394xp Big Bore Issue

[wireedm]

My 394xp was getting impossible to restart once warm so I knew the compression was getting low. Had it checked and sure enough, it was down to 100psi.

In looking at the options I decided on the big bore kit from Little Red Barn. http://www.lilredbarn.net/product-p/394-conversion-big-bore-58mm.htm. Everything seemed to go together fine and started in a couple of pulls after reassembly.

When tuning, I wanted to get the RPM's down to around 11,5k so it would be a little rich but it has a complete dead spot between 9,500 and 12,000 RPM's. It has a brand new factory carb on it. New gaskets that came with the kit, of course.

I have it running at 9,000 rpm's at the moment just to get me by if needed for the hurricane here in NC. Seems to tach up just fine and hold power in the cut, but the rpm's are slow at 9k compared to what I know it will do.

It has been a GREAT saw over the past 25+ years. Any thoughts on a solution?

 

[MGoBlue]

I had an issue with the hot restart and I suspected the known issue of vapor lock. This was happening to me while milling so the saw was about as hot as they can get. After while, I started to suspect a possible coil issue so I popped for one of those cheap azz chinese $12 units. It completely solved the issue! BUT the pos only lasted a few short months before it crapped out, so I bought a new OEM coil. I've been great ever since.
BTW, hope you still have the original cylinder. I'm sure it is probably still usable and worth some $$. Why not just put a new piston/rings in it? OEM always outperforms AM.

 

[wireedm]

I had an issue with the hot restart and I suspected the known issue of vapor lock. This was happening to me while milling so the saw was about as hot as they can get. After while, I started to suspect a possible coil issue so I popped for one of those cheap azz chinese $12 units. It completely solved the issue! BUT the pos only lasted a few short months before it crapped out, so I bought a new OEM coil. I've been great ever since.
BTW, hope you still have the original cylinder. I'm sure it is probably still usable and worth some $$. Why not just put a new piston/rings in it? OEM always outperforms AM.

Yes, still have the old cylinder. I thought it would be fun to go to a big bore for only $20 more. I may have to just bore the OEM cylinder out 2mm and put it back on.

 

[rupedoggy]

Do you have a way to replate the nickisol after this 2mm rebore? If so scores of us would like to hear about it. Us Chrome charges over $200 for that. Mike

 

[Deleted member 117362]

If cylinder and piston are in good condition. New rings and vacuum check, if good, run it for another 25 years.

 

[wireedm]

Do you have a way to replate the nickisol after this 2mm rebore? If so scores of us would like to hear about it. Us Chrome charges over $200 for that. Mike

I don't have my OEM cylinder in front of me...did it come with Nikasil plating from the factory 27 years ago?

 

[rupedoggy]

YES or chrome