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Eleck_Rider

Advice request for Irvine 20 glow engine (new carb needed)

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Hello everybody,

I have been spending a lot of time recently 'chasing the tune' of the carb in my beloved Mardave Marauder, and I'm not talking about squeezing the optimum performance out of it either; I just want the **** thing to idle reliably.

After trying different fuel and plugs I tried a Just Engines aero carb which improved things considerably, but it doesn't sit comfortably in a buggy. Can anybody recommend a modern equivalent? The Irvine Airstream (original carb) has a 13mm stub and rotary throttle. I'm willing to try anything which matches these criteria. Thanks!

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How is the jet?? Can you blow air through it?? Is the needle valve straight??

 Are there any air leaks?? Play between the throttle body and the crankcase attachment?? Might be worth running a light bead of silicon sealant around the base of the carb and attatchment screws. 

As far as i know, the irvine 20 carby on the aeroplane and marine versions is the same as the car-buggy version.

The parts were still available last time i checked.

I have not had much luck mixing and matching carbys.

Mardave and Irvine is like strawberries and cream. 

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Hey thanks for the suggestions guys.

Ferris, I was thinking about an OS carb because of their reputation for quality, but it was tricky finding out which ones had a 13mm stub. The FSR one wouldn't fit in the Marauder chassis because the main needle assembly would hit the fuel tank.

Oz, I agree with everything you write, and since my first post I have done some more tests.

In short, I think it was an air leak. I had used silicon previously to seal the carb, and I reckon the intense vibration which the Irvine creates shook the carb loose and broke the seal. The o-ring was past it's best, so I replaced that and used plumber's tape around the stub. The improvement is profound.

I have yet to give the Marauder a good run yet, but I'm happier now.

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Air leaks can be diagnosed with a can of WD40... spray around all seams whilst engine is running, where it rises pitch it's sucking in air there.

i use Permatex Copper RTV on little engines

not just intake, don't forget exhaust needs to be sealed to to create decent backpressure; also no pressure leaks from the tank & fuel lines. Renew tubing just to be sure

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