New Tecumseh HS40 carb(s)
- Thread starter cfh
- Start date
I have not tried the Dellorto/Lambretta 19mm clone carb yet. I did get a good solution to the choke though. But i need to get an intake manifold to try it.
I would like to say this though... the 16mm Mikini clone carbs on Ebay for $10-20 are really working out quite awesome. They adapt very easily to the stock intake manifold. I use an aluminum extender, because it keeps the throttle cable away from the exhaust. But i guess you don't have to do that.
But the more Tecumseh HS50 motors i mount these 16mm carbs, the more happy i am. They really give a nice performance increase, without much money or time. You get way better throttle control, opposed to the tecumseh carb (where the throttle is really just on or off, without much middle play on the throttle control). And the high end is way improved. Also the governor is not used on these. (I pin it towards the PTO, so there's no stress on internal governor components.) Also just the general feel and motor responsiveness is much better. The choke is perfect too. The HS50 starts right up with this carb, first pull (choke on.) The set up looks cool too!
https://www.ebay.com/itm/Carburetor...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649
Here's my Gemini that i just mounted the 16mm carb upon. I was riding it around on the trails with the stock carb (new china clone tecumseh carb), and it was running just fine. But then i decided to install the 16mm, and wow, what a difference. For all of $30 (including the air cleaner and a new throttle/cable assembly), there really is no better "bang for buck" modification.
Again, i use the Dellorta Ua19 as used on the Rupp black widow as my bench mark. The 16mm is not quite as performance as the Dellorto, but frankly, it's pretty close. And a hell of a lot cheaper/easier to get! I also have a bike with a Dellorto Ub22 (22mm). It performs much like the Ua19. But runs a bit too rich (a lot of back fires), and chews a lot of gas! But even that solution is at least $100 (if not more). So these 16mm carbs really are the best thing going for a nice Tecumseh mod (without much money or time investment.)
Also with the 16mm carb, there's no jets that need to be changed. Really the only adjustment needed is to the idle screw. It's ready to go out of the box. I use an Amazon throttle assembly (comes with a cable), and this works really well and is inexpensive.
https://www.amazon.com/gp/product/B01MPX353V/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
I would like to say this though... the 16mm Mikini clone carbs on Ebay for $10-20 are really working out quite awesome. They adapt very easily to the stock intake manifold. I use an aluminum extender, because it keeps the throttle cable away from the exhaust. But i guess you don't have to do that.
But the more Tecumseh HS50 motors i mount these 16mm carbs, the more happy i am. They really give a nice performance increase, without much money or time. You get way better throttle control, opposed to the tecumseh carb (where the throttle is really just on or off, without much middle play on the throttle control). And the high end is way improved. Also the governor is not used on these. (I pin it towards the PTO, so there's no stress on internal governor components.) Also just the general feel and motor responsiveness is much better. The choke is perfect too. The HS50 starts right up with this carb, first pull (choke on.) The set up looks cool too!
https://www.ebay.com/itm/Carburetor...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649
Here's my Gemini that i just mounted the 16mm carb upon. I was riding it around on the trails with the stock carb (new china clone tecumseh carb), and it was running just fine. But then i decided to install the 16mm, and wow, what a difference. For all of $30 (including the air cleaner and a new throttle/cable assembly), there really is no better "bang for buck" modification.
Again, i use the Dellorta Ua19 as used on the Rupp black widow as my bench mark. The 16mm is not quite as performance as the Dellorto, but frankly, it's pretty close. And a hell of a lot cheaper/easier to get! I also have a bike with a Dellorto Ub22 (22mm). It performs much like the Ua19. But runs a bit too rich (a lot of back fires), and chews a lot of gas! But even that solution is at least $100 (if not more). So these 16mm carbs really are the best thing going for a nice Tecumseh mod (without much money or time investment.)
Also with the 16mm carb, there's no jets that need to be changed. Really the only adjustment needed is to the idle screw. It's ready to go out of the box. I use an Amazon throttle assembly (comes with a cable), and this works really well and is inexpensive.
https://www.amazon.com/gp/product/B01MPX353V/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1
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well if you do the math your going from about a 3/8 or .375 bore carb(stock Tecumseh) to a 16mm carb that has a .630 bore, it should perform better. long as the engine can handle it...:thumbsup: need to do little more testing cfh. get the motor warm up good and then run it hard up to 3800-4000 no higher then that. stock motor? correct? soon has you reach 3800+ shut the motor off and pull the plug and see what it looks like....:thumbsup: then you will have a little better ideal how good it really is running...
I have about 5 of these 16mm carbs installed. All on stock HS50 tecumsehs. I haven't pulled the plugs, but man they really do run great. Been running with them all summer. The only reason the other 5 bikes don't have them is because i need to make more aluminum extenders. That's coming.
I do really like the Dellorto Ua19s (as used on Black Widow). It's my go to bike as the comparison. But man that carb is so expensive and not that easy to find. This 16mm solution is just so much cheaper and easier. The intake manifold for the Ua19 costs more than the entire 16mm carb/filter/throttle assembly!
I do really like the Dellorto Ua19s (as used on Black Widow). It's my go to bike as the comparison. But man that carb is so expensive and not that easy to find. This 16mm solution is just so much cheaper and easier. The intake manifold for the Ua19 costs more than the entire 16mm carb/filter/throttle assembly!
