New Baileys BB kit not a very pretty sight

[Tzed250]

Nope. These are sold as an Asian aftermarket part, not under the name of Stihl, where I expect a Mahle P&C or of the same quality. I do share plenty with Greg that I would like to see improved. I've shared some of that in the open forum as well. I couldn't just let this conversation die you know. You were swallowing it too easy:greenchainsaw:

Strange use of nomenclature. Why is the WP cyl. Asian, and the Stihl cyl. Chi-com?


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[joatmon]

I am not going to post in this thread. This is a ghost post that can't be seen, only felt and heard. Scary, eh? But, this is hilarious with all the usual posters: Brad, Tommie, John, Frank.

Carry on,

joat

 

[blsnelling]

Strange use of nomenclature. Why is the WP cyl. Asian, and the Stihl cyl. Chi-com?


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Because it got a good response. There, you happy:greenchainsaw:

 

[Billy Jack]

I'd just love to see some photos of "squish" being determined.

 

[TRI955]

LoL!!!!

Mike

 

[bitzer]

I'd just love to see some photos of "squish" being determined.

Take the smallest diameter solder you can get to start with. Pull your spark plug and fish the solder in towards the flywheel side until it hits the cylinder wall. Then crank the flywheel by hand until the piston hits TDC and rolls over toward BDC. Measure, then repeat on the clutch side with a fresh piece. Use the smallest number.

 

[billmartin]

Take the smallest diameter solder you can get to start with. Pull your spark plug and fish the solder in towards the flywheel side until it hits the cylinder wall. Then crank the flywheel by hand until the piston hits TDC and rolls over toward BDC. Measure, then repeat on the clutch side with a fresh piece. Use the smallest number.

Some .035 solder I found at radio shack was perfect for me. The piston didn't even touch it with the cyl base gasket in. Went from there made a .025 gasket and came out with .025 squish. No gasket was no squish on my app.

 

[AUSSIE1]

Take the smallest diameter solder you can get to start with. Pull your spark plug and fish the solder in towards the flywheel side until it hits the cylinder wall. Then crank the flywheel by hand until the piston hits TDC and rolls over toward BDC. Measure, then repeat on the clutch side with a fresh piece. Use the smallest number.

Ideally you should measure both sides at the same time, but a bit hard with the saw assembled. When checking one side at a time, I rock the piston back and forth half a doz times as the solder can expand a thou or two. I do as Bob suggests and if the measurement from checking one side at a time gives a reading of .020 or above for me it's fine.

I like to port my aftermarket cyl's as I find the exhaust roof and inlet floor can be quite conservative against OEM. The critical exhaust floor and inlet roof have been spot on. With these kits I can leave the OEM parts on the shelf. Surprisingly my BB395 kit has a squish of .034 gasketless.

 

[Billy Jack]

Take the smallest diameter solder you can get to start with. Pull your spark plug and fish the solder in towards the flywheel side until it hits the cylinder wall. Then crank the flywheel by hand until the piston hits TDC and rolls over toward BDC. Measure, then repeat on the clutch side with a fresh piece. Use the smallest number.

Okay, I get the idea from that, thanks. Now my question is, if this is all because of eliminating the gasket and using sealant, this is just a go/no go type of check, correct? If the solder were to jam the piston before TDC, it obviously has NO clearance and is a no go. Is there a minimum clearance that dictates going gasket-less is un-wise?

Sorry, but I haven't done it before. I have an understanding of car heads and shaving them to boost compression and reduce chamber area - which this seems to accomplish a different way. Still unsure about a sealant in the US that would be the preferred one.

As always, I appreciate the education!

 

[Billy Jack]

Ideally you should measure both sides at the same time, but a bit hard with the saw assembled. When checking one side at a time, I rock the piston back and forth half a doz times as the solder can expand a thou or two. I do as Bob suggests and if the measurement from checking one side at a time gives a reading of .020 or above for me it's fine.

I like to port my aftermarket cyl's as I find the exhaust roof and inlet floor can be quite conservative against OEM. The critical exhaust floor and inlet roof have been spot on. With these kits I can leave the OEM parts on the shelf. Surprisingly my BB395 kit has a squish of .034 gasketless.

So .020 or more is a "go", if I'm following you correctly.

 

[AUSSIE1]

So .020 or more is a "go", if I'm following you correctly.

Yeah mate. .020 and up is considered a safe limit. Make sure when you check you reach the edge of the bore. When you turn it over, it will/should compress the solder.

