Head stay question

[Hutchracer]

I am putting my quad back together after having the motor fully rebuilt and doing a ground up rebuild. My problem and my question is everything is going back the way it should except for the head stay. It seems to be about a 1/4 to 1/2 inch max about half of the mount hole off. All the other mounts line up just fine. Anyone have any ideas I would like your input.

[Honda 250r 001]

You running spacer plate? Any different than stock thickness head gasket or base gasket? Stock motor mounts/never been re-welded? Head been decked?

[TLR-Online]

Just leave the mounting bolt out... Thats the way i run mine. Just mainly use it to strengthen the frame.

[emullen]

Do you think that leaving the bolt out or not using the stay at all may allow for more stress (such as micromotion) on the lower frame motor mount tabs and as you state perhaps the frame- flex maybe?

I think that there may have been some debate about this in the past.

[mxduner]

Originally posted by emullen
Do you think that leaving the bolt out or not using the stay at all may allow for more stress (such as micromotion) on the lower frame motor mount tabs and as you state perhaps the frame- flex maybe?

I think that there may have been some debate about this in the past. i broke my lower left tab on my 88 without the stay in there. i would atleast mount what you can

[Hutchracer]

I am not sure to be honest if the head has been milled or not. I bought the quad and stripped it down the previous owner was not running the head stay and when we blasted the frame the lower mounts were broke as well as some bad cracks in the box section of the frame as well. That frame now lives in the grave yard behind the shop as I bought a replacement. I am going to be running a 310 motor in the new setup with no spacer plate. The holes on the head for the mount are low, I am just not 100% convinced on the no head stay option

[JTRtrx250r]

ran into the same w/ mine and found my cyl/head had been decked/milled

I chose to run the stay w/o the bolt also, it does vibrate and wears the sides of the head mount a bit though:ermm:

[Derrick Adams]

Did you try loosening all the engine mount bolts up and then lifting the engine up to install the bolt? I leave all mine loose until their all installed for this reason.

[C41Xracer]

run a smaller bolt through it if its possible

[jcs003]

if the bolts dont line up precisely you will put unwanted strain on the mounts. this will add to possible engine damage and mou nt failure. the constant stain, on the head stay for example will pull on the head ad may cuse the gasket to start leaking or cause head warpage from the heating and cooling of the aluminum.

[Ruf Racing]

Originally posted by mxduner
i broke my lower left tab on my 88 without the stay in there.

Same here ^^

[C-LEIGH RACING]

Use the head stay, even if you have to use a smaller bolt through the head to make it work.

Or, do you want to go ahead & not use it & end up replacing broken case studs from freeing up those top end revs like I did years ago.
Learned my lesson, head stay is in place, no more case studs broke.
Neil

[mxduner]

might be time for a head change:D go get ya 1 of them esr units with a slotted mount holes and get some ponies

Here is the elaborate procedure BDT Motorsports used to bolt my 330R engine into the frame for each Dyno run:

• Engine was placed into frame, all mounting bolts, nuts and brackets assembled to engine, however; NOT tightened, left loose.
• Head Stay was left loose on frame and engine head.
• Engine was shifted back and forth, side to side and up and down; looking for the “sweet spot”, the spot where all the nuts, bolts and brackets fit best without exerting any unnecessary stress to the engine & frame…still all nuts & bolts where tightened a little more than before, however; still not tight.
• The head stay is shifted up/down relative to engine position; the “U” bracket portion of the head stay fitted to the engine head stay mount by shaving & shimming the head stay relative to the position of the engine. The goal here is to tighten the head stay to engine without inducing ANY stress, up, down or side to side to the engine or frame.
• All nuts, bolts and brackets are tightened; head stay is checked, shaved and shimmed as needed to insure a glove fit, with no induced stress. The head stay is serial numbered along with the shims, frame and engine.

Sounds like a lot of work, to some extent it is initially, however; it goes back together easily as long as the cylinder & head position are not disturbed.

