My rover mower 800 ohv key start takes off to fast how do i adjust to slow it down thank you

You need to adjust the safety bar cable. When you hold it down it starts but when you release in is not coming back all the way, so it runs. Make sure the lever is clear of dirt and give it a shot of WD40 and move the bar handle up and down to work it in. Most likely something is in there keeping it from going all the way back. If that not it let the cable wire out (longer) about an 1/8 inch.

Hope this helps. Mike

Carburetor needs to be cleaned; main jet is clogged with debris, dirt, whatever.

Your mower doesn't have enough power to handle very thick grass at high speed. You need to go slower across the lawn. That's easy to do if this is a push mower (just don't walk so fast) or if it's a self-propelled model with a speed control. But if it's a single-speed model you'll have to mow the lawn in fits and starts: squeeze the lever to move it forward; release it when you hear it bogging down; wait for the motor to reach full speed; squeeze the lever to move it forward again; repeat. Also, is the grass very high? If so, try setting the cutting height higher on the first pass, then lower it for a second pass. Finally, make sure the blade is sharp.

intake adjustment should be set at .004. if not , the valve will blow back through the carb and run slow.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jim_5aec98336eb33c13

throttle spring could be broken stretched or missing

Between the handle and the connection to the drive system, look for adjustment screw or nut and screw on cable. Maybe even check the spring tension, if handle is spring loaded and the spring is stretched it will not engage drive system. If no adjustment to be found then you must get new belt. Good Luck...

On mine there is wing nuts on the end of the rods that move up and down when you push the handle forward. You just back the wing nuts off a little and then try it. If its still going too fast do it a little more.

Got a 1/2" or so bolt head on bottom of bowl at carburetor? If yes, carefully loosen it, remove it, lower bowl & look for debris in there & clean it out. careful with small gasket around it.

After charging the mower, you must place the safety key in the mower before it will start. On models that have a bail handle, be sure to pull the bail handle back to the mower handle before engaging the start lever. If your mower still does not start, remove the safety key and ensure the bail and start lever are in the "off" position. Then firmly re-insert the safety key, pull the bail handle to the mower handle and engage the start lever.

Note - It is important that the bail and start lever are returned to the "off" position before inserting the safety key.
Give it try, if it still will not operate you may have to take it in for service.
Good luck, let me know.
Regards,

sounds to me like you have governor problems. you may want to take that to a shop.