Another MS290 Rebuild Thread

[huskihl]

Should I do anything with the intake timing?

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Thats up to you. 2 jugs from different manufacturers. I don't have the #'s in front of me, but I took the bottom of my intake down a couple degrees and flattened it out a bit. But you already have quite a bit of intake duration so I'd just knock the lip off to direct flow into the bottom

 

[Chainsaw Jim]

The only thing you're really going to not be able to do is lower the cylinder to tighten the squish with a clamshell..which won't really be necessary to see good gains with porting and muffler mod.
It will respond to porting the same as any other cylinder design. The width of the exhaust on the cylinder pictured is plenty wide so I wouldn't widen it any more if I were doing it, though it might not be a bad thing to reshape the roof if it is too square.

 

[Terry Syd]

'High compression' mods for that engine are limited to removing the gaskets under the spark plug and decompression valve - LOL.

Although, I recall someone putting a freaking bolt through the top of the chamber with the head of the bolt in the chamber. (Maybe I shouldn't have mentioned that one...)

 

[94BULLITT]

I ran into a big problem tonight. My MS390, 49mm kit is actually 45mm. I think it was boxed wrong. I've contacted the seller to see what they say. There has also been some porting done to cylinder. I am a little disgusted. There is no point in rebuilding one of the saws with an AM 45mm cylinder. So the lesson for the day is measure the piston and make sure it fit the cylinder when you get it.

 

[MustangMike]

My 390 P&C was a lot larger than my 029.

Decided not to port mine at all, just did a muff mod and minor timing advance. Idles well, runs clean, and tach's right up. If the weather allows, I will try to put it in some real wood tomorrow.

Compression is very modest, so if I did it again, I would plug the C/R (instead of drilling a hole in the cover).

Hey, I only paid $25 for the burned up saw, and $60 in parts. The Walbro carb (that also fits the 044/440 & 046/460) was worth the $25!

 

[94BULLITT]

I contacted the seller and they and they are not going to do anything.

I am going to go ahead and put this cylinder on it.

@MustangMike Where did you get your cylinder and how much was it?

 

[MustangMike]

On line, Huztl, piston, cylinder & seals, shipped, under $35.-.

It starts, idles, & runs good and clean, but compression is just modest, so it is not super strong.

Have not checked compression, but it is not hard to start. If I were doing it again, I would plug the de comp hole instead of installing one (like I did).

 

[huskihl]

On line, Huztl, piston, cylinder & seals, shipped, under $35.-.

It starts, idles, & runs good and clean, but compression is just modest, so it is not super strong.

Have not checked compression, but it is not hard to start. If I were doing it again, I would plug the de comp hole instead of installing one (like I did).

Have your little Italian welder doctor friend weld you a pop up for it. Mine puts out 160 psi oem

 

[huskihl]

Oops...forgot one...

Have your little Italian welder cheese making doctor friend weld you a pop up for it. Mine puts out 160 psi oem

 

[MustangMike]

If anyone can do it, it would be Dr Al, he is a very multi talented individual! His work is incredible.

FYI, that damn clamshell is not coming apart again unless it stops running, and if it does, I may just steel the carb from it and call it a day!

IMO, Dr Al's talents would be wasted on that saw. Conversely, both the 026 and 460 he did for me are beasts in their respective size categories.

 

[MustangMike]

Mine puts out 160 psi oem

How strong is your saw, comparing it to a similar size pro saw?

 

[huskihl]

How strong is your saw, comparing it to a similar size pro saw?

Same as my 036

 

[MustangMike]

My 362 is ported, so it is not a fair comparison. I'm sure more compression would help the 029/390, but I doubt the open port design would keep pace.

 

[huskihl]

My 362 is ported, so it is not a fair comparison. I'm sure more compression would help the 029/390, but I doubt the open port design would keep pace.

Both of mine are ported. The 039 has more torque, 036 has more rpm. They were like this before porting also

 

[Wagnerwerks]

I contacted the seller and they and they are not going to do anything.

I am going to go ahead and put this cylinder on it.

@MustangMike Where did you get your cylinder and how much was it?

Who was the seller? I'd like to know as I was thinking about buying one of the 039 kits to put another one together.

 

[94BULLITT]

Who was the seller? I'd like to know as I was thinking about buying one of the 039 kits to put another one together.

It was Everestparts248. I looked at their feedback and someone else had the same problem. I bet they have a whole batch like that.

I saw someone had a p/c for a 390 with seals, bearings and some other stuff for around $40 or $50.

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[94BULLITT]

How strong is your saw, comparing it to a similar size pro saw?

Here is my 039 and 034s. I made that video pretty much right after I got the 039. It needed a new air filter when I made the video. It is stronger now with the new filter.

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[huskihl]

 

[Motorhead]

Great runners.

 

[94BULLITT]

Here are some pics of the cylinder.

Here is the intake. It does not have a ramp, but the intake port has a flat place right at the edge of the cylinder. If anything was done with it, it would change the port timing.





Here is the OEM intake. It has the same flat place on it too like the AM cylinder.



AM Intake from the cylinder side.



Here is the exhaust





Should I try to square up the ports more at the bore?