I ported a timberpro 6150

[NSEric]

I tried my hand porting a couple Chinese saws, my 62cc timberpro and a 46cc one, this is about the 62.
I widened and squared the intake port but left the top and bottom of it alone.
I opened the bottom of the transfers up as much as I dared, I cut out the devider up to where the top of the wrist pin would be at bdc.
I raised the exhaust port a little over 1/16 and widened it, rounding the sides a bit, it was square stock, I also made the exhaust a little bigger at the muffler flange but theres not a lot of material there stock so its only 1/8 taller and wider than stock.
I ground 1/16 off the bottom off the piston skirt on the intake side, 1/8 off under the wrist pin to help the transfer timing and 1/16 off the top by the transfers to add blow down.
I opened the muffler inlet up to match the now bigger exhaust port, I had gutted the muffler before so that was done, this saw was loud as hell so I welded up one of the muffler outlets, its still plenty loud.
With no base gasket the squish is .027 and the cold compression is 160.
This saw has a tiny carb, intake and exhaust/muffler flange so I didn't do anything extreme as it never going to rev really high.
This worked out well, the saw free revs the same rpm as before out of the cut but doesn't drop as much rpm in the cut, its about a 1000 rpm higher while cutting and has more tq so you can push on it more without it slowing down.
I have a 8 pin rim and archer .325 chain on the 20 inch timberpro bar. It came with a 7 tooth spur sprocket, I up graded to the 8 a while ago, with the stock motor the 8 would slow it down in big wood if you pushed on it, ported it doesn't slow down.
Pics in the next post I hope.

 

[NSEric]

Heres more pics.

 

[NSEric]

The 46 responds to porting much better than the 62. Stock it was slow it only revved about 10000 rpm, now its up to 13000(im guessing I don't have a tach) or so and not slowing down at all while cutting.
I did the same things to it as the 62 except I left the intake port alone and the 46 has single open transfers so I didn't have to grind on a devider.
The squish was .055 with the gasket, I didn't check it without, it would still have lots, I didn't check the compression either.
This saw after porting was faster than the stock 62cc timber pro, even after porting the 62 the 46 keeps up with it until you start cutting over 12 inch trees. It has a 7pin rim with Oregon 21lpx chain on the 16 inch timberpro bar.
The 46 and 62 have the same carbs, slightly different but about the same sized intakes, the same exhaust port and the mufflers interchange. The muffler on the older 46 was wide open inside stock with one outlet, so all I did to it was open up the inlet to match the bigger exhaust port.
I didn't take any pics of the saw while it was apart, I did this one first and didn't expect it to come out as good as it did.

In hindsight if your buying one of these cheap saws, get the 52 and spend an hour porting it, the 62's aren't much faster and cost more.

 

[Chainsaw Jim]

Can you describe to us how it sounds?

 

[NSEric]

The 62 sounds a touch lean when just revving it you can hardly hear it four stroke but setting it richer slows it down when leaned on in the cut so its not running lean, it just doesn't four stoke heavily.
The 46 four strokes really heavily just revving it but setting it leaner bogs/stalls it out, it maybe running at the coils/ignitions limit, its revving pretty high.
I adjusted both saws for fastest cutting while leaning on them cutting a 10-12 inch log not by just revving them.

 

[Czed]

The 58cc version does very well
When ported.
Less than 100.00 shipped ebay

 

[NSEric]

I'd be surprized if the 62 makes more power than the 52 or 58cc versions. The intake and carb are so tiny they're holding the saw back so having a few less cc's wouldn't matter.
Overall im happy with my timberpro, it runs more like a 50cc saw than a 60cc saw but that's ok as it's the same size/weight as 50cc saws.
Its more like 200 bucks because im in Canada but 200 dollars doesn't get you a very good saw around here.
Used pro saws are either worn out junk or 400 bucks and the only other new saws in this price range are small home owner saws that are slower and not any better quality wise.
I had a small jonserd 46cc poulan lookalike for years, I bought it new in the early 2000's, the timberpro was better than it out of the box then the timberpro got quite a bit faster with a good chain and 8 pin rim and then faster again with porting.
It also only weighs 1 pound more than the 46cc poulan/jred.

 

[Leafy]

Does the 62cc have an external impulse line? That makes finding a bigger carb easier. Any HDA or C3 carb with the same inputs will swap with it, though you have a better chance of having the shafts be a direct swap with a c3 clone.

 

[TBS]

The 45 through 62cc thave an external inpulse unless the 62cc is based on a g621 instead of g450 or g5200 zenoah. This saw is based on a g5200.

 

[Leafy]

If you 62cc isnt based on the G621 its actually a 52cc with 62cc on the stickers only.

 

[TBS]

If you 62cc isnt based on the G621 its actually a 52cc with 62cc on the stickers only.

Not necessarily. I've got 3 saws of g5200 vintage, tanaka 5601/zenoah g5200, noname 52cc, and a surpass 56cc. I can switch cylinders across all three but the piston on the 56cc doesn't fit the 52cc cylinders.

