RE: How sensitive is intake mani length on a little 4 stroke?
Yes I should have explained I ran thin cyno all over the ply.
Posted on: 5/1/2011 12:25 PM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=10494921

RE: How sensitive is intake mani length on a little 4 stroke?
I made an intake manifold for my GX31 from a piece of steel from a kids bicycle it worked a treat.
Posted on: 4/30/2011 3:36 PM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=10493478

RE: FOUR STROKE GAS ENGINES FOR SALE!!!!!!!!!
Looks very much like a Honda GX31 copy or there a bouts.
Posted on: 5/21/2010 10:32 AM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=9749209

RE: Best prop sizes for a Zenoah G38
Slow flying aircraft 20" X 8", faster WW2 type 19" X 10" both Menz. Nose overs will displace or bend the crank easily enough on a G38 with a wood prop let alone a nylon, G38 runs better with wood anyway.
Posted on: 1/13/2010 6:13 PM by Author "NorfolknGood" in the forum "Gas Engines"
http://www.rcuniverse.com/forum/fb.asp?m=9413205

RE: Honda GX-31 and Giant Eindekker??
Try a heavier nylon prop, mine runs better, higher revs and better low end with a cheap heavy prop. My GX31 is going in a 1/4 scale SE5a I'm in the process of building.
Posted on: 10/6/2009 5:30 AM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=9150455

RE: Honda GX-31 and Giant Eindekker??
I have flown my Honda GX31 in a 91" Volksplane with several props, best pull was from a 20 x 8 Master nylon jobbie, ran better than with a same size Menz wood! [youtube]http://www.youtube.com/watch?v=3xsT4tnPZ0k[/youtube]
Posted on: 9/26/2009 6:38 PM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=9125958

RE: Briggs and Stratton 34cc Fource?
I have a vid of my Honda GX31 in a 91" Volksplane, prop was a 20 X 8 Menz but it appears to prefer heavy nylon props so I expect to get more pull from it once I get some other props to try. [link=http://www.youtube.com/watch?v=3xsT4tnPZ0k]Youtube Vid[/link]
Posted on: 9/25/2009 5:50 PM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=9123818

RE: Honda GX-31 and Giant Eindekker??
I have an XYZ CDI unit, maybe I will have to get another driver/flywheel replacement made :(
Posted on: 8/26/2009 11:39 AM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=9046530

RE: Honda GX-31 and Giant Eindekker??
[quote]ORIGINAL: av8tor1977 I was getting 6900 to 7000 on the test stand with an 18 x 8 prop. I think I may try an 18 x 6 to fly it. AV8TOR [/quote] do you think the CDI improves rpm?
Posted on: 8/26/2009 3:32 AM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=9045784

RE: Honda GX-31 and Giant Eindekker??
Looking forward to seeing more details and also how it finally flies with the Honda :)
Posted on: 8/25/2009 3:22 PM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=9044095

RE: Honda GX-31 and Giant Eindekker??
I have no flash kit, just a pillar drill but it's worked well in the past. Since my last post I have flown the Honda with several props on and I have found it to prefer the nasty nylon masters! It's had a Menz 18x8, home carved 18x8 (broad blade) Menz 20x8 and a master 18x8. The master spun aster and produced more thrust than the Menz. It flew in a 91" Volksplane VP1 and flew it in a very scale manner needing a slight dive before looping but would roll from level easily. It's a heavy bird so will be tried in a 1/4 scale Sopwith Pup next which is light. Engine hand starts easily and never missed a beat in any attitude.
Posted on: 8/24/2009 10:53 AM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=9040252

RE: 1/4 scale SE5a Wing Loading
I would imagine you have plenty of power, I flew the DB 1/4 scale with a Zenoah 22cc which had adequate power. I'm planning on building another and fitting a Honda GX31cc fourstroke petrol.
Posted on: 7/30/2009 4:22 AM by Author "NorfolknGood" in the forum "RC Scale Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=8975778

RE: Honda GX-31 and Giant Eindekker??
[quote]ORIGINAL: Nosedragger Fuel drop out is caused by the air fuel mixture slowing down while traveling in the intake.The inside radius of the intake could cause that. If the performance now is that same as with the stock carb, its probably not a problem.[/quote] So it looks like my inlet manifold is ok then. [quote]ORIGINAL: Nosedragger The only time the stock muffler is a restriction to be concerend with, is if the spark arrestor screen is clogged. We have gutted them and all it does is make it louder.[/quote] I have removed the spark arrestor already so just eh exit pipe now, I now believe this to be flowing ok as it runs no better without the exhaust. [quote]ORIGINAL: Nosedragger Don't waste your time looking for a buttefly smaller than 12.5mm, if you do find one the venturi will be too small. 9.5 -10mm is about right for a GX31, any larger is a waste because the engine can't use it and the vacuum signal in the venturi gets weaker as you go larger.[/quote] The venturi can be drilled out and re profiled to suit, I have done it with good affect in the past but perhaps not suitable for the GX31. [quote]ORIGINAL: Nosedragger If you try a straight pipe on the exhaust make the inside match the opening at the exhaust port face and leave the pipe long, paint it with cheap spray on paint, run the engine (without prop) until it burns the paint off the pipe close to the engine, where the paint stops burning off is the shortest you want to cut it. [/quote] I will make another exhaust alter to fit inside the cowl of the SE5a but I don't think I can better the standard flow and sound. I ran it up on a nasty paint stirring Master classic 20" X 8" which weighs a ton! Whilst it only revved to 5000rpm and took a little longer to get there than with my home brew wooden 18x8 the thrust was right up and would pull my B&D workmate over so perhaps that's what I will settle for as a forum member said: "[i]According to Reivers', that gives about 12 lbs of thrust and 1.5 hp. (Master Airstirrer prop used as basis for calculation)"[/i] which I would have thought plenty to pull around a 80" SE5a?
Posted on: 7/21/2009 12:21 PM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8951850