Ran into my first failure on the 16mm $12 china carbs today. I have a new (to me) powerdyne xl1500 ( http://www.pinrepair.com/minibikes/powerdyne_1500xl_ad.jpg ) and i've been getting it into shape. I put the 16mm carb on the HS50 and rode it around. Wow what a great ride! but then the bike start to stall. I looked down, and gas was pouring out of the carb.
I removed the carb and found that float needle was hanging up. Also would like to note that the float bowl carb gasket did not get all weird and expand or shrink... no problems with that! but since i had the carb off, and had ridden the bike quite a bit with the 16mm, thought i might try the new 22mm carb that showed up in the mail today. (I would have liked to try the 19mm carb, but it hasn't come yet.)
Check the pictures out. The 22mm is quite a bit bigger than the 16mm. Also quite a bit heavier. But the bolt patterns are the same, so it should bolt right into place instead of the 16mm carb.
I'll check that out tomorrow. Well providing i can get the front tire on the Powerdyne changed, as there's a nail in the front tire and the tube is shot. Gawd i hate changing tubes, i always puncture the new one putting the tire back on...
I removed the carb and found that float needle was hanging up. Also would like to note that the float bowl carb gasket did not get all weird and expand or shrink... no problems with that! but since i had the carb off, and had ridden the bike quite a bit with the 16mm, thought i might try the new 22mm carb that showed up in the mail today. (I would have liked to try the 19mm carb, but it hasn't come yet.)
Check the pictures out. The 22mm is quite a bit bigger than the 16mm. Also quite a bit heavier. But the bolt patterns are the same, so it should bolt right into place instead of the 16mm carb.
I'll check that out tomorrow. Well providing i can get the front tire on the Powerdyne changed, as there's a nail in the front tire and the tube is shot. Gawd i hate changing tubes, i always puncture the new one putting the tire back on...
It’s really hard to compare the UA19s to pretty much any of the other carbs. Why? Because it’s on a black widow. The black widow uses a different torque converter system and has 12 inch wheels. Rupps in general just have a different feel. Personally I think their torque converter system is way better than comets. or certainly different enough that it’s hard to compare two bikes. All the other bikes have 10 inch wheels and are using a comet torque converter. So it’s a lot easier to compare apples to apples.
There is no doubt though that the dellorto UA19s with a five horse power tecumseh and the Rupp torque converter is the ideal set up. If I could buy Rupp torque converters at a reasonable price for all my bikes, I definitely would
There is no doubt though that the dellorto UA19s with a five horse power tecumseh and the Rupp torque converter is the ideal set up. If I could buy Rupp torque converters at a reasonable price for all my bikes, I definitely would
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I'm not a big fan of Comet torque converters either (drive or driven.) But they are at a very nice price point, so i use them. If i could find a source for original Rupp or Fairbank Morse torque converters, i would be using them! I really like the Fairbank Morse ones a lot. I have an original Fox with one, it's as good as the Rupp TC. They seem to be pretty close in design.
I mounted up the 22mm Mikuni china copy I bought on eBay for $15. It’s a bit more work to mount then the 16 mm $12 carburetors. Also the choke lever is all plastic which isn’t as nice as the completely metal choke on the 16 mm China carb.
So I fired it up driving around for a bit. I would say that it runs way too rich. And there was no performance difference between the 16mm and the 22 mm. In fact the 22mm actually ran worse with lesser performance. Probably because the jetting is not ideal for the HS50 motor.
Now mind you that I am not changing the jetting on either of these two carbs. I don’t want to go down that road, I don’t want to be bothered by the whole affair. The 16mm works perfect out of the box. The only thing you have to adjust is maybe the idle speed. 22 mm curb just ran way too rich with tons of backfires and motor lagging. I’m sure you could make it work but that would involve time energy and money
So I fired it up driving around for a bit. I would say that it runs way too rich. And there was no performance difference between the 16mm and the 22 mm. In fact the 22mm actually ran worse with lesser performance. Probably because the jetting is not ideal for the HS50 motor.
Now mind you that I am not changing the jetting on either of these two carbs. I don’t want to go down that road, I don’t want to be bothered by the whole affair. The 16mm works perfect out of the box. The only thing you have to adjust is maybe the idle speed. 22 mm curb just ran way too rich with tons of backfires and motor lagging. I’m sure you could make it work but that would involve time energy and money
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My guess is that the 22mm was just a little too big. I might be willing to play around with the 19 mm. I will keep everyone abreast when it comes in the mail. I’ll post how that works. I don’t have any extra jets. So that would involve me having to buy more stuff and fiddle around with things. And I’m not entirely sure that forcing a bigger carb was really going to get more performance then the already bigger 16 mm. I use the 22 mm dellorto as a reference point. That one is jeted correctly and runs well. Does it perform better than the 16 mm? Maybe a little but not significantly. There’s probably only so big you can go and get any kind of performance change
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I took the china 16mm carb apart that was leaking gas, and found the reason. First i think i need to start running fuel filters. But the other reason is shown in the picture below... too much travel on the float needle (red circle). It gets out of it's "hole" too much, canted, and then won't go back in (because it stops the floats from moving). This leaves the gas leaking from the float bowl. The answer is to bend the metal tab on the float to limit travel (blue arrow). You don't need much travel...
