Brian Winch two stroke tuning article?

[mightypeesh]

Hi Gents. Does anybody know which issue had the artical regarding tuning using a tacho? I think it was called 'Two stroke tuner' or something. there was a four stroke article in the adjacent months edition too. Maybe last year (or the one before!) I know there used to be a content index on here somewhere but I can't find it for looking.......

Cheers, Simon

[Dai Fledermaus]

Not last year or the year before, but November 2012. Time flies don't it.

[Nigel Grant 1]

November 2012. The article starts with- if you follow a few simple rules, tuning model engines can be incredibly satisfying. Certainly his advice has always served me well.

Nigel

[mightypeesh]

Thank you gents - much further back than I realised. That will be why I could not find it!

Cheers, Simon

[bert baker]

Not sure what you are looking for, is it repair and tune / installs or make your own from plans.

Not sure how many years ago,but there was a article on making a Vega twin,, Also A Matador, there was various types of Matador,, Single ,,Flat twin,, may have been been a boxer twin.

Another I read was a Falcon it was a boxer engine for large planes,you could buy honda pistons to save time.

I have a book on model egines gives loads of instal and tune tips for two and four stroke engines.

Bert

[bert baker]

Google search, How to tune an engine Brian winch.

Loads to ead and some vids as well

Is there anything specific you are looking to find out..

Bert

[Former Member]

[This posting has been removed]

[bert baker]

Hi Percy,

I meant the Vega 9cc Twin as designed and made by David Parker ,Circa 1986.

Plans are still avalible at Myhobbystores. under vega 9cc twin

His son used to show his engines at Soundown engineering show many moons ago.

Hope you are enjoing the nice weather

Bert

[bert baker]

The other Vega engine was a four stroke using side valves.

Edited By bert baker on 08/05/2016 17:38:22

[Former Member]

[This posting has been removed]

[bert baker]

Perhaps origons of Ken robinson of Rochester,,

No I know nothing about them

But I do own a G/mark twin.

Edited By bert baker on 08/05/2016 18:24:23

[bert baker]

Back to the origons of this thread.

I use a handheld Tacko meter on a regular basis. My ears ain't as good as they used to be.

I find it very usfull to see the difference of rpm levels after some very fine tuning, I do have an electronic rpm meter fitted to a electronic ignition petrol engine and it does seem quite accurate.

[mightypeesh]

Hi Bert, you are way too advanced for me! I have over the last couple of years been defecting over to ic from electric and am on a steep learning curve with it all!

I am just trying to tune up an old OS Max.20 and suspect the previous owner was a bit of a needle fiddler which is causing the running problems. I am meeting the clubs engine guru later on this week but like to explore all avenues myself and hopefully sort it out before hand. I remembered reading the article before but have maybe been lucky with all my others engines in that they run sweetly just by normal adjustment of the needle. I have a tacho so should with the aid of Brians article be ok. I wil have a search and look for the videos though as every little helps.

Cheers, Simon

[Jon H]

While i have not read the article in question the idea of tuning with a tacho is quite alarming to us at Laser.

Now i dont know exactly the procedure detailed in this article so i might be off track here, but if it involves watching the tacho while leaning the engine then i would not recommend it as it will probably lead to an engine that is too lean and/or too hot. The reason for this is that when the engine is cold and first run up to full power/tuned it will run faster than a minute or two later when it is fully warmed up due to normal expansion of the engine. What we have found in the past is that some people have seen this high rpm figure (say 8500) on the first run up, then spent quite some time fiddling with the needle trying to get those rpm back after the engine has warmed up and come down to 8300. This has lead to an engine being flat out on the ground for far longer than it should be and getting rather toasted which is not good for its health and results in the rpm dropping further as it heats up. This in turn leads to more fiddling and more heat.

Given that engine rpm will vary day to day with atmospheric conditions i would recommend tacho's are only used for a reality check as Bert seems to suggest and not as a direct tuning aid.

One final thing on tuning, be careful not mix up and overheated engine with a lean one. They are different things. If the engine runs fine on the ground and fine for the first few minutes in the air before loosing power is is likely too hot and not too lean. This can be checked by landing the model, letting it cool and flying again without refueling. If the cycle repeats then clearly the lower level of fuel in the tank is not leaning engine out too far and problem is heat, most likely due to inadequate cooling or excessive full throttle use.

