HELP! OS won't start when hot

[hobebru]

Hey guys, need your help....I have an OS Hyper CV-.12 in my RC10-GT. It starts and runs fine when its cold...After a tankful of fuel (updated RC10-GT Team Associated tank), it is very hard to start (I'm using a starter box). Head temp is 230F; It takes a long while to start it and I have to "goose the throttle on my radio and prime it several times to get it started. Once it starts and I rev it a few times, it idles fine, and runs fine. I'm using SIG fuel, 15% Nitro, HS needle is 1 3/4 and low speed needle is flush with it's housing. As I said once this engine starts, hot or cold , it idles well and runs strong with NO hesitation, if I change needle settings it definitely affects performance on the negative side. What do you think is causing the hard starting when it is hot? Thank you. (possibly a problem with the SIG fuel due to its high oil content?)

 

[jcchase]

How much have you run this engine? If you have put a few gallons through or have overheated it a couple times the piston might not be tight in the top of the sleeve. Take your piston and sleeve out of your engine and see how hard it is to push the piston up through the sleeve. If it gives alot of resistance the sleeve is probably fine. So that means either a air leak or try replacing the glow plug.

jcchase

 

[emu67]

I think it's because your carb is heating up. So, when you turn it off, the fuel get vaporized as it hits the carb and puts a pack pressure in the fuel line. So, no more fuel at the carb to start it. When we bump it and goose the throttle, you pressurize the tank, fight the back pressure and allow the fuel to reach the carb. Once the engine is started, the tank is getting the pressure it needs to push the fuel to the carb despite the back pressure being generated from your hot carb.

I don't think you have a problem at all. Maybe you ought to keep the engine running,fuel her up and just keep running til you want to rest. Just temp the engine to make sure she's not heating up on you.

This happens to my hyper and mayhem when its about 100 F in Las Vegas. Both engines run fine, about 240F. I have to de-tune a little when it's this hot so they both don't over heat. Carb bodies get hot, though.

That's my $0.02.

 

[hobebru]

Thanks guys, I'll do both...check piston/sleeve clearance and I'll try to richen up some...the problem occurred yesterday here in KC, MO. (85Fand very humid)) and I was running partially on grass and packed down gravel. Grass always seem to heat the engine up much more than any other surface. I'd love to just keep it running but sometimes a couple of end over end 360's will kill the engine. It's amazing how well the truck (RC10-GT) survives these bashings.

 

[redhatman]

Hey, I have an rc10gt also, and I bought mine used from lhs. Bad idea, it had so many things that I had to buy for it. I now have everything like new, except I think the engine has a big compression loss, but the problem is. Is that the motor heatsink head screws are stripped so I cannot get the head off. So I cannot get the piston/sleeve out for a new one or repinching, so pretty much I have to buy a whole new motor. I went to the lhs that sold it to me and they are going to look at it. They said that if it is something besides out of tune, I will pay for it. Besides the fact that it will not run for more than 30 secs since I bought it.
-Pat (redhatman)

 

[racin_38]

if your very careful you can take a drill and drill off the heads of the allen heads and whats left of the screws should pop right off and allow you to remove the head without damaging it ,i had 2 strip out on me and i did just that ,but you have to be very careful is all

 

[redhatman]

Hey Racin_38, So I dont completely jack his thread, I have started a new one here. https://www.rcnitrotalk.com/forum/showthread.php?p=321773#post321773 Please help. Thanks
-Pat (redhatman)

 

[beason]

maby try just putting your finger over the stinger for a second when you try to restart so it pushes the fuel into the motor faster.. also the low nitro content of your fuel may make the motor run hotter plus the nitro will evaporate faster leaving just oil and causeing it to not want to start..

 

[racin_38]

just curious,where exactly do you have your fuel line running ,
it is close to your header then it is more or less vaporlocking on ya ,the fuel gets that hot that it boils and therfore doesn't move just stays there till it cools of then re starts
even thow your only running 230 the header temps will be close to 400 plus ,
i try to reroute mine away from the header if at all possible if not then i use the traxxas yellow fuel tubing protectors

 

[CorradoPsi]

try running 20-25% nitro fuel instead of 15%. it will be easier to start and tune, and will run cooler too. try trinity monster horsepower brand if you can get it.

 

[Lessen]

I've run into the same thing with my RG. I just let it cool for a few minutes then "zoom" fires right back up again.

 

[slothy]

repinch da bitch

 

[xdamxincx]

sounds like ur too lean on the bottom...