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Anybody on this forum good with 500 motors o need some serious help. Thanks in advance 

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sure is, what can we help you with ?, we need the full year/make/model !.

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I talked to Jeremy and referred him here. He’s working on an 05 500 footshift. 

Spins over great with the head off, but when he puts the head on it won’t turn over/starter struggles.

He’s swapped on a known good starter (several actually) and also swapped a top end off of a running 500. Same result.

Stumped me. Sounds like a bad battery or starter to me.

In the videos he sent on bookface he was using jumper cables to turn the starter over. I suggested he run reg lines and attach them with nuts, but he’s rebuilt a few engines and this one stumped him.

 

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I don't have a 500 , does a 500 have a starting aid decompression mechanism ? -----   

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I'd say bad battery or bad ground personally. 

 

No mention of piston ring condition though...? Low compression is a possibility, as is timing.

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Sounds like the OP needs to chime in and start from the beginning. Previous issues. History. What internal work was done. What led up to him posting here?

 

Next thing you know He bought a cam from China with no exhaust lobs.(being funny) Engine is just a air pump. Air in. Air out.

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He sent me videos of it spinning over fine with the head off, but when you put the head on it acts like it doesn’t want to turn over, like the starter doesn’t have the power to do it. 

 

He sent me videos but they are .mov format

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19 hours ago, Big Bird said:

Sounds like the OP needs to chime in and start from the beginning. Previous issues. History. What internal work was done. What led up to him posting here?

 

Next thing you know He bought a cam from China with no exhaust lobs.(being funny) Engine is just a air pump. Air in. Air out.

Big bird im not familiar with this forum so don't know how notifications work and I don't know how to post the videos, but new oem timing chain, tensioner,  guide .50 over shindy piston and bored jug, no dragging or funny noises that would have me assume crank is bad. Like jeep started ot will turn over all day with either plug out or valve cover off but with both on it'll turn until it hits compression stroke and stop.  Sorry for the delayed responses 

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3 hours ago, Jeremey said:

Big bird im not familiar with this forum so don't know how notifications work and I don't know how to post the videos, but new oem timing chain, tensioner,  guide .50 over shindy piston and bored jug, no dragging or funny noises that would have me assume crank is bad. Like jeep started ot will turn over all day with either plug out or valve cover off but with both on it'll turn until it hits compression stroke and stop.  Sorry for the delayed responses 

No need to say sorry. I like to have ALL the info posted up when there is a problem.

What led up to going in and rebuilding the top end?? I would like to see a comp test first.

If it spins over OK with the plug out but when you put the plug back in it stops on compression. One would think the piston is hitting the plug or a VERY high compression.

 

Do a comp test first. Rules out a bunch of stuff.

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15 hours ago, Big Bird said:

No need to say sorry. I like to have ALL the info posted up when there is a problem.

What led up to going in and rebuilding the top end?? I would like to see a comp test first.

If it spins over OK with the plug out but when you put the plug back in it stops on compression. One would think the piston is hitting the plug or a VERY high compression.

 

Do a comp test first. Rules out a bunch of stuff.

In the video it sounds like my daughters 300 that had a dead cell in the battery. I still think it’s a starter/electrical issue.

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15 hours ago, Big Bird said:

Big bird, just did a comp test on my bench with a brand new oem starter and jumper cables coming off my truck with it running and at the hit of the compression stroke it Is showing 70psi and still stops on that stroke. And im getting 13.98 volts from my truck to the starter on the wheeler.

 

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Posted (edited)

Does it also get stuck or stop when you pull it over by hand with the pull start?

Any indication when the head was removed form valves contacting the piston?

Sure SEEMS like a weak starter or low battery, I wonder if the decompressor might be not functioning on the cam?

70 pounds sounds about right though with decompressor working

I have done a few of these motors too and have never seen this come up before, so I hope we can help figure it out

Edited by AKATV

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Akatv, pull cord assembly is no good.

And no if the spark plug is out it turns freely with no issues or dragging or anything indicating something's in a bind. Have checked and triple checked timing, pulled top end apart twice and no signs of plug of valves hitting the piston. If I leave the plug in and pull valve cover off it will spin over fine. I have swapped heads and valve covers as well and still same results.

