Rod’s Hoglet

[Howard LewisParticipant @howardlewis46836]

If changing bthe ignition timing does not cure the problem, of blowing back throughn the carb, could the Inlet valve need to close a little earlier? Assumes that the valves seal OK.

"Rule of thumb" timings are ususally Inlet opens 5 degrees btdc and closes 5 degrees abdc, to allow for gas inertia.

Maybe a longer induction trumpet may help. A long exhaust system may help scavenge and also help

Howard.

[GrahamSParticipant @grahams]

Hi Jason,Rod,Ian,

I am close to fitting the timing magnets for the Rxcel ignition to the timing gear.

One is fitted as north pole, one south to trigger the correct spark plug. On the drawing, one it fitted 120 degrees before vertical, the other 39 after. I am probably overthinking this, but does it matter which pole is fitted in each position?

If this system uses a specific pole to trigger a specific plug I am thinking the magnet fitting position will be relevant to coincide with the valve timing.

Many thanks

Graham

[JasonBModerator @jasonb]

You will want to have the correct ignition timing for each cylinder so magnet polarity will affect which fires when. Simple option is to stick them in as you want and just swap over plug leads if not the right firing positions.

[GrahamSParticipant @grahams]

Many thanks, it totally went over my head with IC engines you of course have the option to set this in multiple places.

A real doh moment.

Thanks

[ianjParticipant @ians]

Graham.

The way mine is, looking from the front (gears facing you)

39* position North facing, Left hand cylinder.

120* position South facing, Right hand cylinder.

I can get mine to fire but not run. I think it's the carb, I've tried the Jerry Howell one I made and one off a small RC aero engine.Tried with Coleman's camping stove fuel and normal unleaded with no success.

Ian

[GrahamSParticipant @grahams]

Thanks Ian, very useful.

Whats your plan to get it running?

[Roderick JenkinsParticipant @roderickjenkins93242]

Update. Here's the carb and fuel tank I've made. At the moment it's too rich on idle and starved on full throttle – If it's running ok at tick over it dies when I open it up. I might have to look for a more sophisticated carb design.

It's not been straightforward progress. The grip on one side of the crank pin has been slackening, causing the whole assembly to twist and sieze. I replaced the hardened crank pin with un-hardened silver steel and drilled half and half to insert a screw but this didn't stop a small amount of rotation which was enough for the assembly to skew when running. This is quite a powerful engine. One side of the crank pin holds very well with the clamping screw so I have Loctited all the others. By loosening the "good" grip the assembly can still be separated to free the con rods if necessary.

Rod

[JasonBModerator @jasonb]

Might be worth seeing if you can add an air bleed to the carb which quite a few small RC carbs have to lean things out on idle.

I know your crank problem, I've just got my Alyn Foundry Nattie to run and that has a two piece crank so you can run ballraces on the pin and that was slipping causing wobbly crank and flywheels.

Edited By JasonB on 20/04/2023 06:54:19

[GrahamSParticipant @grahams]

I do like that dinky petrol tank Rod. Was it from an existing plan or designed on the hoof ?

[MichaelRParticipant @michaelr]

Rod, When I was into model boats I had a 15cc Gannet OHV petrol engine it had a suction feed carb and the throttle needle was arranged to drop as it came off full throttle which leaned out the mixture for slow running (Tick Over), it worked well.

Maybe something like that arrangement may help your rich mixture slow running,

MichaelR

[Roderick JenkinsParticipant @roderickjenkins93242]

Thanks for the comments guys. The current carb does have an air bleed. I've just downloaded Jerry Howell's 2 jet drawings so I'll have a go at making that. Oh, and the fuel tank is way too small, it's a thirsty beast.

Cheers,

Rod

[KEITH BEAUMONTParticipant @keithbeaumont45476]

Super piece of work Rod. I had similar running problems with my Chenery Vee- Twin and made several differant size intakes before I got the engine to have good slow tick over and transition to fast running.

Keith

[ianjParticipant @ians]

 

 

Well some progress today. After putting to one side for a couple of weeks, I revisited the Hoglet today and managed to get it to run (in a fashion) Using the JH 2 jet carb and Colemans camping stove fuel . It runs very hot and is impossible to restart until it cools down.

I tried to embed the youtube video but failed.

