CRRC Pro GF26I

[rcign]

Send me the engine with the carb that doesn't work...If I can't fix it the shipping is free both ways...

[FLZman]

Thanks Ralph, may take you up on that. Will know by the end of day. he is redoing carb today at his shop and we will most likely try again tonite. If no go, will probably get it headed your way . But whether fixed or not, I will pay for shipping and services.

Z

[dealinrc]

	Quote: Originally Posted by ken crane
	what did china say? i would try a known working ignition for a 50. i would bet that the ignitions are from a 26. a 26 and 50 cannot be mixed up as the advance is different. i learned this the hard way and it was doing just what you are saying. look on the back of the ign module and verify that it is the correct one. try an rexel ignition as a test. i would bet my rep on that one.lol.. symtoms are hard starting with much kick back and only infrequent running after its totaly loaded up with fuel then followed by long back firing and the cycle starts over and over until you get fed up.

Yong sent me pictures to show where the sensor should be, but we tried that with the same results. The engine would run for 3 flights, (lots of power but rough idle} and than it would just backfire and spit and break props. We also tried new ignitions straight out of a brand new 50 box. I am wondering if the factory got a batch of faulty ignitions.

[ken crane]

	Quote: Originally Posted by 3Dguy
	Yea, but I'm working on it. The engine is tuned perfectly on the ground, but as I begin the takeoff, the engine revs up fully, but as the airspeed builds, the engine loses RPM and quits. Richening the needles does not help. That's the current problem. I asked a guy from my LHS, and he said to make a aft-facing curve on the end of the velocity stack because the carb may not be drawing air in properly. I'll give that a shot, and then I'll try a new carb (it's on order anyway).

i have the velocity stacks off on all my motors. made spacers to take up the space and ditched them.

[ken crane]

	Quote: Originally Posted by dealinrc
	Yong sent me pictures to show where the sensor should be, but we tried that with the same results. The engine would run for 3 flights, (lots of power but rough idle} and than it would just backfire and spit and break props. We also tried new ignitions straight out of a brand new 50 box. I am wondering if the factory got a batch of faulty ignitions.

how about just trying a known working ign from a fifty you have in the air that works? maybe an aftermarket to compare it to? did you ask yong for the number off the back of the module that is the correct version for the 50? are they isolated from heat and vibration? did you try to power one at 6 volt. robinhood had one the ran crappy on 4.8 but worked fine on 6.

[FLZman]

3dguy and others that may be interested. Possibly good news. The friend who took the carb to shop to do a rebuild on it has verified that this carb (wt745) was missing a gasket on the intake (plunger) side of carb. He was on phone with Walbro (USA) and they pulled the schematic and verified it should have a gasket as well as the black plunger piece. He got a rebuild kit for it and put it back together. The Walbro guy said this could definetly cause the problems I was experiencing but there wont be any guarantees until we put it back and see if she purrs which won't be until tomorrow. I will report what happens. The REALLY nice thing is the Walbro guy said if that doesnt fix it, send it to him and he will send me new carb free of charge. GREAT customer service. If this is it, I wonder if there may be a batch of 745's out there where this gasket was missed on assembly line, maybe a Monday assembly 3d guy, if you want to do a quick check, on the side of carb with 4 screws holding plate on, there should be the black plunger as well as a gasket.

Z

[rcign]

never saw a Walbro without the gasket...The engine wouldn't run good at all if the gasket was missing, the thing you call the black plunger is a viton tipped inlet needle...Without the gasket the needle can't control the fuel flow and would be rich ALL the time, not just after 3 flights...
Put the gasket on first, the diaphragm goes on top..The gasket is very thin, sometimes it looks like no gasket.....Good luck....

[FLZman]

Will do, the guy that picked up on no gasket wasn't me. I know how to tune but couldnt tell you all the parts of a walbro. This guy has been fiddling with walbros and similar for 30+ years as he is a former kart champion and now rc flyer. Hopefully this is it and that was reason I posted in case they had a few carbs get past QC without the gasket. Will know tomorrow

[3Dguy]

I'll check it out, thanks.

[ken crane]

whats the outcome?

[2robinhood]

	Quote: Originally Posted by ken crane
	whats the outcome?

I'm looking for it also.

[FLZman]

Hey Guys.

Outcome: New engine coming from Ray.

Reason: Put the newly rebuilt carb on and fired her up. Sounded great for about 20-30 seconds and WHAMMO.......seized up. Pulled the jug and the cir clip from connecting rod had broken and took the piston, ring and liner with it.. We only worked on carb, never opened up engine so not sure why the clip failed but haven't seen anywhere else in forums of this failure so doubt it is anything to worry about. The piston showed zero signs of lean run, actually looked perfect except for the big gouge from clip.

Talking to Ray, yes, I could rebuild a bit cheaper but Ray sensed my frustration with this particular engine and offered me one with a little discount if I didnt want to rebuild, my choice. He really is a great guy. I chose new engine from him. He is going to do a little initial break in this weekend with it and send it off to me. Probably will have it flying by next weekend, look forward to it.

So all in all, I would say the first engine's problem was the crack in intake manifold causing an airleak and this one was sounding better right off bat after we rebuilt the carb but since it only ran for 20-30 seconds, I can't absolutely say it was carb but would put money on it.

There certainly could be worse things in life going on so I just put this in perspective with that and go on. Frustration, anger won't make the engine rebuild itself so time to go on and start having some fun.

Z

[3Dguy]

Sorry about the old engine, and congrats on the new one! Man, Ray's even goinng to break it in for you? Sweet.

Mine has a gasket. Since airflow is my next culprit, I will run the engine without a velocity stack to see if that solves anything. It's really down to trial and error now. I looked it over, and the carb/engine is fine.

[MTS247]

What NGK plug have you all been using NGK CMR7H?

[3Dguy]

I have.