jadec241

My Feedback: (29)

I have a CRRC 40cc gas engine fairly new with a excel ignition. The ignition calls for a 6 to 7.4 5 cell battery. My problem is it pulsates thruout the running of the engine. It will idle OK but if I give it fuel it will pulsate up & down. Have checked the carb gaskets, set the Hi & L o at 1 1/2 turns & ran both screws out & in. The ignition is set @ 28 Deg. just what rcexel calls for. The only thing I think is it might have is a air leak somewhere. Any help would be appreciated.

Lifer

My Feedback: (1)

Are your needles set a little lean? Is there an external pulse line that could be leaking? What is the state of your battery? What prop are you using?

coralcape

My Feedback: (4)

Squirt a little starter fluid around suspected trouble spots and listen for RPM change. red

jadec241

My Feedback: (29)

Have adjusted Hi & Lo out to 3 to 4 + turns & it makes no difference. The 5 cell battery reads 6.5 when charged. Even used another one thinking it might be the battery. I am using a 22X 6 Zingger prop

jadec241

My Feedback: (29)

Am thinking it might be a air leak. Either around the pulsel line or the front seal. Will try squirting fluid & see if the rpms change. Thanks

speedracerntrixie

My Feedback: (29)

What is the plug gap?

kmeyers

Is that the 40cc kit engine? If yes take it completely apart and put it back together. The engine should not even run with the needles 4 turns out. You can start with the carb insulator block and pressure pulse hole because bad pump pulse could cause very low fuel delivery, but, you probably won't get that llucky.
Goodl luck

kmeyers

Completely apart...Oops Ah no not really. Just loosen the jug bolts, carb bolts and crankcase halves align them and tiighten them back up. That should be enough, I wouldn't think you need sealer, but, if it is what it takes there is no harm in it.

jadec241

My Feedback: (29)

The CRRC 40cc engine has no insulator. The carb is mounted to a metal spacer which is mounted to the block.

jadec241

My Feedback: (29)

Am using a new NGK plug set @ 20 thousands.

coralcape

My Feedback: (4)

Silly question, but is the pulse hole lined up with the carb? Engine will run if not lined up, but will starve for fuel. Has this engine run well in the past to your knowledge?

jadec241

My Feedback: (29)

There is no hole for the carb. They have a fitting in the engine block with a line running to the carb.

Lifer

My Feedback: (1)

That's the pulse line.

oldbassard

One thing that comes to mind for me is to check the throttle body for excessive slop. What I mean by that is check the linkage that goes through the carburetor body for to see if the holes are loose enough to let air get by as the throttle is opened and rotates. Sometimes these carburetors after a short time will allow that to happen because they are simply drilled and don't have bushings therefor after a period of being used will "worm out" the holes and let air get by. Just something to check. To check for that disconnect the linkage and get the pin that goes through the carburetor and holds the butterfly try to rattle it and see if the pin moves in the holes.

Just a thought

LARRYKOP

I spent the last several weeks working on a Pouland 42 CC gas motor and have a similar problem. I'm retired and was just looking for a project to keep myself busy. I have a machine shop and did what I consider to be a first class conversion. My 42 would run and idle at 1050 rpm with a 20-8 Dyna Thrust prop. It required the NV's to be open 4 turns. It had very little compression and would barley accelerate. I put a Frank Bowman ring in it and the compression improved but not really good enough to put it on an airplane. I can get 6.300 RPM out of it but it backfires running at high speed. I let it idle for 2 hours at about 1,500 RPM and it got stronger. It needs more running time to fully seat the ring. I'm using 40-1 87 octain gas, a Melody Ignition at 28 degrees and a custom muffler. The motor is really quiet, you can hear the bearings spinning. I rerouted the carb pulse line and it improved but is still starving for gas. [email protected]

jadec241

My Feedback: (29)

I have converted Homies for my engines & they all have a pulse hole for the carb. The newer chinese engines use a line from the block to the diaphram side of the carb. I like the other way with the hole on the carb lined up. The engine is primed when I hold my finger over the carb throttle body & rotate the prop till my finger gets wet. This way I know that the pulse line is working. When I flip the prop it will fire on the prime & run. As I incress the throttle it will run but will not run steady. It pulsates up & down which gives me the impression that there is a air leak somewhere. I am going to spray fluid around all the gasket openings & especially the frount bearing seal. I have found some engines that have not had any seals around there which will cause a leak.

Texastbird

Try an 18X8 prop. This is not the most powerful engine in the world. Mine barely pulls a 19X6 Xoar.

Gizmo-RCU

My Feedback: (27)

Ditto on the prop...I had two these engines and they did best in the 18 in. range. I suspect you have an air leak in the crank case. These are mostly "kit" engines to be assembled by the purchaser,
As such many folks have never assembled and sealed any engine before. Both of the ones I had leaked air and had to be re-sealed on the bottom end. I was not really impressed with these engines
for reliability, quality and power and got rid of them.

Others report good results.............

jadec241

My Feedback: (29)

My thoughts are the same. Poor craftmanship. I have found out that some engines are missing a front seal. Will take it apart & reseal with sealer or new gaskets. Will post my results
Well I took the pulse line off from the carb side, blew into the line after I sprayed soap liq. all around gaskets, front seal & carb.Could not find any leaks. Changed the carb, no difference. Next thing I will contact Milton @ ecexel & see what his thoughts are.

Gizmo-RCU

My Feedback: (27)

I think you are on the right track, might try a Bowman ring while you are in there. I never took that step but have a DLE 55 with his ring. Very large increase in compression , power and ease in starting.

Lifer

My Feedback: (1)

Ditto on the Bowman ring. Best investment you can make in an engine.