Author Topic: 2 cylinder OHV 29ccm  (Read 14185 times)

Offline Perry

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Re: 2 cylinder OHV 29ccm
« Reply #15 on: October 01, 2014, 08:02:33 PM »
One of the chalanges for me was to machine solid crankshaft and was a great satisfaction once finished  :cheers:
« Last Edit: October 01, 2014, 09:32:34 PM by Perry »

Offline Perry

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Re: 2 cylinder OHV 29ccm
« Reply #16 on: October 01, 2014, 08:04:37 PM »
with flywheel and counterweights
« Last Edit: October 01, 2014, 08:07:44 PM by Perry »

Offline Perry

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Re: 2 cylinder OHV 29ccm
« Reply #17 on: October 01, 2014, 08:10:35 PM »
cuting gears - module 1

Offline Allen Smithee

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Re: 2 cylinder OHV 29ccm
« Reply #18 on: October 01, 2014, 08:12:57 PM »
I'm curious as to why you've made it a simultaneous-firing twin?

PDR
Quidquid latine dictum sit altum sonatur

Offline Perry

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Re: 2 cylinder OHV 29ccm
« Reply #19 on: October 01, 2014, 08:16:04 PM »
Camshaft was another first time experience.
The gear can be turned few deegrees agains the hub for fine adjustments.

Offline Perry

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Re: 2 cylinder OHV 29ccm
« Reply #20 on: October 01, 2014, 08:25:18 PM »
I'm curious as to why you've made it a simultaneous-firing twin?

PDR

hi Allen, while the pistons are traveling up and down together, valve timing makes them breath 360degrees of crank revolution apart
which means if 1st cylinder is in compression, the other is in exhaust cycle already. common for motorcycle paralel twin engines.

P.

Offline Perry

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Re: 2 cylinder OHV 29ccm
« Reply #21 on: October 01, 2014, 08:30:19 PM »
yet another first time experience -split bearings for connecting rods

Offline Perry

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Re: 2 cylinder OHV 29ccm
« Reply #22 on: October 01, 2014, 08:33:11 PM »
brass tappet-guide and steel tappet

Offline Perry

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Re: 2 cylinder OHV 29ccm
« Reply #23 on: October 01, 2014, 08:37:38 PM »
some "work in progress" photos

Offline Perry

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Re: 2 cylinder OHV 29ccm
« Reply #24 on: October 01, 2014, 08:45:06 PM »
waterpump with magnetic field driven impeller - inspired by drawings from Jerry Howell

Offline Perry

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Re: 2 cylinder OHV 29ccm
« Reply #25 on: October 01, 2014, 09:11:06 PM »
that glorious and exciting moment when my scratch build engine started for the first time was well worth all the troubles I had during machining.

There were quite a few serious problems revealed during the first runs :

- really bad vibrations - I did not make any calculations and only estimated the counterweight size prior to first run
- arcing distributor and overheating ignition coil
- oil being pushed out of the one exhaust
- dragster-like fuel consumption  :Lol:

but all in all a success :cheers:


<a href="https://www.youtube.com/watch?v=EFdKTwXDT4A" target="_blank">http://www.youtube.com/watch?v=EFdKTwXDT4A</a>

« Last Edit: October 01, 2014, 11:14:19 PM by Perry »

Online Jo

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Re: 2 cylinder OHV 29ccm
« Reply #26 on: October 01, 2014, 09:20:58 PM »
 8)

Well done  :ThumbsUp:

Jo
Enjoyment is more important than achievement.

Offline Perry

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Re: 2 cylinder OHV 29ccm
« Reply #27 on: October 01, 2014, 09:23:20 PM »
first necessary step was to balance rotating mass as good as possible.

while this is paralel twin, the same  static balance rules apply just like for single cylinder. 

calculating with 100% rotating mass +50% Reciprocating mass I've ended up with missing 80 grams at the counter weights !  ups..

Offline Perry

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Re: 2 cylinder OHV 29ccm
« Reply #28 on: October 01, 2014, 09:24:04 PM »

Offline Perry

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Re: 2 cylinder OHV 29ccm
« Reply #29 on: October 01, 2014, 10:26:20 PM »
most recent update report :

- crankshaft balancing prooved to be success  :cartwheel:

- brass fuel tank can now be bolted directly to engine as it is not shaking anymore, but is getting quite hot quickly -need thermal insulation insert/shield

- intergated "fuel constant level tank" is not working reliably, perhaps due to very thin tubes (capilars) used to keep it compact + as the fuel tends to heat up from engine quickly, raising internal pressure is pushing fuel out  of the venting capilar

- distributor crossarcing was successfuly eliminated by rather thick black nilon insert.

- conventional ignition and breaker point was replaced by CDI unit with hall sensor from S/S Machine & Engineering -works great! very strong and reliable spark

- water pump does not work continuosly - will need to investigate

water cooler still needs to be finished
reliable fuel level control must be ensured - perhaps external float chamber

video of the latest run

<a href="https://www.youtube.com/watch?v=-Xmk6aKVdWA" target="_blank">http://www.youtube.com/watch?v=-Xmk6aKVdWA</a>



 

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