ATV Drag Racer Forums banner

new 7mm cub noise

3986 Views 32 Replies 8 Participants Last post by  BBIII
Hey guys I just took my cub out for the frist trip and after the first day of riding the next morning its was really cold and i have a noise coming from the motor and its kind like a card in the spokes king of noise that goes faster and slower with the rpm range tell the motor heats up is this just the pistons needing to warm up or any ideas. It goes away as soon as the motor is good and warm and it runs like a monster and I road it the hole day with no proablems.
1 - 14 of 33 Posts
QUOTE (phatboyz @ Jun 15 2008, 06:33 PM) index.php?act=findpost&pid=2843how cold? is it in gear or neutral? are you sure its in the motor and not travling up from the clutch basket or lock up if you have one?
Its in neutral and its got a lock up and strait cut gears and a 2 - 5 override its just never made this noise before but the bottom end has never had this much power going to it either
QUOTE (phatboyz @ Jun 15 2008, 07:26 PM) index.php?act=findpost&pid=2852it would be hard to tell you what it might be or is but id take your lockup cover off and look around the lockup just to make sure everythings tight.
I pulled the lock up and the only thing I saw for wear on it was where the waits are getting loss from moving back and forth in the lock up but everything is tight and its only the second ride on the lock up and the first ride on the cub and lots of rides on the crank.
QUOTE (phatboyz @ Jun 15 2008, 09:07 PM) index.php?act=findpost&pid=2868why i suggest that is because I had a buddy whos bike made the same sound at the dunes and it ran fine went away and would come back ,well it ended up being the finger nuts and it tore alot of stuff up once it worked its way off!
I'm not sure that I know what nuts your talking about
QUOTE (phatboyz @ Jun 16 2008, 09:11 AM) index.php?act=findpost&pid=2893the nuts that are considered the weights on the fingers that spin.
QUOTE (phatboyz @ Jun 16 2008, 02:08 PM) index.php?act=findpost&pid=2911doesnt mean they wont work loose,,I gaurentee they can!! Ive seen it! just check those and make sure there might be your water pump or gear making that sound as you have a billet pump?
yea I have a billet pump and strait cut gears to I checked the lock up and everything is tight I just put a new seal in the water pump when I put the lock up in.
QUOTE (phatboyz @ Jun 16 2008, 07:06 PM) index.php?act=findpost&pid=2932cool,,just tryin to think of the easy stuff it might be!
yea I don't get it I'm doing the same thing and I'm glad that you have some ideas but im just lost on this one
QUOTE (Tedder @ Jun 17 2008, 05:49 AM) index.php?act=findpost&pid=2966When you went to straight cuts did you go to an overdrive ratio like 2.68??
If so, did grind the water pump washer diameter down?
Usually the washer would slip between two crank gear teeth and keep the motor from turning over but if you were to get it fired up it would sound like a "card in the spokes".
no its the stock ratio and it started doing it after I ran about 5 gallons throw it and I road it a hole day making this noise because it goes away after you get the motor warmed up so Its like something has to grow to fit thats why I was thinking pistons but I have never heard of this on a 2 stroke before
QUOTE (phatboyz @ Jun 17 2008, 10:14 AM) index.php?act=findpost&pid=3003I doubt its pistions,,,,the noise wouldnt go away,,,mite be pistons hitting the tops of your domes!LOL .....has it done it since then?
yea It will do it right now if I start it up could it be the crank going bad or would it have allready went
I'm thinking it might be the water pump gear or the strait cut gears making the noise I'm think that its the water pump gear the most because when I took it off the c clip has wear and is really lose and the washer that sets behind the clip has wear from it spinning in there plus the gears teeth look to be worn on the crank gear side and some of the teeth have very little chips in them but all of the teeth look arounded off on the side of the crank gear I think I might have got a little bit crazy with the sealer to make the key way stop leeking what do you guys think.
why would you think its a collapsed piston it still runs really good its still just as fast. there wisco pistong and it was the first trip with them.
QUOTE (REDLINE @ Jun 20 2008, 10:04 PM) index.php?act=findpost&pid=3315I could write a book on the reasons, and you might not like hearing the explaination of how and why it could have happened. Just do yourself a favor, pull the pipe and take a look at the piston through the exhaust port to start, then pull the head and look for scoring, then eventually measure your piston to wall clearance. It is just part of the correct way to diagnose your problem. On the good side; A piston and hone are a WHOLE lot cheaper and easier to fix than a crank.
wouldn't a compression check tell me anything are would I be better to just tear it down
well thanks guys for all the help it did end up being the water pump gear I just fired it up and all I hear now is the strait cut gears.
QUOTE (REDLINE @ Jun 22 2008, 01:38 AM) index.php?act=findpost&pid=3360Good to hear it man. I hate to see $ wasted.
I hate to have to waist cash my self to
1 - 14 of 33 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.