Having carb issues with HS 50 mini bike I just bought.
- Thread starter hd94vett
- Start date
The shroud is a 1978, and from a snowblower, but it most likely does not match the engine, For that you want to look at the tag that is screwed down over the TC on the cylinder air deflector. you will probably want to research both numbers though and compare whats actually there, if you go deeper into it after what you are working on now, since there will be a difference between Snowblower and Recreational setup in parts/seals used, plus it can give you an idea of what they actually swapped around.
To bad they screwed up and rigged that intake to the block, they actually had the right combination in parts to work with and could have simply used a threaded insert to fix the thread and the proper gasket would sit correctly and seal correctly and not weaken the setup. common sense is not that common when it comes to small engines though.
The rod between the gov arm and carb is causing the bind. in a slanted application the position is a bit different than a standard setup to that rod, many times it will need to be tweaked/bent to fully clear the throttle shaft as it rotates from idle to WOT, tweaking/twisting the governor arm as well can help too. It is important that the upper assembly does not have to rely in any way on the lower spring to throttle cable return assembly. The tiny spring on the throttle shaft of the carb should be more than enough to quickly and smoothly snap it back to idle position, no hesitation.
The gasket they shoved in the intake is actually the HS50 exhaust gasket, It probably bottomed out with just that homemade gasket on that bolt or something and they rigged that gasket in to take up space...Get-R-dun. you will always have fitment/sealing issues since they reamed the hole so large on the intake for that bolt taking away what little surface area the proper gasket had to work with in the first place, so take your time to true out imperfections on the flanges of intake and block, double check the intake and upper drilled threaded hole for cracks, that may pass into the port if the drilled to far (looks pretty rough in the pic) modify the correct intake gasket to fit as best it can with that larger bolt if you going to keep using it, make sure you get the fine line of bolt length correct so you get maximum threads in the hole without bottoming out, etc....
Dont forget to maybe focus on the exhaust header as well, since its for a n HS40 specific and Not and HS50 is leaking badly as well at the flange..
To bad they screwed up and rigged that intake to the block, they actually had the right combination in parts to work with and could have simply used a threaded insert to fix the thread and the proper gasket would sit correctly and seal correctly and not weaken the setup. common sense is not that common when it comes to small engines though.
The rod between the gov arm and carb is causing the bind. in a slanted application the position is a bit different than a standard setup to that rod, many times it will need to be tweaked/bent to fully clear the throttle shaft as it rotates from idle to WOT, tweaking/twisting the governor arm as well can help too. It is important that the upper assembly does not have to rely in any way on the lower spring to throttle cable return assembly. The tiny spring on the throttle shaft of the carb should be more than enough to quickly and smoothly snap it back to idle position, no hesitation.
The gasket they shoved in the intake is actually the HS50 exhaust gasket, It probably bottomed out with just that homemade gasket on that bolt or something and they rigged that gasket in to take up space...Get-R-dun. you will always have fitment/sealing issues since they reamed the hole so large on the intake for that bolt taking away what little surface area the proper gasket had to work with in the first place, so take your time to true out imperfections on the flanges of intake and block, double check the intake and upper drilled threaded hole for cracks, that may pass into the port if the drilled to far (looks pretty rough in the pic) modify the correct intake gasket to fit as best it can with that larger bolt if you going to keep using it, make sure you get the fine line of bolt length correct so you get maximum threads in the hole without bottoming out, etc....
Dont forget to maybe focus on the exhaust header as well, since its for a n HS40 specific and Not and HS50 is leaking badly as well at the flange..
Thanks markus for all that great information. Do you think this engine is a hs 40 not a hs 50? I seen the little tag on the side of the engine, I will try to get that posted. Will the tag tell us more about the engine? You correct on the extra gasket it was there to keep the bolt from bottoming out. I used a car brake caliper copper washer for the brake hose to take up that space and it worked nicely so far. One of the bolts on the exhaust header is larger too, but there is no exhaust leak. I will look at that today. I am a little confused on the engine horse power, could it be a 4 hp with a 5 hp shroud on it. I order some new intake gaskets but they won’t be here for a few days. The spring on the carb to return it to idle is too week or disconnect but I will look at it today. Thanks again Markus for the help the last time I worked on minibikes was in the early 70s. It sure is a good feeling to work on them again.
