IanInJordan Posted May 24, 2020 Share Posted May 24, 2020 Hi all. Struggling to tune the Walbro carb on my MY19 Moster 185. Seems to be running rich at idle from the spark plug colour and exhaust smell. If I lean it using the low jet screw, it stalls when I throttle up from idle. The high jet is still capped with the factory tamper proof cover, so that has not moved. Any advice much appreciated. Quote Link to comment Share on other sites More sharing options...
kiwi k Posted May 24, 2020 Share Posted May 24, 2020 5 hours ago, IanInJordan said: Hi all. Struggling to tune the Walbro carb on my MY19 Moster 185. Seems to be running rich at idle from the spark plug colour and exhaust smell. If I lean it using the low jet screw, it stalls when I throttle up from idle. The high jet is still capped with the factory tamper proof cover, so that has not moved. Any advice much appreciated. Official settings for L screw 1/4 to 1/3 of turn but i would set it so it ticks over and then adjust accordingly so it revs cleanly, i would not worry about plug colour at idle just get it ticking over and cleanly revving, the only way to do a plug chop is to warm it up and do a 15 minute flight and turn it off then glide in and land, if not possible there might be other problems ?, how many hours on motor ?, how long since carb rebuilt?, how long since flown ? the list goes on. Quote Link to comment Share on other sites More sharing options...
IanInJordan Posted May 26, 2020 Author Share Posted May 26, 2020 Thanks Kiwi. Useful. Motor is sub 10 hours run time. Putting fresh fuel mix in and will give it another go. Regards, Ian. Quote Link to comment Share on other sites More sharing options...
IanInJordan Posted May 30, 2020 Author Share Posted May 30, 2020 Fresh fuel/oil mix plus tuning as described above did the trick. Thanks again for input. Regards, Ian. Quote Link to comment Share on other sites More sharing options...
kiwi k Posted May 30, 2020 Share Posted May 30, 2020 Numerous times people have mentioned this and several times goes down to incorrect fuel mixture , only other thing i would ask is oil Make your using and ratio percentage ? Quote Link to comment Share on other sites More sharing options...
IanInJordan Posted May 31, 2020 Author Share Posted May 31, 2020 I am using 95 RON fuel mixed at 2% with Motul 710, as per latest Vittorazi guidance. Quote Link to comment Share on other sites More sharing options...
Pete S Posted June 1, 2020 Share Posted June 1, 2020 I am not sure if the advice has changed but the Vittorazi Manual on the Parajet website has the oil/fuel ratios below. Quote Link to comment Share on other sites More sharing options...
IanInJordan Posted June 1, 2020 Author Share Posted June 1, 2020 There seems to be a variety of guidance on this. Parajet now seem to suggest Motul 800 only, whereas I had the attached originating from Vittorazi and dated Apr 2020 forwarded to me from a dealer. Quote Link to comment Share on other sites More sharing options...
kiwi k Posted June 5, 2020 Share Posted June 5, 2020 And that it exactly what everybody else goes by only some tend to use 710 more because it seems not to carbon up crown ans head so quick as 800. Quote Link to comment Share on other sites More sharing options...
IanInJordan Posted June 21, 2020 Author Share Posted June 21, 2020 All, Thanks again for input on this. Still struggling with the tuning to be honest. I have tuned according to above settings and advice so it idles properly and accelerates cleanly to max revs with a sudden application of throttle from idle. If however I hold it at 3,000-3,500rpm and then give it rapid full throttle, the engine dies completely. I read elsewhere that this a characteristic of a diaphragm carb at mid range revs and 'flooring' it from mid revs should be avoided. Quote Link to comment Share on other sites More sharing options...
admin (Simon W) Posted June 21, 2020 Share Posted June 21, 2020 I once heard from a Moster wizard, tune the low jet until the engine vibration is minimal. Also, the adjustments on the low jet should be every so very tiny 1 min increments. That same wizard came to Membury one day and sorted out 5 machines doing exactly the above. SW 1 Quote Link to comment Share on other sites More sharing options...
kiwi k Posted July 21, 2020 Share Posted July 21, 2020 On 21/06/2020 at 19:30, admin (Simon W) said: I once heard from a Moster wizard, tune the low jet until the engine vibration is minimal. Also, the adjustments on the low jet should be every so very tiny 1 min increments. That same wizard came to Membury one day and sorted out 5 machines doing exactly the above. SW Very true adjustments are only like a screw driver blade thickness adjustment and experienced tuners do it by sight and listening to engine, when set right after you give it some throttle the revs will drop then pick up again as should. Quote Link to comment Share on other sites More sharing options...
Quentin Brendemuhl Posted July 21, 2020 Share Posted July 21, 2020 Can you burn up your engine by tuning it too lean? I recently installed a CHT and EGT, and it seems really hot. Like I could pretty easily push the CHT to 420F. That's really hot isn't it? Maybe my gauge just isn't reading accurately? My EGT is running 1,100F. Quote Link to comment Share on other sites More sharing options...
IanInJordan Posted September 13, 2020 Author Share Posted September 13, 2020 The attached section of the Vittorazi user manual suggests max CHT and EGT to be 250C/482F and 550C/1,022F respectively, so sounds like yours is running lean. I now seem to have sorted my tuning woes with which I started this thread. Engine now runs sweetly on startup and in the air. I was surprised at how small the low speed adjustments needed to be however. My CHT is now steady at approx 150C/300F in cruise. I think this may be slightly rich but I am starting and taking off at 2,700ft altitude but grateful for other views on this. Moster 185 Specs.pdf Quote Link to comment Share on other sites More sharing options...
kiwi k Posted September 13, 2020 Share Posted September 13, 2020 1 hour ago, IanInJordan said: I now seem to have sorted my tuning woes with which I started this thread. Engine now runs sweetly on startup and in the air. I think this may be slightly rich but I am starting and taking off at 2,700ft altitude but grateful for other views on this. Moster 185 Specs.pdf 949.01 kB · 0 downloads So it was purely down to minute adjustment on Low screw , slightly rich just means slightly more fuel burn but saves from wrecking the motor Quote Link to comment Share on other sites More sharing options...
IanInJordan Posted September 13, 2020 Author Share Posted September 13, 2020 Seems like it. Feels like a finer thread on the Low screw might have been a good idea, as that would have made it less of a blunt instrument for tuning. Quote Link to comment Share on other sites More sharing options...
kiwi k Posted September 13, 2020 Share Posted September 13, 2020 5 hours ago, IanInJordan said: Seems like it. Feels like a finer thread on the Low screw might have been a good idea, as that would have made it less of a blunt instrument for tuning. Not true but once you have done it a few times you will just start to learn why and how Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.