coupar

I have a brand new Tower Hobbies .76 ABC engine. It is new and is meant to be pretty tight but I can barely turn it over even with the prop. I cant see any realistic way of starting it. A starter is right out and turning it over with a chicken stick is slow and requires a lot of effort. I've tried lubricting with fuel in the port - does'nt help.

Anybody any suggestions to getting some kind of burn completed to loosen it? Anybody had experience with these engines? Is it plain bad?

Any advice would help.

daveopam

My Feedback: (9)

I would put some fuel in it and try to run it on a test stand. Just use the chicked stick and flip it till it starts. Once it fires it will loosen up from the heat. On ABC motors the tighter the better. I'll bet it will fire on the 2nd or3rd flip.
If it absolutly is to tight to start, warm up the head with an iron and try it again.later daveo

RCPAUL

My Feedback: (1)

Yes, heat the cylinder and head with a heat gun or propane torch - this will let you get it started and , when it runs, it will be a lot better.


RCPAUL

3dd

My Feedback: (6)

if it is an abc engine a little trick duke fox taught me years ago is to take the prop off put the spinner back on and remove the head,put some pearl drops tooth polise in the cylinder and turn it over with an electric starter, do this three or four times and then put it back together and run it really rich and follow the breack in directions to the tee. it really made a screamer out of a fox 60 that was way to tight

maxtenet

don't use the tooth polish on an engine with an aluminum piston! Foxes had steel pistons and that was OK. A propane torch will melt the damn thing! Take the plug out, throw some oil in and turn the bugger over with an electric starter a bit to loosen it up. If this doesn't work you got a serious engine problem and need to send it back!
Max

Flyboy Dickie

this sounds like the problem that I had with my Enya 40. The tolerances were so tight that it was impossible to start with a starter. The guys at the club losened the glow plug slightly to decrease the pressure. Once the engine started, we tightened the glow plug, and everythig was fine. After a dozen or so starts, everything was ok and I could start it normally. Since then everythng is fine. Since then, eveything is fine.

twostroker

My Feedback: (37)

Go with the "HEAT ON THE HEAD" method. It is an ABC engine which means there is no, I repeat "NO" clearance between the piston and cylinder near top dead center. If you turn it over by hand until you can easily roll it over you just wore away some engine life. The best way to do it is to heat the head with a propane torch so that it expands the cylinder at the top where it is tight. While you are warming it up, you will notice it loosening up on TDC. That's when you want to start it and let the heat of combustion take over. You will have to do this more than once until the break-in is done. Also with an ABC engine especially a tight one like yours you do not want to run it rich during break-in. It's best to get it two-stroking right away and get the heat in it to expand that tight spot so you do not cause excessive wear at such a young age. Also it is best to make several short runs with cool down time in between, the heat cycles stess relieve the metals in the engine.

maxtenet

Do not use a torch, you may melt the aluminum! I can't believe this ridiculous advice. Take the plug out and turn it with the starter. It should loosen up. Once you run it, break it in at nearly max speed as ABC's break in differently than older engines. I could get into reasons, but it has to do with metal expansion rates. Email if you want more info.

Max

twostroker

My Feedback: (37)

Max,
I apologize whole heartedly, I seem to forget that not everyone is as intelligent as you or I. And I'm sure Coupar would hold that torch on one spot until the aluminum melted before his very eyes, without even knowing what happened. Coupar it would be much better for you to get your metalurgy degree from your local University before you play with model airplanes. Or you could use Max's advice and just take the glow plug out and grind that piston into the cylinder until it fits. After all the piston is softer material than the chrome cylinder. So after the piston has enough material wore from it, it will fit. I could get into reasons some metals are harder than others, but I'm sure it's over your head so I won't go into detail. After all you'd melt the head off that thing if someone gave you a propane torch.

daveopam

My Feedback: (9)

Two stroker I'm sorry I didn't get to see your original post before editing. I'll bet it was interesting.
later daveo

dogsbody

I just used my propane torch to free the carb. barrel on a tag sale OS Max FP .20 that had sat too long without being cleaned. Lo and behold I didn't melt anything. I set the flame tiny,touched the tip to a couple of spots on the carb body for a second or so each,penetrant,waite a couple minutes,then repeted and voila,slight movement of the throttle arm.Off went the torch and the rest was oil and excercise.I'm glad now I resisted prying or hammering.Practice THC,total heat control. Remember,too tight is usually better than too loose,like too long is better than too short. See you.

maxtenet

Hey two stroker,
I'll bet you'd probably use your torch to loosen up the cap of your fuel cans too! Makes as much sense!
Max

RaceCity

The YS two strokes were this tight. WOW!

Do NOT use a torch! A monokote iron to warm the head will permit easier initial starting.

Using abrasives on a plated piston/liner is NO GOOD either. The Fox is a different design...the abrasive idea was fine for them.

Warm the head with the iron set on "high" and proceed with the break in as per the instructions.

Good Luck!

'Nite

coupar

Many thanks for all the advice. .....I did'nt mean to start any arguments.

Taking the glow plug out does'nt work. It is just as stiff without the glowplug as with it!

I'll heat the cylinder as suggested. If I use a propane torch, I'll use it very sparingly. I'm able to try starting at home where I can reach electricity(!) so I'll probably heat the cylinder with a heat gun.

Thanks again for everyone's advice. It helps a lot.


Cheers for now!

George Coupar

Jim Thomerson

It does sound like your engine is set up too tight--better than too loose, for sure. When you heat it you just want to get the top end up to about running temperature. A heat gun should work fine. If that doesn work, here is what I would do. I would take the head off and put a little Dupont white buffing compound in, with the piston at about the top of the exhaust port. Put the head back on and rock the piston back and forth. DO NOT TURN IT OVER! Work up to about 1/4 of the way to TDC. Clean it out, heat it up and give it a try. If it still is too tight do it again, going up a little more. Do not lap the top 1/8 inch or so of the stroke. Be slow, careful, and cautious, else you'll ruin the engine. If this works, the engine will be fitted just right and be an outstanding runner. If it doesn't, Tower will give you excellent service sending a new piston and liner.

Jim

WhiteRook

My Feedback: (38)

how bout letting it sit in the hot sun for an hour, before starting

southern_touch99

you want to know what to do? Send it back to tower thats what you do. I have NEVER seen a motor that was as tight turning over without the glow plug in it as it is with the glowplug. See by removing the plug you are releasing the compression on the motor that is suppose to make it "tight". From what you explained it sounds to me like something is bent somewhere along the motor. If you for some reason cant send it back to tower then try warming the head with the heat gun, I dont know about the heat from a tourch??? And if that dont work then invest in a sullivan dynatron starter rigged up on 24 volts, that thing starts 200cc engines so I think it will start your tower engine.

maxtenet

Send it back if its that tight!
Max

rcairplanenut

Put one oz. of R/C fuel into the cylinder and the the opening of the carb. let it sit for a day and try turning it agan.

rcairplanenut

You could also take the back and the top off the engine and see if any thing looks odd.