# Hoglet carburetor



## seadragonfoundry (May 7, 2013)

I will shortly be starting to build a Hoglet V twin to the Randall Cox design. Reading through the plans, the carburetor specified is an OS 10, which has been superceded. Can any one suggest a replacement for this, or another that will do the job? Or perhaps an alternative set of carburetor plans? I have built a number of single cylinder engines but not a multi. One further question, the plans also specify viton o rings for the piston rings. I have not gone down this path before and while I understand that it works I am a bit of a traditionalist, has anyone used  conventional piston rings successfully or is this a No No?Thanks for your help


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## canadianhorsepower (May 7, 2013)

I can't help you with the carb but i think you will like this link and can be tranlated in english

http://fabrication-moteur.over-blog.com/pages/the_hoglet_V_twin-3412520.html

enjoy


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## trumpy81 (May 7, 2013)

seadragonfoundry said:


> I will shortly be starting to build a Hoglet V twin to the Randall Cox design. Reading through the plans, the carburetor specified is an OS 10, which has been superceded. Can any one suggest a replacement for this, or another that will do the job? Or perhaps an alternative set of carburetor plans? I have built a number of single cylinder engines but not a multi. One further question, the plans also specify viton o rings for the piston rings. I have not gone down this path before and while I understand that it works I am a bit of a traditionalist, has anyone used  conventional piston rings successfully or is this a No No?Thanks for your help



OS 10 refers to it's size in cubic inches (.10 C.I.) OS refers to the maker, so any two stroke RC engine in that size range will yield a suitable carb. You could probably go up to a .15 size carb without any ill effects.

I recall seeing some Thunder Tiger engines in the .12 size range also. They would be suitable as well.

The Viton O-Rings will work quite well. Just be careful you don't have too much 'pinch' in the cylinders, you don't want too much drag. I suspect that cast iron rings would work just as well though, but a lot more work.


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## Jasonb (May 7, 2013)

The OS 10ER would be the neearest which is for 12-15 size engines, you can get the carb from the OS 10LA engine but that has a remote needle valve.

Funny that link has it with an enclosed crankcase I drew one up the other day that could be cut from a slice of 5" dia bar.


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## crankshafter (May 7, 2013)

seadragonfoundry said:


> I will shortly be starting to build a Hoglet V twin to the Randall Cox design. Reading through the plans, the carburetor specified is an OS 10, which has been superceded. Can any one suggest a replacement for this, or another that will do the job? Or perhaps an alternative set of carburetor plans? I have built a number of single cylinder engines but not a multi. One further question, the plans also specify viton o rings for the piston rings. I have not gone down this path before and while I understand that it works I am a bit of a traditionalist, has anyone used  conventional piston rings successfully or is this a No No?Thanks for your help



seadragon.
I have buildt the Hoglet and I made up a carb for it from plans I got from a member  on this forum. I do not remember who, but the Hoglet runs and perform wery good whit this carb. From 600 rpm idling to 5000 rpm max
I would like to build one more Hoglet ang that one will have enclosed crankcase. 
BTW I run mine with viton-orings no problems . Never run it for long time so it get to hot. But i thinking of using proper pistonrings for the next one.

Regards CS.


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## crankshafter (May 7, 2013)

Jasonb said:


> The OS 10ER would be the neearest which is for 12-15 size engines, you can get the carb from the OS 10LA engine but that has a remote needle valve.
> 
> Funny that link has it with an enclosed crankcase I drew one up the other day that could be cut from a slice of 5" dia bar.



Hi Jasonb.
Nice drawing of the Hoglet crankcase. 
This is exactly what I have in mind when I will build my 2nd Hoglett, but I have not a clue how to draw it. Mybee you .can give some dimesions on this one?
I am sure many on here would be interested.

Regards CS.


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## seadragonfoundry (May 7, 2013)

Thank you for your help and advice, amazing what a wealth of knowledge there is in this group.
Thanks
Graeme


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## Jasonb (May 8, 2013)

The crankcase drawing needs a bit of final tweaking then I'll see what I can do.

J


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## seadragonfoundry (Jun 11, 2013)

Have made a start on two Hoglets, this is a fun engine to build. Problem, plans specify Stressproof steel 1144 for the cam. This material is not available in Australia to my knowledge, can anyone suggest a source of supply for a small amount of 1/2" diameter or a suitable alternative ? I have emailed the manufacturer in the USA but received no reply.Thanks
Graeme


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## kuhncw (Jun 11, 2013)

Hi Graeme,

I would think you could use drill rod for the cams.  

