Engine Problem :( Help Needed..........
 

Hi Guys,

Hope someone can shead some insight into this problem of mine........... i flew my tigershark today which is in the pic below....... its powered by a Leo 46 2 Stroke engine.......... now to the problem....................

1) Not sure about what the best prop size i should be using at the mo i currently have a 11 x 6..............
2) The engine doesnt seem to peak, its a new engine but just doesnt sound like its peaking like my other 2 strokes.
3) With the glow plug off the engine turns fine........ when the glow plug is on a clicking is heard and its VERY stiff not every turn but once every 3 turns say its extremely stiff...... but like i said with the glow plug out it turns without clicking......... i looked at the engine and i can think is the glow plug too long and is hitting the engine when the cylinder reaches the top ?????? is that whats causing the click as it makes it when it hits compression.... but im using a OS 8 Glow plug, soo im not sure if u can buy shorter ones or even if this is the problem...................

Any help or insight into any of these above points will be very helpful........

Cheers guys.......

RE: Engine Problem :( Help Needed..........
 

The OS #8 is not really a long plug but actually rather medium in length if you put it beside other brands.

Maybe you are feeling and hearing the pinch at the top of the ABC cylinder?

Enjoy,

Jim

RE: Engine Problem :( Help Needed..........
 

Thx for the reply................ so is that normal the clicking and normal to be that tight ?????????

RE: Engine Problem :( Help Needed..........
 

Some ABC engines are tighter than others. It is more prominent in a new engine.

Enjoy,

Jim

RE: Engine Problem :( Help Needed..........
 

Not familiar with Leo's, but if it has a taper bore. i.e. tho top of he cylinder bore is slightly smaller than the rest of the cylinder to give a more precise piston to cylinder fit at TDC, the pinch should be felt even with the plug out. With the plug in, it will be even tighter as the extra compression is felt.

The clicking may be the connecting crank pin and rod bearing that is common with many of todays engines like OS, Magnum and the like that have the tapered bore. This will occur at TDC. The piston is tight at the top and as the crank comes off TDC and any slack in the pin and rod bearing will be heard. Some clearance is required to allow the lubricant to do its job. This is known as oil clearance.

To make sure that the piston is not striking the glow plug, measure the depth from top of piston at TDC to the outside top of the plug hole. With a depth gage or use a small plastic straw inserted in the glow plug hole. Make a mark where the top of the hole of the glow plug is and then compare this length to the glow plug's threaded portion. Make measurements with the copper washer removed. Another method is to place a small dab of grease, vaseline, etc. on the base of the plug and let it extend about .5 mm. Then place the plug in engine, and rotate the crank. Remove the plug and check the grease for any indication of contact.

I have several brand new engines, OS, Magnum, TT, and they were so tight that I could not turn them over by hand unless I had a prop on the engine. Once I broke them in, they were still tight but I could turn them over. I can hear the clicking just as the piston begins to come off TDC. Make sure you dont use synthetic to break the motor in. Syn. is very slick, as it is supposed to be, and will take for ever to break in the engine.

RE: Engine Problem :( Help Needed..........
 

Thx magyarbacsi for the detailed info

I think the piston is hitting the glow plug head........... would this be the cause of the problem....... althou i have an OS 8 Glow Plug in, i treid a OS 3 but it looks the same length ?????? are there any shorter ones avalible ??

RE: Engine Problem :( Help Needed..........
 

Hi!
Can't think this is possible, because the combustion chamber dome in the head is much higher/deeper than the glow plug is long...and remember that you are using a medium length glowplug (like all Japanese glowplugs).
Are you sure you hear a metallic clicking sound only when you have the plug removed ?
Is the engine real tight ?? Most modern ABN and ABC engines aren't so tight compared to the old K&B engines 6.5cc engines of the past so they don't squeak when the piston reaches the top dead center.
Can you feel if the piston/cylinder fit tightens when piston reaches the top? Try wiggling the prop back and forth past the piston top dead center...is there much play?
If it is it ...might be the big end in the connecting rod that has a little too much play...
There are shorter glowplugs available but all modern engines use long or medium length glowplugs and so does yours.

Regards!
Jan K
Sweden

RE: Engine Problem :( Help Needed..........
 

Got a couple extra glow plug washers? Put them on so the plug can't go in as far and then try it. Don't try to run it this way, just turn it over. Odds are the noise is the conrod, not the plug hitting the piston. You're may be hearing the noise because the piston is going up against compression when the plug is in, but is more free to move when there's no compression.

One more comment, if the engine is new, why are you trying to peak it? Break it in before you start torturing it with lean runs. :D

RE: Engine Problem :( Help Needed..........
 

As jaka said, it's not the plug hitting the piston (or even the piston hitting the plug :D ) because there's far too much clearance in a Schneurle engine (at least 1/8" ). What you're feeling seems to have something to do with the normal pinch plus compression (with the plug in) but why you don't feel it every turn is something of a mystery.

RE: Engine Problem :( Help Needed..........
 

I think your question is answered above, but as far as you not getting the rpm is concerned, perhaps you are on the bit of the large size with your 11 X 6. Drop down a bit to to a 11X5 or 10X7 and it should spool up better. Different prop manufacturers will give you different RPMs as well. I prefer APC, and others may like different brands. Also if it is new, your engine may not have broken in yet. Dont run it too rich. Most tachometers are accurate and a wise investment. You may wish to invest in one or ask for one for Birthday or fathers day.