Found a Honda G200 engine ...

[OzFab]

What did the tach read at idle?

 

[NewbCarter]

What did the tach read at idle?

It was "wrong" on idle . It would read OK the first 10 seconds of the startup but then it would jump to around 3k RPM and stay there ...
As the engine gained RPM past the 3k RPM mark it would move up with the engine ...

But it would not drop below that .. so thats weird ...

 

[itsid]

easy...

it's very likely exactly HALF of your readings;
since the engine will fire once per revolution (although it wouldn't have to)
and many (nearly all fancy looking ones) tachs double that number;
chances are it's just exactly half the reading.

A proper motorbike engine would only fire a cylinder every other rotation, like a car would...
so tachs made for those need to be tweaked to work (or need to be settable)

'sid

 

[NewbCarter]

Could this work as an "interposer" between the engine and tach ?
http://www.homemade-circuits.com/2012/05/make-this-simple-tachometer-circuit.html

I have a breadboard to test this on .... just missing the voltmeter ..

 

[OzFab]

easy...

it's very likely exactly HALF of your readings;
since the engine will fire once per revolution (although it wouldn't have to)
and many (nearly all fancy looking ones) tachs double that number;
chances are it's just exactly half the reading.

A proper motorbike engine would only fire a cylinder every other rotation, like a car would...
so tachs made for those need to be tweaked to work (or need to be settable)

'sid

Exactly what I was thinking; it's a relatively simple fix, the hard part is figuring out which resistor is needed...

 

[karte_m0lim]

so you are saying that he hits max of 3050 rpm on full throttle without load and removed governor?

what I have on mine tacho (small Chinese , digital); on idle I have 1400 rpm, on full power 5600 (with governor).. after that on idle its shows 700 rpm.. than again on full throttle it shows 2000.. after that I do no want to look...

 

[OzFab]

Your tach has issues...

 

[karte_m0lim]

Well, for 3$ chinese tacho, it works just fine

 

[Miky]

Buy a small VDO tacho, I bet your problems will be over

 

[NewbCarter]

Tachometer aside ( will be testing a mockup soon ...) ... the engine is out of commision for now.

Long story short , i started up the engine let it warm up so i can do some tests ... couple of revs later i heard a nasty grind in the flywheel area so i shut it down immediatly .

Taking off the flywheel i find that the nut was half way unscrewed , and a part of the key stuck in the flywheel...

So i took of the flywheel ... key was nowhere to be found... it literally desintegrated into a milion pieces which got stuck inside the flywheel hole... so theres that.

 

[Miky]

Sorry to hear that, hope you get it running soon.

 

[NewbCarter]

Well it was my fault anyways ... for revving the bejezus out of it xd

O well .. i need help.

So .. the engine "broke down" because the key in the crank got busted ..

With my new dremel tool , i managed to make a new key , and also polished the intake exhaust , and some work on the cylinder head .

It runs terrible ... or doesnt run at all . Everything seems in order , the carb is set on Honda factory settings ( 1 and 1/2 turns ) , yet it just barely idles , and if i add any throttle , it backfires into the carburetor .

Any ideas ? Also , the sparkplug was dry but like charcoal color ...

I suspect its to do with timing issues .. but i dont understand how ? The key now sits in its place , the flywheel doesnt move around , and has no "play" to it ..

 

[Poboy kartman]

Well it was my fault anyways ... for revving the bejezus out of it xd

O well .. i need help.

So .. the engine "broke down" because the key in the crank got busted ..

With my new dremel tool , i managed to make a new key , and also polished the intake exhaust , and some work on the cylinder head .

It runs terrible ... or doesnt run at all . Everything seems in order , the carb is set on Honda factory settings ( 1 and 1/2 turns ) , yet it just barely idles , and if i add any throttle , it backfires into the carburetor .

Any ideas ? Also , the sparkplug was dry but like charcoal color ...

I suspect its to do with timing issues .. but i dont understand how ? The key now sits in its place , the flywheel doesnt move around , and has no "play" to it ..

Is it aligned EXACTLY as it was before? (It doesn't sound like it is...)

EDIT: It could be a carb issue, but let's eliminate timing first.

---------- Post added at 12:04 PM ---------- Previous post was at 11:49 AM ----------

BTW:

You should know by now!!! You should have taken pics of everything and posted up!

It may be it needs re-jetting, ("factory " needle settings are only starting points....you must turn in or out until it runs at the highest rpm, but, when turning in (clockwise) , you must then give it throttle, ....and if it hesitates, open the needle up a bit more...(counterclockwise) ....until it doesn't stumble.

 

[NewbCarter]

ll try to take some tomorrow , when il be back working on it ..

Also , could you explain how it could be a carb issue ? Like clogged up or something ?

 

[Poboy kartman]

Well it was my fault anyways ...

With my new dremel tool , i polished the intake exhaust , and some work on the cylinder head .

It runs terrible ... ..

When you make an engine move more air (which you did)....you need to move more fuel....also...without seeing what you did...you could have done more harm than good..."polishing" the intake causes fuel/air mix to separate and lose suspension, and you can also decrease low end velocity...making the engine run worse on the low end.

BTW: "Rejetting" means changing the orifice size of the jets, not just turning counterclockwise....another thing...you're moving more air IN.....therefore, you must also now move more air OUT....(you may need to revamp your exhaust as well, as you can see, with so many variables, a picture REALLY is worth a thousand words!)

 

[NewbCarter]

There. So i put back everything , checked the flywheel , compression seems fine..

 

[NewbCarter]

Also , doesnt even want to start.. one time i pulled an it literally exploded out of the exhaust.. like someone put a firecracker in it

 

[Poboy kartman]

At this point, my money is on broken teeth on cam and/or crank ....I mention it here to help document for other members that may run into this in the future
....

 

[NewbCarter]

Well , alot of idea sharing with karte_molim later , and i think i isolated the problem to the carb .. when i tried to pull the cord it would literally spray a mist out of the carb ..

But il see more tomorrow.

 

[Poboy kartman]

Well , alot of idea sharing with karte_molim later , and i think i isolated the problem to the carb .. when i tried to pull the cord it would literally spray a mist out of the carb ..

But il see more tomorrow.

Once again, as I told you on Chat....yet another classic symptom of a crank and cam out of time. Carbs don't spit gas OUT without the valve timing being off...(valve is open while piston is moving up!!!!!!!)