Hs-40 build
- Thread starter delray
- Start date
wasn't option on a 245 cam. that was something I did to my 245 cam that has never been done before. something that I wanted to see if it could be done or not and the other stuff I did could be done.....:thumbsup:
this engine wasn't really even something I was planning on going extreme at first. then it lead to one thing after the other. it's all tied into a future ohh engine build. this flathead build was more of a test bed for my future ohh motor....:thumbsup:
this engine wasn't really even something I was planning on going extreme at first. then it lead to one thing after the other. it's all tied into a future ohh engine build. this flathead build was more of a test bed for my future ohh motor....:thumbsup:
well guys I going to mount a mikuni carb on this little hs-40 and see how it does. I feel my max power will be a mikuni or a tilly. the big bore tecumseh10hp carb works good,but I want to see how it performs with a real carb...:thumbsup:
first thing was to get a piece of round stock aluminum and mock up a bolt pattern and also see how much material I will need.
this will be little tricky to do. the Tecumseh bolt pattern is just little wider and the throttle bore is center with the bolt pattern. the mikuni bolt pattern is just a tad smaller in width and the carb throttle bore is off set down by a 1/8 or so.
Tecumseh side
keeping the hole little under size for now. come back later and open it up some more.
here is what it looks like with the bore through to the mikuni side.
before I go any farther I am going to thin up the adapter.
first thing was to get a piece of round stock aluminum and mock up a bolt pattern and also see how much material I will need.
this will be little tricky to do. the Tecumseh bolt pattern is just little wider and the throttle bore is center with the bolt pattern. the mikuni bolt pattern is just a tad smaller in width and the carb throttle bore is off set down by a 1/8 or so.
Tecumseh side
keeping the hole little under size for now. come back later and open it up some more.
here is what it looks like with the bore through to the mikuni side.
before I go any farther I am going to thin up the adapter.
this is where it gets little tricky. trying to get both bores to match up with one side being off-set.
when I got close to where I wanted to be I decided cut the extra aluminum off. making it more of a V shape.
after cleaning up the piece little I learn quickly the choke lever on would hit the adapter. so off more material..:grind:
the final result took a lot more work then I thought it would take. getting a straight edge bore from one to the other took little time. wanted to makesure it was spot on and was going to flow correct.
when I got close to where I wanted to be I decided cut the extra aluminum off. making it more of a V shape.
after cleaning up the piece little I learn quickly the choke lever on would hit the adapter. so off more material..:grind:
the final result took a lot more work then I thought it would take. getting a straight edge bore from one to the other took little time. wanted to makesure it was spot on and was going to flow correct.
I fired it up with 125 jet and 15 pilot and it runs good. weather here as been changing here and I thought that it might be a problem getting it dialed in,but everything seem to be ok. runs real good and pulls me hard(power) for just a hs-40 motor.
I remember when I first use one of these carb's on a 196cc grey hound and that engine had a CL2 cam with 1.3 rockers,25mm intake 24mm exhaust, .050 milled head and was ported and that would only take a 120 jet. so it's kind of crazy to see this little guy running a bigger jet. for any of you guys that have purchase a 22mm carb they come with a 95 jet. so you can see there is a big increase in changing the jet size.
one of the reason's I wet with the stock modified intake. it allow me to mount the carb in a location were nothing wound get in the way and with the adapter it work slick. with the mikuni bore sitting just little lower then the Tecumseh bore. it allow the direction of air to flow straight up at a angle....:thumbsup:
if I was to build a new intake that curve out to the left side. the bottom of the carb would of hit the clutch cover and anything beyond that would of just hung way to far out for me.
choke works slick too on this mikuni. click it up and one pull and off it go's......
I remember when I first use one of these carb's on a 196cc grey hound and that engine had a CL2 cam with 1.3 rockers,25mm intake 24mm exhaust, .050 milled head and was ported and that would only take a 120 jet. so it's kind of crazy to see this little guy running a bigger jet. for any of you guys that have purchase a 22mm carb they come with a 95 jet. so you can see there is a big increase in changing the jet size.
one of the reason's I wet with the stock modified intake. it allow me to mount the carb in a location were nothing wound get in the way and with the adapter it work slick. with the mikuni bore sitting just little lower then the Tecumseh bore. it allow the direction of air to flow straight up at a angle....:thumbsup:
if I was to build a new intake that curve out to the left side. the bottom of the carb would of hit the clutch cover and anything beyond that would of just hung way to far out for me.
choke works slick too on this mikuni. click it up and one pull and off it go's......
