crank reliability & crank alignment questions???
- Thread starter jminor
- Start date
AL P
Moderator
Yeah as I`ve been reading this thread, I`ve been thinking that I`d be worried about my chain/case and my drive shaft probley just as much if not more then my lower end, not that the lower end would`nt be more costly, but it just seams like the drive shaft and or the chain/case would really be under alot of stress!
AL P
AL P
Maha
New member
I was reading this and feel special, I run my 92 ( 750 ) with a RPC 840 BB kit, RPC Stealth quads, Digial 90 degree CDI with the 7900-10,000 rpm chip in snow and have had NO problems in snow with my stock crank. Now I don't race on grass or dirt and have no studs but my concerns would be the chain or drive shaft first. My avatar speaks for itself......
als92vmax4
New member
how hard is it to weld a crank? anybody have any instructions or pics how to?
AL P
Moderator
I dont think it would be hard at all for a very good weldor, with the right equiptment.
but, you`d want to be absolutly 100% positive it was lined up, and not out of whack at all, before ya welded it.
I`m pretty sure Racer7x posted a pic recently of one that has been welded, I`ll look around later and see If I can find it.
AL P
but, you`d want to be absolutly 100% positive it was lined up, and not out of whack at all, before ya welded it.
I`m pretty sure Racer7x posted a pic recently of one that has been welded, I`ll look around later and see If I can find it.
AL P
racerrob
New member
Another Crank Question?
Okay, go easy on me here for the following "dumb question"
Mom told me as a kid that there were no "dumb questions", hope I dont proove her wrong here!!:frech32:
I plan to get my crank welded during my upcoming tear down-updates & conversion in the next few weeks.
Are there markings on the end of the cranks that show the gears have not "slipped" a bit over the years?
Is that a possiblity that the crank could "twist" a little, as a few degrees from the factory setting, or has the pattern been if its gonna "twist" it would be a big obvious "twist" and ya would know it by how the sled is running now??
Thx for the input
Rob
Okay, go easy on me here for the following "dumb question"
Mom told me as a kid that there were no "dumb questions", hope I dont proove her wrong here!!:frech32:
I plan to get my crank welded during my upcoming tear down-updates & conversion in the next few weeks.
Are there markings on the end of the cranks that show the gears have not "slipped" a bit over the years?
Is that a possiblity that the crank could "twist" a little, as a few degrees from the factory setting, or has the pattern been if its gonna "twist" it would be a big obvious "twist" and ya would know it by how the sled is running now??
Thx for the input
Rob
AL P
Moderator
To the best of my knowledge, there are no markings showing where to locate the gear on the crank. only markings I know of, is the dots on the gears themselve`s (750), and the holes on the 800`s gears., that you use to align the two crank halves. could be wrong though?? would`nt be the first time, thats for sure.. LOL
Here`s a pic of my 800 crank when I had it apart, and I did`nt see any kind of markings?
AL P
Here`s a pic of my 800 crank when I had it apart, and I did`nt see any kind of markings?
AL P
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racerrob
New member
Hey guys, glad I asked the question!!!! Dont fee too dumb right now!!:frech32:
Maybe, we need to put this out as a new, renamed post so that we get the real "brain trust" of the Vmax 4 guru's to wiegh in on this??
I might be missing something here, but I would think that it would be really critical to performance, reliability etc to know how the crank & pistons are to be aligned, BEFORE ya weld them!!
How do we get this to be a new "different named" post w/o redoing the whole thing?
Al, got any ideas???:2dontknow
Rob
Maybe, we need to put this out as a new, renamed post so that we get the real "brain trust" of the Vmax 4 guru's to wiegh in on this??
I might be missing something here, but I would think that it would be really critical to performance, reliability etc to know how the crank & pistons are to be aligned, BEFORE ya weld them!!
How do we get this to be a new "different named" post w/o redoing the whole thing?
Al, got any ideas???:2dontknow
Rob
AL P
Moderator
when i first got my vmax4, i had read about crant twist, but did`nt know it was the 750`s that it usually happens to, anyway, what i did, was get cylinder one (nearest the clutch) at TDC, then checked to see if cylinder two was at BDC, and cylinders three and four were at half stroke.
I just did the test with a straw in the plug hole, and measured it that way, figuring if it was off, hopefully it would be off enough that this would show it, and if this did`nt, it was probley alright.
but...to check to see if it is infact DEAD ON, I`d say a TDC dial gauge, and degree wheel would do the trick..
you could locate TDC with your dial gauge, then line up some kind of pointer to your degree wheel, and set the wheel to 0 degree, then rotate the crank 90 degree at a time, and check to see if the next cylinder in the firing order had its piston at TDC, and so on..
the plan here, would be to bolt the degree wheel onto the clutch and then take a lengh of coat hanger or whatever you can come up with to make a pointer..and point it at 0 degree when you get piston one (nearest the clutch) at TDC, and go from there, piston one should be your base, cause its least likely to be off..
just be sure to rotate the clutch in its normal direction of travel, and if you pass your mark, back up plenty, then move forward again.
reason bieng, the clutch PTO shaft, seams to have a little bit of play (where the bears meet in the case`s), so if ya aint carefull, that could throw off your readings.
