Simon Lumsdon 1

To reiterate, its not a shrader valve, its just the same outside diameter, it has no internal valve whatsoever nor thread to hold one etc. its categorically not a non return valve. my assumption is the blue t pieces branded “spark” must be non return valves and i wondered if anyone had seen this before? pumped it up earlier and its holding air and now no air is leaking out of the fill valve now which is odd. anyway, restrictors have arrived and i plan to fit these ahead of the legs to slow the operation speed and stop the slamming. I will then connect it all up again, pump it up to pressure and go for another test

Its a shrader thread on outside but definitely not a non return valve, just a hole through the middle

I can only assume the blue t pieces contain a one way valve?

Check the wiring, has the connection loosened or dirty/oily

Thanks for all the good advice which is taken. Im still a bit puzzles as to where the dill non return valve is since the fill valve definitely has nothing inside, just an adaptor to allow a shrader valve to attach to the airline? Anyway, have now ordered a non return fill valve since it cant so any harm.

Hello Finishing an old topgun? Spitfire artf and it came with air retracts which i dont seem to be getting on with. Firstly one of the legs was sticking, eventually fixed. Now when i pump air in via the fill valve its slowly leaking out again via the fill valve (can hear it hissing). They slam up and down so have ordered some delay couplings from MSL’s, hopefully they will help Question, where is the non return valve that stops the air escaping? The fill valve doesnt appear to be non return which is confusing? There is a blue three way adaptor after the fill valve that connects the reservoir to the fill valve and the switch body, im guessing it must be that? If so, surprised its leaking Think i have the valve switch servo movement correct adjusted, goes to circlip on both ends all advice welcomed, thks

Three switch posns, up, down1 & down2

On the T6K radio you have to use the air brake function to mix flaps into the ailerons, i use a 3 position top switch and this give two levels of drop. Works well

Having recently battled with a barely used asp 90 fs and had troubles with idling, bearings and compression i switched to a similar os 90 fs which was immediately perfect. I have now had a few asp engines and all seem to have poorer carbs than os engines, all idle poorly and build quality isnt quite as good. My lesson learned is to stick with os. Power wise think the 70 will be more than enough, good luck

As a returning flyer i settled on this setup plywood flying box with cut out for a 12v gel battery and MFA board. Use the MFA board for the glow lead and fuel pump, the MFA board shows glow current which is useful. Used to use the board for a 12v starter as well but realised (as prev comments) that for big (60 2 stroke) motors a geared starter is a must , now use a JustEngines geared starter in a cradle with 3s lipo. Try to keep it simple

Hi Jon, sorry, to be clear i am screwing idle in a bit and checking it throttles up ok as you describe. Next step is to replace o rings and manifold paper gasket to eliminate possible air leaks

Correct, That was the absolute slowest i could get it to run, screwing the low speed idle clockwise, inwards until it cut. (12x6 prop, optifuel 12% fuel) in comparison the os 91 runs at 9600 max revs and will idle slightly slower but definitely a more reliable idle that the sc. thanks to all for all the help, i find this incredibly useful, so much to learn

Sorry, tried to save it in a compatible format but failed, not easy is it …

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Well ran it on the bench this morning and end float issue resolved, only normal float now spent some time dissling with the low speed idle and could just about get it down to 2800 revs, wot gives 9100. compression seems fine to answer a prev question. Will give it another chance in a model but wondering if inverted position is a factor. Loathe to use an onboard flow

Its on the test bench (upright) ready for the weekend and some more running in and testing. Compression seems fine, my moneys on the carb …

Bearings replaced and end float reduced to acceptable amount Engine still wont idle below 3500, fiddled with low speed idle but thats not the issue, got fed up, whipped it out and changed it for an os 91 fs i had, immediately did 9600 on a 14x6 and would idle 2500 nicely. Was able to go to field and practise landings with Mustang, much improved Need to pull sc 91 fs carb apart and perhaps try new o rings etc? Hmmm

Sorry 10mm

Interesting, dont think front bearing sits on a shoulder in this instance, just a plain shaft. Suspect the taper collar isnt seating back far enough and leaving a gap allowing crank to float in and out. If it does it again i am going to buy some 8mm shims of ebay and pack between from bearing and taper collar which should fix it

Thanks Engine Doc, fitted new bearings and rebuilt engine, compression seems fine. Thinking about it cannot see how end float occurs unless taper behind prop driver not properly seated? The crank is pulled against the driver so no float unless that taper wasnt seated. Dont think it can be the bearings floating etc Anyway will bench test it this week and hopefully sort out the low speed running

I had thought about thread lock but how would i get the bearing out next time? However might be forces to look at this

Thanks to all for this fantastic advice. Agreed two likely separate issues have ordered new bearings, £10 so no reason not to. Suggestion of ensuring taper is firmly against front bearing is gold advice, if not securely seating that would allow end float. low speed running, will set it up on the bench once above all sorted, agree it should easily do 2000 revs (and i now have a tacho to check)

Thanks, yes, new bearings ordered, i will then have another bash at the low speed tuning.

Thanks Jon, noted on the lean low speed needle. I bough a tacho, very useful, full throttle on a 14x6 gives 9300 but low speed difficult to get below 3000. Noticed engine would bog down in flight when idling and throttle opened, took some time to pick up think you might be right and front bearing is becoming loose in crankcase, witness marks on outside of bearing are suspicious new bearings ordered