homemade rat racer

OK, bout language, I get the idea. Think you mean advance and retard timeing auto- maticlly. Vacuum advance on cars from eariler days. Now there is electronic types. But this on a small engine, I did not know about.

The other thing you metioned with easier starting is automatic compression release for hand start engines. You would with big engine displacement and even more so with high compression ones, too much to pull. So this helps and starts with leaking out the exhaust till gets up to idle speed after starting.

I remember the lawn mowers with the crank & ratchet, then release with out and rope to pull. You could still wear your self out tring to start one of those, but if timing wrong, still your hand is not on a cord to get yanked and a dislocated sholder if your grasp was tight. Yikes, I had my fingers sort of friction burn, but never my sholder dislocated. That I leave to getting lauched while a gale force gust when I'm out windsurfing, NOT!

Measure Twice

What do you make of the Valve Overlap on post #14.

That I added later more info, when I searched.

Ah but something on the power stroke you say, I'm then not sure it is right my explantion it being an advantage for some kind of porting.

I'll let other see what they know, an maybe try a search with the word power stroke in 4 stroke engine and valve timing.

Measure Twice

See this I found

Valve-timing diagram

"The exhaust valve opens a little before bottom dead center, and stays open a little past top dead center."

Measure Twice

The pictures of the crankcase and the cams that you tried adjusting are what I wanted to see. Also the fact that the intake an exhaust valve on opposite sides, just wanted to see how the cam(s) are done. On one with two lobes or two separate ones driven by some gear connection to crankshaft?

Please don't unassemble it unless you’re going to need to do this for some other reason though, I don't really need to know that badly! Pictures would be nice.

From the pictures you did post, I was trying to see what was wrong with the flywheel? A crack in it you were saying maybe I think? Where is it?

Buying a new one in my area is usually not worth the money, just getting a whole engine used at a flea market is way better economically. Then if you do find the same engine or parting out an engine and the parts fit great, keep the one you got and swap in the new/used part.

Was wondering, the shops where you are, they can find parts by the model serial number on the engine?

From the other thread I read on how did you get injured today, I think for me, I’d get a hoist and lower a 60lb weighing bike out of a window to the ground with some contraption. Going down stairs carrying heavy stuff I try to keep from doing. Also up stairs too.

I almost was able to carry 100 lb sac of flour up stairs once, but opted to just help with 50lb sacs of sugar when I worked in a bakery. Neither now would I do that easy? I have built a gantry hoist for a small 90lb outboard motor to help make things easier, but mostly just using leverage and a cart to move stuff around does the trick.

Maybe your answer for the back firing and when valves open an close can be answered by Click & Clack Radio Show, those guys are hilarious!
Car Talk. Car tips, advice, and troubleshooting.

But seriously the valves porting overlap whatever, what you describe is like the power stoke is just starting and lets out the exhaust almost right immediately after top dead center. You got me stumped.

Measure Twice

Har MT, Click and Clack are great! That is my Sunday mornings. Sitting in the shop with them on and a cup of coffee. (then "wait, wait don't tell me")

Great thread Harly. Thanks for sharing.

Your English is fine and easy to follow. Even with speaking with other native tongue English speakers or even folks from different areas, it some times is hard for every one to be clear or understood. Most especially in text only. No worries. All friends here!

It is a little different then Europe. Very understanding of how hard a second or even 3rd language is to speak much less write.

Thanks again!

As I’ve said before, hey no problem about the English, as Dan says it is mostly the technical stuff hard to understand without seeing close up in person what your working on and talking about what you know about a situation. Like the picture with the intake routing.

The cracked area you mention in the keyway slot on the flywheel. That is just what these other people had mention to me could mess up the timing. They were talking about a mashed up, not cracked keyway, but it is all the same since the flywheel is not exact in position with the corresponding keyway slot on the shaft. Especially if the flywheel does not stay tight on the shaft and moves back and forth with respect to the shaft, while it is turning, that is even worse.