RE: Honda GX-31 and Giant Eindekker??
Thanks for the post Nosedragger. The head has a port of 1mm, manifold is 10mm inside dia, my butterfly is IIRC 12.5mm, the transition taper is only in the ply isolation block which is 10mm. I overcame the impulse port issue by adding a nipple to the manifold and drilling the Walbro to accept another nipple, a small length of Tygon connects them up and it pumps very well. I'm not familiar with "Fuel Drop Out", by that do you mean fuel spat back out of the induction venturi? I had quite a bit of that at full throttle with a butterfly of 14mm dia, the current carb appears to be performing much better, idle at 1100rpm, throttling instant to 6000rpm and returns back to idle very well. I have noticed no drop in performance with my home brew manifold over the stock one. I binned the original carb, the barrel type as I screwed it up trying to lesson the return spring tension, I am very reluctant to go back to a barrel carb especially as I would have to buy a new one as my local garden machinery place has no 2nd hand ones with needle adjustment. I am keeping my eye out for a Walbro with a smaller butterfly and twin needles but they are hard to come by 2nd hand........... I have a non existent budget to work with. Could my rpm issue be the difference between a 8" and 6" pitches? I have the stock exhaust on, that may be another source of restriction?
Posted on: 7/17/2009 10:02 AM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8940788

RE: Honda GX-31 and Giant Eindekker??
I could do with something like that to use as a test bed for my 31 [;)] I got brave and put my mechanical tacho on the prop nut........... it's a different hand carved prop 18" X 8" WW1 style profile but I cannot get it to swing any faster than 6100rpm. Perhaps it will unwind a bit in the air or maybe try a 18" X 6" [8|] I have also made a manifold to get the carb inside my intended steed the SE5a and the prop awaiting stain and varnish (see below):
Posted on: 7/17/2009 9:27 AM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8940716

RE: Honda GX-31 and Giant Eindekker??
Prop driver is almost done now, looking forward to seeing what props I can spin up. [youtube]http://www.youtube.com/watch?v=UOhz1fab-uM[/youtube] It's on a home carved 18" x 8", no idea of what revs it's doing as I only have a mechanical rev counter and I am not gonna put that on the prop nut at full chat, I don't fancy slipping!
Posted on: 7/10/2009 11:20 AM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8909987

RE: Briggs and Stratton 34cc Fource?
[quote]ORIGINAL: stevelesl I is pretty low on power but flies the 14lb model ok. noise is low and sounds great, idles at @ 1300rpm with a ''put put'' sound !! Which carb did you use ?, the carb on it is a walbro but the return spring issue is a real pain in the a**. [/quote] That sounds promising, I intend to put my 31 in a 1/4 scale SE5a. I cant tell you which carb I used, it came from my local garden machinery shop off a scrap strimmer, it's at my mates right now having the prop driver made so I cant just nip out and get numbers for you. I'm hoping to throw a 18 x 6 wood prop at about 7,000rpm with any luck. I will report as soon as I have run it with the newly made driver.
Posted on: 7/9/2009 6:15 PM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8919838

RE: Briggs and Stratton 34cc Fource?
Certainly am watching and with much interest. Nice to see the Honda in an airframe, how does it fly? What's the noise like with just a header pipe? I have changed my carb to a normal type Walbro and it's transformed it, I just had to drill the manifold to fit a pipe to the carb for the pump and it works a treat. I forgot to mention mine is the GX31.
Posted on: 7/9/2009 6:06 PM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8919816

RE: Honda GX-31 and Giant Eindekker??
I have sent my engine to a mate who will take a look at making the driver, could be a little while before it's done though :( I have cut 18 ribs for the SE5a and run out of material, I will goto Slec in Watton (UK) to top up on balsa, ply etc when I return from Italy after next weekend. I would like to use a 20" prop for looks mainly on the SE5a but with your comments noted will probably go with the 18". Once the airframe is proven and engine to I can play with props to see what suits the airframe best. As I'm trying to do this all on teh cheap I am considering using Diatex 1000 then Warbirds paint ofr finish
Posted on: 6/14/2009 2:12 PM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8851163

