# Issue after Rebuilds......Please Help!!



## JPBrute750 (Apr 27, 2010)

OK so to make a long story short I had to get my motor rebuilt due to spun rod bearing in front cylinder and once i got it back it only lasted 5 hours before it spun another rod bearing(Front Cylinder again). So under warranty the motor was rebuilt again replacing the damaged parts.

New parts for 1st rebuild:
New Crank
New Rod Bearings
New Connecting Rods
New Wiseco Piston Kits (Piston,Rings,Wrist Pins)
New Timing Chains
New Gaskets and Seals

New Parts after 2nd rebuild:
Another New Crank
New Rod Bearings
New Oil Pump Chain
New Oil Pump Gears (I think but maybe not)
Whatever gaskets or seals needed

My problem now is after the 2nd rebuild, I went to pick it up from the shop and it is making a little knocking sound almost like clutch noise with just a touch of the throttle. As soon as the RPMs start to change you can hear it but can not really hear it over the exhaust if you rev it up. My Mechanic didnt want me to take it until he checks that noise. Well he has had it for another 2weeks and cannot find anything wrong. He has triple checked the rod bearings, even changing the connecting rods out with the old one that was still good. The noise is only there after it warms up and it is diff not the clutch as it still makes the noise with the clutches off. Also checked the exhaust for leaks. So if anybody as any ideas that would help us please let me know.


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## Stogi (Feb 24, 2010)

If one of the pistons in backwards it will make a knocking sound sometimes.


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## JPBrute750 (Apr 27, 2010)

What do you mean by backwards?


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## wolf_36 (Jul 7, 2010)

The piston should have an F or some sort of mark on the top of it off to one side , that mark should be closest to the front of the motor


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## Brute 840 (Feb 9, 2012)

Yes Wiseco has a DOT on it and on all the Wiseco Piston they tell everone to make the dot face to the exhaust well on this motor the front piston should face the exhaust BUT the rear should Face the Intake,another guy just done this on another forum and bent his valves,just make sure the rear piston's Dot is torward the front of the bike,then you can rule that out,if you ask Wiseco witch way they will tell to make it face the exhaust thats what they done to the other guy and trashed his valves,but he got it turned around I sent him some valves and its all straight,also the if you done a 85mm drop wiseco they are all made 1 size and you arent boring it to fit so it will have a slight piston slap on some of these motor I have seen that before also.


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## Stogi (Feb 24, 2010)

You'll see in this pic there is a dot with the "FWD" mark below it. The wristpins are offset slightly and if that offset is on the wrong side it will cause it to knock. 
BTW .... these are not "off the shelf" Wiseco's


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## Brute 840 (Feb 9, 2012)

Bad thing is the shelf wisecosdont say forward it just has a dot,instructions say face dot torward exhaust but on the V Twin the rear is faced forward not to the rear exhaust


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## JPBrute750 (Apr 27, 2010)

Ok well I just checked with my guy at the shop and he said they are both pointing toward the front cylinder exhaust, so they are both in correct. We are both lost as to what the noise is. He stated that the cylinders look new so I don't think it is piston slap either.


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## gotmuddy (Jul 15, 2011)

If the pistons were in backwards you would likely have bent valves. IF they put the motor together correctly you would have no noises. How well do you trust this mechanic?


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## JPBrute750 (Apr 27, 2010)

I trust him to a degree but at this point, I dont have much of a choice but to trust him to finsh. But that is why i am asking the question here.


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## Brute 840 (Feb 9, 2012)

The only way you would have piston slap for sure is if those jugs were replated to the size of those pistons,drop in pistons are what they are dop ins,when you do a bbk they have to have the piston to bore and plate them,no piston is alike with that being said you can have a slight tap or tic do to the drop in piston.Just my 2 cents but maybe you got more issues else where with it.


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## JPBrute750 (Apr 27, 2010)

Brute 840 said:


> The only way you would have piston slap for sure is if those jugs were replated to the size of those pistons,drop in pistons are what they are dop ins,when you do a bbk they have to have the piston to bore and plate them,no piston is alike with that being said you can have a slight tap or tic do to the drop in piston.Just my 2 cents but maybe you got more issues else where with it.


So from what I understand from what you said is the only way to eliminate the possibility of it being piston slap is to have the cylinders replated? If so how much does that usually run?


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## JPBrute750 (Apr 27, 2010)

Anyone?


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## Brute 840 (Feb 9, 2012)

I am just saying that could be it,but if the guy rebuilt it once and it lasted 5 hours it could be anything really.replating runs around 450.00 550.00 for both jugs and if you have it done make sure you send the pistons to them also


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## JPBrute750 (Apr 27, 2010)

OK well after more time of waiting and him checking things he supposably sent my cylinders and pistons to a shop and they said they were within spec. He then reinstalled everything and changed the pistons around so the front was now in the back. He now says that he is almost postive that it is piston slap cause now the noise is in the front cylinder and with a stethoscope it sounds like a bell ringing. My question now is what do i do? buy another set of pistons, replate/bore it and oversized pistons, replace rings and reuse old pistons (that were in perfect shape just figured for only $100 more i would go with the HC pistons incase I wanted to change the cams one day) or what???? Please help i already have so much money in it.


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## JPBrute750 (Apr 27, 2010)

Anyone have any advice?


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## Hangingfor8 (Oct 3, 2009)

I feel your pain and wish I had an answer for you. I hope you get it back in time for Mud Muckers


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## Ap1510 (Mar 25, 2020)

JPBrute750 said:


> OK well after more time of waiting and him checking things he supposably sent my cylinders and pistons to a shop and they said they were within spec. He then reinstalled everything and changed the pistons around so the front was now in the back. He now says that he is almost postive that it is piston slap cause now the noise is in the front cylinder and with a stethoscope it sounds like a bell ringing. My question now is what do i do? buy another set of pistons, replate/bore it and oversized pistons, replace rings and reuse old pistons (that were in perfect shape just figured for only $100 more i would go with the HC pistons incase I wanted to change the cams one day) or what???? Please help i already have so much money in it.


I do realize this post is ancient, however I have 08 750 teryx I’m having the exact same problem with. I was hoping someone could share an answer with me. I’m tired of throwing money at this thing.


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## dman66 (Feb 20, 2011)

Ap1510 said:


> I do realize this post is ancient, however I have 08 750 teryx I’m having the exact same problem with. I was hoping someone could share an answer with me. I’m tired of throwing money at this thing.


This is a very old post, but no where did this guy say they tried to contact where he bought the piston and return it for a new piston. If it was knocking in the back cylinder, then the mechanic switched the pistons and the noise transferred to the front, I would say its the piston. Something measures different on those new pistons to do that. Hell, we dont know if it the timing was set properly.


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## Ap1510 (Mar 25, 2020)

Thanks for replying! I’m going crazy trying to figure this thing out!


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