CY Engine Dead! Body Smashed!

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hamster huey

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Last weekend I broke a dogbone pin, servo saver got loose, and servo horn got loose- regular things that happen over time, no big deal. One time my engine acted up it was a worn throttle shaft. It drove me nuts until I could figure it out. Today all I got is ????? I put the engine together myself. I checked the H and L before and after it died. I use the blue headgaskets cuz they don't blow out. It has a 668 carb on it with fresh gaskets. The carb setting were at the base starting points which is a little rich. Tank is vented. Throttle servo horn is new. Coil to flywheel gap is good. The air filter is clean with only 2 tanks on it. What happened: Ran great for 3/4 tank, then idle rpm came up slightly, died once, started back up drove it hard, died again, wont start, when I pull the cord it sounds like the chamber has cotton in it. So now Im gonna take the head off and look. I just put new gaskets on over winter and added a ZRC and Shreadstack. Im going to check my holes through the carb,stacks, and head but I triple checked them before I put it together. Ill probably tear it apart to see and try a different carb. Or try a different spare engine. And I rolled it over and broke the body. Drywall tape, scrap lexan, and shoe goo here I come! I love my hobby! :o
 
idle rpm came up hmmmmmm sounds like a classic air leak on the intake side. at least thats what I would think on my nitro.
 
Im thinking airleak too.......but where!!??? Thats why Im thinking just put a different engine or carb in it and maybe not with the ZRC just to see what happens. Sometimes I wonder why Im in this hobby!!?? When they run its magical when they don't it brings out the carnal animal side of men that want to destroy (never seen a woman on here yet but Im sure it would her too)! Sometimes I think I should go into management training like Andy Bernard. My body is obliterated! Its going to take some pounds of goo and lexan to repair it.....it was only 53 degrees outside! I cant blame redcat for the CY engine that I put together though. Also I recall someone who blew apart their Proline body as well..................................................................................................
 
If u have not allready replace the crank case brearing and seals with TFE ones that should solve the air leak, check the Pipe for any junk that might of fell in there at some point, it could be blocking air flow, and one thing also to check is pulse port on the intake, for some odd reason when i replace my carb gasket some juck got stuck in the pulse port and cause my engine to run like Shi#, so just get a tooth pick to stick in the hole just to check to make sure is clean, (just take to carb off and the two little holes on the space thats bolted on the head those are the pulse ports,I thinks thats what there called , but there at a sight angle so just get something like a tooth pick to check them
 
hamster huey said:
Im thinking airleak too.......but where!!??? Thats why Im thinking just put a different engine or carb in it and maybe not with the ZRC just to see what happens. Sometimes I wonder why Im in this hobby!!?? When they run its magical when they don't it brings out the carnal animal side of men that want to destroy (never seen a woman on here yet but Im sure it would her too)! Sometimes I think I should go into management training like Andy Bernard. My body is obliterated! Its going to take some pounds of goo and lexan to repair it.....it was only 53 degrees outside! I cant blame redcat for the CY engine that I put together though. Also I recall someone who blew apart their Proline body as well..................................................................................................
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Are you using solvent based paints or water based? I use Auto air and parm only. solvent based paints destroy the oils in the lexan which makes it harden and get brittle. I pound my bodies and have only cracked the front fender on my mt/sc. the back end is foulded and crunched like paper with no breakage. nice thing about the water bases is fuel does not effect them at all.
 
The Ded HedzAre the parma polycarb paints from hobbytown ok? That what I have always used on lexan. I figured out whats wrong with my Ramp:o. The head are itself all the way around the piston. The head, piston, ring, and piston bearing are dead. Not sure why. Plug looked good, air filter good, needle settings good. Piston bearing had more play than normal. I don't know if I had an air leak which lead to lean or if the engine was wore out or sucked up dirt maybe even dirt from an air leak. I just have to pay attention to the clues and rebuild. The head gasket suggests it tightest around the 2 bolts than the area without bolts but thats the way 2 bolts are by design. I used my orignal ZRC gaskets which are some kind of hard plastic so its possible. As Lagamn suggested I did not replace my crank gaskets or bearings yet, only the head gasket and carb etc top end gaskets so its prob a good idea on an engine that has at least 30 tanks and is about a year old and been taken apart a few time. Any ways Im thinking complete CY gasket kit, gasket sealer, crank bearings, new head, new piston, new piston bearing, new ring, new zrc gaskets, etc, rebuild the whole engine. Its pretty cheap. Probably the 28.9 stroker kit. In any case next year my annual rebuild will include a COMPLETE engine tear down and Cy gasket kit with a new ring/piston-rod bearings and plug. I am so happy the engine maintanence on these is easy. I hade the engine out and apart in 20 minutes. I could very easlily replaced it with my spare in 35 minutes!!!

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Heres the plug for all you wrench hedz. Oh yeah the pulse port was not plugged. Thanks for the tip Lagnman.The exhaust port pic is when I figures it out. Please don't laugh at my white fingures kung fu death gripping the plug.

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Well Threre your problem lol, what do u think cause the scaring? I really don't know how long a Engine is suppost to last, well you said that u have about 30 tanks on it so that about 30hours or run time , should these engines be getting more than that, hell Ill be happy if i See 30 hours out of mine lol
 
My first Ramp (not this one) I bought used. The 23cc head and piston on my first one were scarred up too but not this bad so the person I got it from had the same prob. Anyone else seen this or have an idea why?
 
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From the thread you said to check out:


"I have been dyno testing the new 4 bolt 29cc kits for the last month and Im on my 3rd top end with this combination. The first two would rev fine with most pipes except the Jetpro 3 which lets the motor rev past the 16K mark that the other pipes would not reach. I ran 25:1 on the first set of run and it seized with the Jetpro pipe on the first run at 19k rpms with very rich carb settings. I ordered a 2nd kit and changed the fuel mix to 16:1 and ran the exact same tests, bolted up the Jetpro and on the first run over 17K it seized again at very rich settings again. Carlo at CC racing advised me to cut the piston down .003 and this will never happen again. He stated what most people think is a lean seizure is really an expanding piston crown at high rpms.


On my 3rd kit I cut the piston down and ran the exact same dyno tests. Like twice before I bolted up the Jetpro after break in and running 15 other runs with various pipes, I have made a dozen runs over 19K rpms and she is still singing!"


Maybe the engine was fine thats just the nature of the beast: I drove it too hard? The pics on there were cool too. Id like to find someone to cut my piston down or somewhere to buy one already done.
 
Thanks a lot Rudi for pointing me in the right direction. This makes more sense to me because I carefully put the engine together, the clues point in no particualr direction, I railed it hard for the whole tank at high rpm before it died (see video), fuel mix good, carb settings good, plug good,and it rapidly got worse as it got clser to dying, it wasnt intermittent at all. Im thinking basically the harder its driven the more the piston swells which your link mentions is more common in gopeds (same motors). It can happen to motors in top shape with no air leaks.


Something else just occured to me. I have heard the dark soul marine head is very prone to the same thing but at a higher failure rate. Do you think releiving the ring area would solve that problem too? I have to get 4 engines together and not sure what I should build. So far I have decided ONB Reeded and ported Zen 27.2, unported 28.9 (stroker), and a plain 25.4. If I can get the releived piston for the 4th engine Id do a 27.2 Dark Sould marine head ported? Id like to do relieved pistons in all of them, now.
 
i do believe you will have to change ring style with the relieved piston as there will be less support for the ring. Might be wrong but worth checking out.
 
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