357xp mods

[Chainsaw Jim]

You can either jb weld the barb to plug it or twist it out with pliars and plug the hole with a screw. A regular decomp valve will thread right in to the cylinder.

 

[Tothemax]

First off sorry OP, I'm not trying to hijack your thread but does it take a special fitting to plug the decomp? I picked up a 357 last fall but haven't put much time on it, it had been sitting for a while apparently and when I ran it it seemed to warm up and not run properly. I assumed it had crap in the carb, gummed up, maybe bad fuel line and filter. I replaced all that with new air filter and plug but still acted up.
It would bog down when I hit the throttle and wanted to die as well. I took it into a shop to have them check it out and they went through it I got it back and it seemed fine till I ran it hard then started acting up again. I took it back they went through it again, cleaned carb and tried a new plug and I ran it yesterday. Started fine but had the bog for a lil bit when it was cold, once I got it warmed up good it cleared up and ran like as scolded dog!!! Very impressed with this saw!!!

Does that sound like the decomp acting up? I'm not against plugging it if it will save me some headaches down the road.

By the way this saw is very clean and I don't think it has a lot of run time on it.

I'm wondering if it was the decomp from the get go, maybe stuck from sitting?!?

Thanks for the info in your thread, keep it coming.

Its all good.

They make a plug for the decompression hole on the side of the cyl. I think I jb welded the other hole shut.

Make sure they installed the proper carb kit. There are a couple kits that look identical but one doesn't have a hole cut into one of the gaskets on the diaphram side. You need that hole cut in it to run properly.

Also make sure yours doesn't have the cheap plastic band on the intake manifold. IF it does it needs to be Replaced with the updated clamp, or you need to install a hose clamp.

 

[Tothemax]

I got to moding last night. I cleaned up the transfer ports, bored out thr exhaust, widened the exhaust shield opening, and cleaned off the casting marks in the intake.

In the next couple days I am going to mod the muffler, check squish and put it back together.

 

[Tothemax]

Easier if you search squish & base gasket delete. But squish is the clearance between the piston and top of cylinder. You want that the be around .020" and that is usually what you get when the gasket is removed. There are a number of sealants to use at the base of the cylinder.

Got around to checking it today. .022 is what I measured without the gasket

 

[Tothemax]

I found some Motoseal at one of the local autoparts stores and I got it back together this afternoon. A quick compression check showed 150PSI. Now I need to mod the muffler and I am ready to start.

 

[sunfish]

I found some Motoseal at one of the local autoparts stores and I got it back together this afternoon. A quick compression check showed 150PSI. Now I need to mod the muffler and I am ready to start.

150 psi is no good with a gasket delete? I get around 190 on a 357.

 

[Chainsaw Jim]

I suppose weakened rings at that comp strength can deliver a similar function as thin rings with the whole less drag thing.

 

[spudulike]

If you widen the ports, make sure you re-bevel the port edges or wait for the ring to snag in a real bad way! 190 - 200 psi is normal once the base gasket is dropped.

 

[jr27236]

Mine after my base gasket delete and only a few pulls

 

[Tothemax]

Hum.... I can go recheck. Sometimes my compression gauge is off. Its done it before..

 

[jr27236]

Hum.... I can go recheck. Sometimes my compression gauge is off. Its done it before..

Then you need to get a new one lol. Id hate for anbad gauge to cause me to break down an engine prematurely

 

[Tothemax]

Sad thing is, it is "new"

 

[Tothemax]

Just checked it again. 150 is what I got.

As far as the tester goes I bought it new last year. I have gotten a few funky reading out of it. Figured it was the O ring letting air by. Whenever I put my air compressor air gun to it, it reads close to what the output pressure says on the regulator.

 

[blsnelling]

I've read, I'm just over saturated with info. Its time to start cutting...

That means it's time to re-read.

 

[Tothemax]

That means it's time to re-read.

Little late to the party

 

[sunfish]

If the piston, ring & cylinder look good, then your gauge is likely bad. This assuming the decomp vale isn't leaking & you're cranking until the gauge stops climbing..

 

[Tothemax]

When I checked compression prior to tearing it down I got 130. Piston and cyl look good.

Yes I am cranking till it stops.

Any suggestions on a new quality gauge?

 

[sunfish]

How'd it run before?

 

[Tothemax]

Awesome. No issues

 

[Tothemax]

I just bought a tester off amazon. Had hundreds of reviews. 4 out of 5 stars