farbs

My Feedback: (19)

Hello everyone,

I have an older SAITO 40 and I need some help - I can't get it to run. I even put in a BRAND NEW 4 stroke style glow plug. Will not even fire - nada, its dead. Let me tell you what's going on and maybe someone can help me get the engine running.

There is a little "clicking" sound when the engine is rotated. When I hear the click, around top dead center, I move the prop back and forth ever so slightly and can hear the clicking as I move the prop - about 1/2 inch in movement. It only makes this "clicking' sound in the prop position - the prop is positioned approximately in the 11 - 1 o'clock position. Does not make the sound when the prop is in the 3 or 9 o'clock position.

I took the valve covers off and everything looks fine. The valves are moving and do not appear to be stuck. I checked the gap between the valves and they seemed a little off so I adjusted them per the directions from the manual. The clicking still occured.

I also removed the carburator to make sure there was nothing wrong. It did not appear anything was malfunctioning, the rubber gaskets between the engine and the intake manifold and the carb itself look a little old (hard) but are not torn or rotting.

The compression is also very, very weak. It felt OK when I first got the engine but after attempting to start it several times the compression felt like it "disappeared". I'm not sure what is going on.

I bought the engine from a guy off ebay. I thought it was in good condition. Cosmetically it looks great. But I think I bought a lemon.

Is there anyone out there in RCU that can lend me some words of wisdom? OR, can someone recommend a place/person that I can send the engine to for overhaual/repair. I would like to keep the engine but if it will cost too much to fix - either by myself or by some other expert R/C engine guy - then I will just sell it and try my luck with another engine.

Please respond to this post or email me directly if you have any suggetsions.

w8ye

My Feedback: (16)

Forget about the clicking. Most of the four strokes make this noise.

It might be possible that it has either jumped valve timing or someone has had it apart and put it back together out of place?

When you first got the engine, there was some heavy oil or gum that had the compression up. When you put fuel in it, you washed some of this away. The ring may still be stuck by this gum? Put some oil down the glow plug hole and see what you get?

You don't want to be taking the engine apart if you don't have to.

A electric starter may get you going?

Enjoy,

Jim

farbs

My Feedback: (19)

Thanks for the advice. I'll try putting some oil in the engine to free up the stuck rings. I have been using an electric starter too but that didn't matter.

Anyone else have some thoughts on what I should do??
The more info I have the more troubleshooting tips I can try out.

w8ye

My Feedback: (16)

Take your glow plug out and hook it up to the ignitor and make sure it is glowing red?

Make sure you have fuel dripping out the bottom of the carb before you stick the starter to it?

Enjoy,

Jim

farbs

My Feedback: (19)

Thanks again. I'll try the fuel tip. The glow plug is new and I checked to make sure my battery was good too - glowing red hot.

Do you have any tips on checking and setting the valves?

w8ye

My Feedback: (16)

Adjusting Valves...
I'm sure you know the basic routine including the dimensions etc so I just want to talk about the art of adjusting valves. First, we have to talk about feel.
The problem is… feeling with the feeler gauge. (hence, it's name). Do you realize that when adjusting a valve, (even on a hot rod car), it is so easy to force a thicker gauge in the gap than what gap exist. The reason you can do this is because the valve is held up by a spring. It's possible to tighten a valve down on a .002" feeler gauge to the point where no gap actually exist though you have the feeler gauge right in there in the correct position. The rocker arm does not hit on the valve stem square and it is possible to slide a .004" gauge under a rocker arm that only has .002" clearance because in forcing it in there, you push the valve down against the spring.
To overcome this, you have to just have a very slight resistance on the feeler gauge when it is set correctly. If you buy a set of them at the discount store or auto parts store, you can try different thickness gauges in there (starting with a very thin one) until you encounter a very slight resistance to sliding the feeler under the rocker arm. The number on this gauge will be the clearance on that valve. (You should be trying to do this on a car motor with it running and squirting hot oil on your hands?) So you see a 4 cycle model engine is a piece of cake.
All 4 cycle model engines with rocker arm type valves all have the same clearance. They give a dimension in mm but right off I don't remember what it is. I set all of them between .002" and .004". I just use a .003" gauge. Some purist may have a fit over this but I haven’t had any trouble. On the calculator, that comes out to be from .05mm to .1mm.
You need to be certain that you have the engine on top dead center and on the compression stroke. After setting the valves, turn the engine over a few strokes and put it back on TDC and give them a feel once again. If everything is OK, then button it up.
Don't wear your rocker arm screws out adjust the valves. A periodic check is all that is necessary. Eventually, you will be where you can feel the rocker arms with your fingers with no gauge and know about all that's needed as far as valve clearance goes.
The reason for valve clearance:
If the metal expands too much or you make a slight mistake in clearance judgment, it could hold the valve off the seat slightly. This will burn the valve because it cannot transfer its heat to the seat, plus all those hot gases will now be blowing past the valve heating it up more. If your valves are too loose, the push rod could fall from under the rocker arm and the engine will stop. If the push rod doesn't fall out, then the extra clearance will be just that much valve lift that you didn't get. The engine will not run as fast on high speed but will probably idle real well. It will also cause extra wear on the valve train

farbs

My Feedback: (19)

Happy TGIF everyone,

Well, I've tried several more times to get the engine started and carefully adjusted the valves. Nothing worked. So I disassembled the engine and I noticed the ring was frozen to the piston and the piston appears to be damaged. I am in the process of gettting a new ring for the engine and will install. BUT, I think I should go ahead and replace the piston too, the top of it just looks wierd. Looks like it has suffered over the years. My problem - question - is:

How do I remove the piston from the connecting rod? The piston pin looks like it is stuck in there pretty good. How do I get this sucker out? I don't want to have to buy a new piston, connecting rod, piston pin, and everything else. Just replace the ring and probably the piston.

Please help?? How do I remove the piston from the connecting rod?

Thanks in advance,

Bob

chris-fla

My Feedback: (2)

Compression on a 4-stroke is much lower than a 2-stroke, so don't be thrown off by low compression. Have you checked the carb settings? The high speed needle should be 4 turns out from closed and the low end screw should be set flush and than one turn in. If this doesn't work, you need to verify that the cam timing is correct. The easiest way to verify this is that both valves open once every other resolution on either side of TDC. You can verify this by removing the back plate. A lot of buildup on the piston is a symptom of running castor based fuels, nothing more, I have seen engines with 1/16th of an inch of buildup that run perfectly, this is why I only run full synthetic in my 4-strokes.

Chris