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CRRC pro GP50R Porting. (What the??)

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CRRC pro GP50R Porting. (What the??)

Old 05-23-2012, 02:35 AM
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Ozpulse
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Default CRRC pro GP50R Porting. (What the??)

Has any body else had a look at the porting of one of these? I was given one to put new bearings in (third set) and do a polish job on the ports for a friend.
Talk about rough casting!! Most of the weed wacker engines I play with are a lot cleaner/smoother than this thing by far!
Already spent quite a few hours just smoothing the port castings out and still not ready to do a proper polish on them, so many pits, dags, high spots I couldnt believe it.
Never mind that the crank bearings are that tight in the casing that they feel rough before the crank goes in, which is why his engine is far too tight once assembled and he is now on his third set.
Not real good for a engine with only minimal run time!
Old 05-23-2012, 02:44 PM
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3136
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Default RE: CRRC pro GP50R Porting. (What the??)

If he has done such little run time and on a 3rd set of bearings he should give up on it and buy a DLE or better yet a DA
If you would like to warn more people about the poor quality of CRRC post some pics
Old 05-23-2012, 08:39 PM
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Default RE: CRRC pro GP50R Porting. (What the??)

I did not intend to bag their product but was more hoping someone would have posted up that he got a dud engine and that this is not normally the case.
As I said, I usually play with converting weedies for myself and a couple of friends. I am not a flyer (more boats/Airboats)so have not had much experiance with these purpose built engines but I would never pay good money to end up with something like this one.
I have pretty much smoothed out all the ports now and polished the exhaust port already but still have to start on one of the transfer ports so will try to get a good enough pic to post up if you guys would like.
I will be skimming the main case to relieve the bearing areas by a thou. or two, so that will fix the binding problem. Im also thinking of getting a seal with a larger ID so I can spin up a sleeve to go between the two bearings to stop loading them up when the prop adapter is torqued up as they are only standard bearings and not designed for side load as proper 'thrust' bearings are .
I actually have 12 years experience as an Overhaul Tech. working with full scale Aircraft so I have access to all the tooling needed, so its really just time to get it all done and put together right and he should have a good engine will last.
It will probably perform a lot better (rpm etc.) by just fixing the binding bearing problem without all the port work so it will be interesting to see once its all back together how it performs compared to other peoples stock versions.
Old 05-23-2012, 08:52 PM
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Default RE: CRRC pro GP50R Porting. (What the??)

Is this the engine?
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Old 05-23-2012, 11:44 PM
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Default RE: CRRC pro GP50R Porting. (What the??)

Looks pretty close, its the same muffler, rear carby but slightly different prop adapter. The one here has cutouts around it.
Old 05-24-2012, 04:33 AM
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Default RE: CRRC pro GP50R Porting. (What the??)

I worked with these a bit about 4 years ago.

If you make good power you'll brake the mounting lugs off the engine, they are very weak.

I made a mount out of aluminum for mine.
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Old 05-24-2012, 04:42 AM
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Default RE: CRRC pro GP50R Porting. (What the??)

When I first got mine I could swing a Xoar 22x8 6200 rpm after timing it properly. I played with the ports, not much can be done there, they are small and the walls are thin. I played with putting a window in the piston too, I finally got 6400 rpm.

I looked at the carb block and did this modification with a dremal to give the fuel/air mix a better shot at the reeds, it takes about 30 seconds to do. I was able to get 67~6800 rpm out of it before I started blowing the mounting lugs off and need to make the aluminum box mount.
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Old 05-24-2012, 04:49 AM
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Default RE: CRRC pro GP50R Porting. (What the??)

The first engines I got where pretty smooth, but if you had a tail-dragger and the engine stopped at the right place the con-rod slid back into the transfer port and the engine locked up. I doesn't happen while the engine is running, but it was annoying. The factory then started putting a steel button on the crankshaft to hold the con-rod on, but this made the engine a real shaker.

I replaced the sheet metal bar that holds the reeds on with a thick aluminum bar, this prevented the con-rod from sliding into the transfer passage.
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Old 05-24-2012, 05:09 AM
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Default RE: CRRC pro GP50R Porting. (What the??)

The intake ports need not be smooth. The fuel mixture is wet and will cling more to a smooth surface. Exhaust can be smooth. Matching all ports is a very good idea, that way there is no stepbetween bolt together parts that have ports. My cousin had a flow tester and did many, many port jobs. Also the engines he worked on held National Records for ten years strait. All 2 stroke Snomobile engines. Capt,n
Old 05-24-2012, 09:54 AM
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Default RE: CRRC pro GP50R Porting. (What the??)

It would be best to think of the motor as a 40cc and prop it that way, 18x10 or 20x8 and let it spin up more.
Old 05-27-2012, 07:32 PM
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Default RE: CRRC pro GP50R Porting. (What the??)

