any high/low spots.
Then do the same after welding and shaping.

ain't asking too much of a fellow here am i? .......i hope.

 

[drf255]

I plan on measuring and posting.

This entire thing may be a waste of time and cash, but who knows.

Just bought some 4047 tig rod. The highest silicon content, twice that of 4043. The one to use on pistons.

 

[Moparmyway]

Machine set at

AC
60Hz
65% EN
Preflow .2
Postflow 6.0
150 amps
. If I hit a piston again, I'm gonna turn the AC frequency up to max (150) and used less amps with smaller filler wire and preheat.

I wouldn't change too much just yet ............
IMHO;@ 65% EN, you are getting deep penetration without too much cleaning. That could explain the pin holes/pimples and turning the balance lower will give you better cleaning action around and within the weld puddle, plus less heat going into the crown .......... probably making the water bath unnecessary and definitely changing the wetting out of the puddle and HAZ during the weld

 

[Moparmyway]

I plan on measuring and posting.

This entire thing may be a waste of time and cash, but who knows.

Just bought some 4047 tig rod. The highest silicon content, twice that of 4043. The one to use on pistons.

Uuummmmm ........ I do
It definitely is NOT a waste of time.
The cabbage ............ its yours, so my opinion might not mean squat, but the experience you will have after you see a good clean weld without a doubt will put a smile on your face.

Please keep at it, you are just about there ............ I think its all in the machine setup !!!
Best choice for rod !! I wish I could double like your last post

 

[drf255]

Cool, thanks.

Enjoying it.

The long cups will be here by the weekend. I plan on fooling with welding on a spent jugs chamber first. If that fails, it's the piston crown.

 

[Moparmyway]

Cool, thanks.

Enjoying it.

The long cups will be here by the weekend. I plan on fooling with welding on a spent jugs chamber first. If that fails, it's the piston crown.

Its a tough angle to add filler rod to ..... and its going to be very hard to see a few seconds after you establish your arc, you will also get funny turbulence of the shielding gas at the weld puddle due to the cylinder walls and the heat trying to get out of there ................ turn up the gas flow !!

IMHO, the piston is where the best results will be

 

[drf255]

Its a tough angle to add filler rod to ..... and its going to be very hard to see a few seconds after you establish your arc, you will also get funny turbulence of the shielding gas at the weld puddle due to the cylinder walls and the heat trying to get out of there ................ turn up the gas flow !!

IMHO, the piston is where the best results will be

Ummm. Yeah.

Got the XXL cup today. Even with that, no way I'm gonna see the puddle in that chamber.

It's gonna be the piston.