Just cranked an .21 engine!

[Greyhound]

I just cracked an .21 engine(Old Brat Engine). It had a leak some where around the headsink connect to body and been running at 280up for a few tanks. I think I couldn't bring the heat down cuased by the leak. Does this sound right or something else cuased this?

Further question on Tuning, if I set all needles at factory set, I would not get the temp at 200f (no matter how long I run, bash), so I lean the HSN little by little until I get around 210f. Ran just fine the whole tank (LSN seems abit too rich, but I can't reach it easy enough so I just left it as it was). Then right after an empty tank I just refueled, started it up and ran again. It ran even better right from the start but after 2 minute run I checked the temp, it got to 285f. There were only 8-9 tanks thru this engine (OS.21). I think I had break-in well enough. What can cuase this? Thanks all!!

 

[vbgagnon]

Sounds like an air leak to me. Check all fuel lines, fuel tank, and seal the engine up. Backplate and carb then try it again.

 

[Greyhound]

I would say air leak too, but engine is only 8-9 tanks thru. So, I didn't think it would be. Would it be so easy to get air leak?? Can I put locktight in all screws that attached to the engines (Heatsink, backplate, etc.)??? Thank you.

 

[vbgagnon]

Most engines should be sealed before any fuel goes through it. All my engines get the rtv treatment before they see fuel. Don't put locktite because if you strip a screw you won't be able to get it out.

 

[Greyhound]

vbgagnon, What rtv treatment? Is is the same as after run oil? or I can use the after run oil for fresh engine too. Thanks vbgagnon!

 

[greenwing7]

RTV is silicone sealant DO NOT PUT THIS INTO your engine, it seals, the carb and the back plate from air leaks

 

[Tweak]

RTV acts kind of like a gasket, wherin it is pliable and wet when applied, but forms a airtight heat resistant barrier between the surfaces applied. I used to use the blue stuff to seal up the gasket on my Jeep.

 

[vbgagnon]

Get yourself some high temp rtv. Just make sure you don't get any inside of the engine. I put it on the base of the carb (where the carb seals to the block) and on the base of the backplate (where the backplate seals to the block) That should take care of your airleaks. If its not that then the leak is in the fuel lines or the fuel tank.

 

[Greyhound]

vbgagnon, would you put rtv on the gasket of the heatsink head?? Becuase the engine I cracked had a leak from there. Thanks a bunch!