Very nice work on your Hoglets!

Regards,

Chuck


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## enfieldbullet (Jun 11, 2013)

the stressproof is there probably because it machines nicer than a similar strong steel.

drill rod is probably good enough.

in the cam you definitely want some wear strength.


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## waynes world (Jun 11, 2013)

for your carby requirements contact model engines in melb or go to there web site they will fix your carby needs as they are the o.s engines import agents in aus. stress proof yes you should be able to get from smorgon steel they had it in a cattle dog that i had.


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## AndrewW (Dec 5, 2021)

crankshafter said:


> seadragon.
> I have buildt the Hoglet and I made up a carb for it from plans I got from a member  on this forum. I do not remember who, but the Hoglet runs and perform wery good whit this carb. From 600 rpm idling to 5000 rpm max
> I would like to build one more Hoglet ang that one will have enclosed crankcase.
> BTW I run mine with viton-orings no problems . Never run it for long time so it get to hot. But i thinking of using proper pistonrings for the next one.
> ...


Hi crankshafter
I realise that this is an old thread but wonder if you could help me. I've just completed a Hoglet but struggling with carburation. I have an OS21 carb but I think it might be too large.
Have you still got the drawings of the carb that you made? If so, could you share them with me?
Cheers
Andrew


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## doc1955 (Dec 5, 2021)

My version that I designed up.


			https://www.youtube.com/playlist?list=PLp95TDxCzDrX1ZxWM9eWvrRIosdbCuX1o


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## AndrewW (Dec 5, 2021)

Thanks Doc. It looks like you lost some of your footage. Do you have any drawings you can share?
Cheers
Andrew


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## mrehmus (Dec 6, 2021)

Here is Randy's HOGLET built on a Harley Sportster frame. Randy built custom motorcycles. This one was rideable. 



The cylinders are from Briggs and .Stratton off e-Bay. Note the open crankcase and gearbox.


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## Vietti (Dec 6, 2021)

Mike,

I think it was a Hummer frame he bought over in Salt Lake, it looked so good many spectators thought it as an original!


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## mrehmus (Dec 6, 2021)

With my memory, I'm glad I remember Randy! Wouldn't let me ride it though.


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## bluejets (Dec 6, 2021)

AndrewW said:


> Hi crankshafter
> I realise that this is an old thread but wonder if you could help me. I've just completed a Hoglet but struggling with carburation. I have an OS21 carb but I think it might be too large.
> Have you still got the drawings of the carb that you made? If so, could you share them with me?
> Cheers
> Andrew


Looks like Doc's engine has a venturi around 6 to 8mm .
What makes you think the OS21 carby is too large?


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## AndrewW (Dec 7, 2021)

Hi
The Hoglet build docs mention a carb with a conventional barrel type throttle 1/4" dia with a venturi bore of 1/8" (circa 3.2mm). I guess that the os21 carb I have has a venturi of 5.4mm, but I can't find any technical spec for it.
The Hoglet has decent compression and I believe valve timing is spot on. Ignition set to 30 degrees btdc, which might be a little too early?
The engine starts well but stops after 15 secs or so. My 'MT44 Part 15' video on YouTube shows it running.

Cheers
Andrew Whale


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## rpf (Dec 7, 2021)

mrehmus said:


> Here is Randy's HOGLET built on a Harley Sportster frame. Randy built custom motorcycles. This one was rideable. View attachment 131650
> 
> The cylinders are from Briggs and .Stratton off e-Bay. Note the open crankcase and gearbox.


Have you got a larger picture of this? sounds very good!!


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## dsage (Dec 7, 2021)

Andrew:
I sent an email to Mike Rehmus of Model Engine Builder Magazine (where you got the plans) asking him to chime in here with his experience on what has been working for others. I'm sure he has reports of lots of them working down his way in California. I also gave him a link to your Youtube channel to have a look.
Good luck.


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## AndrewW (Dec 7, 2021)

dsage said:


> Andrew:
> I sent an email to Mike Rehmus of Model Engine Builder Magazine (where you got the plans) asking him to chime in here with his experience on what has been working for others. I'm sure he has reports of lots of them working down his way in California. I also gave him a link to your Youtube channel to have a look.
> Good luck.


Many thanks! That's a great idea. I recall I had a bit of an email exchange in August with Mike, but it never dawned on me to ask him.
Thanks again for your help.
Cheers
Andrew


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## mrehmus (Dec 7, 2021)

based on the sound and how well it runs, I don't think the carburetor is the problem. Fuel feed might be though. What was the temperature where you were running it?


