266xp wierd at wot.

[Primos75]

So this is my first post here so hello everyone. Been around saws for a long time put im kinda stumped on this one. I've got a 266xp that was getting a little low on compression so I put a new 268xp cylinder and piston and carb on it. Fired it up and tuned the carb. At wot I can set the rpm but after about 2 seconds the rpms jump up another 2 grand or so. I've adjusted it every way I can. If I turn down the high speed to make it stop then it will only get to around 9000 rpm. If I leave it high while in the cut the rpms start surging. I've replaced the fuel line, fuel filter, air filter and plug. Put the old carb back on, same thing. Checked fuel vent and ordered a new one..Haven't tried yet. I've looked for leaks around intake..replaced all gaskets and can't find it. Do ya'll have any ideas? Thanks in advance.

 

[ballisticdoughnut]

You put crank seals in it?

 

[Primos75]

The original was a tillotson hs234. The one I put on new was a aftermarket hs260.

 

[Primos75]

You put crank seals in it?

I did not but I pulled it apart tonight to do just that. I figured I had the tank off to get to the vent so why not.

 

[ballisticdoughnut]

I did not but I pulled it apart tonight to do just that. I figured I had the tank off to get to the vent so why not.

Replace the o-rings as well. The oil pump and flywheel side seal carrier both have one.

 

[Squareground3691]

Do a pressure, vac test check for leaks . If after you do work to it ,

 

[huskihl]

So this is my first post here so hello everyone. Been around saws for a long time put im kinda stumped on this one. I've got a 266xp that was getting a little low on compression so I put a new 268xp cylinder and piston and carb on it. Fired it up and tuned the carb. At wot I can set the rpm but after about 2 seconds the rpms jump up another 2 grand or so. I've adjusted it every way I can. If I turn down the high speed to make it stop then it will only get to around 9000 rpm. If I leave it high while in the cut the rpms start surging. I've replaced the fuel line, fuel filter, air filter and plug. Put the old carb back on, same thing. Checked fuel vent and ordered a new one..Haven't tried yet. I've looked for leaks around intake..replaced all gaskets and can't find it. Do ya'll have any ideas? Thanks in advance.

Revving up to the screw setting for a half second and then screaming is indicative of an air leak, usually the seals, or something flexible

 

[Primos75]

Replace the o-rings as well. The oil pump and flywheel side seal carrier both have one.

Will do.

 

[Primos75]

Do a pressure, vac test check for leaks . If after you do work to it ,

Unfortunately I dont have the stuff to test pressure and vacuum. What exactly would I need?

 

[Squareground3691]

There’s different vac/ pressure kits available for that Mity Vac is a popular one EBay or Amazon has others as well check YouTube videos will give you informational on chainsaw vac/ pressure testing and what you need to do so .

 

[Dennbb]

So this is my first post here so hello everyone. Been around saws for a long time put im kinda stumped on this one. I've got a 266xp that was getting a little low on compression so I put a new 268xp cylinder and piston and carb on it. Fired it up and tuned the carb. At wot I can set the rpm but after about 2 seconds the rpms jump up another 2 grand or so. I've adjusted it every way I can. If I turn down the high speed to make it stop then it will only get to around 9000 rpm. If I leave it high while in the cut the rpms start surging. I've replaced the fuel line, fuel filter, air filter and plug. Put the old carb back on, same thing. Checked fuel vent and ordered a new one..Haven't tried yet. I've looked for leaks around intake..replaced all gaskets and can't find it. Do ya'll have any ideas? Thanks in advance.

Crank seals take 1/2 hour to change on those saws.

 

[president]

Crank seals take 1/2 hour to change on those saws.

no special tools required either. The seal carrier on the FW side takes
3 srews ,and pto side seal is in the oil pump housing.

 

[Primos75]

no special tools required either. The seal carrier on the FW side takes
3 srews ,and pto side seal is in the oil pump housing.

Good to know. Got some parts ordered. Waiting on them to put it all together. Really hope this fixes it.

 

[Tomos770]

Try/test also this...

 

[Primos75]

So just for an update. Got all the parts in the other day and finally got around to putting it back together. New seals and orings, gaskets and fuel tank vent as well as new vibration mounts. Used the old hs234 carb and she fired right up. Alittle adjusting on the high speed and its running good. No rpm pickup at wot. Haven't cut with it yet but it sounds good.

 

[ballisticdoughnut]

Sounds like you got it fixed man. Once you make a few cuts you’ll know for sure but I’d bet money it’s good.

 

[Primos75]

Well made some cuts in red oak yesterday. No screaming rpms..no surging in the cut. Rpms seem alittle low in the cut. Dont know why that is. Might need more on the high speed screw but it seemed about right setting it up. Idk might have to play with it a bit.