Alternate carb for a LRP 28 S3

[Littlemotor]

Most any nitro/methanol/petroleum resistant anaerobic sealant should suffice-this stuff is tried & true for nitro engine carbs specifically. I used it for a lonnnnng time on my Picco carbs 20+ years back with excellent results..

Also Absolute Hobbyz is tremendous. I’ve been dealing with Joe for years now..

https://www.absolutehobbyz.com/lucky-7rc-engine-sealant.html

 

[Littlemotor]

Obvious question though-you ARE lubricating the O-ring with a proper O-ring grease; yes?

I’m willing to bet that the sharp edge of the freshly machined barrel is causing the issue since it was just in the lathe. You could always chuck it back up, and bevel the sharp corners-IF that’s the culprit..

 

[Steamdonkey]

Obvious question though-you ARE lubricating the O-ring with a proper O-ring grease; yes?

I’m willing to bet that the sharp edge of the freshly machined barrel is causing the issue since it was just in the lathe. You could always chuck it back up, and bevel the sharp corners-IF that’s the culprit..

Well... Yes and no. I am lubricating the o-ring but with after run oil, not grease. I'll give the O-ring groove a slight bevel and try some grease. Any specific type of grease? I have a few different types but I don't think any of them are identified as O-ring grease.

 

[Littlemotor]

Well... Yes and no. I am lubricating the o-ring but with after run oil, not grease. I'll give the O-ring groove a slight bevel and try some grease. Any specific type of grease? I have a few different types but I don't think any of them are identified as O-ring grease.

Yeah-ARO won’t cut it for that.

Any grease that’s OK for the composition of the O-ring. Associated Green Slime is one (though it starts a LOT of arguments), ProTek RC offers their “Premium Blue” grease for them, also Maxima SG920 is what I’ve moved to recently (based on cost per volume, as well as performance, compared to “RC specific” stuff)..

The beveled edges & proper lubricant will help the tearing, so try that first. You won’t be able to use grease AND anaerobic sealant for obvious reasons..

If the grease and beveled edges don’t remedy the tearing, I’d instead run one over the barrel, up at the base of the carb body. Simply press down on the Venturi as you lock it in place with the carburetor locking pin.

 

[Steamdonkey]

Does anyone have a rough idea for needle settings on this Hobao carb? I've got the low speed needle down to 1/2 turn and it still belches smoke and chokes horribly when getting back on the throttle. It won't idle more than a few seconds. Something's clearly wrong. Maybe it's me.

 

[Littlemotor]

Does anyone have a rough idea for needle settings on this Hobao carb? I've got the low speed needle down to 1/2 turn and it still belches smoke and chokes horribly when getting back on the throttle. It won't idle more than a few seconds. Something's clearly wrong. Maybe it's me.

Needle settings are 10000% dependent on your piston to head clearance, fuel, plug, load, and weather conditions. Never listen to anyone that says, “here’s your factory settings-that should get you close!”.. The ONLY factory setting that matters to tune correctly is your idle gap. Know what the carb/engine manufacturer designed it to be, set it, and literally forget it.

JQ will show you how to tune it on the box with either scenario-knowing it vs NOT knowing it. Either way will end up with the idle stop screw in the same location. SO many people band-aid around their tune with the idle adjustment, and that’s how you end up with a motor that runs like shiit, and has a “dual stage” idle. He has SEVERAL nitro tuning video’s, and they’re ALL invaluable. Feel free to go through his channel for all of them.

 

[Steamdonkey]

The only problem is I'm well outside the realm of JQ's tuning videos at the moment. Without fundamental baseline settings, it's a trick just to have a remotely functional carburetor. Early testing revealed the low end was super rich and I ended up fully closing the low speed needle only to find the low end was still impossibly rich. Sounds crazy, but that's what happened. It wasn't until I became desperate enough to break the 11th commandment (by adjusting the fuel control valve / midrange), that I was able to get control of the low speed mixture and get this thing to act like a carburetor. I'm sure it needs more work, but on the box it idles more than 2 seconds and has nice throttle response which is a huge improvement. Having some kind of starting point would have saved me a few headaches.