Engine won’t start! HELP!! Rovan 5sc

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Your engine seems to be one hell of a riddle. Do you have an air compressor, welder, and the ability to make block-off plates for the intake and exhaust ports? If yes to all of the above, then make block-off plates and some rubber gaskets. Take an old spark plug and destroy the porcelain so that you are left with the steel hex and threads. Weld a male pneumatic quick connector to the hex. Remove the flywheel and clutch, install the newly fabricated spark plug/air adapter, hook it to an air hose with the pressure set to around 90 - 110 psi. Dunk it in a bucket of water or spray soapy water at all the seals, base gasket, and crankcase gasket to find any possible air leaks.
Losi125 said:
Just buy a long block from ddm 169 you already spent to much on that motor plus the aggravation. ....
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Why didn't I think of that? Instead, I'm thinking of building a convoluted leak-down tester.
 
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Top Dead Center said:
Your engine seems to be one hell of a riddle. Do you have an air compressor, welder, and the ability to make block-off plates for the intake and exhaust ports? If yes to all of the above, then make block-off plates and some rubber gaskets. Take an old spark plug and destroy the porcelain so that you are left with the steel hex and threads. Weld a male pneumatic quick connector to the hex. Remove the flywheel and clutch, install the newly fabricated spark plug/air adapter, hook it to an air hose with the pressure set to around 90 - 110 psi. Dunk it in a bucket of water or spray soapy water at all the seals, base gasket, and crankcase gasket to find any possible air leaks.

Why didn't I think of that? Instead, I'm thinking of building a convoluted leak-down tester.
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Holy molly ? !
 
dougstar said:
Holy molly ? !
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LOL, you should see my toolbox at work. I have that set-up for every manufacturer and model of chainsaw, demo saw, weed eater, and compactor that my employer owns.

Sometimes it is hard for me to shut off the work mind set and switch over to RC. Nothing leaves my shop nonfunctional unless the cost of repairs is over 65% of replacement. In the scheme of things a lot of us have throw away engines compared to the cost of our rigs.
 
What got into the engine that made you rebuild it ???

I feel that you either left some debre inside the engine or your carb is bad.

I would suggest a new spark plug and new carb....

Is fuel even getting into the engine ?? You could have also flooded the engine from trying to start it ??
 
1Coopgt said:
You didn't by chance put one of the the carb gaskets on upside down did you or the isolator block? That would cover the little vacuum hole you need. Think you mentioned you had removed the carb.
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The carb has to be removed to rebuild the top end so yes I removed it. The gasket is installed correctly and I also removed the carb at one point and sprayed starting fluid into the cylinder and still could not a get a sputter.
 
Zach619 said:
Ok so I bought a rovan 5sc with the 36cc 2 stroke 2 months ago. It ran fine until about 2 weeks ago. I couldn’t get it to start but it sputtered. I swapped spark plugs and it started but did not want to stay running. Once I got it started I ran it full speed down the street to try to get it warmed up. Halfway down the street the engine died. Not sputtered and shut off but died entirely. Something got into the engine and scarred my piston and cylinder. So I bought a top end rebuild kit and put it on there. I now have compression and air. Now to the fire. I have a factory replacement spark plug. When I take it out of the head and ground it to the head while turning over the engine it sparks. I cannot however tell if it is firing at top dead center. I read that coils can go bad and still spark but the timing be off so I replaced it. The car still will not start. The flywheel is keyed so it can’t be off on the timing. Top end is fresh rebuild so I have compression. I figured maybe it’s my carb so I took it apart and cleaned it and reinstalled it to factory settings on the high and low. Still can’t get this to fire. I took the carb off and sprayed starting fluid into the intake slot in the engine while turning over the engine and couldn’t even get it to start like that. I can’t even get a sputter. Does anyone have any clue what I need to do to get this car running again. In theory there is absolutely no reason why it will not run. PLEASE HELP!!
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Does anyone have any other ideas... still haven’t gotten anything that can help me here!!!
 
crucialRC said:
Post some pics of your setup or a video would be even better. ? I think you have managed to stump the whole community. Maybe pics may help with the investigation. I still think its ignition related.
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It’s just a standard rovan 5sc. Nothing special or picture worthy. Being that it seems something is wrong and nobody has a clue I think my next step is to replace the whole engine instead of sinking more money into this one without a clue as to what is wrong. So does anyone have any suggestion as to what I should replace it with? I have heard there are some good aftermarket options. I want something that is going to bolt into place without modifying my car to make it fit. Just simple swap. Any suggestions?
 
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