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have you tried to rotate engine with pull cord assembly removed by turning crank over slowly by hand or with a wrench?

Does it seem to lock up like its hitting something or does it seem to just not be able to power through the stroke from compression

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Yes sir, with the valve cover on and plug in its tight with a ratchet but do able. Have pulled plug and slowly rolled ot over and everything sounds good. It really seems like it can't get past the compression stroke when it's all together(plug in and cover on). Ordered a brand new starter and tried it on top of the other 5 and still the same result.

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1 hour ago, Jeremey said:

Yes sir, with the valve cover on and plug in its tight with a ratchet but do able. Have pulled plug and slowly rolled ot over and everything sounds good. It really seems like it can't get past the compression stroke when it's all together(plug in and cover on). Ordered a brand new starter and tried it on top of the other 5 and still the same result.

load that dang thing up, bring it up here to me, i'll fix it, make sure to bring all parts !..lol.

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You are seeing 13.98 volts coming off your battery , but what kind of reserve does your battery have ,  you could have a bad battery , if I didn't have a load tester , I would take the battery to an auto parts store and have it load tested ---- also would clean all the connections , especially the ground at the engine and check the length of the cables for a cut or hole where corrosion could have gotten inside the cable ---another thing comes to mind , are you sure you adjusted the valves on the correct stroke 

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Ok. Seems like we shall go down the electrical path. OK. a fully charged battery is 12.6VOLTS. Anything above that is just a static or surface charge.(6 cells at 2.1Volts=12.6Volts)  Make sure all the connections are clean and in good shape. Now it is time to do a voltage drop on the starter system. If the battery is good.

 

 If your battery is good. I would do a voltage drop. Easy to do and will pin point where a voltage is lost. If you have a poor ground voltage is lost in that poor ground. Starter will not see full voltage. 12 volt systems have a beginning and a end of the circuit. The load will decide where the voltage drop is. Hard to say in typing on a forum.

 

On a simple note or example. If you had a bad ground that used up 4 VOLTS. Battery is 12.6 volts. If all the connections are good your starter is only using 8.6 Volts to turn over the engine. If you repair the bad ground. Now your starter is using 12.6 Volts and is WAY more powerful.

 

A voltage drop is the best way to test a poor connection and how much voltage loss is getting to a load.

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On 7/12/2020 at 8:15 AM, Fishfiles said:

You are seeing 13.98 volts coming off your battery , but what kind of reserve does your battery have ,  you could have a bad battery , if I didn't have a load tester , I would take the battery to an auto parts store and have it load tested ---- also would clean all the connections , especially the ground at the engine and check the length of the cables for a cut or hole where corrosion could have gotten inside the cable ---another thing comes to mind , are you sure you adjusted the valves on the correct stroke 

Thinking he has his truck hooked up with jumper cables with truck running. Regulated voltage from the truck(?)

 

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4 minutes ago, Big Bird said:

Thinking he has his truck hooked up with jumper cables with truck running. Regulated voltage from the truck(?)

 

Yep , I cut that sentence short    ----- what I meant was  " You are seeing 13.98 volts coming off your battery  "  of your truck running -------------  

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a couple of  test I use  on starters , after load testing the battery at the terminals  and verifying that battery  will hold a load , I connect my load meter to the battery cables at the starter and the ground at the case , put a load on it , this will show if the cables are good ---- then with the meter still connect but not under a load , try to start the engine , if the voltage drops below 9 volts , and the battery load tested good , then the starter is bad 

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no, but did speak to him about 2-3 months ago on the phone.

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Guys I threw in the towel on the motor, last thing I tried was tearing it back apart and cutting the decompressor off the cam and that made no difference. Going to assume the crank was bad, that would be the only thing I could figure out. The motor was never installed on the wheeler except that one time all the other times testing it were on my work bench with several diff starters as well as a new one I ordered from D&B and made no difference. I appreciate all the input but sometimes you gotta know when to quit befor labor over runs the cost of the 4 wheeler.

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Hope you stick around.  Sounds like you have enough experience tinkering on these things to be an asset to the forum.  Good group of guys here. 

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