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gbritnell said:
Thanks George, that sounds great!
Call me any time your ready, I'm always available.
-Rick
90 degree V-twin engine
- Thread starter gbritnell
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Help Support Home Model Engine Machinist Forum:
Thanks George, that sounds great!
Call me any time your ready, I'm always available.
-Rick
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Hi everyone, Rick got in touch with me and asked how the engine was going as he hadn't heard anything. Here's the latest on the engine.
As you'll recall in one of my last posts I said that I've never had one run great right out of the box, well this one is no different than the others. Here's the events up to this point.
My original idea for starting it was to put a hex on the end of the crankshaft and use a socket on a cordless drill. Several days ago I tried starting it for the first time. The engine would hit but when it did I couldn't get the socket of in time and it wouldn't keep running but along with that I wasn't sure of the ignition setup. The first thing that needed to be done was to make a starting clutch for the engine.
I had an extra .50 dia. one way roller bearing in my parts box so I made up a flange to bolt to the outside of my flywheel. The next step was to see if each cylinder would start on it's own so I hooked up one plug and pulled the other out of the head. I cranked it over and it fired right up on the rear cylinder but man did it shake. I then tried the front cylinder. It would try to run a little but I noticed the compression was down a little. At that point I hooked up both plugs figuring that the higher rpm would overcome any loss in compression on the front cylinder. It worked to some extent.
Yesterday afternoon I pulled both cylinders off to see what was going on. The back cylinder was fine but the head gasket (Teflon sheet) on the front cylinder was burned through. I made a new gasket and bolted everything together but the front cylinder was still down on compression. While I was tightening the 5-40 socket head head bolts I noticed the one near where the gasket blow out had occurred seemed soft. By that I mean it didn't seem to tighten like the others. I looked between the fins where the tapped hole exits and noticed that the screw wasn't as deep as the others. When I was tapping the holes I forgot to run the bottom tap through that hole and the bolt was bottoming out in the threads. I fixed that but the compression was still down a little. I pulled the head again and turned the engine over with the heel of my hand over the cylinder. It had tremendous vacuum and compression as I turned it over so the cylinder was sealing ok.
The only thing left was the valves. I pulled each valve and checked the seats. When I first made the heads I had made a seat cutter that aligned with the port and valve guide hole so I was quite confident that the valves were sealing ok. and with the rear cylinder having great compression I just figured the front should too, wrong. I then lapped both valves and kept checking the seats with my magnivisor. I finally got a nice gray color all the way around on both seats so I cleaned everything up and reassembled the engine. Now it has good compression on both cylinders. This was last night at 9:30 pm. Today is supposed to be nice so I'm going to try and start it again. As far as the ignition, my rear cylinder is the one with the bad waste spark. It occurs just as the intake is opening. Having worked on engines most of my life I figured that without compression and what little fuel was being drawn in at that point it shouldn't pose a problem. When I ran each cylinder separately the rear one ran great so it seems like my guess (at this point) was correct.
Well that's where I'm at right now. I'll keep you appraised of my progress.
George
As you'll recall in one of my last posts I said that I've never had one run great right out of the box, well this one is no different than the others. Here's the events up to this point.
My original idea for starting it was to put a hex on the end of the crankshaft and use a socket on a cordless drill. Several days ago I tried starting it for the first time. The engine would hit but when it did I couldn't get the socket of in time and it wouldn't keep running but along with that I wasn't sure of the ignition setup. The first thing that needed to be done was to make a starting clutch for the engine.
I had an extra .50 dia. one way roller bearing in my parts box so I made up a flange to bolt to the outside of my flywheel. The next step was to see if each cylinder would start on it's own so I hooked up one plug and pulled the other out of the head. I cranked it over and it fired right up on the rear cylinder but man did it shake. I then tried the front cylinder. It would try to run a little but I noticed the compression was down a little. At that point I hooked up both plugs figuring that the higher rpm would overcome any loss in compression on the front cylinder. It worked to some extent.
Yesterday afternoon I pulled both cylinders off to see what was going on. The back cylinder was fine but the head gasket (Teflon sheet) on the front cylinder was burned through. I made a new gasket and bolted everything together but the front cylinder was still down on compression. While I was tightening the 5-40 socket head head bolts I noticed the one near where the gasket blow out had occurred seemed soft. By that I mean it didn't seem to tighten like the others. I looked between the fins where the tapped hole exits and noticed that the screw wasn't as deep as the others. When I was tapping the holes I forgot to run the bottom tap through that hole and the bolt was bottoming out in the threads. I fixed that but the compression was still down a little. I pulled the head again and turned the engine over with the heel of my hand over the cylinder. It had tremendous vacuum and compression as I turned it over so the cylinder was sealing ok.
The only thing left was the valves. I pulled each valve and checked the seats. When I first made the heads I had made a seat cutter that aligned with the port and valve guide hole so I was quite confident that the valves were sealing ok. and with the rear cylinder having great compression I just figured the front should too, wrong. I then lapped both valves and kept checking the seats with my magnivisor. I finally got a nice gray color all the way around on both seats so I cleaned everything up and reassembled the engine. Now it has good compression on both cylinders. This was last night at 9:30 pm. Today is supposed to be nice so I'm going to try and start it again. As far as the ignition, my rear cylinder is the one with the bad waste spark. It occurs just as the intake is opening. Having worked on engines most of my life I figured that without compression and what little fuel was being drawn in at that point it shouldn't pose a problem. When I ran each cylinder separately the rear one ran great so it seems like my guess (at this point) was correct.
Well that's where I'm at right now. I'll keep you appraised of my progress.
George
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Gentlemen, today I went out for the second trial. All it needs now is some fine tuning on the carb. As with other small engines it doesn't have near enough flywheel action but to this point I'm thrilled.
George
[ame]http://www.youtube.com/watch?v=opvp1sGQtJU[/ame]
George
[ame]http://www.youtube.com/watch?v=opvp1sGQtJU[/ame]
George,
What a great build. :bow:
The engine sounds great. :bow:
The engine looks great. :bow:
What a great build diary. :bow:
Every day I look into this forum I see what a talented bunch there is.
I'm so glad that I am allowed to absorb the lessons that you and the other members provide.
Please keep up the great work. :bow:
SAM
What a great build. :bow:
The engine sounds great. :bow:
The engine looks great. :bow:
What a great build diary. :bow:
Every day I look into this forum I see what a talented bunch there is.
I'm so glad that I am allowed to absorb the lessons that you and the other members provide.
Please keep up the great work. :bow:
SAM
putputman
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George, you should be totally thrilled. That engine sounds great for the first run. I don't know how you can improve on that.
It has been a pleasure following along with your build log.
I hope you plan to take it to NAMES this year.
It has been a pleasure following along with your build log.
I hope you plan to take it to NAMES this year.
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Thanks everyone. It's been quite a journey from the design to the build along with the documentation. The other day I was excited to hear it pop, today I'm thrilled with the results. Arv, yes I'll have it at NAMES. I'm going to have to mount it to a cement block because it sure likes to jump around. I'm going to retard the timing a little and see if that helps. Right now I have it at about 12 degrees BTDC. I'll try about 6 or 7.
George
George
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Congratulations George! :bow:
Glad to see your project up and running. I knew you would get it going.
Sorry if I got a little impatient, You had me sitting on the edge of my bench in suspense.
Oh what a relief!
-MB
Glad to see your project up and running. I knew you would get it going.
Sorry if I got a little impatient, You had me sitting on the edge of my bench in suspense.
Oh what a relief!
-MB
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