Hoglet V twin engine first run on youtube

Edited By JasonB on 08/05/2023 06:56:58

[GrahamSParticipant @grahams]

A good day ! It runs , but after a fashion seemingly on one and a half cylinders.

One cylinder seems to run hotter than the other? Sparks and timing checked ok on both. It runs on one cylinder at a time ok ( alternatively one plug out at a time to test the other side is ok ). Still puzzling it out.

 https://youtube.com/shorts/JKKMBLYXlIA?feature=share

 

 

Edited By GrahamS on 24/05/2023 16:32:08

[ianjParticipant @ians]

That's brilliant Graham. Seems to respond well to the carb, Which one are you using?

[GrahamSParticipant @grahams]

Hi Ian ,

Its an Enya 52535 6mm bore , 35 quid from Steve Webb models in Frodsham. It looks like  this https://www.ebay.co.uk/itm/293047194494    though that says it has twin needle valves which mine doesnt.

Not having much IC experience I am still getting used to the settings so I can start reliably and get a nice slow tick over , but progress is being made. Flooding it via the intake using a pipette, and having the needle further out than required for running seems to help with starting ! Then when running screw the needle in slightly to get a smoother tickover. This carb has a air bypass control as well – a screw that controls how much air bypasses the throttle so is always supplied – I have found having this just half a turn out helps. As I play with it more I am sure this will evolve.

Where I am currently investigating is, as mentioned above, the right hand cylinder not getting warm when running so it doesnt look like it is doing much. But when I run it just using that cylinder it runs ok ?

Edited By GrahamS on 24/05/2023 19:45:43

Edited By GrahamS on 24/05/2023 19:51:25

[ianjParticipant @ians]

Graham.

Thanks for the link for the carb. from Steve Webb.

The S2535 you bought was out of stock, but they had S2530 which is still 6mm bore, just the needle valve isn't at an angle.

Any way with it fitted the engine now starts and responds to the throttle, so I'm very happy.!

 

One thing I noticed when setting the ignition timing for 10* BTDC the hall sensor was at the quarter past position but I noticed on yours and others it was at the half past position the engine was difficult to start and run when I rotated the hall sensor to the half past position it was a big improvement. I now have it in that position and it reliably starts and runs.

Hoglet V twin

Edited By ian j on 30/05/2023 23:21:27

[JasonBModerator @jasonb]

That will likely be due to the autoadvance on the Rcexl ignition

[GrahamSParticipant @grahams]

That looks great Ian , well done.

Agreeing with Jason, I think your hall sensor position is to do with the advance angle. I notice you say 10* BTDC – on the data sheet supplied with my Rxcel ignition , and confirmed by Just Engines, it should be 28 to 30* BTDC. I suspect this will position your sensor roughly vertical. Interestingly, they also confirmed with this ignition the advance is not adjustable and cant be disabled. In other words we have to live with it and set to and advance of 30* to get a spark at ( or just after?) TDC. They also confirmed the advance feature kicks in at revs higher than the Hoglet will achieve – so apart from conforming to the the angle they advise – we can ignore it ! They commented this feature is aimed at small high revving aero engines. I have trawled the internet for more details on this and drawn a blank. Given it is a reasonably cheap, easy to fit ignition, for future engines I would be interested to see rev vs advance angle data.

To help set the ignition I made a TDC mark ( for the right hand cylinder TDC when viewed from the cam side  on the flywheel. This mark is made close to the engine frame on the right hand side. I then made a small brass sheet pointer which when fastened to the frame by one of the frame bolts, points at the TDC mark. I wanted to take the engine apart to get a better finish on some of the parts anyway and took the opportunity to mount the crankshaft in the lathe to make a mark 30* BTDC, and a 180* ( BDC ) mark.

Timing the cams so the right hand intake closes by the 180* BDC mark ( thanks Rod ) and the timing the ignition so the right cylinder fires as close to the 28* BTDC mark.

I find a reliable startup procedure is to set the carb needle to one turn open, air bypass two turns open, slightly flood the carb with fuel ( thanks Jason ) and go for it. I find this to be a reliable procedure.

Re fuel , I started with Colmans but found it rapidly created soot on the valves and the valve faces needed cleaning regularly to stop sooting up. I now use unleaded pump petrol , mixed 40 to 1 with 2 stroke oil ( thanks Jason ) and it runs much cleaner. This is the same mix as my 2 stroke strimmer – bonus !

