Yet Another Webster Begins

[CFLBob]

Hi Bob, just and odd point. It looked to me that you need to remove the sharp corners on the flywheel to stop it shaving the skin off your thumb and finger?

To be honest, when I first saw this, my reaction was to look at my right hand to see where skin was missing, but I would have felt that. No skinned areas or injuries.

I've been using the method that werowance talked about - a rubber, automotive pinstripe remover in my cordless drill. It seems to really do a good job. The only drawback is leaving rubber shavings everywhere, but if my engine would run, it wouldn't be in contact long enough to matter.

I ran into a real point of confusion last night. I went and looked at videos, and one of the first ones I ever watched, Pat Pending's Webster, is starting with flywheel going clockwise.

This one starts going CCW

I've been trying to start mine going CCW. I thought Joe Webster said CCW from this viewpoint that these two videos show, but between these two, one has to be backwards.

Edit to add: I meant to just have links to those videos, not embed them.

 

[scottyp]

The factors that determine which direction the engine will run are the exhaust valve cam and ignition cam timing. Take out the spark plug and connect the ignition. Slowly turn the flywheel and think about what is happening vs what should be happening and when things are happening, through all 4 strokes. It should only make sense it the flywheel is turning in the correct direction. Suck, squish, bang, blow.

OR - if you leave the spark plug in (without ignition) and turn the flywheel slowly. In the CORRECT direction, you should feel compression on the correct compression stroke ONLY. If you turn it in the WRONG direction, you will have compression whenever the piston is going into the cylinder and every other one of these compressions, you will get a puff out of the exhaust when you near top dead and the exhaust valve opens.

Just my observations...

 

[awake]

Bob, I had similar almost-but-not-quite response from my Webster when I first attempted to start it. I moved the exhaust timing by one gear tooth, and on the next spin it started right up. Which is to say, it sounds to me like you are really, really close, and just need a small adjustment. Since you've already been working on compression and carburetor settings, and based on my own "vast" experience - as in, the Webster is the only engine I've built so far! - I'm putting my money on the exhaust timing.

 

[CFLBob]

I need to ask a question about something I've noticed but never thought was wrong. My spark plug fires on every stroke approaching TDC.

I decided to check my timing, the only way I know how. This starts just before the start of the exhaust stroke, like Webster's diagram on the last page, how he set the cam. I set my flywheel to the point where the exhaust valve just starts to open, then rotate between TDC and BDC.

Rotate to BDC - about 15 degrees, then...
Rotate to TDC - spark plug fires just before the top of the exhaust stroke
Rotate to BDC - the intake stroke
Rotate to TDC - compression stroke and spark plug fires (with the piston about 1/8" before TDC)
Rotate to BDC - this is the bang pushing the piston down - where we started

The spark at the top of the exhaust stroke has no fuel to burn so I see it as wasted energy but not something that will mess up anything.

Am I missing something?

 

[awake]

Right - I think this is called a "wasted spark" configuration - ? In any case, the spark plug fires on every revolution, when it fires into the exhaust stroke, it does no harm.

 

[scottyp]

The extra spark is a result of the ignition cam being driven from the crankshaft and closing/opening every revolution of the crank and nothing to worry about.

So, if your exhaust valve is opening about 15 deg before BDC at the end of the power stoke and closing again around TDC before the intake stroke begins, you should be good.

 

[CFLBob]

Thanks, guys.

The only thing I can think to do is to try to make my intake valve spring weaker. I can't get over how I can see them moving on so many videos, while I know several guys here say they never see their valve move.

 

[werowance]

seeing them move is i believe a product of camera trickery if videoed right at the correct rpm vs frame rate of the camera then you can see them move. just started learning this on my upshur videos. one i couldnt see the rockers move at all and the next i could. at anyrate keep on truckin and good luck Bob.

 

[CFLBob]

seeing them move is i believe a product of camera trickery if videoed right at the correct rpm vs frame rate of the camera then you can see them move. just started learning this on my upshur videos. one i couldnt see the rockers move at all and the next i could. at anyrate keep on truckin and good luck Bob.

I was thinking that, but my wife answers by holding her finger at the end of the valve and says she can't feel it move. I know that I can move it and it seals, I've pushed the valve down, leaving the intake valve open. It changes the sounds.

But the new spring made no difference. Still won't run.

 

[CFLBob]

Today, a major breakthrough. I got it to run, although not very well.



One of those things I've meant to try was to use an old AC-powered Black and Decker 3/8" drill. I compared it to my Ryobi battery powered drill and it seemed faster. With the B&D it started almost immediately. I realized I didn't have a camera and left it running to run into the house and get the camera. Predictably, when I got back to the engine it stopped running. The next several minutes were spent trying many combinations of the throttle setting and the position of my fuel tank. The throttle lever is very sensitive, there's a narrow range over which it will run. The tank seems better about 1/4" higher than my fixture was built for (I added some shims of 1/4" plate). It's easy to add those in.

This is a major breakthrough, though. The video has a surprise ending. Well, it surprised me.