[mightypeesh]

Thank you for the warnings John.

The gist of the article (as I read it) is to use the tacho as a visual tool rather than the pitch change - something I have trouble discerning with my ears. He says that the initial revs will drop by about 300 and then to wind the needle out again 3-4 clicks. The visual indication of the tacho was the reason I sought out the artical because as like I say I have difficulty discerning the subtleties of the pitch change. It also goes into setting the idle too.

The Max.20 I have got fires up straight away, and runs at full throttle no problems and transitions smoothly. The problem is that at anything below full chat it starts slowing over about 5 seconds before cutting.

Like I say I am on a learning curve with this IC lark but enjoy what I see as challenges of getting a stubbon engine running.

Thank you once again for your input

Cheers, Simon

[Jon H]

Is that the os max20? if so they had air bleed carbs if i recall and the air bleed screw could be out of its adjustment range. Its worth resetting it and starting again. The base setting i use is with the screw blocking about half of the air bleed hole.

Also, when it slows down and cuts does it cough/splutter down or does it just slowly wind down?

[stu knowles]

To set the slow running needle (or screw in the case of an air bleed carb) start and tune the engine for max rpm then add a couple of clicks to be on the safe side.

Reduce the throttle to the slowest reliable idle, (if the slow running is miles out, then in the first instance, leave the glow lead/stick attached. When the engine has settled to a steady speed, pinch the fuel line just out from the carb and wait.

If the rpm just dies away until the engine stops, then the slow running adjustment is too lean - adjust to richen the slow running mixture (keep off the main needle!)

If the engine rpm increases significantly before slowing & stopping, the slow running mixture is too rich. Adjust and try again.

If the rpms just increase slightly and then die off, the adjustment is correct. Go fly.

Others may have their on pet method but this one always works for me

stu k

[stu knowles]

Incidentally, while I'm on, I've always found the method once promoted by the well known purveyor of certain Italian engines which involved pins and blowing through tubes pretty carp as a means of adjusting a carb

[Jon H]

While i wouldnt 100% agree with Stu's method its a pretty good way to go. Personally i set my engines to maximum performance, ie no few clicks rich and i also set them a tiny bit lean on the slow run needle to allow for the engine to richen up in the air. I know everyone will yell at me because apparently engines go lean in flight, but they dont, they go rich so i set my engines accordingly.

For slow run tuning i find that punching the throttle open from idle is a better way to set the slow run. If it accelerates lean it off and keep going until the bogs down. Then come back a bit. And i have had mixed experiences with the pin/blowing method. I found it gave a reasonable setting for getting the thing started but as i was able to figure that out on my own by...err, starting it, and making adjustments if it didnt start that i dont use it any more. I dont like the pinch method as an engine that is at the limit on the throttle test may still pick up revs if pinched which will lead to a lean slow run and possibly a lean cut on acceleration.

I have a video here of me setting up a Laser 150 with both needles really rich. Please ignore my filthy old test bench though. Its been replaced with a new once since this was taken!

[mightypeesh]

Wow, thanks for the input folks. I have had a play today at the field with this engine and am getting closer with the low end setting as she does not cut out so easily, though still well above what I would call an Idle. I will give your methods above a go to see if I can nail it on Wednesday. It is a (very well) used OS Max.20, and it is just slows before stopping so need to refine the air bleed needle more. The video make a lot of sense too, thanks Jon.

On another note whilst I have your expert attention I was also trying to get another OS Max.20 running today - this one is brand new though and was un-run until this morning. She fires on the button and runs the full range until you take the glow off........ I have tried two new plugs that both glowed bright and also one that a club mate gave me with an 'idle bar' on it - a metal strip across the filament which improved it a bit but still she would suddenly stop when the glow was switched off. not sure where to go with this one?

I am learning a lot here so thank you all for your input and time taken for replying.

Cheers, Simon

 

Edited By mightypeesh on 09/05/2016 17:23:49

[cymaz]

MightyP

This article on RcU has saved me several times from brain melt down , very useful if you lose the needle settings entirely

[mightypeesh]

Thanks to all your tips and tricks and some time spent at the foggy field this morning fiddling both engines are now running beautifully on tune

Thanks to all, Simon

[cymaz]

Good to hear....now don't fiddle with them!