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## doc1955 (Dec 7, 2021)

The carb I use is the Jerry Howell 2jet carb but I did change it slightly the needles were to blunt and was hard to get a good setting so I sharpened the ends and that helped a lot. But I would guess it is your valve timing I know I had to mess with mine to get it to idle and run. Plus had trouble getting the crank gear to not slip.


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## AndrewW (Dec 7, 2021)

mrehmus said:


> based on the sound and how well it runs, I don't think the carburetor is the problem. Fuel feed might be though. What was the temperature where you were running it?


Hi Mike
Thanks for your thoughts on this. The room temperature was about 10°C. The bottom of the fuel tank is about level with the inlet on the carb. I put a vent hole in the fuel tank filler, but I'm just wondering if it might not be big enough. I will do some more tests.
Many thanks
Andrew


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## AndrewW (Dec 7, 2021)

doc1955 said:


> The carb I use is the Jerry Howell 2jet carb but I did change it slightly the needles were to blunt and was hard to get a good setting so I sharpened the ends and that helped a lot. But I would guess it is your valve timing I know I had to mess with mine to get it to idle and run. Plus had trouble getting the crank gear to not slip.


Many thanks for the advice. I was wondering whether to make a JH 2jet carb. I will need to make two when I tackle the JH v-twin . I'll check valve timing and probably reduce the tappet gap from 10 thou to 3.
Mike thinks it could be fuel delivery, so I will open up the breather hole in the fuel tank. I might try adjusting ignition timing to 20° BTDC too.
I've also found a cheap carb on eBay, so I will try that too.
Yeah that crank gear is quite different to lock.
So I've got a few things to try out now.
Thanks again.
Andrew


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## dsage (Dec 7, 2021)

Andrew:
The vent hole in the tank only needs to be as big as required for air to replace the amount of fuel being burned  - which is next to nothing. A 1/16 hole would be overkill.
If the carb has a way to control the air intake volume - like a choke or a variable barrel type throttle opening  - within reason almost any carb should work because you have control over both the air and fuel. The fuel with the needle valve and the air as above. So somewhere in there should be a setting that works.
You can reduce your valve lash to a minimum. The amount of lash is only there to allow for expansion of components when hot. So I'd think that a few thou would be plenty. And it can always be checked when hot if you have doubts.
While the engine is running you can experiment with a bit with choking off the air and / or adding fuel with the needle or perhaps a bit of starting fluid when it begins to stall to see what makes it happy to lead you in the right direction.
Keep at it. As you know all new engines requre a bit of fiddling to find out what makes them happy. I wouldn't jump into a new carb right away. The manufactured one you have IMHO should work. As MIke suggested maybe a bit more heat would help.


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## bluejets (Dec 7, 2021)

AndrewW said:


> The Hoglet build docs mention a carb with a conventional barrel type throttle 1/4" dia with a venturi bore of 1/8"


Video 54 at around 24:30 clearly shows what I quoted at 6 to 8mm bore.
Shouldn't make much diffiernce anyhow if you keep the throttle closed a bit more.


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## AndrewW (Dec 8, 2021)

Thanks to everyone for the advice.
I've now got a list of things to try.
All the best!
Andrew


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## Basil (Dec 8, 2021)

AndrewW said:


> Thanks to everyone for the advice.
> I've now got a list of things to try.
> All the best!
> Andrew


Hi Andrew
I agree on the timing @30deg. This sounds like an aweful lot for such a small cylinder. What does that work out to mm piston travel BTDC? I would think 15deg would be plenty.


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## dsage (Dec 8, 2021)

Don't forget valve lash figures into your VALVE timing. A lot of lash will make your VALVE timing later.


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## propclock (Dec 8, 2021)

Well I have had a lot of fun with my Hoglet.  I cheated and used
a carb from a Saito 450 4 cycle.  I can give the model # and pictures if interested.  Last time I looked ~80$
 I added a venturi reducer and it took
quite a bit of adjustment to get all it right.  My contribution
here is to make the timing easily adjustable. I have a long knurled
handle on mine. Start retarded advance as desired , or my favorite get it running REAL STRONG   and advance the throttle
and retard the timing. Then it sounds very realistic practically
firing out the exhaust. I had an Indian Scout with left handed throttle and right hand ignition advance/ retard.  
For a small engine it sounds very realistic when very retarded.
 I added a handlebar throttle
and work the timing on the side. That and the kick start is a real 
crowd pleaser at shows. 
Just my 1.414 cents worth.