BDT-M followed this procedure every time the engine was removed from my frame during the 330R’s 68HP development.

The sequence listed above was not developed by BDT-M, it was employed by Team Honda back in the early days of Honda’s TRX250R racing program; obviously it yielded excellent results.

The question; how many of us shave & shim an engines head stay into place and how many of us should? All of us should…

Carlos.

[speedfreek]

Why dont you just slot the head stay hole? That's what I did. Whatever you do, get a bolt through it. It's there for a reason.

Slotting the head stay or the engine head does not solve the issue of the head getting pulled side to side when the head stay bolt is tightened down. It only attempts to solve the issue of misalignment in the vertical direction.

Imagine your engine head stay sides not being parallel to the frames head stay; now you bolt it all together, and tighten up, you will induce unnecessary side to side & out of parallel stresses into your engine/cylinder…pulling or pushing is not what you want.

Check your engines head stay sides being parallel to the frames head stay and you will see they are not. Also check how your head stay pulls or pushes your engine head as you tighten it all together. You want absolutely NO forced movement or stress on your cylinder when bolting it all together.

Only way to insure no induced or unwanted cylinder/head stress, is to shave and shim to fit…

Carlos.

[jcs003]

what exactly is the , "sweet spot"? the most important thing is the sprocket alignment. limiting tolerancing defines the degree of accuracy you have to accomplish the ideal alignment. your approach is not accurate.

[JTRtrx250r]

mines WAY to tight to try fitting a bolt thru it, hardly any hole left at all...when I say that ...Im talking I "might " be able to fit jet needle thru it haha

I did try what ever I could get to fit just for the hell of it...and it snapped w/ the quickness:ermm:

just last night , I stuck my stock motor in it and it all fits like a glove, gonna run the bolt w/ this 1 b/c I can now:blah:

“what exactly is the , "sweet spot"? the most important thing is the sprocket alignment. limiting tolerancing defines the degree of accuracy you have to accomplish the ideal alignment. your approach is not accurate”

Please read what I wrote, I am very clear…what you don’t want to do is induce any unnecessary stress to the cylinder and head when it all bolts together. You want the frame head stay and the engine head to bolt together and fit as a glove. When the head stay bolt is inserted and tightened down, you absolutely don’t want any forces puling, pushing, or twisting the engine into place…that is why they shave & shim to fit.

This approach is the most accurate and the one that offers the least amount of unnecessary stress transferred to the cylinder & head.

Yes sprocket alignment is an important part, however; you can still achieve perfect sprocket alignment while shaving & shimming the head stay relative to the location & position of the engine head. Remember we are talking about out of parallelism, misalignment, and twisting forces that can be eliminated by proper fitment.

The reason some experience an engine to perform better, rev higher or easier without a head stay in place, or the head not tightened to the stay is the misalignment of the head stay to the cylinder/head and the resulting stressed final assembly.

Carlos.

[speedfreek]

When I slotted my head stay hole it did not move the engine side to side any. The holes were misaligned up and down. I did not have to pry anything over to fit. The holes were merely misaligned. So I slotted the head stay and tightened it down. I ran it for years with no problems.

No real problems will occur and it will run for years, the engine will not be pulled side to side when you bolt it down even if everything is misaligned. It isn’t necessarily visible, it is the stress of the misaligned assembly you are putting together. I can assure you your build will NOT align perfectly and the assembly will be stressed unless you fit the head stay to the cylinder/head by shaving & shimming.

The method I described insures everything bolts up correctly, and any stress due to misalignment, out of parallelism or twisting caused when tightening everything up is eliminated…

The engine will rev higher, run freer and put out more HP…

Carlos.

[All250R]

People ride the bikes and the frame places non-vertical stress on the head stay. The engine acts as a connecting member between the upper and lower frame rails strengthening the frame as it absorbs force while riding. I would shim a headstay if it were out of alignment to avoid unnecessary stress, but it's either not complete or just idealistic if the point is to eliminate non-vertical stress on the cylinder head, or to imply all head stays need to be shimmed. A value or stress against failure or other variables would be useful if the intention is to actually be definitive.

