H25 will not run off idle.

[cruhr1]

I'm trying to get the H25 on my Rupp Chopper running before I proceed with my build and not matter what I try it will not run off idle. It will sit there and idle all day long but the second you give it any throttle it start to pop and sputter like it's flooding and will not come out of it. If I let off the throttle it goes back to idling just fine.

Here is what I have checked so far. I have checked and verified the timing and points gap, I've tried two different carbs, one known good and the other is brand new, no difference in the way it runs and I've tried different carb adjustments. New intake and carb gaskets and the plug is new. To me it seems to be an ignition problem. Do I have a bad/weak coil/condensor? Or what else could it be? The engine is clean and looks great inside. This one is driving me crazy! Thanks, Chad

 

[OND]

cruhr, did you try a new spark plug yet, start with the easy stuff first. jmo

 

[Dr. Shop Teacher]

I'm trying to get the H25 on my Rupp Chopper running before I proceed with my build and not matter what I try it will not run off idle. It will sit there and idle all day long but the second you give it any throttle it start to pop and sputter like it's flooding and will not come out of it. If I let off the throttle it goes back to idling just fine.

Here is what I have checked so far. I have checked and verified the timing and points gap, I've tried two different carbs, one known good and the other is brand new, no difference in the way it runs and I've tried different carb adjustments. New intake and carb gaskets and the plug is new. To me it seems to be an ignition problem. Do I have a bad/weak coil/condensor? Or what else could it be? The engine is clean and looks great inside. This one is driving me crazy! Thanks, Chad

Had the same problem...For some reason, mine would not go without an air cleaner installed. Solved the flooding problem and I could adjust the mixture to get it running smoothly. Try this before dropping cash on a coil/condensor--though I've gotten in the habit of putting new coils on all my engines.

 

[cruhr1]

cruhr, did you try a new spark plug yet, start with the easy stuff first. jmo

Plug is new as stated in the original post

 

[Rupp 72]

I don't see how it would be an electrical issue if it runs when it idles. I'd imagine you need to tune the main jet on the carb in some to not flood, lean it out a bit. See if that does anything for ya

 

[cruhr1]

Had the same problem...For some reason, mine would not go without an air cleaner installed. Solved the flooding problem and I could adjust the mixture to get it running smoothly. Try this before dropping cash on a coil/condensor--though I've gotten in the habit of putting new coils on all my engines.

I had the air cleaner on it with a new filter element.

 

[cruhr1]

I don't see how it would be an electrical issue if it runs when it idles. I'd imagine you need to tune the main jet on the carb in some to not flood, lean it out a bit. See if that does anything for ya

Believe me I've done this many times with both carbs. It doesn't help. I'm not saying it's flooding for sure, it's just how I'm describing the way it acts.

 

[capguncowboy]

You said it's both carbs. Do you have the air mixture screw adjusted properly?

I wouldn't eliminate electrical just yet -- unless you've already replaced the condenser and coil

 

[OND]

Does it have a high speed jet adjustment on the bottom of the carb ? Will It go past Idle if the choke is on a little ?

 

[cruhr1]

You said it's both carbs. Do you have the air mixture screw adjusted properly?

I wouldn't eliminate electrical just yet -- unless you've already replaced the condenser and coil

I have not changed the condensor/ coil. Yes it's both carbs. I took a carb of an h30 that runs like top and the same result.

 

[cruhr1]

Does it have a high speed jet adjustment on the bottom of the carb ? Will It go past Idle if the choke is on a little ?

Nope. I tried half choke, same thing. If I hold the throttle open it will just sit there and pop...pop....pop with about a one second pause in between each pop. Let off and idles fine.

 

[OND]

Sounds like a loss of fire to me...that's why I said bad plug .

 

[cruhr1]

Main needle is out 1 1/2 turns, low speed needle is out 5/8 turn. I've tried leaning and richening the main needle and I end up back at 1 1/2 turns.

 

[cruhr1]

Sounds like a loss of fire to me...that's why I said bad plug .

I think it has to be weak or intermittent spark.

 

[capguncowboy]

Sounds like a loss of fire to me...that's why I said bad plug .

Could also be a short somewhere. Check your wires for a crack or cut. If they ground, it would sputter or shut off

 

[Dr. Shop Teacher]

I think it has to be weak or intermittent spark.

Well, you've done all of the stuff all of us do first...so time to get a coil and condenser. Points were in good shape and no wear? Ground wire not loose?

 

[OND]

Could also be a short somewhere. Check your wires for a crack or cut. If they ground, it would sputter or shut off

Yea I think you ran in to that problem, didn't you Andrew ?

 

[cruhr1]

Well, you've done all of the stuff all of us do first...so time to get a coil and condenser. Points were in good shape and no wear?

Points looked good. If the coil/condensor the same as an h30? I have one of those laying around. I could rob it from that engine and check if it fixed the problem.

 

[OND]

Points looked good. If the coil/condensor the same as an h30? I have one of those laying around. I could rob it from that engine and check if it fixed the problem.

^^^^^^^^^^^^^^^^^:thumbsup:.........

Keep us updated..please ?

 

[1971_MB1A]

File very well and re-gap points. I've had and seen where even minor pitting on them will cause that problem. Is this an engine that ran well for you before,or is it new to you with an unknown history ?