70cc Jog built from parts won't run long

[datt]

Hey everybody,


I won an auction for a 1998 Yamaha jog as a bunch of parts enough to build a running scoot, it turns out it was actually a 5BM jog exported from Japan.

The auction included a bunch of engines as well, I've gone ahead and assembled up a 3kj engine and thrown the loom on the frame and I cannot get the engine to run longer than 20 seconds. It won't idle either no matter what you do with the idle adjustment screw.

So far the engine has -

DR 70cc BBK kit with stock replacement gaskets (Don't think this would affect squish too much?)
Technigas exhaust
Generic Taiwanese performance intake with reed block
Dellorto PHGB 21mm/19mm Carb with pod filter 
Racing coil pack/ignition
New crank bearings/ seals.

Whatever I try I cannot get it to run or idle for any period of time. It seems to be getting too much fuel, with the intake the carb is on the slightest tilt forward. I changed from my used Dellorto PHGB 19mm to a new 21mm PHGB and playing around the with mixture screw I could get it running rough for a minute at 1/4 throttle, any less or more and it died.

With the 19mm carb on I tried different main jets 82 - 110 with very no noticeable affect but the bike was barely operable throughout the rev range so hard to tell.
I've ordered a needle kit as well as some pilot jets and more main jets. 

Compression tested at 150PSI, all the electrics seem to be working fine, when it does start I can see the voltage across the battery increase to around 12.8-13VDC. Fuel line has been changed to an on/off tap and has no blockage, fuel tank cap can breathe. 

When I did have the vacuum petcock and the vacuum line attached to the intake manifold I did notice when it was running fuel was bubbling up the vacuum line from the manifold end, my scooter shop mentioned this would be way too much fuel and should be atomized at that point.
The pilot jet in the 19mm carb was .40 so on the leaner end. Could this entire issue be related to jetting?
I've had badly tuned carbs before, but I've never had something I couldn't at least get idling rough, I've spent hours on this now lol

Here's a vid of it (barely) running www.youtube.com/watch?v=DOiotMmPJfI

Any help would be appreciated!

-EDIT-

I should add - I've checked the float in the 19mm carb and it was shutting off correctly, the 21mm carb is new and I've yet to open the float bowl. 
Initially after the first few days I had to pull the cylinder off and drain the exhaust of oil and fuel. Cleaned everything out and made sure there was no possibility it was flooded, after a few kicks it fired up and went back to doing the same exact thing. 
I can't run it long enough to get any colour on the plug.

It starts easily every single time without choke and then dies

[Rune 75]

Do you have another reed to try on ?

[datt]

Oct 29, 2019 3:23:25 GMT -5 Rune 75 said:

Do you have another reed to try on ?

I still had the original carb with auto choke although the manifold was a little cracked so I tried that with the original reeds and the engine started and ran very lean for a few seconds before dying and then due to the autochoke I couldn't get it started again.

The reeds i'm using now with the dellorto carbs are brand new and have only been used on this engine 

[Rune 75]

From the sound of it it's not getting enough fuel. It fires up and quickly runs out of fuel and gets harder to start after it stops. If you let it sit for a minute, will it fire up relatively easy again ?

[geoffh]

I,m not a 70cc guy but have you plugged the vacume line? Try it with the original air box and smaller carb get it running and then move up in small steps.

Geoff

[Zino]

All 3 carbs are having trouble holding a idle SO the problem is a overalap from all 3 .

Have you tried sucking on the vacuum line to see if the fuel line flows fuel ?

Is the carb bowl full after it dies ?

[oldgeek]

Pod air filters on a 2T can make you want to kill yourself. Do yourself a favor and find a stockish air box. The 19mm carb should be fine. 40 PJ is a little big. IMO
Once you get it running good, then you can go back to the pod and retune to your hearts content.

[repherence2]

did you change parts in your CVT?

clutch springs, roller weights, or contra spring? or is it stock? you might have to stall the clutch to a higher rpm being that you changed out the bore and pipe.

I think you should sort out the Pilot Jet issue and get it to idle nicely before you move on to the main jet. how many turns out is the air mixture screw?