hey guys I just bought my daughter her first quad for her 7th birthday in 5 days time.

Second hand 50cc 4stroke Chinese quad. Not sure on brand. paid £250 for it so I need it running for her birthday because I can't afford to buy her anything else

PZ19 carburettor

it ran when I picked it up but when I got it home and took it on the field it would start to lose power when opening throttle up.

it starts and idles fine but when pulling off there's no power and it cuts out.

i have stripped the carb, cleaned the fuel tank and replaced the small inline fuel filter but it did not improve so I watched a video on how to reset the carb, screwed the a/f mixture screw all the way in then 2.5 turns out all that has done is made it harder to start, it takes a minute or two to get it running now.

i know it's nothing to do with any kill switches, I'm pretty confident the engine is sound and it has oil, I know the fuel is clean and I've also replaced the air filter so that's not clogged up either

im 99.9% sure it's a carb issue, starts first time with a bit of ether sprayed into air input, but no matter what I try and do with the carb nothing improves it. Pz19 carb any advise would be great thanks guys rich

oh and I just need to add that the pin that attaches to the throttle cable inside the card is on the middle notch

 

It does seem like carburettor, but change the plug just in case it is that, check compression, some of those Honda derived engines will run with hardly any compression, but won't pull weight. If a plug change and compression check do not show anything, you will have to clean the carb again. Make sure all jets and the holes they came out of are clean with a blast of compressed air. Make sure the choke is working properly.

 

Thanks for the reply merryman.

I have changed plugs but to no avail, what i did notice though was before changing the plug i took it out and cleaned it, took it out a day or two later after trying to get it running right and it was black with soot, possibly related?

I cant do a compression test because my brother borrowed my gauge a few months ago and works away during the week, i will go fetch it at the weekend and check compression.

Now some thing thats been bothering me.....

carburetor cleaning, when i cleaned it, all i did was take it apart, removed the two jets and blew them out with my compressor, removed float and cleaned out the reservoir then rebuilt it ensuring the float was seated correctly is this the correct procedure? did i miss some thing?

Should i remove the air fuel mixture screw and idle screw to clean behind them?

When i screw the jets back in do i just screw them all the way in or should it line up with some thing. Do the tiny holes in the jets have to face a certain way?

sorry for the long winded reply but like i said in my original post this is a present for my daughter and i need it sorting for saturday morning

thanks for your help

ps i assume the choke is working correctly, if i remove the air filter and move the choke switch i can see it open and close

 

When I clean a carb out, I blow through the holes the jets came out of as well. Look through the jets against the light to ensure they are clear. I avoid removing mixture screws, as you have to set the mixture again if you disturb them. A sooty plug indicates a rich mixture, choke sticking, clogged filter, or float level too high, but as you have been trying to get it to run right you may have had it on choke more than usual. Try it without the air filter and see if it runs better.

Jets should be screwed all the way back in.

Could be an idea to check valve clearances as these can affect compression. At a guess, between 0.003" and 0.006" should be OK.

 

Sounds like it's too rich to me. Is the mixture screw on the air side or the motor side of the carb? Is there an idle speed screw? I started with just 1 turn out and the idle high to get it running, then turned the mixture screw till I got the highest idle, then set the idle speed back down to what I wanted. Set up the back axle so the wheels can spin freely.

 

I'm thinking valve adj/compression.