If that were true I wouldn't have any stihl dealers near me. One stihl dealer only keeps 2-4 saws on the shelf.
Dolmar 7900 Carb upgrade?
- Thread starter plowin-fire
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If that were true I wouldn't have any stihl dealers near me. One stihl dealer only keeps 2-4 saws on the shelf.
Poleman
Addicted to ArboristSite
Ya....made me almost cry when the party wasn't interested in a trade.....looked like an AWSOME saw!!!!! Red Elm did have me in mind when he got it.....I didn't know that.....and made another deal.Important thing is I think I got a GOOD one coming.
Ya guys I have to be serious about my Dolmar parts man....he may live 800 miles away but the service is FANTASTIC!!!! I have Clint to thank for hooking me up!!!!!
And yes.....I'm slowly in the process of getting rid of the Stilhs and Huskys I have. I have been totally captivated by the Dolmar!!!!
Ya guys I have to be serious about my Dolmar parts man....he may live 800 miles away but the service is FANTASTIC!!!! I have Clint to thank for hooking me up!!!!!
And yes.....I'm slowly in the process of getting rid of the Stilhs and Huskys I have. I have been totally captivated by the Dolmar!!!!
Fly By Night
ArboristSite Operative
Terry, what is the idea behind cutting the butterfly instead of opening it up with the screw?
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Poleman
Addicted to ArboristSite
After you drill the jets the saw/carb is in a rich condition and needs more air. You've increased the fuel to the saw for added performance and power and you also need more air.
Where the problem is is at Idle because of more fuel...now you needmore air for the saw to idle. The idle screw doesn't allow that much adjustment thus the notch in the throttle plate or better yet pull the jet and drill out the first idle hole to .55. This gives more air through the carb and idle adjustment returns.
Where the problem is is at Idle because of more fuel...now you needmore air for the saw to idle. The idle screw doesn't allow that much adjustment thus the notch in the throttle plate or better yet pull the jet and drill out the first idle hole to .55. This gives more air through the carb and idle adjustment returns.
Poleman
Addicted to ArboristSite
Well....just got the BB365 in some wood. I'm impressed with the 30/35 combo and like the idle hole drilled to .55!!!! Very easy to adjust and REALLY RUNS well. I was cutting Pine with 24" bar and could dog in hard and couldn't slow it down...didn't get a tack on it in the cut but it was good and held speed well.
NOTE:I had found a membrain under the jet last night and wasn't expecting to see that. I drilled jet as usuall and it didn't seem to cause any I'll effects, saw idles has excellent throttle response and is FAST in the cut. The carb I modded was a Farmer Tec from a Chinese supplyer.
Rich
NOTE:I had found a membrain under the jet last night and wasn't expecting to see that. I drilled jet as usuall and it didn't seem to cause any I'll effects, saw idles has excellent throttle response and is FAST in the cut. The carb I modded was a Farmer Tec from a Chinese supplyer.
Rich
RyanTowry_81
Educated redneck
You are making me excited to get to mine Rich!
Glad to hear it worked out well.
What elevation are you at again?
Glad to hear it worked out well.
What elevation are you at again?
Poleman
Addicted to ArboristSite
I'm at about 4000 ft where I live just out of town. Work areas are can be 5000+!!
I will have to play a little more with this on the Husky but I'm REALLY happy with the way it runs at preasant!! Hate to go backwards and mess up a good thing!!
It IS a FUN thing!!!
I will have to play a little more with this on the Husky but I'm REALLY happy with the way it runs at preasant!! Hate to go backwards and mess up a good thing!!
It IS a FUN thing!!!
Fly By Night
ArboristSite Operative
Has anyone ordered drill bits for this yet? The ones Terry posted a link to on Ebay ship from the UK and they will not ship them to me here in the US.
Poleman
Addicted to ArboristSite
Just look on eBay under micro drill bits.....just make sure you get a pin vice.....those drills art tiny. I also drill by hand so I can feel the action....it doesn't take long. I think using a dremel or something you may risk breaking a bit. Also be sure you measure the bits as they may be mixed up on delivery. You want to make sure of the drill size you are using to drill the jets.
RyanTowry_81
Educated redneck
Sweet. That is close to where I am, at about 3000, but cut up to 6000.
Can't wait to play with the zama I have, just have to do the BB kit first.
Poleman
Addicted to ArboristSite
Well here's what you'll need to make these carb mods....
Next you'll need to identify the idle jet and the auxiliary jet.
This is what I used to pull the jet. Just filed down the edge to make it thinner to be able to grab the jet. Grab firmly and twist...it comes right out. Using this I was able to remove the jet with out doing any grinding to the carb body.
That's about it....45 minutes later (taking pictures also) I had a modded carb.
Hope this is helpful!!!
Rich
Next you'll need to identify the idle jet and the auxiliary jet.
