066 Top End # ..... uh, whatever
- Thread starter mtngun
- Start date
Help Support Arborist Forum:
mtngun
Addicted to ArboristSite
A little update on the new BB top end........
The new compression gage is still backordered from Bailey's, so no compression data until the new gage arrives.
But, the BB finally made it to the woods to do some milling. A 17" doug fir blowdown at about 5000 feet elevation.
Milling with injecta-sharp lo-pro chain, a modded 404x7 rim, and 36" bar. An ENM tach is mounted on the Alaskan so RPM's can be monitored in the cut.
The new BB & lo-pro combo is definitely easier to mill with than the old BB & 3/8 chain.
The old BB fell off a cliff below 8400 rpm. The new BB/lo-pro will lug along as low as 7500 before it threatens to bog.
Top practical speed in the cut with this particular chain was around 9500 rpm. It wouldn't rev much higher and still take a bite. Most of the time it runs at 8500 - 9000 rpm. I didn't have to baby the feed like the old BB/3/8 chain.
I'll update again if the compression tester ever shows up.
Might as well throw in a pic of the scenery.
The new compression gage is still backordered from Bailey's, so no compression data until the new gage arrives.
But, the BB finally made it to the woods to do some milling. A 17" doug fir blowdown at about 5000 feet elevation.
Milling with injecta-sharp lo-pro chain, a modded 404x7 rim, and 36" bar. An ENM tach is mounted on the Alaskan so RPM's can be monitored in the cut.
The new BB & lo-pro combo is definitely easier to mill with than the old BB & 3/8 chain.
The old BB fell off a cliff below 8400 rpm. The new BB/lo-pro will lug along as low as 7500 before it threatens to bog.
Top practical speed in the cut with this particular chain was around 9500 rpm. It wouldn't rev much higher and still take a bite. Most of the time it runs at 8500 - 9000 rpm. I didn't have to baby the feed like the old BB/3/8 chain.
I'll update again if the compression tester ever shows up.
Might as well throw in a pic of the scenery.
mtngun
Addicted to ArboristSite
Finally received the new Trisco compression tester from Bailey's.
While I was waiting for the new tester, I calibrated my old gage by connecting it, along with a couple of other gages, to shop air. Compared to the other gages, the old compression tester was reading 10% low. I took the gage apart and tweaked the bourdon tube until the old gage read the same as the others.
I also replaced the shrader valve, even though the old valve seemed to be in good order. I used a special valve made for compression gages, not a tire valve.
The BB blows 150 psi on the Trisco, at 4500 feet elevation.
The refurbished old gage also blows 150 psi.
Now when someone suggests "maybe there is something wrong with your gage ?", I can back up my data with gage #2.
150 psi at 4500 feet elevation is equivalent to 171 psi at sea level. That's very, very good. I'm pleased.
Note that the timed milling cuts with 3/8" chain showed absolutely no improvement with this top end, compared to the previous lame top ends. Yet, this top end has a completely different personality that makes it much easier to operate.
It doesn't bog unless you really try to make it bog. You don't have to baby the feed like the old BB -- cutting speed seems to be about the same regardless of how you feed it into the cut.
The old BB never idled reliably at normal idle speed, probably because of the freeporting exhaust. The new BB will idle smoothly all day long.
Only bad thing is, the decomp button won't stay down when you are starting the saw. That's the kind of problem I like having.
While I was waiting for the new tester, I calibrated my old gage by connecting it, along with a couple of other gages, to shop air. Compared to the other gages, the old compression tester was reading 10% low. I took the gage apart and tweaked the bourdon tube until the old gage read the same as the others.
I also replaced the shrader valve, even though the old valve seemed to be in good order. I used a special valve made for compression gages, not a tire valve.
The BB blows 150 psi on the Trisco, at 4500 feet elevation.
The refurbished old gage also blows 150 psi.
Now when someone suggests "maybe there is something wrong with your gage ?", I can back up my data with gage #2.150 psi at 4500 feet elevation is equivalent to 171 psi at sea level. That's very, very good. I'm pleased.
Note that the timed milling cuts with 3/8" chain showed absolutely no improvement with this top end, compared to the previous lame top ends. Yet, this top end has a completely different personality that makes it much easier to operate.
It doesn't bog unless you really try to make it bog. You don't have to baby the feed like the old BB -- cutting speed seems to be about the same regardless of how you feed it into the cut.
The old BB never idled reliably at normal idle speed, probably because of the freeporting exhaust. The new BB will idle smoothly all day long.
Only bad thing is, the decomp button won't stay down when you are starting the saw. That's the kind of problem I like having.
splitpost
Nothing but 32:1
good to see you got it sorted ,probs like that are always a PITA
parrisw
Tree Freak
Good to hear!
