Author Topic: What is spec on hot rods +4? (Read 6430 times)

86_350r · « **on:** July 07, 2013, 06:31:25 PM »

First off I have a +4 78mm sphinx that was done about a year and half ago. The crank is about 3 years old and the cylinder and piston are maybe 1 1/2 years old. The last ride I went on it started making a "knocking noise". Alot more than the usual 250r motor makes IMO. I pulled the topend and the wrist pin seems to have alot of movement. The connecting rod on the bottom seems to have a little bit of side to side movement as well. My questions are how much movement are they suppose to have? What is spec on the upper and lower end of the rod?

Thanks
Ryan

Polonda · « **Reply #1 on:** July 07, 2013, 06:57:26 PM »

Then big end can have some side to side play. What your concerned with is making sure you have no up and down play.

86_350r · « **Reply #2 on:** July 07, 2013, 07:05:59 PM »

The big end does not have any up and down play. The wrist pin does have movement up and down. I know the piston can move side to side but I can also "rotate" the piston left and right. I dont know how to explain that. Im trying to figure out what could be causing that louder knocking noise without tearing into the bottom end.

Polonda · « **Reply #3 on:** July 07, 2013, 07:10:16 PM »

Sounds like the wrist pin bearing is shot? Should have play like your are speaking of. I would grab a new bearing and c clips and see if that resolves the play.

Pumashine · « **Reply #4 on:** July 07, 2013, 07:13:23 PM »

Check for up and down play on the crankshaft. Main bearings could be going. Who did your motor? Piston should not be moving up and down only side to side. Was the piston hitting the head at all?

Polonda · « **Reply #5 on:** July 07, 2013, 07:21:24 PM »

Easiest way to check at least the stator side crank bearing is to simply pull the stator cover off and try to move the flywheel up and down. Should have zero play. Zero up and down play should be seen at any of the crank or rod bearings.

86_350r · « **Reply #6 on:** July 07, 2013, 07:42:07 PM »

Polanda: Pulled the cover and it has no play.

Puma: I had Dave Moore do the lower end (which worries me), and Cameron at Redline do the topend. The piston was not hitting the top of the cylinder from what I can see.

Polonda · « **Reply #7 on:** July 07, 2013, 07:53:38 PM »

So the only play you can find is in the wrist pin?

Thinking of it now when was the last time the counter balancer bearing was changed? Definitely check that one.

jcs003 · « **Reply #8 on:** July 07, 2013, 07:55:18 PM »

could be your counter-balancer. it has bearings on both sides.

john

Polonda · « **Reply #9 on:** July 07, 2013, 07:56:20 PM »

Quote from: jcs003;1601

could be your counter-balancer. it has bearings on both sides.

john

Beat you to it...:sign0188:

jcs003 · « **Reply #10 on:** July 07, 2013, 08:02:13 PM »

Quote from: Polonda;1603

Beat you to it...:sign0188:

you are fast.haha

john

Polonda · « **Reply #11 on:** July 07, 2013, 08:04:26 PM »

:onthego:

86_350r · « **Reply #12 on:** July 07, 2013, 08:40:34 PM »

I honestly dont know. My guess is when I had the whole motor torn down for a rebuild 3 years ago, but that I dont know if Dave changed.

Polonda · « **Reply #13 on:** July 07, 2013, 08:42:24 PM »

I would definitely check it. And if your wrist pin bearing has play replace it also. Make sure the piston pin is not also worn while your at it.

86_350r · « **Reply #14 on:** July 07, 2013, 08:44:14 PM »

Ill check it out. Thanks again.