Turn a HDA 120 into a HDA 87

[super3]

I have a 144. I'll do it next.

 

[Mattyo]

i'd like to know how many people have 120's sitting around because they went with 87's they paid an arm and a leg for. I'm willing to bet its more than a few. If you could get the process down, i'll bet there is a niche market here

 

[Tor R]

i'd like to know how many people have 120's sitting around because they went with 87's they paid an arm and a leg for. I'm willing to bet its more than a few. If you could get the process down, i'll bet there is a niche market here

I have 5×120, aint gone rebuild them, all head for the 254's.
Never stressed with those 87, they came when they came. I bought 2 without saw, paid 50$ for the first and 10$ for the last.
144 is more interesting for modd since we still can purchase it new.
The only thing I stress with nowadays is to get more 199, only have 5

 

[super3]

I bored a 144 today. I ground a radius in a separate cutter for the throttle side as to cut the bore and the radius of the venturi at the same time. The venturi radius came out very smooth and saved shaping a small stone several times to get the desired shape. I got lucky with the first attempt on the cutter radius and it cuts the veturi bore just .020 oversize, much less work to finish it up now.
I need to pick up a few carb kits to finish these 2 up as soon as some other parts that I have ordered are in.
More to follow.
The throttle side cutter.



44 throttle side, choke side same as the 120 carb.

 

[super3]

I finally got around to getting the carbs back together and on a saw for a comparison run.

I warned ya I was slooooow.

The difference on the saw I had at the time was 6/10 s.

I'm too stupid to reformat a vid, you'll just have to take my word.

 

[Stihlbro]

Your word is good in my book!

 

[super3]

Thanks bud.

 

[jb-chainsaws]

This is the kind of genius I *f-wording love about this forum! Awesome work

 

[Mastermind]

Yep....your word is gold to me too.

 

[lwhaples]

Good read,enjoyed the info.

 

[cgraham1]

I'll pay ya to make me a 20mm for my saw.

PM sent.

I'm wondering if this was ever done, and if so, how did it turn out?

 

[Chainsaw Jim]

Great thread and good looking work.

There's one important thing to watch out for when doing this mod on most carbs. When enlarging the venturi ring the area around the hole for the main nozzle can only be taken so far before it exposes the valves side passage area which will ruin the carb.
In my experience with larger saws the stihl saws seem to like this mod more than the Husqvarnas do. I hogged out a wj39 for my 394 and it almost coughed the carb right back off the saw. Right before junking it I figured I'd try it out on my 075 and it ran like Judah Friedlander.

 

[Tor R]

I thought I should do no more chainsaws before 2017 (exept one project from @Landmark @rattler that I really want to finish), but this thread made me interested to try out the famous MasterMind 199....

Parts:

choke&trottle shaft is from HDA 120

 

[super3]

I'm wondering if this was ever done, and if so, how did it turn out?

Nope .
If someone wants to send me a doner I'll bore it to 20mm to see if it is too much.

 

[Chainsaw Jim]

I just measured a 120 and the largest you can safely go on the choke side is 19mm.
The hda 199 will safely go 20mm and has a much larger venturi. The best way to do a swap to the 199 is to file the smashed portion of the shafts that holds the plates on and they wiggle right off to re solder the 120 plates back on. Or drill and tap them to fasten the plates with the little screws.

 

[super3]

You lost me.
The 120 plates are way too small for the 199.

 

[cgraham1]

Maybe put the 199 plates on the 120 shafts?

 

[super3]

My bad. Jim was just saying change the outer plates.
I had throttle and choke valves on my mind after talking to you.

 

[Chainsaw Jim]

Yeah just the outer plate because the throttle shafts between the 199 and 120 aren't interchangeable with the difference they have in length. It appears that the choke shafts will interchange.

 

[drf256]

The 199 is the same bore and Venturi as the 87. I believe the 198 replaced the 199 and is readily avaiable OEM.

Please correct me if I'm wrong, but the 199 has an accelerator pump? That should be great for throttle response.

Randy modified and swapped 120 shafts and linkages onto a 199 and made it work for the 262.

In the 262 thread, we looked at a bunch of carbs. I believe an 036 Zama can be modified to fit the 262. It measures very close to an 87 in size.

I have 5 sets of choke and throttle plates I bought here's for the 87 carb with intentions of boring out a 120 for them. Never got around to it.