DAVESDAD

Hi All

Recently got a CRRC 50, our second gas engine, the first being a DA 50. The DA ran really well straight out of the box and has only needed a minor tweak on the low end to get it running sweetly but seriously expensive with the MTW canister. Anyway really impessed by the look and build of the CRRC but !!!!! the CRRC 50 has had about an hours running on 25:1 mixture and although it runs ok on the ground and shows no sign of stopping, when we tried it in the air yesterday it ran pretty rough at anything other than full throttle. On landing also found there was a black tar like residue, not gritty or any signs of metal in it, from the exhaust. Do you think we've a) been too quick to get it in the air and it needs more running in b) got the mixture wrong, too much oil which is causing the black residue as burnt oil, c) need to adjust the low end or d) something else! The oil is a mineral based oil, Castrol 2T, fuel is normal pump unleaded and the prop is a 22x8.

Any clues?

By the way the CRRC is in a Hangar 9 Extra 260.

arobatx

25:1 is a lot of oil, if you are running it rich....until the ring fully seats I would imagine you would have some spit out the muffler. Also, if the pressure while in flight, around the carb is different, or turbulent as compared to sitting still on the ground, this could be causing an overly rich condition in midrange like you explain. Baffling the air through only the fins of the engine, and out the cowl, rather than allowing turbulent air all around in the cowl, could help out considerably. Otherwise, you can also run a line from the hole on the carb plate into the fuse to a spot without turbulence. Solder on a small brass tube and away you go.

DAVESDAD

Thanks for the quick reply Arobatx. The CRRC has the carb mounted on the side of the cylinder and because it came close to the inside of the cowl we cut a hole so the intake was clear. Could be this was a mistake and is upsetting the carb?

Don M.

My Feedback: (5)

One thing that MUST be checked on these engines is the timing. I have a 45 and it was badly out of time and I have noticed that most of the others ( including the 50 ) are the same. Mine was set at 10 degrees and should be 28. I had to modify the pick up holder to move it far enough. It too ran very rough but is now a very nice engine. I ran 1 gal. @ 32:1 and then went to 50:1 with no ill effects. I run maybe 1/2 tank through on the ground and then airborne. I've done this with all my gas / glow engines and have no regrets.

DAVESDAD

Thanks Don. I'll check the timing and let you know the result. Your advice about the oil mixture sounds right to me. Although CRRC say 25:1 for break in 32:1 sounds more like it and is what we used for the DA if I remember right.

Don M.

My Feedback: (5)

I think they also recommend 45:1 AFTER break in but my other gassers use 50:1 so I'll roll the dice.

DAVESDAD

I'll try 50:1 after breakin as the DA seems fine and I really don't want to carry 2 fuel tanks with me. Don, on the subject of the timing, I presume I just measure the angle of the magnet in the prop driver from the sensor when the engines' at Top Dead Centre? By the way I've read on other CRRC threads on RCU that mistimed engines are reluctant to start or kick back. Mine starts ok and doesn't kick back. The main problem seems to be the rough running at anything below about 3/4 throttle, after that it sort of clears its throat and sounds like a proper 2 stroke. On a glow engine I'd be adjusting the low end needle but I'm still pretty inexperienced with gas engines and I'm reluctant to mess with the needles, particularly if I've got the mixture wrong.

arobatx

OH....if you haven't messed with the needles, there ya go. Running rich with a lot of oil could definitely cause what you are experiencing. There is no such thing as a factory setting. Tune the top end for peak RPM minus a little. Turn the low end IN, until the transition begins to hesitate, and back it out about 1/8, or until the transition is good, plus a tiny bit. Then return to the high end and retune for max, minus a little. Pull your plug, and post a picture of it...

DAVESDAD

Ok, this sounds like a plan. I'll mix a fresh batch of fuel, go for 32:1 as Don suggests and tweak the needles. Next chance I'll get to run the engine is this weekend (weather permitting, here in the UK only manged about 15 flying sessions this year due to wind, rain or both!) and let you know how it goes.

Thanks for all the advice, previous biggest engine was a Saito 82 this is a different world but these gas engines do sound nice.

arobatx

Good luck, let us know how things go! Happy Flyin

Don M.

My Feedback: (5)

I didn't realise that you never set the needles. A rich low speed will affect you to at least 1/2 throttle or more. I had to richen up the low end on my Taurus a few days ago and I went a bit too far and it burbled like crazy in the mid range. Turned it in a hair and it smoothed right out. Go that route before anything else.

As far as timing your engine it is very easy to do but you need a few pieces of equipment to do it right. I'll give you a link when I find it - it's too much typing for me.

Here's your link http://www.ch-ignitions.com/CHinst.html It looks complicated but it's not.

