Help routing fuel pump system to carb!!!

[Poboy kartman]

Ok....I want a nice clean pissen match here boys....no munching below the belt...in the event of a knockoff...return to your corner and start Googling.....

Now....touch lips and come out hugging!

 

[itsid]

LOOOL
I'm good, and I'm nearly certain Bret will be too in a few hours from now.

'sid

 

[Poboy kartman]

Soooo...here's something to ponder while y'all are getting it together:

My old buddy told me years ago that he raced gokarts. He said his dad put a ball bearing check valve in the top of the piston. Now...here's the thing....he said it worked well until it got clogged with oil.

The whole idea being it was supposed to let the piston return on the downstroke easier and quicker.....Thoughts?

 

[Krispy]

in order to test the elbow you showed me i would just have to crank it and see if i feel any pulses of air correct? I will let you know how it turns out on Wednesday due to work. away from home until then.

If it requires the Motor to actually be started then it might be a little longer. I have No Spark. I read out the Coil and it was bad so i bought a new one and still no spark. I'm guessing the CDI.. which sucks if it is that cuz that is around $200l.

 

[itsid]

yes the engine should be running to properly test for pulse;

'sid

 

[Poboy kartman]

yes the engine should be running to properly test for pulse;

'sid

I'm not sure....but I think that works for people, too?

 

[Krispy]

okay. so i need to get electrical system figured out then...

---------- Post added at 06:44 PM ---------- Previous post was at 06:11 PM ----------

I'm not sure....but I think that works for people, too?

 

[Krispy]

Wow it has been a long time. So i got the electrical system fixed FINALLY. Ended up being a burned up Stator.

Now that it is all replaced and running i checked to see if there's a pulse from the line you were talking about. There is a pulse but it is very light.

I have routed the fuel lines the way i thought was going to work if that port was a good enough pulse. When i start it up it isn't sucking any fuel through the feed hose AT ALL which is why i'm assuming it isn't enough of a pulse.

Im uploading pictures to better reference what i have.

 

[anderkart]

Is there enough room to instal a barbed fitting in your rubber carb mount in-between the reed cage and carb?

 

[Krispy]

there might be but it will be tight. When i was researching in the beginning of this project, that is where people were drilling a hole and tapping it to put a nozzle for the vacuum.

But theirs were metal and mine is rubber. so i don't quite know how i would do that.

Idk how much it moves and vibrates during riding and/or if it would cause a fitting to get loose.

 

[itsid]

hmm..
first you need to fill the fuel lines
(generally just bring the tank up and open the flush valve on your carb.)
trapped air might hinder the fuel flow...
or to be more precise, the pulse might be enough to move fuel, but not enough to suck fuel through an empty line (many fuel pumps can't)

if it still fails, then you could check if the wrapped line coming from the elbow is leaking,
or just skip it alltogether and pop up the crankcase to drill the hole Desertduler talked about.
(tap it and insert fitting as per his' instructions)

If your's is indeed rubber (and not silicone or PU or something) you can find a rubber valve stem, drill/poke a hole in the rubber mount and re-vulcanize it as you did back then with your bicycle tubes...
it'll be airtight (apart from the valve stem that is )
Personally.. I'd buy a rubber manifold and use that for all the hole poking thing..
test it's seal and if it's tight, install it (if not, scrap the idea and find a different option )

'sid

 

[Krispy]

Thanks Sid, I didn't even think of filling the lines first. Now i'm kicking myself in the butt for not trying that.

 

[Joe-405]

The exhaust side won't work as a pulse on a ktm engine FYI. They have a pressure return that makes it easier to start and don't produce enough vacuum on the exhaust side to run a pump. Needs to be between carb and cylinder to work.

 

[Krispy]

Yea i think i'm going to try that. thanks! will let you guys know later this week how it goes!

 

[itsid]

The exhaust side won't work as a pulse on a ktm engine FYI. They have a pressure return that makes it easier to start and don't produce enough vacuum on the exhaust side to run a pump. Needs to be between carb and cylinder to work.

while that's true;
(that engine is equipped with exhaust port control, so technically not a pressure return...)
Anyways I hoped that the pressure inside the crankcase is uniform enough for a good pulse (so that there is no new hole to drill )
but chances are the pathway to that vent is narrow enough to render it useless.
Still as long as there's a detectable pulse signal, it's worth a try, right?

Frankly.. since that engine has an alternator.. I still vote for an electric fuelpump over drilling a hole...
but that's just me

'sid

 

[Joe-405]

Everything in our line of play is always worth a shot. And 99% of the time you post something its spot on Sid. I would use your advise any day.. Only reason i remember is because i remember somebody else having the same issue and somebody else said the ktm's are tempermental with vacuum.

