Brewz Saw Builds

[Brewz]

Ahhh
0.94mm

 

[Brewz]

I got a mate to take a pic of under the cover of a HT 12 off his 088

It appears to have an additional jet for the L idle feed (top left).



The HT 5 on my 084 doesnt have the 3rd port to feed the L curcuit so it must draw from the same port as the H
Perhaps the improvement they made to the later HT's?

I may actually put the HT 12 on my 084 and cut off the limiter tabs to shh how it goes as well.

 

[Brewz]

I got the 1308 coil fitted up
Put the HT 5 back on and pulled the cord.

Its a different saw with the 1308
Its as easy to start as my 044 now. I have blood blisters on my hand from the mongrel limited coil biting me.

The 1308's retarded start got it started quick and easy, and it kicked up with a nice slow idle that built and settled to smooth and nice.

It was on dark and my neighbors have little kids so I have a no saws after dark rule.
I gave it a quick rev with the H screw all the way in and it definitely ran much faster than it did with the limited coil.
Will check tunability and RPM tomorrow arvo and will also give the HT 12 a run, see what it can do. I like the idea of a separate jet for the idle circuit on the 12

 

[Brewz]

Just ran it up with the 1308 coil and HT 5 carb and it will lean right out now up over 14000 rpm.
Starts to 4 stroke at 13800 but I have it set at 12800 in the video.

I got in trouble for piss revving saws with no PPE so I covered up this time
@drf256

 

[Brewz]

HT 12 has a seperate jet to supply the idle circuit and the H brass jet is bigger at 1.04mm

I have removed the limiter tabs and will try it on the 084 later on

 

[mdavlee]

Good info. Maybe the 5 I have will work fine.

 

[Brewz]

Here is some more findings
I just fitted the HT 12 from an 088 and the saw loves it.
Tunes easy, better idle stability and will lean out to 14000 rpm but not screaming lean like the HT 5 that bumped 15000 on the tachometer.

I am happy with that cause it's happy running at 13000 rpm and I have no desire to push it to destruction

One thing I discovered during the carb swap is that the later HT carbs with the plastic limiter tab arrangement around the L and H screws has a throttle connecting bar with a bit more of a dog leg in it to get around the plastic thing.



The HT 12 will be staying on it

 

[Brewz]

Good info. Maybe the 5 I have will work fine.

Should do.

It would lean my saw out enough to kill it real quick at 15k

 

[mdavlee]

Should do.

It would lean my saw out enough to kill it real quick at 15k

It needs to go lean enough to work on a 70cc saw.

 

[Red97]

It needs to go lean enough to work on a 70cc saw.

17,500 ought to do the trick

 

[Brewz]

It needs to go lean enough to work on a 70cc saw.

Ahhhh
My guess (it's a guess) is that the brass jet that says .94 on the HT 5 and 1.04 on the HT 12 is the fixed jet limiter because the 5 will lean our more than the 12 that has a larger jet.

Try filling the jet with some solder and see what it does.
If you need more fuel you can always drill it out starting small to get what you need.

If I couldn't adjust this saw enough that was what I planned to do but it's just my hunch

 

[mdavlee]

17,500 ought to do the trick

Maybe on methanol

 

[Red97]

That jet looks like the same one
Some of the hda carbs. 196 I think.

Probably is smaller being off a 50cc saw. then open it to where needed.?

 

[VinceGU05]

Should do.

It would lean my saw out enough to kill it real quick at 15k

Just be careful with high rpm on these saws. They can break cranks [emoji6]

 

[jmssaws]

Just be careful with high rpm on these saws. They can break cranks [emoji6]

The rod can't take it.
It's made from a coat hanger.

 

[Brewz]

Just be careful with high rpm on these saws. They can break cranks [emoji6]

The rod can't take it.
It's made from a coat hanger.

So what do you think would be a safe max rpm to tune the saw to?

I sure wouldn't run it at 15000. That was just a figure it will go to if leaned right out.

 

[jmssaws]

For work I would think 12 to 12.5k
Certainly not 13.5

 

[Brewz]

Copy that.
Will feed it a tad more fuel

 

[Brewz]

Taking it out on Sunday for a run.
I can't wait to see how it goes

 

[jmssaws]

I got one to do soon as the piston gets here
Don't know what carb is on it,forgot to look