No it is an HS50, its just an earlier one than 1978 (actually it falls into oct 1971-73 most likely). Yes you will be able to research both those numbers online in Tecumseh parts lists and can conclude what is correct with parts numbers what the parts list show as there or not there, and cross refencing part numbers etc.. its doubtful that someone put that early HS50 tag on it though after the fact and there are a few key things showing that contradict a 1978 Build date like the snowblower shroud/#'s would have and things that do coincide with it always being a Slanted application HS50 from the factory meaning recreational use. So then why did the shroud get replaced? First thing I would looks at is what lies beneath. If they pulled off that ghetto ass repair job on the flange, what they hell did they do to the flywheel, crankshaft snout, etc.. get that thing to run and the timing is off from a swap out or from replacing damaged or robbed parts, and incorrectly installed flywheel and it will throw the key or worse.
In your close up photo its pretty clear to see the exhaust leak stain due to the header flange being for a an HS40 and not the HS50 so The ports are different and in the earlier days they had specific matched ports (better) but in later years they went to a flange that kinda fits all to make the seal, but didn't match the port on either really well.
one other note, If that is masking tape or paper plugging up the breather (probably from repainting), you may want to pull that out before it takes the seals etc. out when you get it running!!!! Good luck with it!
In your close up photo its pretty clear to see the exhaust leak stain due to the header flange being for a an HS40 and not the HS50 so The ports are different and in the earlier days they had specific matched ports (better) but in later years they went to a flange that kinda fits all to make the seal, but didn't match the port on either really well.
one other note, If that is masking tape or paper plugging up the breather (probably from repainting), you may want to pull that out before it takes the seals etc. out when you get it running!!!! Good luck with it!
You might want to buy or make one of these and replace the one on your exhaust pipe.
https://www.ebay.com/itm/1660395507...486&ssuid=&var=&widget_ver=artemis&media=COPY
https://www.ebay.com/itm/1660395507...486&ssuid=&var=&widget_ver=artemis&media=COPY
Thanks Markus, f4radar and sparkwizard. I worked on it today and put the belt on so I could test drive it. The idle is hard to dial in, I had to have the side idle mixture at 2 turn out exactly to idle. If it is 1/8 of a turn from the 2 turns out it would die out and if I increase the idle a turn or 2 it will die out also. As far as the test drive it ran good in the yard, good power and the engine pulls good. Once in a while it would die out at idle. Seems to restart easy with the throttle wide open. Maybe this carb it not too good, the first carb came with the MiniBike. The first replacement carb is on the MiniBike and I still have one coming that I ordered. I checked the bolts on the exhaust and they are tight. I will remove the exhaust off the bike for further inspection at the block this weekend. The # on the small tag on the side of the engine is HS50-67028A and the bottom # is 3271B I hope this will help determine a little more about this engine. I was told from the seller this engine is from another Rupp could this be true? The engine has a lighting coil and it works but headlight and tail light are dim at idle but are bright above idle. Thanks again guys for the great advice and help, I really appreciate it.
I do not care for Sea Foam and if you watched the video it shows that Sea Foam did not stop the jelling and rust in the float bowl. I have had better luck with the Carb and Injector Cleaner. It is not a stabilizer but I like how it keeps the carbs cleaner during storage and it clean as the engine runs too.
Thanks everyone, I will check the manifold with a straight edge this weekend to see if it is warped. The manifold gasket that came with this engine is paper thin, is that supposed to be like that? I ordered some new manifold gasket but they didn’t arrive yet. Thanks Markus for all the research on the engine I am sure glad it is a Recreational /lighted/slanted engine. My next question is should I be worried about that over size bolt holding the manifold to the engine? Can this be professionally fix by a machine shop? I know this is an engine site but I have a frozen front fork suspension with no travel at all problem. What category should I post this issue in. Also thanks to you guys for all the help, I will keep you informed.