gst 7.7 issue running hot any insite thanks

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jpgearhead

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hi i just got into the hobby have wanted a nitro rc since i was 12 . So now I'm 20 and thought hell ill give them a try. I bought a used cen gts 7.7 in great shape guy said it needed too be tuned as he had put a new carb on it witch he had. As i have the old one too. I turn wreches everyday for a living and can built any motor and tune any car so i thought well this will be a walk in the park for me err WRONG i was ;( when i got it home i coulded get it started for anything! Inlease it was set crazy rich and was still hard too ever start so took motor off checked for air leaks seen the front bearing was leakin bad. So put new one in and when i had the engine apart checked for pinch could push the piston out the top of sleave so made a tool in a lathe too repinched too new. put back togather and since i repiched it put it threw break in by idleing a tank let cool and idle a tank then let cool okay now for my issue when its cold and i first start it my needel setting are top end 4 turns out and bottom end 2 1/2 out from flush factory engine settings are 4 1/2 top an 1 turn out from flush bottom. if i set it too factory if it does start like that it idels crazy up down and sounds like its saying ill blow up if you dont adjust me!! so if i just got it out and start it up it passes pinch test with the setting i described 4half top and 2half bottom and runs strong as one can ask. With good smoke trail but after a lap or 2 around the house starts too do the crazy ideal thing so turn the low end needel out a turn idel drops too normal one lap and its acting crazy agian turn low speed out a turn again just too get the ideal back and by now its in temps are up around 320f witch is when i gave up. only air leak i can find now is front bearing a little but i just can't see getting a conseled bearing thats air tight with air prussure on it any ideals please!!! I also seen that the old carb that came with it the low speed needel. Out of it looks like he grounded it down as its about 2mm shorter. Then the new one and you can tell the point is not factory witch tells me this guy was having this issue and passed it on too me. :angry:
 
Your engine was worn and you tried to re-pinch the sleeve on your own? I hate to tell you this but you probably killed the engine. It is not as easy done as you might think. The tolerances are way smaller than what you can do with typical hand tools. If you can't get it to run right you might have to get a new piston an sleeve. I know it sucks.
 
lol no thats not it have a friend thats 55 and been in tool in die 35 years and makes parts for machians worth 300thousand with crazy persize talerances and has the most accurate tools money can buy with that said tools were made from scratch too repinch was not a hose clamp job lol. I read something about fual i have 33percent nitro fual could that bee why temps climb fast
 
iv sealed the engine same way as your link showed and have checked for air leaks just the front bearing a little and its brand new but runs like a champ when i first get it out after about 5 mins comes it wantin too run hott and can tune it as rich as u want still gets hot
 
Don't make any adjustments until it's warmed up, and don't expect an immediate response.
It sounds like the LSN is a little too lean. If that's lean it will cause an overheat that the HSN can do nothing about.
Richen it by no more than 1/8 turn, then drive it around while checking the temps. If you don't drive it normally, it's hard to know what's working for you.
After the initial adjustment, richen it by 1/16 at a time and see if it will improve.
 
okay took engine off today and found my air leak. For some reason my starter shaft bearing is wore out. Bad i mean can feel and see it by moving shaft back and fourth. But what i dont get is when i put it all back togeather i checked this and was in specs and tight. What could be the reason for this happend any thoughts I'm thinking about parting the truck out. But iv never been the type too give up. So trying too get too the bottom of this and truck ran great when breaking in. No over heating for 4 tanks of fual at a idel so it. Would have wore enough too leak air and cause my lean issue just after break in and me trying too tune it and hot laps really wore it but why? I'm happy i found my air leak but sad that i have this issue now:(
 

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