Jim Hughes 2 Posted August 29, 2021 Share Posted August 29, 2021 Also in the newbie thread. Ok apologies for this late but extremely early post 05:20 in the morning! A couple of weeks ago I had the first flight with the Mirus - terrifying! But, successful! However, we went out last week with it, decided to lean the engine of a bit, after a couple of circuits stood it on its tail - the engine cut. I had to make a hasty landing, the prop broke and I didn’t have a spare. Good old RC World sent me out some new props rapidly and I was running it yesterday. Same thing, absolutely fine on horizontal, point the nose up, after a few seconds it leans off rapidly and just stops. I’ve tried running it richer and it doesn’t make much difference. Clunk is not hitting back of tank etc, it’s had about 15 tanks of fuel through it - so run in? It’s an OS 35 Max (new) running on good quality fuel. Any advice would be welcome. Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted August 29, 2021 Share Posted August 29, 2021 Will it run the tank out horizontally? it sounds like it could be getting air in the fuel, maybe a small pinprick hole in the clunk line near the top of the tank. Quote Link to comment Share on other sites More sharing options...
J D 8 Posted August 29, 2021 Share Posted August 29, 2021 Upright or sidewinder mounted engine ? Standard tank position? And as above pressure test tank. Quote Link to comment Share on other sites More sharing options...
Jim Hughes 2 Posted August 29, 2021 Author Share Posted August 29, 2021 Morning chaps. It’s an upright mounted engine. yeah it will run a full tank in the horizontal. Plumbing in tank? Fuel feed line from clunk? I apologise for repost from newbies. And really appreciate there is a lot of knowledge out there! The last time I was involved in this hobby over a 1/4 of a century ago - the internet was in its infancy! Quote Link to comment Share on other sites More sharing options...
Jim Hughes 2 Posted August 29, 2021 Author Share Posted August 29, 2021 Pffft ? Sorry guys. School boy error. I’ve just taken the tank out - the clunk is hitting the back of the tank. I’ll get my coat…. Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted August 29, 2021 Share Posted August 29, 2021 hello Jim, you mentioned you leaned it out....maybe open it up a couple of clicks and try it nose up.... ken anderson...ne..1...nose up dept. Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted August 29, 2021 Share Posted August 29, 2021 Most clunks have a cross cut which allows fuel to be drawn even with it touching the end - the usual problem is it being unable to follow the fuel when inverted. Are you sure that you haven’t simply gone too lean - the rudimentary fuel system relies on suction from the engine (maybe enhanced by exhaust pressurisation) to pull the fuel up hill and with the nose high, a weak mixture can be pushed beyond the point where it will support combustion. This is simple to check with the traditional nose up full throttle check. Best practice is to ensure that the tank is as close to the engine as possible and at a height so that the top is around carburettor height (as shown in most engine manuals). Edit. Ken beat me to it! Martin…A long way south of Ken…Long winded reply dept. Quote Link to comment Share on other sites More sharing options...
Ron Gray Posted August 29, 2021 Share Posted August 29, 2021 I had something similar with one of my Laser 240v installations, the engine would run fine but on climb out after take off one cylinder would cut out. Eventually traced it to a small split in the fuel line from the tank to that cylinder, replaced the line and it ran perfectly. Quote Link to comment Share on other sites More sharing options...
Jon H Posted August 29, 2021 Share Posted August 29, 2021 A tank installed too high would also create the problem you mention. Admittedly its unlikely to be too high with an upright 2 stroke but it might be worth checking. Quote Link to comment Share on other sites More sharing options...
Jim Hughes 2 Posted August 29, 2021 Author Share Posted August 29, 2021 Guys, many thanks for all your advice. ive cut about 5mm off the clunk tube, and renewed other tubing. The tank is at a good height to engine and close. I’m going to fire it up again this afternoon, try a richer setting and I’ll report back later Quote Link to comment Share on other sites More sharing options...
Jim Hughes 2 Posted August 29, 2021 Author Share Posted August 29, 2021 Gentlemen, Absolutely spot on. Second flick and she was away (gotta love an OS!) Wound the needle out two clicks and no problem vertical, wound the needle in a a couple of clicks - perfect in both planes and a full tank through. I’ll try it again later, I think the neighbours are probably awake now! Many, many thanks for all the replies. Sincere regards Jim ? Quote Link to comment Share on other sites More sharing options...
ken anderson. Posted August 29, 2021 Share Posted August 29, 2021 (edited) well done Jim,you sound as you are a new flyer etc......try and get into a routine of once the engine is fired and running to do any adjustments from behind the prop....preserve the carol singers...... ken anderson...ne..1 fingers dept. Edited August 29, 2021 by ken anderson. crepe grammar dept Quote Link to comment Share on other sites More sharing options...