 

[Billy Jack]

Yeah mate. .020 and up is considered a safe limit. Make sure when you check you reach the edge of the bore. When you turn it over, it will/should compress the solder.

I'm all over it now. Thanks for explaining it.

 

[bayshorecs]

The solder is soft and gets smashed by the piston. You measure the diameter of the solder. If you start with .035 solder and the piston hits it at TDC, you know the squish is less than .035. Measure the diameter of the solder where the piston hit it and it tells you the squish. If the piston did not strike the solder, the squish is >.035. So, try again with a large diameter solder, say .050.

You want to try and use the size of solder that closely matches the squish to be accurate.

 

[AUSSIE1]

Howdy,
One thing to remember when it comes to squish is that it's relative to the displacement of the combustion chamber. So, if you have a squish of .025" with 2cc's of combustion chamber, i'ts going to have much more compression than a saw with 3cc's of combustion chamber with the same squish. In the past it was all relative because you only had OEM's building cylinders to spec. We're beginning to cloud the water a little because we're starting to modify size and shape of combustion chambers. The compression reading is going to be more useful in the future.

Evan,
We just had the proto-type BBN 066's come through for testing a few weeks back. I should be receiving the latest generation in about 8 weeks. This BBN 066 is an example of a cylinder that we've decreased the the combustion chamber on by about 1 cc.
Regards
Gregg

The 395 measured 7.5 cc
The BB measured 6 cc

 

[PogoInTheWoods]

It's kind of like the "chicom" 260 P&C. No, it wasn't perfect, but it wasn't anything that would hurt performance. finish

Would that be the 44mm/44.7mm kit from Bailey's for an 026/MS260?

Just put one on my first rebuild and think mebbe I should pull it back off to inspect the whole deal more closely before running the saw. Heck, I just slapped
it together like I knew what I was doing -- which I didn't at the time.

Poge

 

[PogoInTheWoods]

Sounds like you've got the piston backwards. Is the arrow pointing towards the exhaust port? If so, then it was stamped wrong.

Is that a universal stamping standard, or does it vary from kit to kit, mfgr to mfgr? My 026 manual illustrated the exact opposite direction, which I followed accordingly.

Now I'm kinda nervous and wonder if I should pull the saw back apart and do an
inspection of the kit before running it -- now that I'm a little more educated on
the subject.

Don't wanna just blow my first project back up like I found it -- a coupla hundred bux later!

Poge

 

[constantine]

Bailey's BB7900 Kit received yesterday.

Below are some pictures of the kit I received yesterday. I am planning to mod my Dolmar 7900 and wanted to do the porting job on another cylinder. I had read on this thread that the quality of these kits left something to be desired, but Grande Dog assured us all that he is working on the problem. So, I waited for my kit to arrive. Here it is.

On the outside, the fins are well formed, no major flaws, random sprue, etc. The inlet and outlet look good. Mounting holes in the base are a perfect match for a Dolmar OEM gasket. So far, so good. Now on the the inside:

The bore is smooth and clean. The chamfering on the ports is well-done and very uniform. Looks as if there is a small registration problem with the two halves of the mold, which you can see on the first internal photo. Also some pits at the top of the combustion chamber, which should polish out nicely with minimal stock removal when I port the thing. The coating appears to be evenly distributed, clear up to the top of the cylinder. Insides of the transfers look fine, with no globs or random material caused by mold flaws.

If anybody wants more photos or specific views, I can send them.

Also, I'll keep you posted as my porting job progresses. I don't claim to be any sort of expert, but I read a lot and can learn from my mistakes and the mistakes of others. If anyone has tips to pass along, I'm all ears!

Also, I'd be interested if someone who is familiar with the process knows how these cylinders are made. It looks like investment casting, but I'm not sure. There are other processes which will yield a better result, but they are pretty expensive.

 

[AUSSIE1]

Looks good.
Strange shape on that upper transfer. Is that typical with the OEM also?
Yeah I like to keep the OEM on the shelf and play with the kits.

 

[bayshorecs]

Don't expect to use a base gasket. I just installed mine and it was .042 squish without the base basket.

If you plan on porting it, might want to mill it down .015. Of course, measure yours first!

 

[constantine]

Don't expect to use a base gasket. I just installed mine and it was .042 squish without the base basket.

If you plan on porting it, might want to mill it down .015. Of course, measure yours first!

Exactly what do I measure? I have a depth gauge. Do I measure from the bottom of the mounting surface to the shoulder at the top of the cylinder? Please let me know.