Tempestv
ArboristSite Operative
I sent a message to the previous owner asking just what had been done. Like I said, it does run real nice. However, I'd like to know just what I've got here.
.404 chain on Dolmar 7900 BB? Also, bar questions
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Tempestv
ArboristSite Operative
I just got word back from the previous owner- he removed the cylinder gasket, raised intake and exhaust back to stock and widened ports, MM, and advanced the timing.
Edit: I just measured 150psi compression with my automotive style compression tester. As I understand it, auto gauges tend to read low?
Edit: I just measured 150psi compression with my automotive style compression tester. As I understand it, auto gauges tend to read low?
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deye223
Addicted to ArboristSite
hope not mine is at 220PSI now :msp_ohmy:
Tempestv
ArboristSite Operative
I did some reading on compression testing, it looks like my tester is the kind that gives accurate numbers, but I might have done my test wrong. I'll try to redo the test tomorrow.
MCW
Somebody's talking crap here & it ain't the tree!
I think you'll find it is mainly due to the possibility of poor quality Nikasil plating. I've heard of a number of AM kits where the Nikasil has started peeling off of the bore where the ports have been widened etc. In saying that though I've seen Nikasil peeling off unported AM kits
I know of a number of builders, including racers, that are quite happy to work on and heavily modify better quality AM kits. There are a few aftermarket finger ported 372XP BB, 395XP BB, and 3120XP kits pulling 16,000rpm + (including methanol) in Australia at the moment with no problems.
MCW
Somebody's talking crap here & it ain't the tree!
It's been done a few times including the use of Husky 288/MS460 BB pistons with a pin position change. I'm getting one done at the moment by Al (AUSSIE1) and I've sent 3 kits to Nik (Fatguy) for machining to fit 288 pistons in. One is for me and the others are for Nik and Andre I believe.
Tempestv
ArboristSite Operative
I decided I wanted to know for sure what's been done to this saw, so I yanked the cylinder.
When you install the cylinder without the gasket, shouldn't you seal it with form-a-gasket or something? This saw had nothing- just bare metal to bare metal.
Anyways, here's the pics.
When you install the cylinder without the gasket, shouldn't you seal it with form-a-gasket or something? This saw had nothing- just bare metal to bare metal.
Anyways, here's the pics.
SawTroll
Information Collector
I decided I wanted to know for sure what's been done to this saw, so I yanked the cylinder.
When you install the cylinder without the gasket, shouldn't you seal it with form-a-gasket or something? This saw had nothing- just bare metal to bare metal.
Anyways, here's the pics.
Ouuuucch - those transfers looks really bad! :jawdrop:
Tempestv
ArboristSite Operative
That was my reaction too. Would it be possible to clean them up and make them better?
fearofpavement
Trying them all
Looks a bit "rough". Doesn't mean it won't work great, just not done by a dentist...
Yes, use some sealant when you put it back together.
Yes, use some sealant when you put it back together.
SawTroll
Information Collector
Yes, if you have the right tools.
Tempestv
ArboristSite Operative
what exactly would those be?
SawTroll
Information Collector
Ask my brother, or another competent saw modifier - I know about what they are, but not what they are called....:msp_wink:
Tempestv
ArboristSite Operative
I would assume a dremel, but what tip? (not a question for sawtroll, but for the whole forum)
I wish I could get files or rasps to fit in my power carving chisel, that would be great for reaching way down in there.
I wish I could get files or rasps to fit in my power carving chisel, that would be great for reaching way down in there.
SawTroll
Information Collector
I think you need something better than a dremel, but I'm no expert....
nmurph
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I thought I got it right the first time, and it has bugged me since. But I chalked the error up to my mis-reading of the OP. Now that I have had time to reread, the OP does read that YOU did the MM. I know it is not what you meant to say, but when you put the clause in there, it changed the meaning of the sentence as written.
You need to read up on porting bf you do anything. There certainly is some reshaping that needs to be done, but you need to know where the ring pins are and how wide the ports are, and what the timing is bf anything else is done. You might end up taking a marginal cylinder and making it unuseable with a little Dremeling in the wrong places.
Honesly, for $100, I would pop a new BB kit on it bf I spend much time trying to correct it.
A credit card and a phone number to get a new Mahle cylinder:msp_rolleyes::msp_rolleyes::msp_rolleyes:
GBD
ArboristSite Operative
Look up ccspecialtytool.com
marimus
ArboristSite Lurker
It costs the same as 3/8 or 325 chain, but it lasts longer.
When you are ripping logs, the 404 cuts a wider kerf allowing you to put your bar or wedge in the cut, so you can roll the log with a bar, or split out the fence post.
Other than that, 404 has no advantage over 3/8" that I know of.
Which Chain and Bar
There are a number of good threads regarding porting and tuning the aftermarket kit and a careful search will show solid work out of BC and Idaho.
Personally I really like running 404 on big saws. There is something about running it, the pile of chips it creates, the feel of it in wood. To me it is magic. I've not run it on my BB saw with a bar over 30. I don't doubt it would pull it, just haven't done it. I've run it for work in up to 42. When I help friends out stumping, I run the 27AX just cause you never know what your going to find. If you want to run chisel see if you can find the round or square ground 59 or 68.
If your interested in playing around with it. Make sure that you buy replacable nose 63 guage bars then it is 1 rivet and a new rim and you've switched over (404 all the way to 325 - especially if you are looking at 24" bar).
But, the reality is that you can get it done with 3/8 or even 325 (24" and under). Longer bars, heavier cutting, you can still get it done with 3/8.
There are a number of good threads regarding porting and tuning the aftermarket kit and a careful search will show solid work out of BC and Idaho.
Personally I really like running 404 on big saws. There is something about running it, the pile of chips it creates, the feel of it in wood. To me it is magic. I've not run it on my BB saw with a bar over 30. I don't doubt it would pull it, just haven't done it. I've run it for work in up to 42. When I help friends out stumping, I run the 27AX just cause you never know what your going to find. If you want to run chisel see if you can find the round or square ground 59 or 68.
If your interested in playing around with it. Make sure that you buy replacable nose 63 guage bars then it is 1 rivet and a new rim and you've switched over (404 all the way to 325 - especially if you are looking at 24" bar).
But, the reality is that you can get it done with 3/8 or even 325 (24" and under). Longer bars, heavier cutting, you can still get it done with 3/8.
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