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## mrehmus (Dec 8, 2021)

I think the ignition timing is quite a bit too soon. As my old mentor said, if it has compression , fuel and proper spark timing, it will run.
Another thing to check: Could it be heating up and binding? Some folks have had problems in that regard with o-rings.
Here is the drawing page on the use of O-rings by Tom Stuart in Issue # 15 of Model Engine Builder magazine.


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## coulsea (Dec 8, 2021)

One problem might be that the fuel tank is too high. the fuel level must be below the venturi / jet or it will flood, you should have to choke it by putting your finger over the inlet for a second to get it to start.


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## AndrewW (Dec 9, 2021)

Basil said:


> Hi Andrew
> I agree on the timing @30deg. This sounds like an aweful lot for such a small cylinder. What does that work out to mm piston travel BTDC? I would think 15deg would be plenty.


Thanks for the advice - added to my list of things to check/change.


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## AndrewW (Dec 9, 2021)

mrehmus said:


> I think the ignition timing is quite a bit too soon. As my old mentor said, if it has compression , fuel and proper spark timing, it will run.
> Another thing to check: Could it be heating up and binding? Some folks have had problems in that regard with o-rings.
> Here is the drawing page on the use of O-rings by Tom Stuart in Issue # 15 of Model Engine Builder magazine.
> View attachment 131717


Thanks for the info Mike - very useful. As luck would have it I don't think I'm far off the dimensions quoted. I was previously concerned that my o-rings might be on the small side, as they are only a few tenths of a thou bigger than the cylinders (similar to my Farm Boy which has good compression). I think the piston grooves are  pretty close to that suggested in the article too - but I will double check.


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## Majormallock (Dec 9, 2021)

Hi, Sorry late to the Thread... I have built a Hoglet. used cast iron rings, as i do on all my engines,... tried and tested method..  find attached a drawing of the carburettor used. I used the float chamber,but you don't need to! for me it just gave extra flexibility of where to mount the fuel tank.


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## AndrewW (Dec 9, 2021)

Majormallock said:


> Hi, Sorry late to the Thread... I have built a Hoglet. used cast iron rings, as i do on all my engines,... tried and tested method..  find attached a drawing of the carburettor used. I used the float chamber,but you don't need to! for me it just gave extra flexibility of where to mount the fuel tank.


Thanks - very interesting! I've just purchased a cheap carb and will give that a try first. This could be my 'Plan B'!
Cheers
Andrew


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## Harglo (Dec 10, 2021)

AndrewW said:


> Thanks for the info Mike - very useful. As luck would have it I don't think I'm far off the dimensions quoted. I was previously concerned that my o-rings might be on the small side, as they are only a few tenths of a thou bigger than the cylinders (similar to my Farm Boy which has good compression). I think the piston grooves are  pretty close to that suggested in the article too - but I will double check.


Any chance you could post the drawing of your carb?
thanks
Harvey


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## AndrewW (Dec 11, 2021)

Harglo said:


> Any chance you could post the drawing of your carb?
> thanks
> Harvey


Hi Harvey - I've now got the engine running. I'll post a video which shows the carb.
Cheers
Andrew


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## AndrewW (Dec 11, 2021)

Hi all - thanks for all the help and suggestions.
I've made various tweaks and got the engine running.
See video:


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## mrehmus (Dec 11, 2021)

I am not certain to which carburetor to which you refer. The Hoglet never did have a specific carburetor because Randy thought everyone was like him and would just naturally know what to do/use. Here is Dave Bowes take on a carburetor.


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## Harglo (Apr 20, 2022)

mrehmus said:


> I am not certain to which carburetor to which you refer. The Hoglet never did have a specific carburetor because Randy thought everyone was like him and would just naturally know what to do/use. Here is Dave Bowes take on a carburetor.View attachment 131821
> View attachment 131822


Many thanks for the info about these carbs. I run all my engines on propane which complicates the carbs performance.
Harvey


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## AndrewW (Apr 21, 2022)

Harvey's latest message has just reminded me to update this thread!
I decided to make a Jerry Howell 2-Jet carb. There are two designs and I decided to opt for the one suitable for the Howell v-twin engine - because that is the next engine I hope to make. Not the best design for the Hoglet as access to one of the jet screws is a bit restricted. However it works well after a bit of tweaking.
I've attached a link to a video showing the first test run - some 15 mins into the video. I also made a video series of making the Howell 2-Jet carb - which might be of interest to others.
Cheers
Andrew


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