Checking the carb

[kickasskev]

Hi people I have a hyper 8 problem, I have been through all the tests of pipes and tank, air leaks on engine etc, but can't get fuel to my engine unless I blow through the exhaust line while trying to fire it up with full throttle on the transmitter then it floods.

Can anyone tell me what ways I can check the carb to see if its in full working order, I have already had it off and apart cleaned it all etc it does seem in good condition.


I have adjusted all my tunings back to stock, and tried adjusting slightly.

There is no airlock in the engine or pipes

Glow plug and start are fine

Air filter is clean


Even when I pour fuel down the carb it wont start, it will if i put fuel direct in the top where the piston is, but obviously only fires up for a split second.

I had the engine off the other day to give that a good clean inside and out, and check for compression and it seemed fine.

I'm STUMPED

Any help appreciated

Cheers Kev

 

[scottc]

will the engine start and run, is the idle set to about 1mm opening on the carb, I've used a AE primer bulb on many of my nitros, kinda sounds like the carb is closed and dose not have a idle point set

 

[hamz9561]

Scott, the carb opening at idle should be about 1mm.

 

[kickasskev]

Scott, the carb opening at idle should be about 1mm.

yeah I thought that the carb was meant to open about 1mm but anyway, the car wont start, I have changed the roto start for pull start, and it seems to pull better, but there still isn't any fuel getting to the carb.

Had the carb off again and recleaned it all, then I tested it by blowing down the exhaust line while the fuel pipe was attached to the carb, but the carb wasn't on the car, I adjusted the idle so that fuel trickled out at approx 2mm opening then reattached it and still wouldn't start??????

I have ordered a new carb so will wait till that arrives, if it's not that then I am baffled

 

[w bill]

If its been sitting for some time you may have had some fuel that gooed up inside the spray bar or the other passages in the carb. Take out all adj screws and needle valve soak it for a couple hours in some fresh fuel then blow every opening out with compressed air.

 

[kickasskev]

If its been sitting for some time you may have had some fuel that gooed up inside the spray bar or the other passages in the carb. Take out all adj screws and needle valve soak it for a couple hours in some fresh fuel then blow every opening out with compressed air.

Hi I have had the whole of the carb apart and washed with every pin hole cleaned there are no blockages any where.

 

[w bill]

Hi I have had the whole of the carb apart and washed with every pin hole cleaned there are no blockages any where.

Then a new carb won't do you much good . The only other thing i could think of if the compression is so crapy that the engine is not producing enough vacuum to draw the fuel.Otherwise I'm out of suggestions.Good luck with it your missing something.:

 

[scottc]

my mistake on the 3mm carb opening. sorry

 

[Rolex]

Prime it by plugging the exhaust with your finger till the fuel reaches the carb. It should start in the idle position. You will only flood it out by giving it full throttle during the start.
Other than that, check your glow plug and ignitor and make sure you are getting a bright glow.

How far did you tear it down for the cleanup? If you had the piston and rod out, you might have reinstalled them backwards.

 

[kickasskev]

Then a new carb won't do you much good . The only other thing i could think of if the compression is so crapy that the engine is not producing enough vacuum to draw the fuel.Otherwise I'm out of suggestions.Good luck with it your missing something.:

Whats the best way to check for compression without taking the engine back off?

 

[bgbdwlf2500]

Whats the best way to check for compression without taking the engine back off?

take the glow plug out and spin it to top dead center. it should tighten up and be slightly hard to get past that point. it should be even harder to get past that point with the plug in it

 

[kickasskev]

take the glow plug out and spin it to top dead center. it should tighten up and be slightly hard to get past that point. it should be even harder to get past that point with the plug in it

Sorry to be a bit DIM but I dont understand what will tighten up? the piston pulls over easy without the glow plug in, tried that in my other car that runs fines and that pulls really easy?

 

[Jadethread]

The piston should be really tight at the top of the stroke. I gauge my compression by turning the flywheel by hand with the glow plug in it. A good engine should be pretty hard to turn over by hand. In fact on my savage 4.6 using my finger, I can barely get it to spin over. Really good compression on it. Same on my.25.