Porting a Husqvarna 394xp

[subhunter]

Well I have got my 372 ported{I think} for Terry's GTG. Now I am going to try my hand again at grinding.

My questions for this saw are Should I make the windows in the piston bigger than they are now or would it not benefit from that? Also should I change the timing at all or just go for the bigger ports? It seems to have quite a bit of room to widen and clean up the intake and exhaust ports from what I have measured so far.
Any help from you guys is always appreciated!

 

[AUSSIE1]

You want to try and get your comp up some and squish a little tighter. They need an increase in blowdown to 20° plus which means raising the exhaust but if you drop the cyl this will work in your favor. Widen ex and inlet, open up the lowers. They can be raised some. Open up the windows in the piston without going to far. Muffler mod with the 288 deflector.

 

[subhunter]

Forgot to add that I had already ran about two tanks through this saw since I got it. Also I did a muffler mod using the old deflector{had to get a new muffler}. Now another question, I have never worked over a saw that has the lower transfers in the jug, so how would you go about that?

 

[parrisw]

Forgot to add that I had already ran about two tanks through this saw since I got it. Also I did a muffler mod using the old deflector{had to get a new muffler}. Now another question, I have never worked over a saw that has the lower transfers in the jug, so how would you go about that?

Grind them out towards the bottom of the Jug, go all the way.

 

[subhunter]

OK sounds easy enough, just so I am clear, "go all the way" meaning all the way to the bottom of the jug? Thanks Aussie and ParrisW

 

[parrisw]

OK sounds easy enough, just so I am clear, "go all the way" meaning all the way to the bottom of the jug? Thanks Aussie and ParrisW

Yes, just kinda ramp it to the bottom of the jug. Wish I had a pic.

 

[subhunter]

Hmmm,that's definitely different than I was picturing in my head. So you will also remove some of the 'lip' that sticks into the case when opening the lowers? I was thinking to just take them down keeping the 'bowl' like shape that they already have.

 

[subhunter]

Wish I had a pic.

:hmm3grin2orange: seen it

 

[parrisw]

Hmmm,that's definitely different than I was picturing in my head. So you will also remove some of the 'lip' that sticks into the case when opening the lowers? I was thinking to just take them down keeping the 'bowl' like shape that they already have.

Just taper it out all the way to the lower lip of the cylinder.

 

[parrisw]

:hmm3grin2orange: seen it

:msp_wink:

 

[komatsuvarna]

You want to try and get your comp up some and squish a little tighter. They need an increase in blowdown to 20° plus which means raising the exhaust but if you drop the cyl this will work in your favor. Widen ex and inlet, open up the lowers. They can be raised some. Open up the windows in the piston without going to far. Muffler mod with the 288 deflector.

How much is to much blow down Al? On my 395 with 2101 Im at 22 blowdown. I'd like to raise the exhaust 2 degrees or so to match the intake, but my blowdown will be like 24 then.

 

[AUSSIE1]

How much is to much blow down Al? On my 395 with 2101 Im at 22 blowdown. I'd like to raise the exhaust 2 degrees or so to match the intake, but my blowdown will be like 24 then.

I couldn't say Durand how much is too much. Haven't been there. What durations are you running on ex and in? The 395's loose torque with too much Ex. Also you will loose some compression.

If you have nice high compression and conservative no's, you could raise the exhaust some. 22° blowdown sounds good, but if you were to raise the exhaust and have 24° and didn't like it, you could then bring the uppers back up to 22°

My 100cc 395 is running 164° Ex, 158° inlet, 124° trans. 185psi

I didn't want that high an Ex, but it was the only way I could get 20° blowdown but was lucky to end up with 185 psi as the BB kit had a smaller combustion chamber against the OEM.

 

[Kwdog75]

Take it easy on a 394 cylinder, they are expensive to replace if you go too far.

 

[subhunter]

:msp_ohmy: How far is too far? I may have went too far on the exhaust. one side I,accidentally, left only .056" to the skirt. Should I be ok?

 

[parrisw]

:msp_ohmy: How far is too far? I may have went too far on the exhaust. one side I,accidentally, left only .056" to the skirt. Should I be ok?

Well, you got nothing to loose to run it, but that's cutting it close. I leave .100" but many people go farther then that.

 

[subhunter]

It is only on one side{clutch} of the exhaust. I am not sure how I went too far but it is what it is..... luckily I got the bevel I think nicely throughout the entire port. Will give it a start up tomorrow

 

[AUSSIE1]

It is only on one side{clutch} of the exhaust. I am not sure how I went too far but it is what it is..... luckily I got the bevel I think nicely throughout the entire port. Will give it a start up tomorrow

Meteor 395 piston is 39mm across the skirts
2100/101 golf is 44.6mm

 

[subhunter]

I was wondering about that. I know Durand used a 2100 piston in his. I wonder how wide the meteor 2100 skirts are? That piston looks different than the golf one. I am going to fire it up later on and see how it runs.

 

[parrisw]

I was wondering about that. I know Durand used a 2100 piston in his. I wonder how wide the meteor 2100 skirts are? That piston looks different than the golf one. I am going to fire it up later on and see how it runs.

Golf makes the only 2101 full circle piston that I know of.

 

[subhunter]

It starts and idles nicely. I am going to cut on a large oak later and will try o get a video of it. Hopefully it dose not grenade!