I've also got 2 in zenoah g450avs vintage one is a g450avs and the other is a craftsman 42cc( not poulan rebadge) and the cylinders interchange but the piston on the g450 is larger.

 

[Leafy]

At least now theres only 1 stroke of crankshaft between the 4500, 5200, 5800, and 62cc and only 3 bores. 45mm and 45.2mm and whatever limp diameter the 4500 is. 5800 comes with the 45.2mm bore, but has quad transfers over dual of the 5200. If it claims to be 62cc and isnt a g621 based saw then I guarantee its got a 31mm stroke and 45mm bore.

 

[NSEric]

The 62cc timberpro is based off the g5200, its the exact same size and weight as the cs4600 and shares most parts with it.
The 62 cylinder looks like it would bolt right on the 46, the crank case is raised up higher where the cylinder bolts on the 62 tho so it may have a longer stroke, this is why it has a taller and different top cover. The only external parts that wont interchange between the 2 saws I have are the top covers and air filters, the 62's motor is almost 1/2 an inch taller.
I didn't measure the piston or stroke while it was apart, just like I didn't check the port timing, I half assed this porting honestly, I didn't grind enough to hurt the saw even if it had good timing numbers before porting tho.

With how the saw still runs like stock or better at low rpm im temped to raise the exhaust port a little more to see if it will rev a little higher. I may have taken more off the top of the 46's exhaust port than I did the 62's, I don't care about the 46 it was free but I don't want to screw up the 62 so I only took a little off.

 

[Huskitoter]

Haha. I know what you mean about not wanting to mess one up. My only port job was on my only saw.

Did you experience a little anxiety when you cranked it?

 

[Huskybill]

Once you look at what needs to be done porting just go slow. Once the carbide rotary files have the ports close to what you want I have smaller flapping drum discs to smooth it all out.

I arch the exhaust port by raising it up 1/8” in the middle and about 1/16” at the sides. If there’s no pins in the way to stop the piston rings from turning I widen the exhaust port a tad. I raise the exhaust port and lower the intake port. I also advance the timing a tad. I take the base gasket with a scribe, put the four bolts in the gasket to the upside down cylinder. Now scribe the transfer ports from the gasket to the cylinder. The case should match the transfer ports on the gasket already. Matching the port size makes the flow more even. Next I’m going to work on the exhaust port. I’d like to open up from the cylinder exhaust side as stated above but grind a light bulb shape in the port from the cylinder to the exhaust flange. The light bulb shape should pull the exhaust gasses quicker from the cylinder to the muffler and at the same time speed up the intake transfer port process. I already did this on the air cooled husky dirtbikes.

 

[blsnelling]

I opened the bottom of the transfers up as much as I dared.

I raised the exhaust port a little over 1/16 and widened it.

I ground 1/16 off the bottom off the piston skirt on the intake side, 1/8 off under the wrist pin to help the transfer timing and 1/16 off the top by the transfers to add blow down.

Did you degree the cylinder before making these changes?

The crown of the piston is where transfer port timing happens, not below the wrist pin.

 

[blsnelling]

I arch the exhaust port by raising it up 1/8” in the middle and about 1/16” at the sides. If there’s no pins in the way to stop the piston rings from turning I widen the exhaust port a tad. I raise the exhaust port and lower the intake port. I also advance the timing a tad.

Are you degreeing the cylinder before these changes? That's a big change to be raising the exhaust .125".

 

[Huskybill]

All my measurements came from a husky 2100 the husky rep had. I got my hands on his cylinder and compared his to a new cylinder and I copied his. If the exhaust leaves sooner the transfer ports are drawn in by the exiting exhaust and by the piston charging the crankcase. Try it at your own risk.

 

[NSEric]

Did you degree the cylinder before making these changes?

The crown of the piston is where transfer port timing happens, not below the wrist pin.

I took about a 1/16 off of the top of the piston beside the transfers to increase the transfer timing. I took 1/8 off under the wrist pin on the piston, I know removing material below the wrist pin only helps flow into the transfers, that appears to be a problem with open ports so opening them up there helps.

I didn't degree the cylinder as I don't have a degree wheel.
I copied what someone else did porting a 62 that was actually a 52 cc Chinese saw, this worked great on my 46 but I didn't go quite far enough porting the 62, its runs alright and better than stock I just want a little more rpm out of it.

I think I will have another go at porting it, my plan is to raise the exhaust port a touch more, take a touch more off the top of the piston by the transfers and a little more off the piston skirt by the intake.
I know I didn't take as much off the 62's piston and exhaust as I did the 46's.
I have no issues or fear of grinding on stuff I just don't want to raise the ports up too much and have a saw that bogs out really easy.

 

[Huskybill]

I seen the top of the pistons done like cement truck chutes to each transfer port so not much compression is lost they knotching them out on the top of the piston. Plus it starts the flow earlier. Here’s one example, http://www.dragonfly75.com/motorbike/pistonramp.html

I’m not sure about the saws but porting the 250cc dirtbike engines moves most of the power envelope to the upper rpm. Can’t ride a chainsaw to tell but it seems smoother and winds up higher.