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it's been good eric, the compression relief works good.....:thumbsup:
I really like how it starts with the mikuni carb choke. first pull...…...bang
this is my third carb on a performance engine and they seem to work real good after the engine is dialed in.....:thumbsup:
without doing anymore testing with this carb. thinking I may have it spot on or very close...…..:thumbsup:
I really like how it starts with the mikuni carb choke. first pull...…...bang
this is my third carb on a performance engine and they seem to work real good after the engine is dialed in.....:thumbsup:
without doing anymore testing with this carb. thinking I may have it spot on or very close...…..:thumbsup:
I too have basically abandoned the stock tecumseh carb on all my bikes. i don't really modify my Tecumseh HS40 and HS50 motors, other than using a slide carb and an more open exhaust. The 16mm slides i'm using are like $12 (including shipping!) on ebay, you can't beat them. and yes choke on, first pull start. they are pretty awesome. And i don't change the jetting at all, it seems perfect right out of the box.
The only downside is you have to make an adapter. It would be awesome if someone came up with an intake manifold (straight and angled) that you could buy so it would just bolt on. Making the adapter is a bit of work.
Here's a comparison of the 16mm i'm using and the 22mm you're (probably) using. Damn the 22 is a lot bigger!
16mm with adaptor:
The only downside is you have to make an adapter. It would be awesome if someone came up with an intake manifold (straight and angled) that you could buy so it would just bolt on. Making the adapter is a bit of work.
Here's a comparison of the 16mm i'm using and the 22mm you're (probably) using. Damn the 22 is a lot bigger!
16mm with adaptor:
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carb that I am running looks more like this style choke lever and has a different style body/bowl.
I do have one 19mm carb like your black plastic choke lever one you posted. that carb is on a stock 5hp briggs and it works and all ,but when you fire it up cold with the choke you need to throttle it just little to keep it running.
type of carb I have on my built hs-40 you just need to set the choke and it automatically sets the high idle too. it really works slick....:thumbsup:
also nice you can buy the real mikuni jets and pilots for it.:thumbsup:
I do have one 19mm carb like your black plastic choke lever one you posted. that carb is on a stock 5hp briggs and it works and all ,but when you fire it up cold with the choke you need to throttle it just little to keep it running.
type of carb I have on my built hs-40 you just need to set the choke and it automatically sets the high idle too. it really works slick....:thumbsup:
also nice you can buy the real mikuni jets and pilots for it.:thumbsup:
we had the bike out today at some friends house. buddy's really got a kick out of this little hs-40
I let one of my friends hammer on it and hard. lets just say I am glad I have a catch can...:laugh: WOW does that bike sounds bad ass. first time someone else road the bike. I really got here it from a distance. my video of it does not do justice when it comes to sound...
I let one of my friends hammer on it and hard. lets just say I am glad I have a catch can...:laugh: WOW does that bike sounds bad ass. first time someone else road the bike. I really got here it from a distance. my video of it does not do justice when it comes to sound...
this engine really became alive when I installed the 10hp carb and the mikuni and now after riding it to the moon and back at over 7000 rpm's it's starting to take a toll on the max torque clutch. when I first installed the clutch it was new. the bushing was tight and had no slop at all. well clutch is starting to show some good amount of play and yes I do put a light drop of oil in it once and awhile. I am going to look into a better clutch this winter and make a new bushing for this one and install it in something more mild. also the other problem I have with using this it doesn't seem to have enough stall speed for hard take off's. other wise this engine has been a fun build and long one too. but well worth the time and effort I put into this little guy. crazy how smooth it runs at all speeds/rpm's. real happy with that....:thumbsup:
[video=youtube;vb6LOxKlMFw]https://www.youtube.com/watch?v=vb6LOxKlMFw&feature=youtu.be[/video]
just for fun...:thumbsup: here are couple video's from friends sent me goofing off and racing a stock hs-40 with a torque converter on a digger bike. videos quality ain't the best.
[video=youtube;Ad7mkYbnuo8]https://www.youtube.com/watch?v=Ad7mkYbnuo8[/video]
[video=youtube;eFdYu9Y7oPA]https://www.youtube.com/watch?v=eFdYu9Y7oPA[/video]
thanks again for everybody checking out my build …….:thumbsup:
here is a sneak peek on a future build small block with factory full roller bearing motor I pick up. yes ball bearing on inside of the block and on the pto cover. yes Tecumseh made them right at the end of production years.
[video=youtube;vb6LOxKlMFw]https://www.youtube.com/watch?v=vb6LOxKlMFw&feature=youtu.be[/video]
just for fun...:thumbsup: here are couple video's from friends sent me goofing off and racing a stock hs-40 with a torque converter on a digger bike. videos quality ain't the best.
[video=youtube;Ad7mkYbnuo8]https://www.youtube.com/watch?v=Ad7mkYbnuo8[/video]
[video=youtube;eFdYu9Y7oPA]https://www.youtube.com/watch?v=eFdYu9Y7oPA[/video]
thanks again for everybody checking out my build …….:thumbsup:
here is a sneak peek on a future build small block with factory full roller bearing motor I pick up. yes ball bearing on inside of the block and on the pto cover. yes Tecumseh made them right at the end of production years.
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