Jim Hughes 2 Posted August 30, 2021 Author Share Posted August 30, 2021 19 hours ago, ken anderson. said: well done Jim,you sound as you are a new flyer etc......try and get into a routine of once the engine is fired and running to do any adjustments from behind the prop....preserve the carol singers...... ken anderson...ne..1 fingers dept. Hi Ken, I am returning to the hobby after a very long break, about 25 years! I started as a teenager in about 1985 with a Mick Reeves Hawk, then a Ken Stokes Mirus, then an Acro Wot and finally a Cambrian Fun Fighter Spitfire. I then gave it all up. I was idly googling during Lockdown last year and stumbled upon Nick Reeves on YouTube and realised he’d started reproduction of the Mirus. I had no real intention of starting the hobby again, but one thing lead to another - and here I am! 2 Quote Link to comment Share on other sites More sharing options...
Jim Hughes 2 Posted September 16, 2021 Author Share Posted September 16, 2021 Evening Gentlemen! More fuel supply woes tonight - no flying and I’m running out of light in the evenings. Vertical supply again… Stripped it out as soon as I got home and could not feel or see clunk in the tank, when I tried to remove the clunk and pipe it was trapped in a cavity at the front of tank ( it had folded back on itself) so obviously that was the issue. I’d had a far from smooth landing last week which I’m sure resulted in this. I don’t wish to name the tank I’m using, as I feel it’s unnecessary-but I’m far from happy with it. I just think it’s a bit on the cheap side. Back in the day I used to use Kavan, and I’ve found one, but I always remember the rubber bungs always deteriorated over time. I think a good quality tank is the answer. What do you guys recommend? Quote Link to comment Share on other sites More sharing options...
john stones 1 - Moderator Posted September 16, 2021 Share Posted September 16, 2021 I like Kavan and a bungs a bung, they last as well in a Kavan as any other tank. Quote Link to comment Share on other sites More sharing options...
Rich Griff Posted September 16, 2021 Share Posted September 16, 2021 I have used slec rectangular tanks to good effect. They can supply lengths of the thin clunk type fuel line for glow fuel. I had a similar occurrence once on a heavyish landing with a slec tank... They do other style of tanks also... Quote Link to comment Share on other sites More sharing options...
Keith Berriman Posted September 16, 2021 Share Posted September 16, 2021 Having once had the same problem with a cluck at front of tank i was advised to put some short piece of rigid pipe in clung pipe Inner of sullivan but best hole size avaialable Quote Link to comment Share on other sites More sharing options...
Nigel R Posted September 17, 2021 Share Posted September 17, 2021 3.5mm OD nylon tube, find it on ebay for buttons, cut a short length say 2" and put it inside the clunk tube, toward the back of the clunk tube, that will stop it. The folding forward thing can happen in any tank with an abrupt enough arrival. 1 Quote Link to comment Share on other sites More sharing options...
Viv Letherby Posted September 17, 2021 Share Posted September 17, 2021 What size clunk tube do you use? Myself, nearly all my clunk tubes are 2mm bore I wouldn't try to fit a 3.5 mm tube inside one of those. Any way if the clunk is too rigid it probably wouldn't fall to the bottom in flight even less likely inverted. That's why the clunk tubes on Slec tanks are so thin, so that a light weight clunk falls to the bottom. Quote Link to comment Share on other sites More sharing options...
Jim Hughes 2 Posted September 17, 2021 Author Share Posted September 17, 2021 19 minutes ago, Viv Letherby said: What size clunk tube do you use? Myself, nearly all my clunk tubes are 2mm bore I wouldn't try to fit a 3.5 mm tube inside one of those. Any way if the clunk is too rigid it probably wouldn't fall to the bottom in flight even less likely inverted. That's why the clunk tubes on Slec tanks are so thin, so that a light weight clunk falls to the bottom. 20 minutes ago, Viv Letherby said: What size clunk tube do you use? Myself, nearly all my clunk tubes are 2mm bore I wouldn't try to fit a 3.5 mm tube inside one of those. Any way if the clunk is too rigid it probably wouldn't fall to the bottom in flight even less likely inverted. That's why the clunk tubes on Slec tanks are so thin, so that a light weight clunk falls to the bottom Gents apologies for late reply. And thank you all for advice. I’ve been using a Slec tank, I didn’t want to appear critical on an open forum. I have ordered a new Kavan tank today. I appreciate I could have made the Slec one work better, however I wasn’t keen on the design. It’s opaque construction restricted viewing of what was happening inside the tank - I’d like to be able to see what is going on. Regards Jim 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.
Note: Your post will require moderator approval before it will be visible.