Author Topic: Two Cylinder Engine  (Read 21551 times)

Offline Roger B

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Re: Two Cylinder Engine
« Reply #195 on: August 30, 2019, 08:04:04 PM »
The valves and head went in the ultrasonic bath together with the injection test pump components. I managed to reassemble the valves and springs without donating any parts to the swarf gnomes. There seems to be quite good compression without piston rings  :) I then started to make some spark plug connectors from some 0.3mm phosphor bronze sheet. The core diameter was difficult to measure, but I got a reasonable chance with two 0.5 mm drills. 2.5mm was the result so I drilled 2.3 mm and then opened out with a Swiss file. The wire connection was drilled 2mm and the connection was opened out with tin snips along with a 4mm deep cut down the middle. Another step done  :)
Best regards

Roger

Offline Admiral_dk

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Re: Two Cylinder Engine
« Reply #196 on: August 30, 2019, 09:15:57 PM »
Looks like you are moving nicely forward - how much is still to come / has to be made ?

Offline Roger B

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Re: Two Cylinder Engine
« Reply #197 on: September 01, 2019, 07:18:12 AM »
Thank you Per, it just needs piston rings and the seals for the water pump.

The next step was to make a base plate, not as elegant as Old Bill's or Vixen's, but will work. The engine, 6V coil and fuel tank (borrowed from the single) were mounted and connected. I checked that the sparks came at approximately the right moment and decided to give it a try as even without rings the compression was quite good.

I initially got a few short bursts of firing and then nothing  :headscratch: Finally I noticed that the fuel was not being sucked up the fuel pipe to the carb and kept flowing back to the tank. I opened the tank cover to check that there really was enough fuel and got a pop. I hadn't removed the block from the tank breather and had built up a vacuum in the tank  :facepalm: I tried again and got a few pops plus some oil from the exhaust. Finally the rollers fell out of the sprag clutch  :(

Back into the workshop to assess what had gone on. The plugs were very oily, only one showed any real carbon traces. The combustion chambers were full of oil too. I guess that all the choking trying to get fuel into the carb also sucked oil passed the pistons which there was no combustion to burn off. I removed the distributor cap to see what had gone on there. There was a slight (0.5mm?) lack of clearance and the rotor had been rubbing on the outer electrodes spreading brass shavings around. I then removed the cylinder block to check the pistons and the bottom end. All looks ok with no signs of pick up, just a lot of oil.

I will have to make a new housing for the sprag clutch as the original was fitted with Loctite 648.
« Last Edit: September 01, 2019, 08:13:04 PM by Roger B »
Best regards

Roger

Offline fumopuc

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Re: Two Cylinder Engine
« Reply #198 on: September 15, 2019, 06:52:12 AM »
Hi Roger, go to the see the R&D department busy again.
Waiting for the next attempt to get it running.
First pops seems to show that the basics are fine so far.


 
Kind Regards
Achim

Offline Roger B

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Re: Two Cylinder Engine
« Reply #199 on: Today at 08:25:35 AM »
Thank you Achim  :)

I made a new sprag clutch housing and skimmed 0.5mm off the end of the rotor arm to give some clearance. I also found that turning the engine backwards when checking the sparks is not a good idea. As the rotor is not near a plug contact when the contact breaker opens there is a vicious spark down the side of the rotor arm to the cam  :zap:
Next up is some piston rings. Although there is currently only one groove per piston I have space to add a second ring if required and so to allow for breakages I need to make at least 8. The rings are planned to be 0.9mm square. First up I made the setting ring for the skimming jig. This is bored to 0.05mm over the bore size so 2.20mm which was checked using the plug gauge I made for the bores together with a feeler gauge. I then roughed out the piece of cast iron to make the rings and let it relax for a while.
Best regards

Roger