2 stroke mods?

[mike75925]

hmm, i thought taz was a separate country. i visited hobart, and perth, oz. i was drunk so i don't remember which was which!

 

[sideways]

Tasmania, Australia im gonna enlarge both ports but i dont think im quite up to shaping them myself

Don't bother making the exhaust port any bigger unless you've got an expansion chamber, I did and now it runs like a dog lol. Too much unburnt fuel goes out of the exhaust port, you get explosions in the exhaust when its hot.

Hayden

 

[oscaryu1]

porting, bigger carb, decking head and cylinder if possible, copper head gasket, higher comp piston, bigger piston, expansion chamber, tuned pipe, ceramic piston, ceramic bearings, alky or nitro, the list probably goes on further.

Widen intake and exhaust, degree intake and exhaust to whatever specs you like (prefer removing a few thou on the intake and raising exhaust), but I like Zenoah port specs, just me.

Bigger carb, sure. Make sure it's adjustable and you should be fine.

Don't deck head and cylinder, you lose less skirt area covering the exhaust when going to TDC.

No real higher comp piston, lol. They're generally domed depending on the squish band shape and whatnot...

There's plenty you can do... reangle squish band, REDUCE squish band, advance timing/retard timing, nitrous setup, pipe from a similar application that can be had for cheap, stuffing cases, mill down flywheel, so dang much for a 2 stroke.

 

[oscaryu1]

Don't bother making the exhaust port any bigger unless you've got an expansion chamber, I did and now it runs like a dog lol. Too much unburnt fuel goes out of the exhaust port, you get explosions in the exhaust when its hot.

Hayden

Then you ported it wrong. The exhaust is supposed to create a restriction (slightly), and act as an muffler at the same time.

 

[mike75925]

my gixxer back pops through the muffler when i let off the gas. it sets off car alarms like crazy. maybe the carb is just too rich?

 

[sideways]

Widen intake and exhaust, degree intake and exhaust to whatever specs you like (prefer removing a few thou on the intake and raising exhaust), but I like Zenoah port specs, just me.

Bigger carb, sure. Make sure it's adjustable and you should be fine.

Don't deck head and cylinder, you lose less skirt area covering the exhaust when going to TDC.

No real higher comp piston, lol. They're generally domed depending on the squish band shape and whatnot...

There's plenty you can do... reangle squish band, REDUCE squish band, advance timing/retard timing, nitrous setup, pipe from a similar application that can be had for cheap, stuffing cases, mill down flywheel, so dang much for a 2 stroke.

Victas dont have a squish band, thier just a hemi head (not a full hemi but anyways), the piston is also only very slightly domed. And yes, don't mill the cylinder down, just the head.

A better carb is a must on victas, the standard one is **** if you want to do anything but mow lawn with it.

Hayden

 

[sideways]

Then you ported it wrong. The exhaust is supposed to create a restriction (slightly), and act as an muffler at the same time.

I can assure you, I didn't port it wrong, I have lots of experience with these things. The victa was ported (from factory) to make full power at 3500rpm at that is the speed they are always run at. I lifted the exhaust port about 1.5mm, it needs an expansion chamber to mach. The standard muffler (which glows a dull red at night) is just about muffling noise, its just a box full of mesh (later ones had baffles) and doesnt rebound the pressure at all. It is tuned correctly, it idles roughly and doesn't seem to have as much power as normal.

Hayden

 

[Russ2251]

that could work, never thought of lapping something that big though

It works. Such an incredibly easy thing to accomplish. Used to do it back in the '60's on the Mac's right out of the box. I do it to all my engines, 2 or 4 cycle, as long as clearance allows. Just finished a Briggs 5hp.

Couple hours and a lot of patience.

Never took more than 40 minutes total.
Nice thing about this is, it is easily reversible. Simply replace gasket.
Try replacing an ill conceived porting job.

 

[mike75925]

true on repairing the ports. though i have heard of some really good epoxy that you can use to basically make a cylinder sleeve. a friend had a briggs that was all gouged up. his builder told him let me see it, applied the epoxy, bored it, and now it has i think he said 200 races on it?

 

[Kaptain Krunch]

Never took more than 40 minutes total. Nice thing about this is, it is easily reversible. Simply replace gasket.

Really, i would expect it to take more than 40, maybe ill try that on my sled than, i was considering machining the heads but this is a much better option.

 

[Kenny_McCormic]

Really, i would expect it to take more than 40, maybe ill try that on my sled than, i was considering machining the heads but this is a much better option.

Keep in mind this might move a sled engine designed to do something more than cut grass or shovel snow into the high octane fuel area.

 

[Russ2251]

Time will vary according to size of area to be lapped and pressure applied.
I use the Clover silicon carbide grease 320 grit, part #39510. Cuts pretty quick.
Use a good flange sealant such as Permatex Super "300" (preferred) or Hylomar. Make sure assembly is properly torqued to max factory spec.

 

[mike75925]

ah, see gasket material. i thought running gasketless might be too good to be true!

 

[Russ2251]

Use caution!!!
This can be done on a wide variety of engines...but not all.
Take measurements first!!!
Unfortunately this is a trial and error process.
Once done, listen for spark "knock" or detonation. You'll know it when it happens.
If detonation does occur, then replace gasket.
I've done it on 2 and 4 cycle Briggs from 1hp (cast iron) on up to 7hp (aluminum) L head engines as well as all 4 of my Lawn-Boy DuraForce engines. Year of engines tested ranges from early '50's on up to the present. The old Mac's also benefit.
I am considering doing this to my blue clone which is still gathering dust in basement. They may be cheap...but they are also junk. I have no real use for it...if it self destructs, so be it.
I have had zero issues (with all other engines mentioned) to date.
Why this simple mod has been ignored is beyond my scope.