I am trying to fix a DVX90 for a neighbor's kid. When I got it from them had to put in fresh battery and it sounded like grinding metal, Pull the cylinder and wow rings froze in the lands and cylinder wall scored badly. I got a cheapy top end kit and now it just floods the plugs terrible. It has 110-115psi compression and great spark with fresh plug. Checked the float level and cleaned & adjusted carb several times. What are the indicators of bad reed valves? It will fire for just a second after I turn off the fuel and crank for a while. seems then that once I am able to limit the fuel I can get it to fire but just for a few seconds. I am missing something here?

 

Reeds can crack but they don't flood the motor.
Shut fuel off, apply full throttle and start. It'll chug till it reach's high rpm and cleans out.
Turn fuel back on. If it still floods, it's fuel getting by the float needle.
Many needle problems since ethanol.

 

Roger that, it is definitely getting by the needle. I have fuel coming out of the vent and overflow on the bowl. Have cleaned it several times. These carbs come with a rubber tip on the needle these days, can it be replaces with the old all brass units?

 

I know thru the years, Suzuki has used both style needles so I would think you could do that.
Have you tried adjusting the float height? Maybe bend the tab to lower the fuel level (if metal).

 

I am reviving this thread. After letting the atv sit for a couple months while I worked on other toys I ordered another carb and tried again and get same results. Hot spark, good compression and fresh fuel/carb and still no start. I am obviously missing something? What are the symptoms of crank seals? HELP I would like to give this kid his toy back but not til it is running! Could the timing be off. It just wets the plugs with fuel and won't run.

 

Just Googled it and the blurb says Four Stroke so no reed valves and worn crankcase seals just leak oil. Is there an earlier model with a 2 stroke engine, as in Suzukis?

 

From original post first thing i noticed was the compression still being a little low after a fresh top end it should be around 135+. 100psi is around rebuild time when u did top end was it new cyl and all parts that go with that?

Is it still flooding out with the new carb or just no start?

Have you checked timming and valve adjustment

 

Yes this is the two stroke model with the Minarelli based 90cc engine. It is a Taiwanese engine that multiple companies used; Yamaha, Polaris, Arctic Cat, Manco, Kymco etc.

 

No valve adjustment on 2 stroke. The compression is factory speck for these at 115, and the plug is wet with a no start condition.

 

I'd say comp is fine. They still run good at 90.
Maybe try draining the carb. With the fuel shut off still, try a full throttle start. It should eventually start and clean out. It has to spit and sputter and such but hopefully it's good news. Run till it stops. Turn fuel on and give it a go.
Seeins the plug is wet, I'd also say the seals are ok as it's sucking the fuel in. Dry plug would be different.