Poleman
Addicted to ArboristSite
Lol....I like your Business vision!!!! Do I have your permission to use your concept?? I especially like the lightning bolt and colors.....hell Terry I like it all!!!! Blue anodizing.....COOL!!!!
Dolmar 7900 Carb upgrade?
- Thread starter plowin-fire
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RyanTowry_81
Educated redneck
Or a blue like layout die with the lightning bolt etched in that could be cool
Terry Syd
Addicted to ArboristSite
Mate, if you've got the 'nads to go into business, ya got my permission to use anything I've contributed. If you do it, I'd go with the anodized carbs. One of the problems with most of modding is that it is INSIDE the engine. Guys don't have anything to show off.
Even the builders would probably like the concept as when the owner gets the saw back, he can SEE something that looks 'trick' on the saw. They wouldn't be set up to do that kind of work and purchasing the carbs from you would probably be a cheaper option.
AND THEN - Once you got it all going you could have the Chinese do all the work and you just repackage the carbs they send you, then hire an illegal immigrant to do the packing..... Sounds like a familiar business model in today's world.
Even the builders would probably like the concept as when the owner gets the saw back, he can SEE something that looks 'trick' on the saw. They wouldn't be set up to do that kind of work and purchasing the carbs from you would probably be a cheaper option.
AND THEN - Once you got it all going you could have the Chinese do all the work and you just repackage the carbs they send you, then hire an illegal immigrant to do the packing..... Sounds like a familiar business model in today's world.
But SawTroll says the venturi is too small.
But I don't care. I'm excited as hell to see what the modded carb will do on my saw.
Thanks Poleman for the effort in trying to figure this out, and Terry, thanks for sharing your knowledge!
Poleman
Addicted to ArboristSite
Lol....Would you be my Business consultant??? You've got this all figured out!!!!
Poleman
Addicted to ArboristSite
Clint, I'm excited also to see what it does on a quality ported saw and the potential it poses for saws that use this carb or for saws that could.
Figuring out jetting sizes for each application and mods done. Be like custom ground cams in cars.
Hopefully we will be making strides in saw performace.
Figuring out jetting sizes for each application and mods done. Be like custom ground cams in cars.
Hopefully we will be making strides in saw performace.
Terry Syd
Addicted to ArboristSite
If you're trying different sizes, you may want to also get another grading system set of drills. It can give you a few more options on the size of jet you drill - http://www.ebay.com.au/itm/HSS-DRIL...Home_Garden_PowerTools_SM&hash=item4d064b3ac8
Poleman
Addicted to ArboristSite
Thanks Terry...Ive been looking for SAE sizes and anything that would fill in the blanks instead such large jumps. A drill size for every step would be optimal as one could go up 1 size at a time which could lead to ultimate
tuning for each appication.
Rich
tuning for each appication.
Rich
RyanTowry_81
Educated redneck
Even better would be if you could find another small carb that uses thread in jets in similar sizes as needed for the zama c3m and drill and tap the brass jets in the zama to accept a removable jet so you could have a stock pile of drilled and tapped carbs then just put the jets in for the application needed and ship out. Would help you streamline your inventory. As you got bigger you could contract the Chinese like terry said to send you the carbs already drilled and tapped and just out the jets in and done. Would also make your testing for other model saws quicker too
Terry Syd
Addicted to ArboristSite
The Zama carb was designed by a bloke that knew carbs. I already mentioned the flowed venturi that middle management stuffed up - (Rich, you can clean up that venturi before you get it anodized - actually, after it is anodized you can take a rubber hose with some lapping paste and polish up the edge of the venturi, it would look HOT with the anodizing and the polished aluminium on the venturi) - I would bet you 10 to 1 odds that the bloke that designed that carb had designed it with screw in jets.
RyanTowry_81
Educated redneck
Wouldn't it be a better world if money wasn't an object and everyone just listened to the engineer....
Poleman
Addicted to ArboristSite
Well finally got thing pretty much sorted out for the BB Dolmar so I thought I'd try the 30/35 ,carb on my BB 365.
Easy install as it's the Sam carb. Only difference is the size of the choke hole in the carb for the Husky. Put it on and got it fired up....running waaaaay rich, I had both H & L closed....it did clear out a couple times and ran good but loaded up again. Didn't spend much time on that combo.
Next up I put the same carb on a Ported Mastermind 6401. That dialed in and ran good other than a soft bottom end from being a little rich. I put 2 Spacers under the spring and that cleaned everything up. With a 24" bar in Pine with a 7 tooth sprocket it was turning 11,400 to 12,000 and showed no sigh of bogging in the wood. I could lean on it hard and it just kept going. Would do the same from idle in the cut...just pull trigger and throw chips!!!!!!
Don't know the reason yet to why the Husky didn't like this carb as it has more cc,s than the 6401 and should work on it and be better. I guess that will the next project to work on......
Easy install as it's the Sam carb. Only difference is the size of the choke hole in the carb for the Husky. Put it on and got it fired up....running waaaaay rich, I had both H & L closed....it did clear out a couple times and ran good but loaded up again. Didn't spend much time on that combo.
Next up I put the same carb on a Ported Mastermind 6401. That dialed in and ran good other than a soft bottom end from being a little rich. I put 2 Spacers under the spring and that cleaned everything up. With a 24" bar in Pine with a 7 tooth sprocket it was turning 11,400 to 12,000 and showed no sigh of bogging in the wood. I could lean on it hard and it just kept going. Would do the same from idle in the cut...just pull trigger and throw chips!!!!!!
Don't know the reason yet to why the Husky didn't like this carb as it has more cc,s than the 6401 and should work on it and be better. I guess that will the next project to work on......
