scrambler 500 worn camshaft?? - Polaris ATV Forum
Polaris Scrambler Discussions for the Polaris Scrambler

Reply
 
LinkBack Thread Tools Display Modes
post #1 of 13 (permalink) Old 08-26-2019, 04:26 AM Thread Starter
Junior Member
 
crisatv's Avatar
 
Join Date: Jun 2019
Posts: 28
scrambler 500 worn camshaft??

hello i have an 01 scrambler 500 2x4 that im pretty sure has the worn camshaft. idles great but at about a quarter throttle spits fuel back out through the carb. the question i have is when i pull the plug it looks really light brown like its lean? if the exhaust valve wasn't opening wouldn't the plug be black like it was rich?? im pulling the camshaft today to make sure the cam is the problem. ive tried two carbs. one brand new and the bike has the identacle issue with both. valves are set at .006 on both exhaust and intake and timing is perfect. thanks for any advice.
crisatv is offline  
Sponsored Links
Advertisement
 
post #2 of 13 (permalink) Old 08-26-2019, 05:47 AM
Premium Member
 
stave7119's Avatar
 
Join Date: Oct 2013
Location: Lena, IL
Posts: 3,401
The spark plug should be a straw color if the engine is running right. With a lean condition the plug will go more toward the white and rich would be a black color on the plug.

Mine: 2018 Sportsman 850SP - 26" Bear Claw HTRs on OEM steel wheels(I really don't like the Aluminum ones)
Polaris Hand warmers, Mirrors.
Hers: 2019 Sportsman 450. 26" Bear Claw HTRs on Moose 427X Wheels.

2007 Sportsman 500 EFI, Polaris Winch, 25" Bear Claws QSC Clutch Kit, Hand Warmers
2001 Magnum 325 MOSE 12" rear wheel conversion. 25" Sedona Coyote tires
2017 Polaris Ranger 1000XP - Roof and front glass
2018 Kawasaki KLR650
2001 Magnum 325 Warn winch and Moose 60" plow-Sent to Daughter and Son-In-Law since his blew up
SOLD 2004 Sportsman 600 Twin
stave7119 is offline  
post #3 of 13 (permalink) Old 08-26-2019, 06:06 AM Thread Starter
Junior Member
 
crisatv's Avatar
 
Join Date: Jun 2019
Posts: 28
ok the plug is brown. would a worn exhaust lobe on the camshaft cause a lean condition or rich?
crisatv is offline  
Sponsored Links
Advertisement
 
post #4 of 13 (permalink) Old 08-26-2019, 08:38 AM
Polaris ATV Legend
 
latebird's Avatar
 
Join Date: May 2014
Location: Illinois
Posts: 4,497
Probably not - if the valve does not open fully, it will just limit engine performance as the piston struggles with high pressure trying to push the exhaust gasses out.

A worn lobe can be detected easily - first clue is the valves get loose and have to be adjusted tighter (the valves in overhead cam engines typically get tight with use and need to have the clearance adjusted to ease starting - tight valves drop compression making the engine hard to start) - a worn cam means insufficient lift during the combustion cycle - if you just visually observe the movement of the rocker arm as the valve opens and closes and compare it to the intake rocker arm movement, they should be about the same. If you have had to tighten the valves frequently, then the cam and rocker arm may need replaced. If the valves open and close approximately the same amount, then the problem is probably in the carb or fuel system related in some way.

Shop Owner and Mechanic with over 50 years experience
latebird is online now  
post #5 of 13 (permalink) Old 09-15-2019, 10:37 AM Thread Starter
Junior Member
 
crisatv's Avatar
 
Join Date: Jun 2019
Posts: 28
well i figured it out. camshaft is toast. exhaust lobe is pretty much completely gone and and the intake lobes are on their way out! crazy how it can run great one day. shut it off and fire it up the next day and its shot. time for cam and rocker arms! Good times lol
crisatv is offline  
post #6 of 13 (permalink) Old 09-16-2019, 04:26 AM Thread Starter
Junior Member
 
crisatv's Avatar
 
Join Date: Jun 2019
Posts: 28
Hey guys is there a better oil I can use to try and avoid the wear on the new camshaft. Do you guys have any tips you have tried that has helped. Thanks guys.
crisatv is offline  
post #7 of 13 (permalink) Old 09-16-2019, 05:35 AM
Premium Member
 
stave7119's Avatar
 
Join Date: Oct 2013
Location: Lena, IL
Posts: 3,401
I generally stick with the OEM lubricants for all my machines. Never had an issue.

Mine: 2018 Sportsman 850SP - 26" Bear Claw HTRs on OEM steel wheels(I really don't like the Aluminum ones)
Polaris Hand warmers, Mirrors.
Hers: 2019 Sportsman 450. 26" Bear Claw HTRs on Moose 427X Wheels.

2007 Sportsman 500 EFI, Polaris Winch, 25" Bear Claws QSC Clutch Kit, Hand Warmers
2001 Magnum 325 MOSE 12" rear wheel conversion. 25" Sedona Coyote tires
2017 Polaris Ranger 1000XP - Roof and front glass
2018 Kawasaki KLR650
2001 Magnum 325 Warn winch and Moose 60" plow-Sent to Daughter and Son-In-Law since his blew up
SOLD 2004 Sportsman 600 Twin
stave7119 is offline  
post #8 of 13 (permalink) Old 09-16-2019, 06:27 AM Thread Starter
Junior Member
 
crisatv's Avatar
 
Join Date: Jun 2019
Posts: 28
ok great. Im seeing ps4 synthetic. Would that help?
crisatv is offline  
post #9 of 13 (permalink) Old 10-05-2019, 02:41 PM Thread Starter
Junior Member
 
crisatv's Avatar
 
Join Date: Jun 2019
Posts: 28
Well back to the drawing board. so i put the new cam in today. everything went good until i tried to start it. so much compression it would hardly turn over. i checked to make sure the compression release was set right and it was. so next i checked to make sure the valves were set right and all is good. So i took the rockers out and checked out how the compression release is working i found the problem. the ball on the camshaft for the compression release hardly comes out! I looked at the old camshaft and the ball comes out way farther then the new one when moving the release mechanism by hand. Damb ball on the new one barely clears the surface of the camshaft. anybody else had this problem? Thanks guys.
crisatv is offline  
post #10 of 13 (permalink) Old 10-05-2019, 03:57 PM
Premium Member
 
stave7119's Avatar
 
Join Date: Oct 2013
Location: Lena, IL
Posts: 3,401
Well that sucks! Did you get an OEM camshaft or aftermarket?

Mine: 2018 Sportsman 850SP - 26" Bear Claw HTRs on OEM steel wheels(I really don't like the Aluminum ones)
Polaris Hand warmers, Mirrors.
Hers: 2019 Sportsman 450. 26" Bear Claw HTRs on Moose 427X Wheels.

2007 Sportsman 500 EFI, Polaris Winch, 25" Bear Claws QSC Clutch Kit, Hand Warmers
2001 Magnum 325 MOSE 12" rear wheel conversion. 25" Sedona Coyote tires
2017 Polaris Ranger 1000XP - Roof and front glass
2018 Kawasaki KLR650
2001 Magnum 325 Warn winch and Moose 60" plow-Sent to Daughter and Son-In-Law since his blew up
SOLD 2004 Sportsman 600 Twin
stave7119 is offline  
Reply

  Lower Navigation
Go Back   Polaris ATV Forum > Polaris Model Specific Discussions > Polaris Scrambler

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Polaris ATV Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in













Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome