yummyguts

Hi there
Im new to the r/c world so plz be nice
Anyway after letting my Tamiya mighty ballista cooldown i went to start
it and pulled the pullstart a couple times. Then the the pullstart wouldnt budge. Then i went to see if the flywheel was moving but it didnt budge
So what could be the problem?

Thanks

LosiMadMan

iTrader: (2)

Either it's vapor locked, or the piston is stuck at the top of it's stroke. Loosen the glow plug an take a screw driver to the flywheel from the bottom and make it turn over until the piston is at the bottom of it's stroke. Then tighen your glow plug back up.

aussies1129

iTrader: (74)

Hey take out your glow plug get some heat into it by a heat gun aim the gun around he cooling head area get it nice and warm say over 200c is good then you will be good to go
cheers

yummyguts

thanks for the replys guys

dishsoap

iTrader: (8)

Hi I am new as well but tell me if this makes sense. Could he have possibly locked up the clutch shoes and mushroomed them against the clutch bell. This could happen due to giving the buggy gas and not letting the tires spin freely.

vladconnery

iTrader: (35)

Anythings possible but very unlikely. His problem is its a new engine with alot of metal pinch in it. He left the piston at TDC (top dead center) after running. Engine cooled and sleeve contracted around piston. Whenever you run your engine your supposed to always return piston to BDC (bottom dead center) to avoid this problem. Keep in mind in a RC engine the sleeve is conicle shaped. Meaning larger at the bottom and narrower at the top this is how it seals the chamber for compression. Metal pinch is a good problem to have. Leaving your piston at TDC is a bad problem to have. Rookie mistake join the club as we have all done it.

vladconnery

iTrader: (35)

To further answer your question. the shoes are on springs that will return automatically to closed position when rpms drop. it would take a whole lot of mushrooming for this to happen. Not very likely on a new engine and clutch. Mushrooming could lock them slightly open but doubtful that they would lock against the CB. An easy check is to spin the CB. Your CB remains free and spinning even if the flywheel is locked if its not a CB problem.

franklucas

iTrader: (8)

my muggy mushroomed like tht in 5 tanks flywheel was really hard to turn.

JAMMINKRAZY

iTrader: (17)

Muggies are notorious for compleately destroying clutches because they aren't geared correctly. with the stock tires muggies are geared to short(I think its too short). In a normal situation it would be really hard to get a clutch to mushroom that much. His problem is probably a tight engine. throw some heat on it with a heat gun or hairdryer if a heat gun is not available. it will turn over.

chunk t

There was a poster on an other thread who's new engine siezed up after his first break-in run. I've copied below what I posted in that thread, maybe it will help here...

I've broken in some engines before that were very tight. Here's what you do...

Pull the plug, drip some after run oil (I personally like to use STP engine treatment for the car) in the plug hole and rock the piston over TDC while you watch TV (or your fav DVD; & keep a towel handy to keep your hands clean). It will slowly begin to loosen up. The sooner you can get the engine to run on it's own the better, because you need the heat to properly lap and anneal the P&S. Once you can turn the engine over by pull-cord with the plug removed (even if it's stiff) you're ready to add the igniter. Put the plug in, turn it down fingert tight, then back it off 1/2 turn or so. This will allow some blow-bye on the plug and ease getting the engine started. once the engine is going you can finger tighen again (don't go snug yet). It shouldn't be long before you can start the engine with the plug fully seated.

These engines are designed with a taper to the sleeve that is narrow at the top and pinches the piston at/near TDC (some pinch more than others) The top of the sleeve is where the heat is and this will cause the sleeve to swell and loosen up. On the really tight engines, heat cycling is very important. Set the needle rich (too rich) and cover the cooling fins. You want to run the engine for 60 seconds with the temp above 250 and below 300; after 60-sec kill the engine and let it come down to cool-to-the-touch. Do this for two tanks. I know I'm going to catch an earfull from other posters for this but hear me out. Fuel adds cooling, a lot of fuel (really rich) adds a lot of cooling to the sleeve; you must have a lot of oil on the piston when breaking in a super tight motor. The problem is this excess oil is going to hold the temp down. Though the HEAD may read 240, a super rich setting (a burbbling sounding idle w/a lot of smoke) is actully pulling the sleeve temp down 15-20 F below the head reading. To properly anneal the sleeve and create the correct fit between the P&S, the temp must come up above 250. If you do this, you'll get a perfect honeymoon fit with the P&S...

Chill_Will

iTrader: (33)

Check the one-way bearing in the pullstart.

jamminnay

iTrader: (11)

+1

The Working Man

iTrader: (1)

2+

yummyguts

thanks for all the help guys
i manged to get the flywheel undone using a haidryer and started the engine
and let it warm then i shut it down and made sure that it was bdc
anyway thanks for the help