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Terry Syd
Addicted to ArboristSite
Rich, here's something I ran into. On the early carbs the high speed circuit doesn't need any extra fuel as so much is provided by the low circuit. The later carbs had a lean low speed circuit, so they had to add fuel in the high speed circuit to compensate.
On the Zama you will find where the back of the discharge nozzle has been drilled to various jet sizes. On the Walbro I've found a second jet added to the high speed circuit to add the extra fuel.
It may be that you have to block off the jet on the back of the discharge nozzle to get the top end leaned out.
EDIT: Maybe the reason the 64cc engine could use the carb and the 77cc engine couldn't, was because the velocity through the venturi was higher and the additional depression in pressure pulled harder on the high speed jetting. If so, then if you block off the back of the discharge nozzle that should cure the problem.
On the Zama you will find where the back of the discharge nozzle has been drilled to various jet sizes. On the Walbro I've found a second jet added to the high speed circuit to add the extra fuel.
It may be that you have to block off the jet on the back of the discharge nozzle to get the top end leaned out.
EDIT: Maybe the reason the 64cc engine could use the carb and the 77cc engine couldn't, was because the velocity through the venturi was higher and the additional depression in pressure pulled harder on the high speed jetting. If so, then if you block off the back of the discharge nozzle that should cure the problem.
Poleman
Addicted to ArboristSite
Clint,
Nice MM....did the same exact way on saw I got from you!!!
Well they both run quite well. The BB is definatly a bigger wood saw while the 64cc saw would be a good all around saw. It has the power for a felling saw and the speed for a limber. It does has a little quicker throttle responce than the BB. Size maybe, porting on the smaller saw ....not sure the answer there. The 30/35 combo really woke up the MM saw....it was good before but now it if FANTASTIC!!! I really do think the carb mod will help a ported saw.....especially having bigger displacement!!!! Guess we'll find out!!
Nice MM....did the same exact way on saw I got from you!!!
Well they both run quite well. The BB is definatly a bigger wood saw while the 64cc saw would be a good all around saw. It has the power for a felling saw and the speed for a limber. It does has a little quicker throttle responce than the BB. Size maybe, porting on the smaller saw ....not sure the answer there. The 30/35 combo really woke up the MM saw....it was good before but now it if FANTASTIC!!! I really do think the carb mod will help a ported saw.....especially having bigger displacement!!!! Guess we'll find out!!
That's good to hear!!
Poleman
Addicted to ArboristSite
Terry, I noticed that. Its almost like you dont need the H. On the smaller saw the H was just cracked to set at 13,450 top end. The BB saw it was opened slightly more. Your right about the low feeding the high side. That extra fuel down low gives these saws a very wide power band as it getting the fuel it is needing to create this.
On the BB365 it was rich from the get go. I know there is a lot more I could have done to get this better but I will make that chapter two
On the BB365 it was rich from the get go. I know there is a lot more I could have done to get this better but I will make that chapter two
Terry Syd
Addicted to ArboristSite
Rich, if you have another carb to try you might try taking the carb up in sizes in increments on the 6400. If you found that a 25/30 worked better for the 64cc engine, then it may give you an indication of what would work on a 71cc engine.
My gut feeling is the 30/40 would work better on the 365BB. Perhaps try that carb off the 84cc Makita and give it a go on the 365BB.
The low speed circuit can be made to be overly rich and still work well, but why use more fuel than you need to. On the other hand, if you get the low speed circuit a bit too rich and it dampens the flame front, you could advance the ignition timing to compensate and probably pick up a bit more power up in the higher revs.
My gut feeling is the 30/40 would work better on the 365BB. Perhaps try that carb off the 84cc Makita and give it a go on the 365BB.
The low speed circuit can be made to be overly rich and still work well, but why use more fuel than you need to. On the other hand, if you get the low speed circuit a bit too rich and it dampens the flame front, you could advance the ignition timing to compensate and probably pick up a bit more power up in the higher revs.
LegDeLimber
Addicted to ArboristSite
Has anyone spotted a drill bit index set that covers all the decimal, metric and letter sizes?
the seller "gadgetscollection" has a set of numbered and a set of metric sized that looks like a nice range of increments if put together.
http://www.ebay.com/itm/21pc-Micro-...356?pt=LH_DefaultDomain_0&hash=item3f1a93b0f4
http://www.ebay.com/itm/15pc-HSS-Me...321?pt=LH_DefaultDomain_0&hash=item416e1bc2b9
The old gut feeling makes me want that sort of small incremental stepping all the way to about 2.5 mm or so...
I've got some mower carbs that just might benefit from a lil tweaking.
the seller "gadgetscollection" has a set of numbered and a set of metric sized that looks like a nice range of increments if put together.
http://www.ebay.com/itm/21pc-Micro-...356?pt=LH_DefaultDomain_0&hash=item3f1a93b0f4
http://www.ebay.com/itm/15pc-HSS-Me...321?pt=LH_DefaultDomain_0&hash=item416e1bc2b9
The old gut feeling makes me want that sort of small incremental stepping all the way to about 2.5 mm or so...
I've got some mower carbs that just might benefit from a lil tweaking.
Poleman
Addicted to ArboristSite
Ahhhh, forgot about using a timing advance to help!!!!
I do need to get more carbs to go up in size in smaller increments. That way I can see what what size/combination would work best on give saw cc size. I know it woun't be fool proof but will establish a baseline so on a given saw size there would be a starting point.
I guess I dont see how the 30/40 combo would be better on the 365BB....It was so overly rich with the 30/35.
I do need to get more carbs to go up in size in smaller increments. That way I can see what what size/combination would work best on give saw cc size. I know it woun't be fool proof but will establish a baseline so on a given saw size there would be a starting point.
I guess I dont see how the 30/40 combo would be better on the 365BB....It was so overly rich with the 30/35.