RE: Honda GX-31 and Giant Eindekker??
Thanks for that Tauri Flyer what carb were you using? I'm wondering if it was a carb/prop issue or if the 20" is just to much for the Honda. Do you have CDI or mag ignition as again I believe this alters how they perform quite a bit. I'm still waiting for my driver so cannot do any testing till I gets done :(
Posted on: 5/26/2009 8:48 AM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8799219

RE: Honda GX-31 and Giant Eindekker??
Are you guys using the standard plug with 25 thou gap? What should the valve clearances be? what oil should be in the crankcase? Will be Honda throw a 20" X 6" prop for a 1/4 scale WW1 biplane and how many sugars should I put in my coffee [:D]
Posted on: 5/25/2009 6:09 AM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8796266

RE: Honda GX-31 and Giant Eindekker??
That's interesting, I didnt realise the 31 had a decompressor! I have not removed one from mine and TBH would not know where to look for it (other than being behind the cam gear) or how to remove it. I can hand start easily with mag ignition, is this decompressor only relavent to CDI and if so why as either type of spark genaration needs fuel and compression to fire.
Posted on: 5/21/2009 4:13 AM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8786725

RE: Honda GX-31 and Giant Eindekker??
Did you ever try starting it with the Mag ignition? I find a technique is needed, rather than getting the prop at 12-6 O clock and flip (slap) from there as I do with my Zenoah's I have to get the magnets several degrees before they swipe the coil pick up so the slap has given it enough speed to produce a spark, once you master that it starts very easily. Once I get my proper prop driver made up I will see if I can borrow a tacho and get some readings with different props, I hope to run it with a 20" X 6" as I will be using it for a SE5a so don't need speed.
Posted on: 5/20/2009 1:59 PM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8784824

RE: Honda GX-31 and Giant Eindekker??
It never gets to hot to work here in the UK I'm planning on putting my GX31 in a 1/4 scale SE5a, It will justa bout go in all under cover is I make a carb bend and use just a header pipe on the exhaust. so far I have the engine runing well with a Walbro and seperate impulse pipe, the carb is made up from several I picked up from a garden machinery 2nd hand parts place and I drilled it out to. I'm waiting for my mate to be available to make up the prop driver, since I did the carb it's gone from ole neddy to a race horse .......... oh it hand starts easily to :) I cant find any video at all of anyone actually flying a GX31, I would be very interested to see some.
Posted on: 5/20/2009 3:17 AM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8783821

RE: Honda GX-31 and Giant Eindekker??
Any update?
Posted on: 5/14/2009 4:32 AM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8767656

RE: Honda GX31
Oh, I forgot to mention the exhaust, it's loud with none at all, does just a header alone quieten it whilst giving rpm improvement?
Posted on: 5/13/2009 7:37 AM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8764976

RE: Honda GX31
Thanks guys, I have been searching for info but most threads seems to fizzle out before any concrete info comes up. Lots of talk about using the standard type carbs, a few mentions about video which I cant find and no definitive prop size/type for slow flying WW1 type aircraft. I see the easiest method of prop driver using the mag ignition is a basic driver using it as the flywheel nut, this concerns me that it may come off with hand starting and I'm reluctant to put any thread lock on. I think for now I will stick with the mag ignition as I intend to use my XYZ CDI on my Zenoah 62 conversion.
Posted on: 5/13/2009 7:36 AM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8764972

Honda GX31
I'm converting a Honda GX31, the carb has been changed for a normal butterfly type carb so I put a nipple into the inlet manifold and another on the carb as the impulse ports do not line up. This works very well and now gives me the option of trying several size Walbro's although the one I have right now appears to be ok as the induction port on te head is only 10mm in dia so a massive carb would only flood the engine unless I did a lot of porting. I assume the fourstrokes need a smaller port as they only bang every other rotation. for now I'm sticking with the mag ignition but was wondering if I were to go the CDI route whether the timing would be 28 degrees as per 2 stroke or if it's different on a 4? I have read these engines will throw say a 16" X 8" prop at around 6,000, I wonder if they have enough torque to throw a larger dia and less pitch for a slow flying 1st WW type thing such as a 1/4 scale Pup or maybe even a 1/4 scale DVII?
Posted on: 5/12/2009 3:57 AM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8761806

RE: Briggs and Stratton 34cc Fource?
So what wingspan and weight/type aircraft are you guys using your BS, Honda etc 4 strokers in? Ther has been debate on another forum that says they don't have enough hp to be of any use, I have been defending the Honda GT31 as it appears to be the best Honda weight for hp IMO. Any of you guys got pictures of your 4 strokers in your airframes?
Posted on: 4/23/2009 9:58 AM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8708250

RE: Briggs and Stratton 34cc Fource?
[quote]ORIGINAL: jaav The Briggs engine... I work for a briggs dealer and have had too many failures. The plastic cam drive gear on the crank is very weak, had them fail on the 1st tank, the best part is the parts!! GOOD LUCK... [/quote] Sorry I hijacked the thread, I was talking about the Honda GX31 conversion.
Posted on: 4/23/2009 8:47 AM by Author "NorfolknGood" in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8708074