Stihl MS290 Big Bore

[a. palmer jr.]

The 390 I put together already has all the compression I would want. It feels about like the 044 I had when it comes to starting it...

 

[a. palmer jr.]

I didnt figure the fin droop was that big of a deal. Just... Made me nervous right off the bat.

Everyone still throwing away the farmertec wrist pin clips and using Stihl ones?

Those Stihl clips aren't a great fit in some of the AM kits, the diameter of the wire is smaller and it fits kinda loose in the groove. Some of the aftermarket clips are okay, the ones that are dark color are the better ones. Some of the silver colored ones are little more than bailing wire when it comes to springiness.

 

[user 122190]

Increased compression is what you are asking. Best to start by doing a compression test.

If you are going to start messing with small engines, a good investment starts here.

https://www.amazon.com/BETOOLL-HW01...1540579805&sr=8-2-spons&ref=sr_1_2_sspa&psc=1

Same thing I bought, good quality.

One thing I have been contemplating is that I found on eBay, @Definitive Dave is selling a cross brand pop up piston for the 039/390. I just am not sure if I want to tear my saw down just for a pop up piston. Of course, I never checked the squish on my saw after I rebuilt it. It could potentially do even better, if I have a really poor squish right now, by getting that piston and putting it in.

 

[ssm1699]

I realize that the pop up would increase compression. I already have a compression tester, just haven't tested it. Mine doesn't feel much heavier on the pull, than it did when I first got the saw. I don't even have a decomp in my saw, so it should be getting more compression feel on the pull, than someone with a decomp. I guess, why put a pop up in, when I have the MS660 for more power. That one has some serious compression and like the 390, don't have a decomp in it either.