Idle speed

[Dante12016]

I bought my 04 gz250 used, had idle speeds wrong from the start. It would just stall out constantly. Now I have it running but every time I turn it off my exhaust pops. Is this because fuel is too rich, how will I go about finding the correct spot with no tachometer? I'm also only getting a top speed of about 50mph my ass weighs 220lbs but I think I can push the bike faster. An I have no mechanical know how.

[jonathan180iq]

Without a tach you'll have to set idle by feel. Watch some Youtube videos of healthy bikes and try and match that thumping rhythm.

Ensure that your choke isn't left partially on. That'll kill a warmed up bike. Also, be sure to run carb cleaner through every other tank of fuel. This may seem like overkill, but you need to keep that carb clean or you'll run into all kinds of problems.

Your exhaust is popping because the mixture is actually slightly too lean and it's causing more heat to make its way down the exhaust system. That sputtering and mini-popping sound is very different from a situation where the mixture is too rich. In that case, you get what most people refer to as backfire, where the exhaust goes off like a shotgun... (It's actually an AFTERfire. Backfire is where the explosion happens back into the airbox and will literally scare your penis off.)

[k1w1t1m]

I second the carb cleaner suggestion. I weigh more than you and get my wifes GZ up to 70 (just) for short periods. Don't adjust anything at this point until you've put a few tanks of gas through it (with carb cleaner in them). Frequent use is key as crappy gas and carbs don't like sitting and the carb passages will slowly block up.

[5th_bike]

Your bike may be in dire need of a valve clearance check and adjustment.

It would be best to give it a full 3,000 mile type service. The sooner the better. If you don't trust yourself doing it please take it to the dealer.