Bad experience with CRRC Pro 45cc

[Engine Doctor]

Hi all . I am wondering if any other readers have had a similar experience with any CRRC pro petrol engines . I have had a CRRC 45cc for some years now . It was bought new at Watford swapmeet and  has always performed very well until recently when after a long flight it refused to start for another sortie. On closer examination the crank shaft had developed a lot of end float . I stripped the engine down and found that the bearings had started to float and rotate  in the crank case . This produced  aluminium patricles that found their way to the piston ring and decided to pick up on the chrome cylinder walls . Bits of chrome then found their way into bearings etc . I have a couple of these engines and this ,being an early model is the only one to show sloppy fits from new. After a thorough strip and clean ( you'd be amazed at the ammount of metalic particles that wash out of an engine) I decide to rebuild it . New bearings from a local bearing supplier where fitted using  Loctite bearing fit . This should hold them firmly in situ and a  steel shim was made up to reduce the end float on the crank to an accepltable level . Falcon Aviation supplied a new cylinder and piston rings (priced very reasonably and delivered very quickly ) .Once assembled it now runs superbly and is much quiter mecanically . I have run it for about half an hour so far on a 25- 1 mix fuel to get  running in started and it feels very smooth compared to it feel from new . I know these are budget chinese engines but beware of the early examples as the machining was obviously very hit and miss . 

 

E.D

Edited By Engine Doctor on 19/06/2010 11:23:00

[Paul Gauci]

  I have the 45 and it is still nice and snug, but I'll be keeping an eye on it. I haven't done a lot of hours on mine however. 

 

 

 Chinese machining hit and miss?  never! 

[Owain]

Hope you can help with my CRRC Issue?

 

I have a CRRC 45 which was running fine until I had a bit of a mishap and crashed into a field.

I have replaced the cylinder and got it going but it's throttle response is now very poor. I have set the low and high needles to what seams to be a nice smooth mixture setting but if I leave it idle for 20 seconds and go straight to full throttle it just dies and stalls. If I move from Idle to full throttle slowly (in about 3 to 5 seconds) it climes nicely and runs very smoothly? I have tried richening both needles but it doesn't make a difference so I tried leaning them both and its the same? I have checked the fuel filters and all are clear and there doesn't seam to be any fuel starvation??

 

Any ideas what I should check next??

 

Owain....

[stu knowles]

The correct way to set up the Walbro type carb is to get the thing running at about 2000 rpm, which is only just up from a fast tick over. Adjust the slow running jet (which is always furthest away from the carb mouth) for best speed and then screw out one quarter turn.

 

Then open flat out and adjust the high speed jet for best speed, then open '10 to 15 minutes = quarter turn just less)

 

Check and repeat as necessary.

 

 

These instructions are lifted from a husquvarna chainsaw handbook and are contrary to many of the things that I have read about Walbro carbs in the past,To be honest I was very sceptical when I read them.

 

However, since adopting them, I have found them reliable and they have improved the running of my own engines.

 

 

If this doesn't afffect a cure, you know to look elsewhere. Ignition system seem to work or they don't so i would always look at the fuel supply first, and scrupulously clean the carb.

 

Hope you manage to get it sorted.

stu k

Edited By stu knowles on 19/01/2012 15:44:15

Edited By stu knowles on 19/01/2012 15:45:16

[Engine Doctor]

Hello Owian . the CRRC engine I re-built is still running very well . The engine you rebuilt sounds as though it may have an airleak . When you crashed it what sort of damage did it do ? you say that you re-placed the cylinder but did you check that the flange on the crank case is not distorted ? A crash can often result in a twisted crankshaft, this will be felt as a stiff engine or a tight spot and will eventually wreck your engine . Easily corrected though . If the crank is out of line/twisted the oil seals could be leaking air. Another part to check is the neoprene tube from the crank case to the pump . This supplies the air pulses that work the pump in the carb and if it has a tiny hole this will affect the puming of fuel. Hope you sort it.

 

regards