That was when i had the qrc kx125 kart and was searching for answers on mine also.

 

[Desertduler]

News flash dude, I know what I am talking about and you do not. Two strokes do not have a crankcase vent like you think that they do.Why don't you study them and the hows and whys of how they work? The 125 engine is no different than my 300 and I have built 125cc KTM engines and when and if I am wrong I will admit it. You have NO idea how many engines I have built over the years for myself and fellow racers, hook the impulse line to the fuel pump up to that vent line for the transmission and the fuel pump will never get a signal, take a look at the crankcase and see that the engines crankcase is isolated from the transmission case. Googling something and having first hand experience are two opposite ends of the spectrum.
BTW I do not care if I pi$$ you off because you have pissed many of people off before.
You pi$$ed me off by sending me a PM and asking for my advice and when I gave the correct answer you said that I was wrong maybe one day you will actually take one one these engines apart and then it will come to light to what I am trying to convey here. You have many followers that think that you are correct and that is fine but the fact of the matter is I was trying to give advice from my 40 plus years of being an engine mechanic and you say I am wrong and I most certainly am not!

 

[itsid]

News flash dude, I know what I am talking about and you do not. Two strokes do not have a crankcase vent like you think that they do.Why don't you study them and the hows and whys of how they work? The 125 engine is no different than my 300 and I have built 125cc KTM engines and when and if I am wrong I will admit it. You have NO idea how many engines I have built over the years for myself and fellow racers, hook the impulse line to the fuel pump up to that vent line for the transmission and the fuel pump will never get a signal, take a look at the crankcase and see that the engines crankcase is isolated from the transmission case. Googling something and having first hand experience are two opposite ends of the spectrum.
BTW I do not care if I pi$$ you off because you have pissed many of people off before.
You pi$$ed me off by sending me a PM and asking for my advice and when I gave the correct answer you said that I was wrong maybe one day you will actually take one one these engines apart and then it will come to light to what I am trying to convey here. You have many followers that think that you are correct and that is fine but the fact of the matter is I was trying to give advice from my 40 plus years of being an engine mechanic and you say I am wrong and I most certainly am not!

Okay, one last time...

Yes, you've popped open more KTM engines than I would ever be able to, no question about that (and the main reason I asked you to join this conversation)
That's exactly what I was saying..
And yes, I asked you to verify again that drilling the hole is necesary;
not because I said it's the wrong answer (it'll certainly work of course)
but because the manual suggested there's a less destructive way of getting a pulse.
And it's Krispy's engine.. not mine... drilling the engine case is pretty much a final decision.

And yes, when it comes to this particular engine.. all I can do is looking at pictures lacking an actual engine to take apart.
(and the necessary funds and ambition to buy one just for arguments sake)

but pictures and the weak pulse Krispy detects suggest at least some validity of the manual

Pictures?
these...
this looks like carbon deposit, doesn't it:

Yes, I know there are two rotary valves
opening and closing two slots in the exhaust port.
But judging by the pic.. do they seal against the exhaust control?
or are they variating against some corresponding(?) openings in the cylinder wall:


IDK but would you at least agree that this looks like the manual could be correct?
Or say to "some pic-starer" like me

Anyways, I was getting mad because you suggested I only asked you to join in to show you up;
and you should know better than that (at least I hoped so)
that hurt... so yeah; my apologies for getting mad.

I will NOT apologise for asking for confirmation, since you're amongst the people I can surely learn from, and sometimes that requires confirmation.
at most for not picking the right words to do so.

Anyways, good to see you back! (honestly)

Now back to our regular program..

'sid

PS Again, sorry Krispy for all that off topic crap in here, but sometimes we're ordinary people

 

[chancer]

Just stop!
He is already gone, and will not be back.

 

[Krispy]

Hey guys so I got the fuel system working perfect.

I primed all the lines with fuel as suggested but it still wasn't enough pulse to pull fuel from the tank.

What i ended up doing was drilling a hole in the rubber flange after the Carb and adding an air fitting that goes to the diaphragm port of the fuel pump.

Everything else is ran the same. and good thing i added in the Petcock/Fuel Shut-Off to the line because it was still getting a little too much fuel so i had to close it just a bit to get more fuel to go back to the return line.

Thanks so much for all the help. I didn't mean to start any fights or end any friendships. I will keep this discussion going to add Photos and hopefully this thread will help someone else in the same spot i was in.