HS50, lack of power, lowish RPMs, other issues...?

J

JayBell

New Member
#1
#1
ok, followed Joshs directions on the carb, got some help cleaning and setting the points, but the engine exhibits some lousy power probs.

Bike is a 1969 Rupp Roadster
Engine Tec H50

i just put a new Max Torque clutch on it, and it barely engages... mostly, even at full wide open throttle, it hisses cuz its not engaging, and the bike barely will move. clutch is VERY hot cuz its not engaging fully... hope i didn't burn it out

even holding th bike with m off it, at WOT, the rear tire wont turn, even on grass....the clucth just isn't engaging due to RPMs I think.

lowish RPMs, doesn't seem to have power, and i noticed, at no matter what main setting, the carb is spitting gas back OUT the intake at WOT

so, carb shot? engine issue? tuning issue? all the above?

engine SEEMs to run strong, but I feel the RPMs is not enough to engage the clutch correctly, surely a H50 does better than that?

bout ready to toss the h50 and go get a 6.5 clone!

any ideas? this is depressing, i thought the engine was fine, but the clutch was shot... apparently, the NEW clutch is just like the old one.
thanks!
 
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J

jimh

#3
#3
Could be leaking around the throttle shaft too. If it isn't smoking and knocking, there's no need to toss it. It's most likely something small, that you haven't found yet.
 
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J

JayBell

New Member
#4
#4
carb and intake are sealed as far as I can tell, leaks were one of the first things i tried to look for, used propane and carb cleaner to test

if I choke it even a little at warm running idle, it dies quick.

unless something is still gunked or blocked IN the carb, I cant see what it would be...other than some engine prob.

it just doesn;t get high RPMs to my ears.

of course.... I dotn have a tach, so, cant be sure.

but you can imagine how disappointed I was to put the new clutch on, and have it mostly just Hisssssssssssssssss and get hot.

btw, the external bits of the governor are gone, but the internal bits are still there.. could that do something?
 
joshhoward

joshhoward

New Member
#6
#6
I just noticed your in PA. The couple times i went to Windber, PA the elevation was higher. I had to mess with the crbs on all my minibikes. I remember going around 1 1/2 on the low speed, and 2 1/2 on the high. It was odd, but i got them all to run good! Alot of people where having that problem. I dont know how many carbs i had to tune those 2 trips. LOL Put it up on a milk crate and mess with it. It really sounds like its a carb problem.
 
J

JayBell

New Member
#7
#7
joshhoward said:
Can you take a video of it running?
Click to expand...
yeah, I can do that tomorrow most likely ... if i can get the cam to work.

i'm only a little above sea level, so its not an altitude thing:D

carb can probably use a full rebuild... teh throttle shaft is a little loose, but it doesn't really lose anything there.

besides, now that I pulled it apart and really made sure everything was clean, I gotta tune it up again.


again, thanks everybody for all the help... i just feel this thing should be putting out more.
 
J

jimh

#8
#8
It should lock up the clutch with no problem. The H50s really run good. Even a H30 will pull good enough to lock up the clutch on flatter ground with an adult rider. A leak around the throttle shaft will have a bigger effect than you could imagine. When you set the float, it should cut off the fuel when the top of the float is parallel to the bottom of the carb body. Once you have it back together you can check for air leaks with starter fluid or WD40. Shoot a shot around suspect areas while idling. Any missing or surging when you do this will indicate a big enough leak to cause problems.
 
J

JayBell

New Member
#9
#9
I've ordered a carb rebuild kit, intake and manifold gaskets.

I'll rebuild the fuel IN before I do anything else.

I see the throttle shaft is more loose than I thought... that could be it.

who knows. I'll keep folks updated.
 
Motra

Motra

Active Member
#10
#10
As jimh said, a loose throttle shaft will definately cause running problems. Also, rather than replacing the engine, taking it to a local profesional couldn't hurt. It might not be as much of a problem as you think.
 
cncsparky

cncsparky

New Member
#11
#11
jimh said:
A leak around the throttle shaft will have a bigger effect than you could imagine.
Click to expand...
Is there a good way of fixing that? I have a rebuilt carb that I couldn't quite get running right, noticed sloppiness in the throttle shaft. Ended up buying a new carb.