Is your fuel tank from a plan ? I am still using a plastic test tank dangling from a piece of string, and would like to make something I can mount on the base like yours. Also where did you get those fluted beams it is supported on?

Thanks

Graham

Edited By GrahamS on 31/05/2023 10:09:30

[ianjParticipant @ians]

Graham.

I had read the RCEXL data sheet regarding timing and then completely forgot it and followed Andrew Whale's youtube video!

I'm also running on unleaded petrol with a drop of two stroke oil.

Regarding the fuel tank; It's just a 75mm length of 50mm diam thick walled brass tube I had, with ends, filler hole and outlet soldered on ( if I was making it again I would make it longer and have the supporting struts spaced further apart as it is easy to catch the supports when starting with the drill) It's mounted so the fuel out is level with the carb fuel in (180mm from base on mine) The supporting struts are just 10mm x 25mm aluminum angled at the bottom by 5* so they leans out, with the "pockets" milled 2mm deep and then sprayed satin black, (similar to the rails the engine sits on.)

Now I know it runs I may try the JH 2 jet carb again as they took some time to make.

After all the discussion we had regarding the cam shaft I notice the right hand cylinder exhaust lifter hasn't the same amount of travel as the left hand cylinder. I may remake the cam shaft but don't fancy the Cox method again. So ROD do you have the parameters you used for CAMCALC please?

Graham did you sort out the one cylinder running cooler than the other?

I've enjoyed this build and the exchange of information from members with far more experience than me. I think 3 out 3 engines running is a good result.

What's next?

Ian

[GrahamSParticipant @grahams]

Thanks for the tank info Ian. I will do something along those lines.

My lifters are not all equal by the way. I don't have measurements to hand, but something around 10 thou difference ? For me , it would have to be out enough to effect running to warrant a remake – do you think this is the case?

I have spent the last week chasing the 'cool' cylinder issue , pressure testing the valves with the head in situ and off, remaking head gasket and leak checking around the inlet manifold etc. I have confirmed the piston rings are doing their job as there is the same compression as the right. All this activity has improved the situation a bit , but the right cylinder remains lazy compared to the left. By that I mean on startup the right starts first, then the left kicks in after a few seconds and the revs pick up and it runs smoother. As it starts fine now , and runs as long as there is fuel I am tempted to call it quits – other projects beckon!.

I fancy a go at a steam weir pump, one small enough to fit on my Sweet Pea. The injector currently fitted is pretty random in operation , so another way to get water in would be handy. Just sizing up the Blackgates ( ex Southwold) and Kennions ones.

Another option I fancy is the Jerry Howell Farm Boy , which usefully like the Hoglet, has an Andrew Whale vlog !

I have enjoyed the Hoglet build as well, and the forum help from yourself, Jason and Rod has been priceless.

 

Edited By GrahamS on 01/06/2023 09:58:57

[KEITH BEAUMONTParticipant @keithbeaumont45476]

When I was playing with my Chenery Vee -Twin, i too noticed that the right hand cylinder, from the front, was running quite cooler than the left cylinder. After bringing the fact up on this forum,expert opinion said that it is due to the oil being thrown more into the left cylinder by its anti clockwise rotation and that Harley Davidson were known to have the same problem. At that point I stopped being concerned about it.

Keith

[JasonBModerator @jasonb]

No oil in the Hoglets open crankcase but I did suffer it with my opposed twin version of Malcom Stride's bobcat.

[Roderick JenkinsParticipant @roderickjenkins93242]

Ian,

The CamCalc parameters I used were

Working angle 135 degrees

Lift 65 thou

Base radius 0.168"

Flank radius 0.37"

Graham,

I recorded my progress making a Farm boy over on ModelEngine Maker

**LINK**

Incidentally, the ignition I used was one of these:

**LINK**

from ebay. Very neat and compact. Looking again at their website they are offering a ready built half size Hoglet!

**LINK**

Rod

[ianjParticipant @ians]

Thanks for that information Rod. I will give it a try. I've only used CamCalc once before for the JH V 4 cam shafts, will have to see if I made any notes.

I may be back !

Graham.

I also have built the JH Farm Boy (two). Another enjoyable build, be prepared for mountains of swarf. I used the minimag ignition system.

Ian

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