In general, clarity issues can arise when someone is interpreting the meaning or value of what they observe someone else doing instead of gathering from the source. Kind of like how people used to think the sun revolved around the earth because that's what it looked like to them. The problem then was the sun couldn't speak for itself.

[SilverLake250R]

Carlos, you better not ride your quad in case the frame flexes and puts stress on your engine. Just rev it up in the driveway, without sitting on it of course...


...Just kidding... I can understand your theoretical point of view... but a lot of the stuff you suggest may or may not ever make a difference in reality. And there is not really any way to prove it. Unless of course you dared bolt your precious 68hp 330R motor built by none other than the best builder that is or ever was in existence, BDT, into a frame that was tweaked a little and see if it doesn't rev as high as when you shaved and shimmed the headstay.

All head stays do need to be shaved or shimmed, they are fabricated from stamped & welded components…nothing on a head stay is square or parallel relative to the cylinder head. To compound the issue, the cylinder head is never in line to the centerline of the engine, hole clearances, stud tolerances (alignment & location) through the head out of perfect alignment. These misalignments are 3 dimensional in nature…

The truer an engine is maintained and the less stress is induced due to misalignment, out of parallelism & twisting forces the better it will perform; without question…

To relate it is “OK” to bolt a misaligned head stay, induce unnecessary and preventable stress because the frame is part of the system, and since the frame twist, bends and moves vertically during operation we should ignore any attempt to build with less stress onto the engine, is wrong!

I offered a good, sensible approach on how to best minimize stress when bolting on a head stay, and improve engine performance based on experience and proven success, and again; what is not understood or what is beyond the scope of many is dismissed as unnecessary or misinterpreted instead of being looked at in a positive manner…

PS: ever wonder why some seem to always find a way of getting every last bit of performance out of an engine or mechanical system when 98% of the rest struggle to keep up? Well this is a great example of what is not understood and dismissed…

Carlos.

[speedfreek]

Carlos, I understand your second post better than the first one. It does make sense.
But how do you shim the head stay?

The way I have seen it done is with a lot of different brass shims…take small strips of different thickness and use them as you would a set of feeler gauges, checking to see the thickness that fits snug. The shaving is done the opposite; filing or grinding until you remove enough interfering material from the sides of the stay or head to allow a slip fit, not stressing the head or stay in any direction…I think you get the idea.

I sometimes have a bad habit of thinking I am clear in my explanations when I am obviously not, failing to realize most have not seen the process up close.

I firmly believe it is the “little” things that make the most difference between a good build and a great one.

Carlos.

[All250R]

Do you have any objective data available Carlos on how this effects engine performance or structural integrity?

[jcs003]

Originally posted by All250R
Do you have any objective data available Carlos on how this effects engine performance or structural integrity?

x2. im a mechanical engineer and work with limiting tolerincing alot and you shot down my explanation as if i pulled it out of a tree. maybe i wasnt clear enough...

but bottom line is: only two factors have any bearing on the performance.

solid mound-structural integrity.

sprocket orientation-minimal friction while avoiding torsional loads.

if it gains minimal performance without the head stay it is negligable. that minimal performance increase to sacrafice a solid mount is ridiculous.

“objective data”?
“structural integrity”?
“only two factors have any bearing on the performance”?

Read my previous posts carefully… I have explained in detail the importance of not subjecting the engine, to ANY unnecessary stress due to misalignment, out of parallelism, twisting, pushing or pulling via the head stay (or any other frame component)…this is what “structural integrity” means!

To make the argument that a frame will flex, pull & push while in operation, and therefore; the engines stress free alignment is not important, is simply incorrect. If we follow this premise, then why bother building an engine and its components straight, true & parallel, why blue print an engine?

