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MTBF

MTBF

Well-Known Member
Messages
58
Location
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Ok, I decided to post this like the old fashioned street hustle. Pick your preferred item for a .32 Full Mod Reed Motor from OBR.

Not all items are correct for this use :)

spacers.JPG
 
I won't thumbs up anyone for a bit, but I am really appreciate all of your input. But if anyone picks the Vertigo Hex screw or bottle cap, I will personally request Dougstar make your life a living Hell.

Seriously, I'm posting this as a learning lesson. One I just learned.
 
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AnubisBC said:
None of the above. All OBR Full Mod Reed Case motors have a bespoke machined delrin isolator between the reed assembly and the carb:

View attachment 60267
Now if you want to talk piston port OBR engines, it will likely be number 3 with an isolator, much like the one for the Reed Case: View attachment 60268
Click to expand...

This right here.Top pic. Although I do vote for the bottle cap because I'm hoping it was attached to a good beer. If it wasn't then the button head hex screw.
 
The bottle cap was attached to a Long Bow Hard Cider. And if you haven't tried it, I strongly suggest you do.

AnubisBC, congratulations. Much respect.

My question is this: Is the delrin insulator provided by OBR prone to warping, like the the factory composite ones? It seems like the quality is far better. It's even been machined.

I've got an engine that gets weird when warmed up. I'm trying to rule out the insulator, and considering it's an issue with a carb that may have gotten too much dust through the hidden vent hole or the throttle shaft bushing. Big clue is that when warm the priming bulb will NOT draw fuel from the tank. The engine will draw the residual fuel available in the carb and drain the priming bulb. But the carb won't draw more fuel from the tank.
 
MTBF said:
The bottle cap was attached to a Long Bow Hard Cider. And if you haven't tried it, I strongly suggest you do.

AnubisBC, congratulations. Much respect.

My question is this: Is the delrin insulator provided by OBR prone to warping, like the the factory composite ones? It seems like the quality is far better. It's even been machined.

I've got an engine that gets weird when warmed up. I'm trying to rule out the insulator, and considering it's an issue with a carb that may have gotten too much dust through the hidden vent hole or the throttle shaft bushing. Big clue is that when warm the priming bulb will NOT draw fuel from the tank. The engine will draw the residual fuel available in the carb and drain the priming bulb. But the carb won't draw more fuel from the tank.
Click to expand...
?I'm sitting back and waiting on this one also cause my L5B has similar issues.
 
dougstar said:
Id take off the insulators checke to see if its warped ? iv sanded one down before to get it flat?? i have a similar situation with my losi ? im goona put new gasket check the insulator and slap on a new carb?
Click to expand...
Tried checking the insulator with a straight edge. Fine when cold. Engine runs ok when cold. If the defect happens when hot, well then I have to try gauging the spacer after it is heat soaked. Have a new carb, I think that is the problem. Dust/dirt/grit contamination. I haven't done a post mordem on the old one yet, but it has VERY little run time on it.
 
First off all your primer bulb does is prime the carb, other then that its worthless. If your not getting fuel there are really only a few things it can be. Bad impulse signal from engine (this includes the intake manifold, this would also be a running issue. Not a static issue) vaccum in the fuel tank, (tank vent issue again running issue not static) bad fuel lines/ pinched fuel lines, dirty fuel filter, and last but not least bad pump side of the carb. As these are return style carbs it should be tough to get them to vapor lock as the fuel is also used as a coolant being passed through the carb. But its not unheard of either.
Any shaft play would lead to a lean run condition as the throttle shaft is after the venturi. This should be immediately noticable in performance of the engine or lack there of. Low and high end tuning will be near impossible to keep set. Choke shaft play wont affect the engine running, unless it has allowed tons of debris past it. This would be seen as a low compression issue and not a lean run issue. Also there would be a sand blasted or dull color on the intake side of the piston. From the grit ingestion. Think I covered all the bases.
 
Seandonato73 said:
First off all your primer bulb does is prime the carb, other then that its worthless. If your not getting fuel there are really only a few things it can be. Bad impulse signal from engine (this includes the intake manifold, this would also be a running issue. Not a static issue) vaccum in the fuel tank, (tank vent issue again running issue not static) bad fuel lines/ pinched fuel lines, dirty fuel filter, and last but not least bad pump side of the carb. As these are return style carbs it should be tough to get them to vapor lock as the fuel is also used as a coolant being passed through the carb. But its not unheard of either.
Any shaft play would lead to a lean run condition as the throttle shaft is after the venturi. This should be immediately noticable in performance of the engine or lack there of. Low and high end tuning will be near impossible to keep set. Choke shaft play wont affect the engine running, unless it has allowed tons of debris past it. This would be seen as a low compression issue and not a lean run issue. Also there would be a sand blasted or dull color on the intake side of the piston. From the grit ingestion. Think I covered all the bases.
Click to expand...
Thanks, Sean. I'll be using this to narrow it down. From what I can tell, the engine internals are pretty cherry. I know the primer bulb doesn't do anything for supplying fuel while the engine is running, but the fact it wouldn't draw fuel when pushed was giving me the idea there was some sort of vacuum leak. At least at temperature. I was using it to try to troubleshoot a possible vacuum leak in the system/ carb. I'm pretty sure it is sucking in air from a gap somewhere that opens up when hot, and that's why the primer bulb wouldn't pull fuel.

I learned a bit from your post, so thanks again.
 
Ok, now this narrows things down a good bit. This issue has nothing to do with the intake. This is a general supply issue. You can pressure test the carb for leaks. The fuel pump side would be the most likely side for these issues, although you should see a leak or weep from the gaskets. Around the cover plates. Pulling air in would be limited to the fuel lines, and the inlet fitting. I would doubt a vent issue unless it's under severe vacuum would cause a primer bulb not to fill. There is also a check valve under the primer that could be an issue, but is unlikely. Trying to think of what else, any quick disconnect fittings? Or inline filers? They would also be a place to look.
 
Seandonato73 said:
Ok, now this narrows things down a good bit. This issue has nothing to do with the intake. This is a general supply issue. You can pressure test the carb for leaks. The fuel pump side would be the most likely side for these issues, although you should see a leak or weep from the gaskets. Around the cover plates. Pulling air in would be limited to the fuel lines, and the inlet fitting. I would doubt a vent issue unless it's under severe vacuum would cause a primer bulb not to fill. There is also a check valve under the primer that could be an issue, but is unlikely. Trying to think of what else, any quick disconnect fittings? Or inline filers? They would also be a place to look.
Click to expand...
Everything is pretty new. Very low use. No quick disconnect connections. Temperature is the issue, something is creating a vacuum leak under heat and stress. It goes lean. Think it is an internal issue with the carbs? Highly sensitive to contamination? Float?

I'm putting in a new carb, anyways. If this goes away, we'll know where the problem sits. It's a 990 with the bearing insert, plus the Chase filter at the open port on the backside.

CrucialRC saying he is having a similar problem, is not inspiring my confidence.
 
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21bangbang said:
Huh, never considered sanding them. Always just replaced.
Click to expand...
Same here. I come from the automotive and before that aerospace (cars, aircraft) worlds- and certain pieces are just made to be disposable. They show wear and toss them. That being said, hats off to Doug for making that work. I see Doug has a full mod OBR, but not a Reed motor....
 
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