Tom.
 
J

JayBell

New Member
#12
#12
well, just finished rebuilding the crb, gonna wait a bit for the gasket goop to cure, then fire it up, see what goes.

throttle shaft has a tiny bit of slop... hopefully I wont need a carb.
 
J

JayBell

New Member
#13
#13
in the long series of disappointments that is my life, its not unexpected that rebuilding the carb effectively changed nothing.

started it, tuned it so it ran strong, and with me OFF the bike, just holding the bars, at WOT the bike needs almost no force to hold it back.... as in with the seat clamped between my knees, the bike wont get out of its own way, spin the tire on wet grass, no power.

I rechecked for leaks with propane, and such, nothing.

So, short of taking it to an engine shop...any suggestions? I'm getting very frustrated here.

thanks again for all the help... but nothing is working to increase the performance

also, if nothing else works, any recommendations for a decent shop in SE Pa?
 
J

JayBell

New Member
#16
#16
GTO said:
Are you sure the clutch is attached to the shaft correctly?
Click to expand...
LOL! it only goes on one way... keyed, and properly set screwed.... I think.

not even *I* can mess that up, unless its possible to put it on backwards.... and its a one way type clutch.

its on as the other, presumably bad clutch was, with the sprocket on the inside facing the motor.

thats the only way the chain will match up with teh sprocket on the jackshaft.... near as i can tell.

this is what the clutch looked like as i got it.. dont EVEN tell me its somehow backwards:D


as for video, I'll try and get one tomorrow.. and yeah, the shaft is really long.. dunno about that.
 
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kruger

kruger

Member
#17
#17
you said something about gasket goop? when reassembling the carb take wire that is small enough to fit in the holes and jets and stick it through every whole you see in the carb especially the jet/hole in the tube coming from the float bowl, open the throttle and/or choke so you can see the wire when you are pushing it up from the bottom of the tube, it should go through easy.after that make sure you dont get any gasket goop in any hole better yet clean every thing and dont use the goop at all.h50 have plenty of power even with h30 carbs ,idea try carb of another engine that run well on this engine.
 
J

JayBell

New Member
#18
#18
kruger said:
you said something about gasket goop? when reassembling the carb take wire that is small enough to fit in the holes and jets and stick it through every whole you see in the carb especially the jet/hole in the tube coming from the float bowl, open the throttle and/or choke so you can see the wire when you are pushing it up from the bottom of the tube, it should go through easy.after that make sure you dont get any gasket goop in any hole better yet clean every thing and dont use the goop at all.h50 have plenty of power even with h30 carbs ,idea try carb of another engine that run well on this engine.
Click to expand...

I used Permatex Ultra Copper on the intake manifold gasket, and the carb gasket, to make sure I had no leaks...not on the carb itself.

carbs were dipped, and blown out with compressed air, and ALL ports and holes are free and clear of any debris or buildup.

carb was rebuilt using a real Tecumseh carb kit, I replaced everything that came in the package, including the welch plugs, idle circuit needle, floate needle, gaskets, orings, main jet needle and nut, everything!


I dont have another carb, unfortunately.
thanks for the suggestions....video coming managed to make the wheel spin on mud... OH joy!
 
J

jimh

#19
#19
It looks like you need to switch your jackshaft sprockets. That's way too high geared from what I see in the pic. Switch them and you should do wheelies. That would explain the no power. With the taller tires and those gears, the clutch will never lock up.
 
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J

JayBell

New Member
#20
#20
jimh said:
It looks like you need to switch your jackshaft sprockets. That's way too high geared from what I see in the pic. Switch them and you should do wheelies.
Click to expand...

hmm... switch the sprocket that feeds the rear wheel chain?

Source for new 5/8" jackshaft shaft 35 chain sprockets, and recommended sizes?

these are pretty much exactly what came on it...I replaced the hammered jackshaft with one from Northern tool, I think, and the sprockets were like 1 tooth off larger than what was on it.

hmm.. figures it'd be something like that.


the northern tool jackshaft came with a has 13 and 18-tooth sprocket. 13 from the engine side, and 18 on the chain side.
Rear is stock rupp, which MAY be a 72 tooth... not sure
 
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