440 bigbore 52mm, or 54mm?

[Greenclimber]

Cool! How did that carb get so dirty? I cleaned it only 3 tanks ago. Why are you opposed to BB kits?

 

[nmurph]

That sucker is scored and needs to come apart. They can lean seize like that from the clogged screen in your carb. This saw would get a complete tear down and rebuild if it was in my shop. I would NOT mess around with any big bore kit. You probably will be able to clean up the cylinder and get a Meteor piston to run in it. I would replace both crank seals and carefully inspect the intake boot and impulse line.

Ed Zachary...what he said.

 

[blsnelling]

Do yourself a favor and stick with OEM cylinders. Don't be fooled into thinking the BB will automatically make more power.

 

[pioneerguy600]

Cool! How did that carb get so dirty? I cleaned it only 3 tanks ago. Why are you opposed to BB kits?

Dirt inside a carb comes from the fuel tank, your filter in the tank should prevent that but its likely deteriorated/fubared. Replace the filter with a new one check the pickup line for softness , if it feels stretchy or mushy then it needs replacing also.

 

[pioneerguy600]

Common myth, BB kits are touted by sales outlets to be a substantial upgrade for more power when in reality they don`t make as much power as an original OEM set. BB kits can be made to perform but they need lots of port work and squish adjustment to get them there.

 

[Greenclimber]

I'm still not understanding how a 50mm piston is going to give more power than a 52mm. I would expect that the 52mm would give a bit more torque and power. Can someone please explain this to me? I've been looking on baileysonline.com, and reading reviews. Some people liked them, others not so much. Didn't see any reviews on Meteor piston. Also my cylinder is scored. You can't see it in the picture because the scoring is at the exhaust port, and I wasn't able to get a photo of that.

Still haven't gotten around to firing up the saw since I cleaning the carbs. I'd think it would run with the screen cleared up. Still has compression.

 

[nmurph]

Port timing and transfer volume.

Port timing may or may not be what it needs to be.

When the Chinese copy a cylinder and do it in a BB version they just enlarge the bore by X mm. Where does that extra bore dimension come from? The answer is, it comes from the transfers. That reduces their size and the amount of fuel charge they can move from the crankcase into the combustion chamber.

 

[Greenclimber]

Hmmm, so it sounds like a BB kit needs a Dremel and a bit of grinding at the intake and exhaust ports.... I'm just connecting the dots here... That's probably where the term "porting" comes from? I'm under the impression that from there one just needs to remove the limiter screw on the carb and increase the high side for more gas... I'm a fraction of the way there. My saw already has a dual ported muffler...So more fuel/air in, more exhaust out.

I'm sure if I search the forms I'll find an older post on porting somewhere..

 

[Greenclimber]

Would increasing the size of the intake and exhaust ports on a stock 50mm cylinder make a difference at all?

 

[pioneerguy600]

Yes and yes.

 

[Greenclimber]

Gotcha! So would getting a 52mm BB and porting it give me more power VS getting a Meteor 50mm and porting my exhausting jug?

I understand that the "stock 52mm bb" will be less powerful vs the "stock 50mm"

Also, why replace the crank seals? I'm not sure how to do that because I've only gone as far as replacing the top-end on any 2-stroke that I've worked on... How do I get to those?

 

[pioneerguy600]

Depends on who does the porting. There is a lot more to it than hogging out the intake and exhaust ports, that will give you a miniscule boost if any at all.
To replace seals the flywheel and clutch assemblies along with the oil pump needs to be removed, the seals pulled out and new ones pressed in, not real easy for a novice but it can be done with simple hand tools, usually a few seals get ruined by the first timers.

 

[jsmith40004]

If you are dead set on increasing the bore get an 046 jug. You'll have to do some external modifications but it will make more power than an 044 BB even though the bores are the same.

The transfer "tunnels" are larger

Porting the BB kits to run right takes LOTS of transfer work

James

 

[Greenclimber]

Thanks for everything. I'm just going to drop in a new piston, and clean up the cylinder. Replace the fuel line and filter. Inspect the crank seals & if there's play in it, I'll replace those too.

 

[Grande Dog]

Howdy,
BB046 can be installed on the 044 that has a 12mm piston pin. You need to remove a small amount of material on the outside of the cylinder base on the flywheel, and clutch sides of the cylinder. The other thing you need to do is put 5mm spacers on the lower muffler mount bolts in between the muffler, and the crankcase. No matter which way you decide to go, you need to find out what aced the one that's on it.
Regards
Gregg

 

[Greenclimber]

I figured that I could do that somehow... Okay so where can I get a good BB 046/ MS460 piston and cylinder? Any brand? Do you stock them? I need to get an 18" bar + chain from you for my echo CS400... Maybe a 32"-36" bar too for my 066.

As for the melt down, it was a clogged carb screen... It must have made the saw run lean. The reason the carb screen got clogged was because the fuel filter had a small tear in it, and it had all kinds of saw dust in it. Plus black rubber. The fuel line looked good on the outside, but on the inside it's all splintery looking. So I replaced the filter today. Didn't realize that the fuel like was bad until I inspected it closer. I'll have to replace the line as well.

That's all I've got... 100% positive that's what caused it.

 

[Greenclimber]

What will give me more power? The 52mm Stock 460, or the 54mm BB 460? Is there much of a weight difference between the 50mm and the 54mm? I'm not adding like a pound of weight am I?

Lastly, how is the stock 460 52mm different (and better?) than the 440 BB 52mm?

 

[nmurph]

What will give me more power? The 52mm Stock 460, or the 54mm BB 460? Is there much of a weight difference between the 50mm and the 54mm? I'm not adding like a pound of weight am I?

Lastly, how is the stock 460 52mm different (and better?) than the 440 BB 52mm?

Read thread from the beginning.

 

[spindrift7mm]

Thanks for everything. I'm just going to drop in a new piston, and clean up the cylinder. Replace the fuel line and filter. Inspect the crank seals & if there's play in it, I'll replace those too.

Best idea you've had ! Then read up on PORT TIMING it will make the answers to most of your questions make better sense. I would recommend not modifying a milling saw other than muffler mod and tuning until you completely understand port timing and transfer shapes/volumes. Milling is the NASCAR of chainsaws so read a bunch and save yourself some headaches/money. Ken

 

[griffonks]

I would suggest having your dealer, or an AS guy, vacuum / pressure check your saw for leaks.

Then take off the cylinder. It would make more sense to just put a new Meteor kit in your cylinder if the transfer is removed and the Nikasil plating is ok.

No other options are plug and play. They all require mods.