Spuds Porting and Tuning Thread

[Daythe trees]

Scrumpy? You had better check the max octane the engine will take... The Scrumpy may have to be three mix.... Oil, Scrumpy and distilled water!

[mendiplogs]

Thats nice Jon, are we going to run it on premium scrumpy:lol:

 

HI STEVE oyes only just cheaper then ASPEN MATE thanks jon

[spudulike]

Had Burrells 357Xp in today, one of the first I ported. He said that the saw had a changeable idle and traced it back to fine sawdust in the carb gauze strainer.

 

Took the oportunity to measure the compression - 200psi - pretty good considering it just had the base gasket removed and a new piston - it has been run hard for 2-3 years and looks it but the pressure/Vac tests were also perfect.....all good:thumbup:

[mendiplogs]

Had Burrells 357Xp in today, one of the first I ported. He said that the saw had a changeable idle and traced it back to fine sawdust in the carb gauze strainer.

 

Took the oportunity to measure the compression - 200psi - pretty good considering it just had the base gasket removed and a new piston - it has been run hard for 2-3 years and looks it but the pressure/Vac tests were also perfect.....all good:thumbup:

 

HI STEVE will a ported 461 on a 20" bar see off a 650 on a 20" bar thanks jon

[wyk]

Had Burrells 357Xp in today, one of the first I ported. He said that the saw had a changeable idle and traced it back to fine sawdust in the carb gauze strainer.

 

Took the oportunity to measure the compression - 200psi - pretty good considering it just had the base gasket removed and a new piston - it has been run hard for 2-3 years and looks it but the pressure/Vac tests were also perfect.....all good:thumbup:

 

What mix is he running?

[spudulike]

What mix is he running?

 

I believe it is Stihl HP Super at 50:1

[spudulike]

Compression is a funny old thing - we are talking secondary compression and not primary (crankcase) compression!

 

I have had a few engines that have made good compression (150psi+) and severely lacked power, on inspection I have generally found worn piston skirts causing the problem.

 

I have had other low compression saws I have tried to up the compression on by dumping the base gasket and had a good increase in compression but still low on power output.

 

The summary to all this is that if your saw is down on compression and/or power then a "quick bodge" isn't possible on a worn piston. The piston needs more than a decent ring to give good power and the skirts being a good fit do more than stop piston slap and aid low down torque and ultimate power!

[Rich Rule]

Been having a couple of non oiling issues with my little 150. Stripped and cleaned the bar and oiler the other day but it was still sporadic. Today I drained and rinsed the tank with a bit of 2 stroke mix and it seems to have finally flushed out the crud that was in there. Result.

 

I also decided, after trawling through a thread on the TH about modding the 150t, to drill the muffle with a 10mm hole.

 

Jeez, it sounds like a stonker with bags of power for such a tinny saw. Cant wait to use it tomorrow.

 

Anyone else who has done this? MattyF? Did you richen the mix a little bit when you did yours? I will do a few test cuts tomorrow and then check the plug for colour but just wondering if I should richen it up a bit before hand?

 

Any advice appreciated.

[spudulike]

Been having a couple of non oiling issues with my little 150. Stripped and cleaned the bar and oiler the other day but it was still sporadic. Today I drained and rinsed the tank with a bit of 2 stroke mix and it seems to have finally flushed out the crud that was in there. Result.

 

I also decided, after trawling through a thread on the TH about modding the 150t, to drill the muffle with a 10mm hole.

 

Jeez, it sounds like a stonker with bags of power for such a tinny saw. Cant wait to use it tomorrow.

 

Anyone else who has done this? MattyF? Did you richen the mix a little bit when you did yours? I will do a few test cuts tomorrow and then check the plug for colour but just wondering if I should richen it up a bit before hand?

 

Any advice appreciated.

 

It is always easier to start rich and work down than to start lean and seize the engine although that probably won't happen!

[geoff]

Mine didn't need adjustment with a 9mm hole Rich Rule, but as Spud says.. I would tweek it up 1/4 turn on the H screw, then fine tune the L & H from there.