"How To" thread for top end rebuild


I'm sure that one or more of the resident engine gurus will chime in and basically walk you through it step by step.
 
I picked up another viper today with a motor issue. I think it had a power valve or a ring come of and get hung up in the cylinder. The motor is free but will not make full revolutions. It just gets to a certain point and stops. Im thinking its a top end issue so I was just trying to get some info on new pistons and cyl's. I cant be positive what is wrong til i crack the motor this week.
 
Well it looks like the center piston is gone. The outside edge is pitted and the plug was almost clean. the other two plugs were nice and light brown.



when it comes time to get it out and a new one in there, would it be wise to change all of the pistons, or just the center one and the rings of the others?
 
Does it do a full rev now? "center plug almost clean" makes me think that cylinder was lean as would have been fuel/oil mix to rod and crank bearings. As far as other cylinders I would follow the lead on center cylinder. Depending on mileage and condition of other 2. If they are "good used" you could get a "good used" piston and rings and get out on the cheap. If you are going new piston/ring on center I would do the same on other 2. Just my .02.
 
Your piston shows severe detonation. Detonation "can" cause major crankshaft issues, but I suspect you may find your problem when you remove the cylinder. I suspect the exhaust side of that piston is melted some, and pieces may also have found there way to your crankshaft (hope not)
 
Is there any way to know if the crank is harmed with out opening the crack case after the jugs are off? If not, it is easy? Reuse the gasket? is it saft to say it is fine it it moves fine after the jugs are off? I guess what im looking for is, lets say i take the jugs off and it looks like the cyl and the piston are shot and i look down in the crank case (what you can see anyway) should i be concerned about the crank? :dunno:

Thanks again for the help!
 
NO, there is no substitute for taking the engine completely apart, cleaning out all the metal fragments, cleaning everything and rebuilding it. Don't even think of just replacing the top end. I had a buddy try that. He had a meltdown which destroyed a piston, rings and head. He replaced the damage parts with all NEW (EXPENSIVE) parts. He started the engine up, it ran for two minutes then had no compression again. He took the engine apart and the metal fragments which were in the crankcase made their way up into the cylinder, destroyed the new pistons, rings, cylinder and head. Round three, did the job the right way and the engine has been running fine for many miles. I am in the process of rebuilding an SRX engine which had a meltdown. I am sending the crankshaft to Midwest Cranks to have it checked/repaired to be sure. taking shortcuts will leave you starnded and only to have to rebuild the engine again.
 
Ditto on what he said! even if you go on the cheap with a used jug and piston. Split the case and clean and check crank out. Not sure about re-use, havent had a viper apart....YET! The 2000 sxr 700 I just went threw was a Yammabond gasket. 20 bucks a tube
 
JDViper said:
Not good! Center rod has 1/4 to 1/2 inch slop in it at the crank! Looks like a part out. Anyone need 03 viper parts? Should be posted by this weekend...
:o|
Click to expand...

Don't give up so easy.
 
You must log in or register to reply here.


Back
Top