Boll Aero

[Graham Williams 5Participant @grahamwilliams5]

Does anyone know if there are errors in the published plans for the 1.8cc Boll Aero engine. Finished one some time ago and just got around to try to run it but not a peep out of it. Both piston and contra-piston fit are really good and I've stripped it down to re-measure everything and it looks ok, any ideas????

cheers Graham W

[Graham Williams 5Participant @grahamwilliams5]

[geoff walker 1Participant @geoffwalker1]

Graham there is another thread in this forum, have you read it, may help you.

Keywords Bollaero glow plug engine

geoff

[Graham Williams 5Participant @grahamwilliams5]

Hi Graham. That's a different engine altogether, its an approx. 8cc glow engine, mine is a 1.8cc diesel engine, both called Boll Aero..

Cheers

Graham W

[LADmachiningParticipant @ladmachining]

Does it draw fuel to the carburettor if turned over with a finger covering the air intake?

Do you get any signs of life if you prime it (sparingly!) directly into the exhaust port?

From the number of completed examples that were shown on Ron Chernich's website (modelenginenews.org) I don't think there were any show-stoppers in the plans. What date/revision plans do you have?

Regards,

Anthony

[davebParticipant @daveb17630]

Small compression ignition engines can be difficult to start, an electric starter motor would make life easier. I still have the scars from the one I had over 50 years ago.

[Graham Williams 5Participant @grahamwilliams5]

Difficult to see if the fuel line is filling as its a black one, primed the engine to see if it'll fire if not run a number of times and avoided flooding it but there's nothing there. Turned a spinner and tried an electric start, which I always think is a bit dodgy with a diesel, but nothing, changed the fuel as well though it runs an ELFIN perfectly well. Plans are dated 17th August 2009. Just not seeing what's wrong with it.

Cheers

Graham W

[Old SchoolParticipant @oldschool]

For little diesels you need new fresh diesel fuel if you are going to have any chance of starting it

[Howard LewisParticipant @howardlewis46836]

LONG time since I had anything to do with small two stroke C I engines, but just a few thoughts.

Are there no leakages? (Presumably the carb feeds into the crankcase, so if there are leaks, it is unlikely to draw fuel into the crankcase. Crankcase must be airtight, as must the crankshaft/main bearing fit

Is the transfer port a) in the right place (Rude!)

Is the piston flat top, or curved? If curved, is it fitted the right way round?

But if it does not try to fire, is the compression ratio too low? Which implies either the contra piston is too short, or the compression height of the piston is too short.

It ought to start and fire by flicking the prop over. YEARS ago, my Mills 0.75 did.

Since your ELFIN runs OK, the fuel is not the problem.

Let us know how you get on.

Howard

[Mike BlankleyParticipant @mikeblankley]

I have built this engine and it ran ok. You should not use an electric starter on a Diesel due to a possible hydraulic lock. Does the piston completely uncover the exhaust port on the down stroke and uncover the inlet port on the up stroke? You need a really good piston fit with no ovality which should give a really good compression. Good luck.

[Graham Williams 5Participant @grahamwilliams5]

Howard. Crankshaft lapped into front housing and both front and back-plate are sealed with gasket cement so no leakage that I can detect. As near as I can measure all the dimensions to the plan are accurate so I was expecting it to be ok. The piston doesn't uncover the exhaust port completely though. The conrod length, crankpin to crankshaft centre, piston height and gudgeon pin centre all to plan. The only thing I haven't checked is the crankcase top deck to crankshaft centre, will check that in the morning, had enough for today lol.

Cheers Guys.

[KEITH BEAUMONTParticipant @keithbeaumont45476]

Posted by Graham Williams 5 on 19/06/2018 19:00:00:

Howard. Crankshaft lapped into front housing and both front and back-plate are sealed with gasket cement so no leakage that I can detect. As near as I can measure all the dimensions to the plan are accurate so I was expecting it to be ok. The piston doesn't uncover the exhaust port completely though. The conrod length, crankpin to crankshaft centre, piston height and gudgeon pin centre all to plan. The only thing I haven't checked is the crankcase top deck to crankshaft centre, will check that in the morning, had enough for today lol.

Cheers Guys.

Hi Graham, Did you ever get this engine to work OK.

Keith

[Graham Williams 11Participant @grahamwilliams11]

Hello Keith. Sort of lol. Got it to run once only a fuel tank full of fuel after flicking away for what seemed like hours, let it cool down then tried it again and couldn't get a squeak out of it. Walked away to have a think about it but got side-tracked with one of my Velocette motorbikes, Think the piston fit is still not good enough though I have made 3 pistons now, Will have another go when the mood takes me, haven't had this much trouble with any of the other engines I've made or refurbed. You haven't posted in a while have you, what you up to now?

Graham

Edited By Graham Williams 11 on 16/12/2020 12:54:24

Edited By Graham Williams 11 on 16/12/2020 12:55:05

[Ramon WilsonParticipant @ramonwilson3]

Hi Graham – how are you? Any new engines in the making?

Keith – someone else was having similar problems here. After considerable trouble shooting the final solution was a gasket on the crankcase

Regards – Tug

[Graham Williams 11Participant @grahamwilliams11]

Hello Tug, did make a pair of Holly Buddys, one beam mount and one radial as per plan, got those running no trouble, quite taken with them as engines but now more focussed on my bikes for the moment, might go back to the Boll Aero at some point. Did read the link and it's somewhat surprising that many of us have trouble with a simple side port engine. Did experiment with the nva and choke size after some advice from Dynosaw but to no avail.

Regards

Graham W.

[KEITH BEAUMONTParticipant @keithbeaumont45476]

Hi Keith, That is disapointing that you have not got it running to your satisfaction. I made many modifications to the one I made, but used the original timing and carb dimentions. Because I altered it to a beam mount and put the carb at the rear,I added another exhaust port. It starts easily and runs smoothly. Recently have made a beam mount Holly Buddy.. Let us know if you have another session with your Boll-Aearo.

Keith

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