PAPE

well I to just got one of these engine and I really only started it once for like 10sec and It did kick and ran a bit rough so I whent ahead and checked the timing I was exactly at 36 degrees BTDC, adjusted at the lowest seting (the pick up sensor is adjustable a few degrees) so it is a bit advanced. I am going to go ahead and trim the tabs on the sensor to get it down to 28 degrees and se if its runs a bit better.

Don M.

My Feedback: (5)

You have the opposite of my 45 it was set at 10 degrees. These are good engines when you iron out the wrinkles. I know their cheap but they should come ready to run, IMHO.

Lemjim

I just fired up my CRRC50 this afternoon, its mounted in a Giant Stick, started great but I thought it was going to shake te plane apart, not bad at idle and full bore but the midrange really shakes. At first I thought it was vibration from out of balance, checked the prop and it checks out ok, it could be vibration or will a rough carb setting or timming cause the problem? Carb setting is at the factory setting and fuel is 25:1 Klotts. It only ran mabe 15 min or so. Dont want to take this thing to the field till I get it smoothed out a little.

Regards, Lemjim

Tired Old Man

My Feedback: (1)

Problem 1: "Factory Settings". There IS NO SUCH THING!!! It has not been set for your plane/prop/gas/oil ratio/elevation/atmospheric conditions so how can ANYONE anticipate that it will run as well as it could? Reason for the emphasis is that this has been said thousands of times before and is likely covered in the engine instructions as well.

Problem 2: Oil Ratio: See factory settings above.

Possible Problem 3: Check Timing for 28 degrees BTDC.

Problem 4: Age of Engine: It's new and needs to be broken in further.

Don M.

My Feedback: (5)

I've never had an engine that didn't need BOTH needles adjusted and I've never run an engine for more than a couple of minutes without doing these adjustment. As already has been said "there ain't no such thing as factory settings". Welll maybe there are but that's exactly what they are FACTORY settings.

PAPE

To be honest I have a 1/5 scale truck with a 26cc zenoah engine that never ever had to have any H or L adjusment, I acualy bought it and ran it months without tuching the neddles. I did have to adjust it when I added a tuned pipe.

But all the other gas engines (planes) have had to been tweeked.

Abouth my crrc 50 I already set it to 28 degrees, but I havent got to run it. I will be runing it in on my bench at 30:1 regular 2 stroke oil.

Lemjim

Thanks for the info, havent had a chance to run it today yet to check the carb settings, still thinking along the vibration aspect, I hope its not the case, my only other gas job is a Fuji 32EI in a Giant Super Sportster and it is smooth at most RPM'S.
Thought I might get a comment if the CRRC50 was enough engine for the Giant Stick, it sure pull's hard at your heals standing in front of the horz. stab, thanks for good epoxy.

Thanks, Jim

PAPE

Check the timing and also other things to check: spark plug seat (make sure there is a good seal between the plug and the head, and also make sure that the prop shaft is tightly screwed on to the crank shaft.

Lemjim

Will do, got sidetracked on some non related stuff (not by choice, know wat I mean) .

What's with the spark plug that comes with this thing. What plug should I get for back up?.

Later, Jim

Lemjim

Just ran it for about 30 min, sure starts good, smooth at the top with a fair idle, midrange lots of sputter, will run it a little more then try my hand a timing and carb settings. It has a very good transition from idel all the way up.

Thanks, JL

Ratchet

My Feedback: (1)

I would also change the stock plug for an NGK BPMR6F and make sure the gap is set to 0.020.

=R=

DAVESDAD

Hi All

After waiting for 2 weeks we finally got a fantastic afternoon for flying. Temperature 20c and no wind. Following the advice from you guys I started adjusting the needles on the CRRC carb and reset the throttle travel, I didn't have the midpoint quite right. What a difference! Just leaning the bottom end a touch and the engine is now responsive and pulls like a train. I'm still using the 25:1 petrol oil mixture so there is still a little of the black sludge from the exhaust but much less than before.

Thanks for all the advice.

A bit of advice to anyone putting a 50cc such as the CRRC in a Hangar 9 Extra 260. When I checked the aircraft yesterday I found the engine bulhead was loose. In this aircraft there are 2 pieces of metal angle which hold the bulkhead to the sides of the engine box. The angle is hold by 4 plain nuts, not nylocks, and bolts on each. On my aircraft all had come loose and with no glue being used the whole thing was in danger of falling out. I've now tightened everything up, glued the bulkhead in and reinforced it with fibreglass tape. Seems fine after 5 flights today.

Cheers

Tony

Don M.

My Feedback: (5)

Glad your happy now. There are just so many people who are reluctant to adjust the factory needles I don't understand why. As I stated somewhere in one of my post I don't think I have every run an engine that I wasn't adjusting the Hi & Low before I had 1/2 a tank run through it.

PAPE

davesdad Do you think the engine shook to much because of it been out of tune or because its just a cheap engine???

I still havent goten to start mine its still on my engine stand, but Ill post here how it goes when I get to it.