AL P
I just did the test with a straw in the plug hole, and measured it that way, figuring if it was off, hopefully it would be off enough that this would show it, and if this did`nt, it was probley alright.
but...to check to see if it is infact DEAD ON, I`d say a TDC dial gauge, and degree wheel would do the trick..
you could locate TDC with your dial gauge, then line up some kind of pointer to your degree wheel, and set the wheel to 0 degree, then rotate the crank 90 degree at a time, and check to see if the next cylinder in the firing order had its piston at TDC, and so on..
the plan here, would be to bolt the degree wheel onto the clutch and then take a lengh of coat hanger or whatever you can come up with to make a pointer..and point it at 0 degree when you get piston one (nearest the clutch) at TDC, and go from there, piston one should be your base, cause its least likely to be off..
just be sure to rotate the clutch in its normal direction of travel, and if you pass your mark, back up plenty, then move forward again.
reason bieng, the clutch PTO shaft, seams to have a little bit of play (where the bears meet in the case`s), so if ya aint carefull, that could throw off your readings.
AL P
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hontri
New member
AL P ...I thought of what you are talking about but..... what if you find out the crank is a little bit out of phase. Then what...take engine apart press off the gear and reinstall...how much?Put it all back together and check it again! I can see this being very time consuming.I suppose you could take measurements when you move the gear and see how that affects tdc and eventually get it dialed in. There must be an easier way!! But maybe not.
racerrob
New member
Hontri, :agree:
Exactly what I was thinking!!!
You would think that there is some method of "indicating" where the piston/crank/gear relationship is supposed to be.You are right, a guy could go through a lot of time & effort & miss the right setting.
While I have no problem gettin in there to do this, I want to make DAMN sure I am doing it right, especially when we go to weld it. That makes it real permanent!!! Be a bitch to undo that !!!:cussing:
Nothing is said in the service manual about what to look for in this area. Just the 2 punch marks as Al talked about when your reassembling the 2 halves back together.
Well, maybe ya dont have to worry about being a few degrees off, or when the gears/crank "spin", its a BIG move & then ya worry ??.:2dontknow
Does anyone know if this a heated "sweat fit" or "shrink fit" at the factory?
Am guessing this is how these were assembled when new.
Rob
Exactly what I was thinking!!!
You would think that there is some method of "indicating" where the piston/crank/gear relationship is supposed to be.You are right, a guy could go through a lot of time & effort & miss the right setting.
While I have no problem gettin in there to do this, I want to make DAMN sure I am doing it right, especially when we go to weld it. That makes it real permanent!!! Be a bitch to undo that !!!:cussing:
Nothing is said in the service manual about what to look for in this area. Just the 2 punch marks as Al talked about when your reassembling the 2 halves back together.
Well, maybe ya dont have to worry about being a few degrees off, or when the gears/crank "spin", its a BIG move & then ya worry ??.:2dontknow
Does anyone know if this a heated "sweat fit" or "shrink fit" at the factory?
Am guessing this is how these were assembled when new.
Rob
AL P
Moderator
you got me? if I found it to be off, I`d probley just send it out to a shop that could align it, and weld it. I`m not sure if i`d try it myself.
its all about equiptment, which I dont really have for that kind of work, if a shop knew what the crank was suppose to be set at (degree/firing order/crank rotation direction), they`d have equiptment they can use, to get it just right the first time, where as with the crank out of the motor, I`d just have to back yard it, and hope like hell I got it, cause I cant think of a way off hand right now, without the proper equiptment, to be sure it was DEAD on, I`m sure I could get it damn close, but dead on???? I would`nt wanna bet on bieng able to pull that off. myself anyway.
AL P
its all about equiptment, which I dont really have for that kind of work, if a shop knew what the crank was suppose to be set at (degree/firing order/crank rotation direction), they`d have equiptment they can use, to get it just right the first time, where as with the crank out of the motor, I`d just have to back yard it, and hope like hell I got it, cause I cant think of a way off hand right now, without the proper equiptment, to be sure it was DEAD on, I`m sure I could get it damn close, but dead on???? I would`nt wanna bet on bieng able to pull that off. myself anyway.
AL P
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hi guys
when i was racing yamaha tz750s and 373 and 250s it was common to teardown the engine and inspect it and the first thing was alway cranks
we never welded them due to the damage caused when pressing them apart to change bearings
so we watched them like crazy and never buzzed them
but when it did move we would take them to the shop for aligning...
actually it was bazaar to watch them true the cranks, violent abuse is more like it !!!
after checking on v blocks with dials then comes the tweaking...
a lead plate 1 inch thick and a 10 pound lead mallet and some serious blows on the counter weights to true it up, back to the dials , more smacks and thats it your done, true crank ready to bo battle again!!!
but let me tell you the first time i saw this done i grabbed the mallet from the guy and threatened to beat on him but i eventually came back after finding out he was the guy yamaha only reccomends
i never saw a crank failure from this guy or others using his services
in a word dont do this yourself it is a black art !!!
when i was racing yamaha tz750s and 373 and 250s it was common to teardown the engine and inspect it and the first thing was alway cranks
we never welded them due to the damage caused when pressing them apart to change bearings
so we watched them like crazy and never buzzed them
but when it did move we would take them to the shop for aligning...
actually it was bazaar to watch them true the cranks, violent abuse is more like it !!!
after checking on v blocks with dials then comes the tweaking...
a lead plate 1 inch thick and a 10 pound lead mallet and some serious blows on the counter weights to true it up, back to the dials , more smacks and thats it your done, true crank ready to bo battle again!!!
but let me tell you the first time i saw this done i grabbed the mallet from the guy and threatened to beat on him but i eventually came back after finding out he was the guy yamaha only reccomends
i never saw a crank failure from this guy or others using his services
in a word dont do this yourself it is a black art !!!