 

[Brian Rupnow]

Bob---Congratulations!!! You are now a member of a very elite club---"Those who got their engine to run". I can see that you have a few things to address, but IT RUNS!!!!---Brian

 

[werowance]

WONDERFULL NEWS! CONGRATULATIONS.

you and I are using the same carb, so mine starts best on about 1/4 to 1/3 open on the throttle. id say closer to 1/3.
I run straight coleman fuel. I make sure the cylinder oiler is oiled up good and has had a chance to oil up the piston good before starting. also is the cap on your fuel tank vented? if not it wont run long.

maybe above info will help you get a more consistent start up. but I think after you run it more and more it will break in better.

remember it will only run a few mins at wide open throttle as it heats up to much. I guess I get about 10 mins run at idle speed - usually a screw or something vibrates loose by then anyway lol.

CONGRATS AGAIN.

 

[werowance]

Bob, the surprise at the end - I have a video of mine doing the exact same thing. carb falling off

also the head appears to be moving a lot. - speaking of the screws coming loose - mine keeps getting loose there as well. the 2 side screws get loose as well as the larger bottom screw going through the base plate gets loose.

green locktight on the carb is finally what held it in place on mine.

but yours runs really good Id say.

 

[awake]

CONGRATS!!!! Perseverance paid off! And what do you mean, "not very well" - sounds just fine to me. Well, maybe not at the very end of the video ...

 

[scottyp]

Good job Bob! Seems to run fairly smoothly.

 

[cheepo45]

Congratulations!
This is why I keep building I.C Engines.
The longer the struggle, the more exciting it is when it finally runs!
Scott

 

[CFLBob]

Thanks, everyone. Especially, thanks for the help all along the way, everyone.

you and I are using the same carb, so mine starts best on about 1/4 to 1/3 open on the throttle. id say closer to 1/3.
I run straight coleman fuel. I make sure the cylinder oiler is oiled up good and has had a chance to oil up the piston good before starting. also is the cap on your fuel tank vented? if not it wont run long.

maybe above info will help you get a more consistent start up. but I think after you run it more and more it will break in better.

remember it will only run a few mins at wide open throttle as it heats up to much. I guess I get about 10 mins run at idle speed - usually a screw or something vibrates loose by then anyway lol.

CONGRATS AGAIN.

I think that's right where my carb throttle is set, right in that 1/4 to 1/3 area. I basically can't touch the throttle lever without stalling it. It's very touchy. Since I can't touch the throttle, it's running at whatever it thinks it's set to. I can't adjust the speed of the engine up or down.

I don't have an oiler on the cylinder. I put a drop or two in the hole on top of the cylinder for it before I go to start it up. I could always add that.

My fuel tank is an RC Tank with a vent in it, so check on that.

Bob, the surprise at the end - I have a video of mine doing the exact same thing. carb falling off

also the head appears to be moving a lot. - speaking of the screws coming loose - mine keeps getting loose there as well. the 2 side screws get loose as well as the larger bottom screw going through the base plate gets loose.

green locktight on the carb is finally what held it in place on mine.

but yours runs really good Id say.

I tightened the big screw in the bottom of the head, but not the side screws. It doesn't really feel like it's moving when I press on the cylinder when it's not running, but it's very obvious when you watch it.

There's green LocTite on the other end of that adapter on the carb, where it plugs into the intake valve in the stack. A little where the carb plugs into the adapter will be easy.


I'd like it to start more reliably and not stall out if I touch the throttle or the engine shaking it makes it move. To be able to push the throttle open and have it speed up would be really cool.

 

[coulsea]

good work. Be patient it will improve as it runs in, particularly the valves. It will start and run at lower speed once it is run in and when it will start reliably you can adjust the intake valve spring so that it closes the valve with very little tension when closed, this improves the efficiency of the intake stroke and makes it much easier to start at lower revs.
But be patient get to know it and start it every day for a week before you make mods.
you will not get the full use of the throttle movement but you should be able to significantly alter the revs.

 

[Steamchick]

Bob, "You have done a better job than I, Gungadin" - to quote some famous Author.
WELL DONE SIR! I am impressed.
Ignoring the carb - and other little snagging jobs you'll sort in days to come - the real concern I have from watching the video is the L-shaped engine mounting. It definitely is not stiff enough and will wear the piston and bore badly with all the movement from the flexing of the mount. You must make a much stiffer mount. Maybe some side-plates - triangular - to seriously stiffen the bracket you have?
Also make a cylinder oiler. Worth it for keeping the piston from wearing, and it will help cool the piston and cylinder by helping conduct heat from piston to cylinder wall as well as keeping friction to a minimum. You can even black the cylinder and head to improve radiant cooling of the cylinder and head. Most air-cooled motorcycle engines are black for thar reason. Better than risking a seizure! I know people think shiny metal looks nice, but black is part of the engineering of the cooling system. And it can make a model look "professional".
Just my humble advice..
Enjoy running your fine model. Real proof of your skill and effort.
Regards,
K2

 

[werowance]

Bob, could you post some pics of the spark plug wire please. looks smaller than a normal plug wire and just interested to see what you used and how it looks. from what i see i like it.