“objetctive data”: You need to sit back, and visualize what happens when you place an engine onto a frame, and begin to torque down all the mounting bolts, and the head stay is misaligned, out of square, and in an incorrect location relative to the cylinder. The misalignment does not have to be much to force, twist or pull a perfectly good straight & true engine, cylinder out of its straight & true axis’s.

“only two factors have any bearing on the performance”: I am truly embarrassed a ME would make such a ridicules, unprofessional statement, now you don’t really believe what you wrote do you? I am sure I have not clearly defined what I am trying to explain, hence; your comments...

All unnecessary forces induced or produced outside of an engines natural operational envelope, will subject the engine to undesirable loads that WILL at the very least affect performance & wear…

If you cannot visualize and determine for yourself, that pulling, pushing or twisting your engine to your head stay & frame is not a “good thing”, then I don’t know what to tell you…

Carlos.

[jcs003]

ace carlos. you are truely exadurating this situation to try and raise your stock on this site.

i made no reference to the internal mechanics of the engine. my point is related to the head stay in relation to the final drive. you are complicating this to astounding measures. you should learn a few things about finite element analysis to understand the internal stresses and strains on a chassis and the motor connections related. i never heard of this "objective data"

also, everybody knows the head stay is the last mount connected.

JCS003:

“raise your stock on this site”? How narrow minded is that statement…? The more I post, the more I realize forums are like politics…the majority does not post or care to share an opinion, those that do post, fail to understand or are not willing to understand anything they do not know. Everything outside the most common practices is treated and responded to with negativism, some ME responses are so of the mark, that it truly embarrasses me to see professionals lack the most basic knowledge of Engineering. Those that do understand are the silent majority, and understand the futileness of presenting a logical point of view…”just like politics”

You want to talk about FEA & FMEA, go ahead and lets discuss FEA & FMEA from an ME’s perspective, however; that is not the direction this needs to go, it is not necessary as my post is based on as much common sense as science .

With all due respect, it is NOT that complicated and you are missing the point completely. You wrote: “no reference to the internal mechanics of the engine. my point is related to the head stay in relation to the final drive”

I am not arguing your point “to the final drive”…the importance of alignment in that area goes without saying…you are missing the point of why you need to adjust the head stay relative to the engine by shaving & shimming…it is INDEPENDENT OF THE ALIGNMENT OF THE FINAL DRIVE.

Is it that hard to understand…??? And what does a properly aligned head stay to engine assembly have to do with “the head stay is the last mount connected” …??? Regardless if the head stay is the first or last mount connected, it must be part of a straight, true and stress free engine to frame assembly, INDEPENDENT OF THE ALIGNMENT OF THE FINAL DRIVE…You can accomplish both without sacrificing one for the other.

Not complicated at all; just common sense…

Carlos.

[jcs003]

acecarlos. all i can say is WOW!!

this last and most recent redundant statement is why you carry no respect on this forum. you are a true tool.

“Respect”?

Do you think I come on this forum looking for respect? If it is giving fine, if it is not fine…I fully understand not following the common path, questioning how builders build & why, presenting alternate methods that go against current known practice, and not being in the inner circle of “yes” men, will not win me any popularity contests…

If I cared or had concern for what you thought, I would not bother to “WOW” you, I would agree with you and call it a day…

I will take your “WOW”, knowing what I know and what you obviously don’t understand and accept I don’t have your respect...

Carlos.

[jcs003]

Originally posted by acecarlos
“Respect”?

Do you think I come on this forum looking for respect? If it is giving fine, if it is not fine…I fully understand not following the common path, questioning how builders build & why, presenting alternate methods that go against current known practice, and not being in the inner circle of “yes” men, will not win me any popularity contests…

If I cared or had concern for what you thought, I would not bother to “WOW” you, I would agree with you and call it a day…

I will take your “WOW”, knowing what I know and what you obviously don’t understand and accept I don’t have your respect...

Carlos.

WOW!!.

WOW no respect...:devil: