Yamaha Neos, 70cc...Non starter, yeah i know....

[cavboy1980]

Right, i've got this built back up with no issues. I got it in the frame with only one hic-up but it just won't start and i'm not really an expert and need advice to help me get to the root cause.

new carb (Dellorto PHVA) fitted, can anyone let me know what outlets take which hoses as i've no instructions and want to know i've plumbed it up right. Pipes i've got are 3, Main fuel hose, Vac hose and 2 stroke oil vent hose but this has 5 outlets.



It spins over well with a good spark to the plug but no fuel is getting from the tank!!
Sucking on the vacumn pipe draws fuel down from the tank but once re-connected there's nothing.
Is the Petcock knackered?
I've been told that the engine creates vacumn that draws the fuel down to the carb but i've sprayed WD40 over the engine looking for bubbles blowing and nothing.
Compression is good, tried the thumb test.
Can anyone help?

Also re-fitting the CVT brought another issue, the kick start isn't working, i can push it down by my hand with no resistance but everything is intact and looks undamaged.


Arsing bike !!!!!!!!!!!

[geoffh]

Just quickly left= fuel in right=vacuum 2 inlet at rear poss cooling? Not req have you fitted the cold start solenoid to the carb(looks like a stock picture) and go pre mix now!.

Geoff

[aeroxbud]

Like Geoff said. The bigger one on top is fuel. Smaller one vacuum.
The Two on the side are for water cooled bikes to heat the carb. If you blow into one, air should come out the other Just blank them off.

[cavboy1980]

I did blank off the two redundant outlets but still no luck.
Cold start solenoid?
Mine runs an automatic choke but I've refitted everything on the carburettor that can be fitted.
The one other issue was that the magneto wires running from the crankcase to the loom suffered two cut wires. Would this create my lack of fuel?
Straws are being clutched

[aeroxbud]

The choke can be tested by connecting to 12v. Should look like this.

The wires should not effect the fuel. The petcock sounds ok if it's supplying fuel when you apply vacuum.
You could try putting a small amount of fuel down the plug hole. See if it tried to start.

[cavboy1980]

A couple of mates came and helped me to figure out what was wrong and get it running.
Success, it runs and rides though it's only been up the road a couple of hundred yards.
We found that the new Dellorto 17.5mm carb wasn't causing a vacuum.
We refitted the original Gutter carb and it's running well.
So, why is the new carb not right, we noticed that the old carb has a bigger hole for the vacuum.
I'm disappointed with the new carb not being right but at least it's running and sounding sweet.
Any ideas guys?

[aeroxbud]

I would contact the seller. Never had a problem with Dellorto carbs before.

[pinkscoot]

Stupid questions the vacuum hole clear through to the Venturi?