Author Topic: One lung FM Z 1 1/2 HP  (Read 816 times)

Offline Geo46

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One lung FM Z 1 1/2 HP
« on: November 16, 2023, 01:00:18 PM »
Good morning, I am new to the forum and not sure where to post this , anyway we have a Fairbanks Morse 1 1/2 HP Z , someone has removed the original mixer and installed a Flo Jet carburetor, apparently it did run at some point, we are looking for a substitute for this carb as it is prone to leaking, any thoughts?
Thanks
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Offline cnr6400

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Re: One lung FM Z 1 1/2 HP
« Reply #1 on: November 16, 2023, 01:14:30 PM »
Welcome to the forum. Have you looked at all on Smokstak.com? Plenty of info there on FM 'Z's , and a sales / want ad bulletin board too. You might try a rebuild kit for the FloJet carb in the meantime, it might help fix the leaks.  :cheers:
"I've cut that stock three times, and it's still too short!"

Offline Geo46

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Re: One lung FM Z 1 1/2 HP
« Reply #2 on: November 16, 2023, 01:47:18 PM »
Hi, yes I am a member of that forum, just looking for other inputs, carb has been rebuilt, they are prone to leaking.
Geo46🇺🇸
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Online gipetto

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Re: One lung FM Z 1 1/2 HP
« Reply #3 on: November 16, 2023, 02:10:58 PM »
If it were me i think i'd try adapt a motorbike carb to it. Honda 50cc are about the smallest that i know of, they are 4 hp, so they should be a good match.

Offline Geo46

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Re: One lung FM Z 1 1/2 HP
« Reply #4 on: November 16, 2023, 02:21:14 PM »
Thanks, looking at all options, any idea on Honda P/N?
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Offline Bluechip

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Re: One lung FM Z 1 1/2 HP
« Reply #5 on: November 16, 2023, 03:14:04 PM »
« Last Edit: November 16, 2023, 03:17:30 PM by Bluechip »

Offline Geo46

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Re: One lung FM Z 1 1/2 HP
« Reply #6 on: November 16, 2023, 03:35:13 PM »
Thanks, Iíll check it out
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Online Alyn Foundry

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Re: One lung FM Z 1 1/2 HP
« Reply #7 on: November 16, 2023, 04:09:12 PM »
Hi.
I rallied several of these engines years ago. One of which was missing the carburettor. I made patterns and castings for it.

Please see attached.

Cheers Graham.

Online Alyn Foundry

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Re: One lung FM Z 1 1/2 HP
« Reply #8 on: November 17, 2023, 12:36:47 PM »
Not sure whether you missed my previous postÖ.

Originally these engines were dual fuel. The carburettor has a small chamber that is filled with Petrol/Gasoline and an inbuilt needle valve to adjust the mixture. Once running the engine would start to get hot enough to transfer to the main fuel, Paraffin/Kerosene which was stored in a large rectangular tank carried between the skids. The Venturi area has a front cover that has a spring loaded valve, effectively acting as a choke device.

I have a set of Iron castings, unmachined, but I donít think the original style carburettor would be suitable for what appears to be a mobile unit.

 :cheers:  Graham.

Offline Geo46

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Re: One lung FM Z 1 1/2 HP
« Reply #9 on: November 17, 2023, 01:14:04 PM »
Thanks for the reply, I am well aware of the original mixers, seems like you are more capable then we are, someone retro fitted this with a Flo Jet, I believe it was to get better throttle control as this was used on a small locomotive, my main goal now is to find a carb other than Flo Jet even if it means making a new manifold, not sure how to size a carb.
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Online Vixen

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Re: One lung FM Z 1 1/2 HP
« Reply #10 on: November 17, 2023, 06:52:43 PM »
It would help if you were to tell us the engines capacity and required operating speed. It should then be possible to recommend a suitable commercial  carb
Mike
« Last Edit: November 17, 2023, 07:00:42 PM by Vixen »
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Offline Geo46

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Re: One lung FM Z 1 1/2 HP
« Reply #11 on: November 21, 2023, 02:42:13 AM »
Well itís a 1 1/2 HP about 450 RPM, open crankcase , 5Ē piston, intake valve controlled by an external spring.
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Online gipetto

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Re: One lung FM Z 1 1/2 HP
« Reply #12 on: November 21, 2023, 04:05:41 PM »
I suggested a honda 50 carb before, but given your figures it would be way to small. I would suggest a mikuni vm clone. they are flange mount, sold on aliexpress. I love them as they are more reliable than the pz series. I'm just guessing as to a size, but i had one on a 220cc honda fourtrax and it ran great. to be more accurate, you would have to calculate the horsepower of a motorbike/atv engine at the same 450rpm, not especially difficult since horsepower doubles with rpm.
for instance, a honda recon 250cc generates 15.6hp at 6500 rpm, therefore the same engine will generate 1.08hp at 450rpm because 6500/450=14.4 and 15.6/14.4= 1.08hp
I fitted a mikuni vm22 to my honda fourtrax, so it will run, but you might want a larger model such as vm24.

Online Vixen

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Re: One lung FM Z 1 1/2 HP
« Reply #13 on: November 21, 2023, 04:36:40 PM »

 A honda recon 250cc generates 15.6hp at 6500 rpm, therefore the same engine will generate 1.08hp at 450rpm because 6500/450=14.4 and 15.6/14.4= 1.08hp
I fitted a mikuni vm22 to my honda fourtrax, so it will run, but you might want a larger model such as vm24.

If the vm22 can deliver enough air/fuel to run a 250cc engine at 6500RPM then it will be capable of passing about 15 times too much air/fuel for a 450 RPM engine. IMHO, a much smaller carb than a vm22 is required, not larger.

Mike

3mm (correction 6mm) diameter is about 1/15 the area of 22mm diameter. Therefore, the carb from Bluechip's Mantis cultivator, which has a Honda 22cc OHC engine would be much closer to the mark


https://www.ebay.co.uk/itm/175659641621?chn=ps&norover=1&mkevt=1&mkrid=710-153316-527457-8&mkcid=2&itemid=175659641621&targetid=4584757337008490&device=c&mktype=&googleloc=&poi=&campaignid=431353847&mkgroupid=1298523655396099&rlsatarget=pla-4584757337008490&abcId=9301942&merchantid=87779&msclkid=b28ce512d43017a91e818044e67cec4f
« Last Edit: November 21, 2023, 07:03:37 PM by Vixen »
It is the journey that matters, not the destination

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Online gipetto

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Re: One lung FM Z 1 1/2 HP
« Reply #14 on: November 21, 2023, 05:15:32 PM »
Well I could be wrong, but I think my math is correct, since it's not especially difficult to calculate. The only issue i can see is that a vm22 may not allow the engine to idle at that slow a speed, the pilot jet could rev higher than the max rpm of the engine. from a quick search, polaris atv idle at 1200 rpm.
I guess to avoid the idle issue it would be better to go small. It may run, but the power it produces will be abysmal.

 

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