KymcoForum.com
Offroad => Side By Side => Topic started by: dalepatter on August 29, 2019, 10:50:22 PM
-
I recently bought a UXV 700i from a co-worker. It was not running. It would not turn over, it seemed locked up. I took the generator cover off to reveal a stripped starter reduction gear. It had sheared teeth off. The new one I installed has heavy teeth now. The unit is now not locked up, but turns over extremely hard, like turn some stop....turn some stop. There is also some relay clicking sounds near the battery. I have hooked up a brand new huge car battery I still have the same results.
This engine does have a high compression head, but started fine before the broken stater gear issue.
Any help or suggestions would be much appreciated as I am a newbie.
-
Pull the spark plug and see how it turns over. Bet it is the same...
-
With the plug pulled it turns over without stopping. Seems to blow a lot of air out the spark plug hole
-
Delighted to say I was wrong! That lets the bad mechanicals off the hook! Your starter is the problem since you used a car battery. These are permanent magnet starters so they are real simple: just bearings, brushes and armature to fail. Bearings can let the armature touch the poles, brushes can wear down or get stuck and armatures can open circuit or short. Remove starter and inspect. Repair or replace depending how much gold you have buried in the garden! There is one more thing, having re-read your post, you may have a bad connection in the heavy wire from battery cable to start relay, the relay itself or the cable from relay to starter. There is supposed to be a compression release on the 500's but this is a twin cylinder, right?
-
I forgot to mention that I installed a new starter as well. Due to the teeth being scored. It is a single cylinder.
-
OK, check voltage at the starter during cranking just with the car battery. Pop the valve cover off and check the compression reliever.
-
Might still be a bad electrical connection, take apart and really clean all connections. By using a large battery the elctrical connections could have sparked and caused some corrosion
-
How can I tell whether the compression reliever is functioning properly? I will check all the battery connections as well as starter connections and get a voltage when trying to turn it over. Thanks for all the help
-
Remove valve cover and inspect the exhaust cam. There will be a spring loaded thingy with a flat on the side of a small rod. That flat side will be turned 90 degrees so the round part of that shaft will hold the exhaust valve open a tiny bit for starting. May be a bit different but it that spring broke the valve would never close. And, conversely, it could malfunction and never hold the valve open for starting which sounds like your case.
-
I finally got around to pulling this apart and inspecting things. The timing is perfect. The cam appears to be in aftermarket performance cam. There is an oval slot that looks like it is missing something. I have attached a photo.
-
Compression release thingy is missing. Ah-HA! There is a do-dad that goes in that slot that sticks up and holds that valve open just a smidge so the engine spins fast enough for start then retracts flush for run. You gotta replace all that is gone! Or use a car starter! And a car battery! I'm a big help, huh!
-
I have an interesting update, I have not installed the new camshaft yet. I kept going back to the fact that the previous owner said that the engine always turned over nicely. The cam that is in there is a racing cam and the decompression mechanism was removed on purpose.
BUT,
I discovered by accident if I pull the spark plug wire but leave the plug in it turns over just fine. When I attach the spark plug wire the engine really struggles to crank over. After trying to crank two or three times it will start however.
Attaching the spark plug wire makes the engine hard to crank.
An electrical issue maybe?
-
Just a guess here but if it becomes harder to crank with the plug on it would indicate the plug was firing to soon before tdc....turn over shouldnt make any difference if plug wire is connected or not. You sure the plug is right length, have saw cases where plug was to long and hit the piston. Not sure the engine mods were done right from the explanation given
-
Compression release thingy is missing. Ah-HA! There is a do-dad that goes in that slot that sticks up and holds that valve open just a smidge so the engine spins fast enough for start then retracts flush for run. You gotta replace all that is gone! Or use a car starter! And a car battery! I'm a big help, huh!
Karl's advice makes a lot of sense.
I wouldn't be worried about a possible "electrical issue". Chances are about 100% that the absence of the decompression thingy (removed on purpose) is causing the problem.