I was runnig a GP50R in my Sbach. That was until I hit the wall to hard and the Engine/Firewall broke out of my Sbach. It had seen a lot of air time and hard work. It broke it's back when it fell to Earth, luckly I was not to high. Anyway nearly fixed now, so It will fly again.
Now about the GP50R. The only problem's I've had with it, is the pitts muffler that came with it, cracked and the standared reed block. It's made of plastice and it broke. Now running a metal reed block.
Good engine, funny prop hub bolt patten though, can not use a TMM/3WW jig. It comes with one though.
I'm getting good results from a CF 22X8 prop. My engine was one of the first from CRRC. I think they have changed mufflers now.
The blue engine in earlier post took like a early MT50.

Cheers
Grossy
Old 05-27-2012, 08:28 PM
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Default RE: CRRC pro GP50R Porting. (What the??)


ORIGINAL: grossy2


The blue engine in earlier post took like a early MT50.

Cheers
Grossy

No, this is a MT50, mine runs great.
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Old 05-29-2012, 02:08 AM
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Default RE: CRRC pro GP50R Porting. (What the??)

Thanks for the replies and advice guys, will be sure to let him know to keep an eye on the mounting lugs!
This one has the button holding the conrod to the crank so no problems there.
Old 05-29-2012, 03:27 AM
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Default RE: CRRC pro GP50R Porting. (What the??)


ORIGINAL: Ozpulse


This one has the button holding the conrod to the crank so no problems there.

Every one I've seen with the button was a sssssshaker, I'd think about removing the button.
Old 05-29-2012, 05:48 PM
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Default RE: CRRC pro GP50R Porting. (What the??)

There seams to a bit of confusion.
This is the GP50R
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Old 05-29-2012, 05:52 PM
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Default RE: CRRC pro GP50R Porting. (What the??)

Sorry wrong photos. I need to lable them better.
Here is the GP50R in Sbach.
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Old 05-29-2012, 06:35 PM
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Default RE: CRRC pro GP50R Porting. (What the??)

Yea, that's a different engine. The reed block is like the DL50 I've got, and the crankcase looks cnc'ed. With the Chinese you have to be careful thinking you have a billet cnc'ed crankcase, I saw one that was cast, then they ran a cnc machine over it to give it the "look."

Read this, it may save you some tears:
http://www.troybuiltmodels.com/ns/learn/pittsbracket/

The TBM pitts type Silent Beauty is nice I had one it worked well.
Old 05-31-2012, 08:10 PM
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Default RE: CRRC pro GP50R Porting. (What the??)

The pictures that " soarrich " posted are not a CRRC Pro GP50R engine.
I had a prototype GP50R for testing. S/N 0005
Went trough two engines with a too soft of aluminum engine case.
The bearings started to get loose in the engine housing.
Crank, connecting rod, bearings, cylinder were all from DL-50's ( Pre DLE-55 ).
CRRC made their own engine case and there own ignition.
I replaced my ignition with a Rcexl after two failed CRRC units.
Went through some issues with prop hubs ( prototypes were blue, productions were red ).
1st prototypes ran super strong, 2nd and 3rd had less rpm's (-300 ) with the same exact props.

Here is pictures and pictures of it ripped down for repairs.
Compare the machining of your engine to a prototype.























Old 06-01-2012, 05:18 AM
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Default RE: CRRC pro GP50R Porting. (What the??)

The Chinese, as we know them as modell engine manufacturers are fast copiers and hard learners. They still don't tighten their tolerances, why? I don't know. It's like that since they begun with it and it's still so, even for DLx 's. I think they just don't care.
As long as they make good business what the heck.
I had 2 Chinese, 1 crrcpro in which I couldn't keep bearings in and a DL50 I had to replace the crancshaft because of too much
big-end play (tingelingeling). I see more of this with other DLx users. I hate engines with unproper mechanics so I'm done with them
never mind their low cost.
For my knowledge, 3 brands stay upright, 3W, Zenoah and DA in random order. OK count ZDZ in too if you guys in the US have
proper service for them.
Old 06-01-2012, 07:26 AM
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Default RE: CRRC pro GP50R Porting. (What the??)

I don't understand why guys mess with the Chinese POS engines. It's got to be more than price. I've seen a ton of them, probably 10% run well, 40% run lousy and the rest don't last long enough to see how they would run. By the time you replace all the defective parts you could have bought a good quality engine or two and saved a few planes. I can think of one
, just one, of those engines that actually runs well and thats the DLE. Quality is nothing like the DA they cloned but not bad, longevity is another matter.
Larry
Old 06-01-2012, 07:57 AM
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Default RE: CRRC pro GP50R Porting. (What the??)

Yep, DA's are I I have now and all I will have.

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