Hi guys, newbie here. I just bought a vmax last weekend from a guy that thought the crank bearings were bad. Listening to it I think it's more of a topend/ valve adjustment issue. This is my first vmax so any input is highly appreciated! I want to square this away before starting the mods, which I'm ready to do. If it helps, this is a 1986 with 11000 miles showing on the odometer, I guess it's been sitting for a long time before I got it. Thanks in advance for the input guys! http://www.youtube.com/watch?v=fdT1W2ahSIc
engine knock? Sounds like valves to me, but need opinions please!
Help Support VMAX Forum:
I was hoping that it would sound like my 89, then we could figure out both. Yours is a much more noticeably sound though. Mine is there but doesn't get louder when reved. There shouldn't be that kind of noise at 11,000 miles. I'm sure this is way off but it almost sounds like a valve spring popped out of place. Good Luck, sorry I couldn't be of help...
It could be, I guess I just need to tear into it and see what I find. I was just hoping someone would jump on here and know exactly what it is and tell me right where to go lol. It could probably use a valve adjustment anyway, I just hate doing shim and buckets, I've gotten too lazy playing with my Raptor 700 and it's rocker arms, that's the only way to adjust valves.
haha! I'm not scared, I was only revving up a little bit. If it blows up that leaves me with an excellent excuse to jump into the big bore, stroker, high compression, big cams, headporting, intake, exhaust, etc. etc. that I tell my wife all my other toys require. She is convinced that anything with a motor has to have all of the above to run correctly lol.
i dont thing it is a valve thing. more piston and rod issue. chech your compresion in every cylinder, you must have 10.5 less than 10 you have a problem. had a same noise before 1 year. one cylinder had compresion 8.5. did in TTS PERFOMANCE an engine rebuild bored it to 1300cc .with forged pistons and rods. keep us posted
![Bovemanx Motorcycle Phone Mount Holder, [150mph Wind Anti-Shake][7.2inch Big Phone Friendly] Bike Phone Holder, Motorcycle Handlebar Cell Phone Clamp, Compatible with iPhone 16 Pro Max Smartphones](https://m.media-amazon.com/images/I/51F+1sontPL._SL500_.jpg)
I hope that's not what it is but if that's the case I'll just have to do what it takes to fix it. I'll check the valve lash and do a compression check and see what it looks like. Thanks for the replies so far guys!
satariel666
Well-Known Member
Thats not completly tru.
Compression lagging could be the sympthom of worn valves or gasket leakage.
I would dare to say that compression lagging by worn sleeve/piston is a thingy that not happens often.
10,5 - yes this is a compression ratio of stock v-max. Theres no such a thing that messures this. Im sure you mean the compresion/pressure messured by manometer which comes with pressure units like PSI or BAR.
Standard pressure is about 142 PSI/ 10kg/cm2 and minimum about 128psi/ 9kg/cm2 - messured at sea level which is EXTREMLY important.
Some of use can come with 200 PSI even which is provided by high elevation.
Just like with carbs.
He need to do a compression check and if manometer will show normal values then he can exclude the valve problem.
Then, only two things are possible - whirst pin or spun rod bearing.
Whirst is not the problem and spun bearing means engine replace in 70% of cases.
ninjaneer
Well-Known Member
you might be interested in this then. don't know if it is still underway, though. Shim Loaner Program
one2dmax
Well-Known Member
My first guess would be the rod bearing spun. It could be wrist pin but I don't think so. It could also be broken spring in the heads. First thing is to pull the oil drain and see what it looks like. If it looks like you are mining for gold or some really grey looking sludge you're done.
The block may or may not be salvagable. When they spin bearings they more often then not usually wipe out the crank thrust journals. We can fix them but it's cheaper for me to sell you a core that's in good shape.
I actually have a number of engines that we are prepping for sale and can either be bought outright or done on an exchange. Almost done with prepping a 1989 engine taken in on trade (doing a 1527 stroker engine for him). We are regasketing the entire engine (not counting head gaskets), installing a HD oiling kit, Putting the DD Clutch modification in, and setting the valves. All i've got left is the valves and new gaskets up there. Then it's ready for paint (if the customer wants it painted). It made 127rwhp on the last dyno (with stage seven and hindle header). This same engine was rebuilt a couple of years ago so it's fresher anyway. Trans has the updated shift drum and segment and other parts replaced.
We can also build you about anything you'd want.
Sean
The block may or may not be salvagable. When they spin bearings they more often then not usually wipe out the crank thrust journals. We can fix them but it's cheaper for me to sell you a core that's in good shape.
I actually have a number of engines that we are prepping for sale and can either be bought outright or done on an exchange. Almost done with prepping a 1989 engine taken in on trade (doing a 1527 stroker engine for him). We are regasketing the entire engine (not counting head gaskets), installing a HD oiling kit, Putting the DD Clutch modification in, and setting the valves. All i've got left is the valves and new gaskets up there. Then it's ready for paint (if the customer wants it painted). It made 127rwhp on the last dyno (with stage seven and hindle header). This same engine was rebuilt a couple of years ago so it's fresher anyway. Trans has the updated shift drum and segment and other parts replaced.
We can also build you about anything you'd want.
Sean
one2dmax
Well-Known Member
Oh, and the loaner kit is still available too!
Sean
Sean
satariel666
Well-Known Member
Some time ago I have found that knocking along with rpm increasing means wrist pin and knocking under acceleration load means spun bearing.
Just a tought.
the sound seems higher up for sure, I checked the valves real quick and they were at .013 on that cylinder on the exhaust cam so it seems like that part is good, I haven't even downloaded a manual yet but I'm going off of .006 and .010" like a bunch of quad motors and bike motors seem to be. I'll pull the oil plug and see how it looks next. I appreciate the input and I guess I'm going to be modding this motor after all, Sean, do you mind if I call you sometime and pick your brain on different build options? I sure appreciate it!
"Awww, that's just a dash rattle you're hearing. Nothing to worry about." (at least that's what the Mopar mechanic told me just before the #1 piston bit the dust in my Chrysler New Yorker many years ago)
one2dmax
Well-Known Member
Email me and I can send you more info then you want. A call works too though I don't always remember the prices right off the top of my head.
unk:
yeap ,that is what i talking about. spark plug out place the instrument with the manometer and crank it. dont know if you have a valve problem you lose compression . in my "thing" it was a sleeve piston thing. hope it is not that in shorthair88 engine, cause it is $$$.
VMike
Well-Known Member
Just for grins did you try disengaging the clutch to see if the noise changes?
Mike
Mike