I am hoping when you get another flywheel that fits (as I say if economical) you probably can put the valve cogs matching the dot and line as it was intended. But something still has me wondering that if you say the exhaust valve opens just after the spark and explosion near top dead center of the power stroke, how can spark timing really have anything to change valve timing, it does not. The thing about the spark timing being able to be set and stay steady when a good flywheel is in place will maybe have the backfiring stop. The valve timing may be something that I don’t just have enough knowledge about, but I thought if it opened that soon you would lose power in the engine since the piston does not get pushed down the majority of the power stroke, instead the explosion gases just exit the exhaust.

On the other note about the adjusting the points, yes I have a vague idea about some engines adjusting the timing that way like on chain saws engines you say. Thanks for that info, I had a water pump with a two stroke engine that I may salvage for something and should I not be able to get documentation or even parts for it I may have a better idea of how they may work. It was in the trash, the engine part was stated as manufactured in Canada.

I had a Chevette car that I adjusted I think I remember both the points and the dwell angle on the distributor cap. The points set I don’t remember so clearly, but the dwell for the 4 cylinder I had the timing light and shone it on the flywheel and looked for the mark in degrees before top dead center. Think it was 8 degrees. You had stop the engine and loosen the hold down clamp on the distributor cap and then rotate it slightly one way or the other to get it right on the 8 degree mark after you started the engine again and checked with the timing light. All this was in vain for a while as I did not know till later after having tried resetting the dwell so many times, I am surprised I did not wear out the hold down bolt on the distributor cap. **** What it was, was a loose frayed crimp connector to the coil ****
That by itself, I suppose due to the varying resistance of the loose connection had made the (effective) dwell angle vary, even though the distributor cap had not moved at all. @^%* I was going down the 405 in Los Angeles and luckily I was able to pull over under a bridge when the engine was bucking. I fooled with the adjusting the distributor cap and it was not until I got home after getting back to Northern California I found it the loose crimp and redid it. I even did both crimp and solder then heat shrink to do the repair. Some places like in the alternator you cannot use solder, it would melt due to the heat. They I know spot weld the wires to the brushes. On a Ford Ranger they made it so you have to buy the whole voltage regulator with the brushes attached for $70.00 since they made it that way. Loose crimp connector also had me sucking all that was left in the battery when the crimp to the positive battery wire to the alternator was loose. I had to shut off the lights at night while going over an 8 mile bridge. I put on my four way flashers though. Then after a while the battery so low, each time the flashers went on the engine would slow losing power due to the colder spark. I had a battery powered separate emergency flasher I stuck in the back window and then ran the car with no lights other than that to get home. Whew!

A nice old Thunderbird my brother had used an allen wrench for adjusting the dwell on that engine, so you if careful could have the engine running and adjust it that sure is way easier than what the old Brigg’s have you do!

Another car I got to drive for a while I had to get accustomed to resting the side of my foot that was on that gas pedal, to the transmission hump. This steadied my foot; otherwise as it accelerated in 1st or 2nd gear manual shift transmission, I was shoved back in the car seat for just a moment. The next moment reverberation sets in and I am falling forward toward the steering column. Again and again it goes till you manage to fling you foot away from the accelerator. Then you can look back and see sets of pairs of patch out burned rubber marks on the street behind you. Pontiac Grand Sport with 402CI / 4 barrel Holly and also modified gearing down.
Those were the days!

PS Click an Clack are these two guys that take callers on the phone questions about car problems, but have fun making jokes also as well as giving advice. The name of the show is Car Talk Radio, and it is also on line. I've just noticed though now I suppose due to maybe fund limitations on possibly government funding and other, there are some fees beside just short clip of radio shows. I still have to look if you can just read the transcripts for free?

The link http://www.cartalk.com/ct/review/index.jsp
http://www.cartalk.com/menus/show.html
http://www.cartalk.com/Radio/Overseas/
http://www.npr.org/worldwide/shortwave.html
Keflavik, Iceland Upper Side Ban 10320.0kHz Day 6350.0kHz Evening
My geography I think at best the Iceland shortwave station of NPR may get to Switzerland?

Also somewhere if someone out there knows how to find international radio broadcasts in various languages translated, the show may also be available that way.

Measure Twice

Hey harly, I don't know if you have the ball bearing crank, but maybe this info will help.