This is what I used to pull the jet. Just filed down the edge to make it thinner to be able to grab the jet. Grab firmly and twist...it comes right out. Using this I was able to remove the jet with out doing any grinding to the carb body.
That's about it....45 minutes later (taking pictures also) I had a modded carb.
Hope this is helpful!!!
Rich
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Terry Syd
Addicted to ArboristSite
I like your choice of tool for pulling the idle jet better than the diagonal cutters I have been using. If I was just starting out, that would be the tool I'd get for pulling the idle jet. Just trim the bottom of the cutters flat to get low on the jet and you're good to go.
The only tool I'd add to the list is a set of callipers for measuring the drills. You NEED to measure the drills each time you pick one up to use. It is way too easy to get the wrong size.
There are some micro drill offers on Ebay that have various pin holders. Some of them are much better quality than the one that Rich and I are using.
If you take a look at the picture of the inside of the metering chamber, you will notice a hole (jet) on the back of the main discharge nozzle. That hole provides fuel to the main circuit in parallel with the High speed screw. When you bump up the flow from the low speed circuit the amount of adjustment on the High speed needle gets less and less. On one carb I did, I ended up right on the edge of closing the High speed screw completely closed. I then put a dab of GB Weld on the back of the nozzle to close off the jet, that gave me plenty of adjustment on the High speed screw.
The only tool I'd add to the list is a set of callipers for measuring the drills. You NEED to measure the drills each time you pick one up to use. It is way too easy to get the wrong size.
There are some micro drill offers on Ebay that have various pin holders. Some of them are much better quality than the one that Rich and I are using.
If you take a look at the picture of the inside of the metering chamber, you will notice a hole (jet) on the back of the main discharge nozzle. That hole provides fuel to the main circuit in parallel with the High speed screw. When you bump up the flow from the low speed circuit the amount of adjustment on the High speed needle gets less and less. On one carb I did, I ended up right on the edge of closing the High speed screw completely closed. I then put a dab of GB Weld on the back of the nozzle to close off the jet, that gave me plenty of adjustment on the High speed screw.
Poleman
Addicted to ArboristSite
Looking at my post I see about half of it was missing.....oops.
Terry is right...you need a caliper to make sure the drill your using is the right size. Plus if your a clutz like me you'll tip them over a time or two or three. I did right after the first drill under the jet and had to sort them all....again.
I think knowing you can alter the H setting by blocking the second orfis will help in over drilling and still getting good results.
Terry is right...you need a caliper to make sure the drill your using is the right size. Plus if your a clutz like me you'll tip them over a time or two or three. I did right after the first drill under the jet and had to sort them all....again.
I think knowing you can alter the H setting by blocking the second orfis will help in over drilling and still getting good results.
Terry Syd
Addicted to ArboristSite
Rich, I pulled the idle jet on one of my carbs, and yep, there was the membrane. It also had a small hole in it from when I drilled the jet. It doesn't seem to affect the idle, as I was saying, I let it idle for 40-50 minutes while I lapped in the clutch and it never missed a beat.
The hole in the membrane was very small, in fact I couldn't see a distinct hole. Perhaps when I pushed through the membrane it wasn't cut but simply pushed through and then closed back up without removing any material.
The Zama engineers obviously know a lot more about that circuit and decided to install the membrane. Perhaps when we drill the idle jet we just need to be careful about pushing through when that last bit of the brass jet gets drilled out.
The hole in the membrane was very small, in fact I couldn't see a distinct hole. Perhaps when I pushed through the membrane it wasn't cut but simply pushed through and then closed back up without removing any material.
The Zama engineers obviously know a lot more about that circuit and decided to install the membrane. Perhaps when we drill the idle jet we just need to be careful about pushing through when that last bit of the brass jet gets drilled out.
lts really good what everyone is doing in this thread. l like the idea of making a carb more usable and adding more power throughout the rpm range. Terry what is your thoughts of the walbro carb fitted to a Solo 681? Do you think l could basically do the same thing you guys have been doing to the Zammas? Cheers Colin.
Terry Syd
Addicted to ArboristSite
I should receive a Walbro for a 460, probably this week. I think it has some potential and will be modding it. I'll explain the concepts as I go and the concepts can be applied to any of the HD series. I can start a separate thread or just do it on this thread and keep all the carb tuning ideas on one thread for future reference.
Poleman
Addicted to ArboristSite
Your right Terry.... I have seen no ill effects from drilling throught the membrane on the carb I just did. It idled and ran good!!!
If your like me you'd still like to know its purpose, but I think your right in thinking it's to stop bleed back.
If your like me you'd still like to know its purpose, but I think your right in thinking it's to stop bleed back.
Mastermind
Work Saw Specialist
Just now catching up guys. Yesterday was a holiday, so I used it for some other stuff. I'll be getting into Clint's saw this morning.
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