Awful noise coming from lower end..

[jbmason]

Yesterday I was riding and I heard a little pop noise then it stopped I though it might be my exhaust coming loose so I checked it and it was fine rode it around the yard easy and heard it again this time doing a few times.... long story short I shut it off and fired it back up and it started rattling after a few seconds to describe the rattle it sounds like when you was a kid and put playing deck cards on your bicycle spokes sounds like that.. I'm thinking I have a crank bearing or lower rod bearing going out??? What yall think?

[J Whitehurst]

Kind of sounds more like a gear problem with the rapid clicking you are describing. Could be as simple as a broken water pump impeller. Crack the clutch cover off and start there. You can usually feel a crank bearing bad when you roll the kick starter.

[sheerider11]

Maybe an idler gear

[jbmason]

Kind of sounds more like a gear problem with the rapid clicking you are describing. Could be as simple as a broken water pump impeller. Crack the clutch cover off and start there. You can usually feel a crank bearing bad when you roll the kick starter.

im guessing with the plugs out??? i will feel tight spots??

[camatv]

just take the cover off..  takes longer to type all this than to do that.

[J Whitehurst]

Yes you will feel resistance without plugs in it, different than normal, almost like compression. Once you feel a bad crank under rolling kickstart you can pinpoint it pretty easy. Pull the clutch cover and start there. I do not think it is an idler but start there, stranger things have happened. I have experienced these motors make completely different sounds from the same problems.

[jbmason]

I checked the water pump impeller all good there pulled the plugs and rolled the kick starter and have a tight spot where I have to "slam" the kick starter to get past and its fine till I get back to that point.

[J Whitehurst]

Pull the cylinders. Sounds like a hung ring or a crank bearing. May as well pull the motor it is easier at this point bud, sorry.

[jbmason]

it still has good compression and still runs good i redone the top end 2 yrs ago after i bought it.... should have went through the bottom too... i guess if i have to look at the bright side at least i caught it before it came apart. What mods are needed if any to run a 4mil crank? thanks fpr your help..  

[J Whitehurst]

Nothing to the cases. Give Cam a call and have him set up your cylinders for a 4 mil. Best way to go when the crank goes shit.

[jbmason]

when I tear the engine down what things should I replace while I got it all apart?

[Jereme6655]

get a seal kit and replace ALL the seals on the motor.  may want to look into getting a billet water pump also.

[jbmason]

I tore most of it down waiting on my flywheel puller to come in.. one of my pistons skirt has a chunk broke out of it and I have no idea what caused it.

[Jereme6655]

excessive slop between the piston and the piston wall

[jbmason]

I think im going buy a 4 mil setup with everything I have been looking at herjuggsracing 4 mill kit and bore and port and polish about the best deal I found. what do you all think???  i have a cool head with 20 cc domes do you have to have special cut domes for 4 mil???