reliability of a 16mm stroker?

[Flash-FX]

I'd place my bets on the crank not being trued properly causing a stress fracture on the center rod pin.

That's the best answer I've heard yet, makes total sense. The 550 cranks that I had were supposedly "trued" then welded by R&R Jet tech long ago. The tech told me I was doing something wrong, that's why they broke, and no warranty (the 2 cranks were only weeks old, running race gas, Maxima 927oil, no detnonation).

Now, that picture I posted earlier was from the Bun site. It looked like a stroker crank that they use in the freestyle motors (10+mm?), and thought I'd ask. Since the failures were similar. Thanks for the answers guys.

 

[wsuwrhr]

Ok, I thought that was your crank. But I understand what you are saying.

Hard for me to really give an honest answer without knowing the specifics, having the parts in your hands to inspect the damage, look at the crack structure and so on. Sometimes "maybe" glean a little insight by looking at everything as a whole.

and even worse, sometimes sh it "just happens"

Those days suck too.

Brian

That's the best answer I've heard yet, makes total sense. The 550 cranks that I had were supposedly "trued" then welded by R&R Jet tech long ago. The tech told me I was doing something wrong, that's why they broke, and no warranty (the 2 cranks were only weeks old, running race gas, Maxima 927oil, no detnonation).

Now, that picture I posted earlier was from the Bun site. It looked like a stroker crank that they use in the freestyle motors (10+mm?), and thought I'd ask. Since the failures were similar. Thanks for the answers guys.

 

[Waternut]

Unsubstantiated talk? Unbelieveable.

If you put a stainless bolt anywhere on your jetski and it breaks, you can bitch at yourself and your friends about the "cheap stainless bolt" all you want. The simple fact is, any stainless bolt, other than a top grade stainless, isn't worth a sh it. You can take that to the bank.

DASA and SB Products, for the most part, in good faith, have to carry our products for it's lifespan. Any possible foreseable failure or damage needs to be considered no matter how slight.

You break or gall up a stainless bolt on your jetski THAT WE SUPPLIED YOU, I WILL GUARANTEE you will come on here and talk bad about it and will likely tell everyone you know about the failure.

I don't mind hearing about rusted bolts, although everytime it has turned into the same conversation over again. Even in a thread about "broken" stroker cranks.....There has yet to be a thread on here about a fastener failure from DASA or SB Products supplied hardware and there likely won't be.

Your F-16 is paid for by the government(taxpayers) which is you and me, so no doubt they will use the best of the best, sir.

I am sure you have seen the price tag that is attached to them as well.....

AGAIN.....

Doesn't matter anyway, as I have stated TWICE, in this very thread, that the problem has been since resolved.

Brian

I didn't mean to offend you because I know you make good quality parts. I guess I've never been exposed to any kind of bolt that would fail if you boogered it slightly...especially not a stainless bolt. I'm just truly amazed that any company could get away with making a stainless bolt that would fail that easily.

Again sorry for the call out.

 

[wsuwrhr]

I didn't mean to offend you because I know you make good quality parts. I guess I've never been exposed to any kind of bolt that would fail if you boogered it slightly...especially not a stainless bolt. I'm just truly amazed that any company could get away with making a stainless bolt that would fail that easily.

Again sorry for the call out.

No problem.

Stainless has very little resistance to stretch, or tensile. Which is why it is such a poor choice of materials for bolts, unfortunately sometimes has to be used in some applications for its corrosion properties and little other reason.

Brian

 

[2XLR8]

I have covered this subject 20 times already in the other threads.

Buy one for yourself and compare it to an EQUIVALENT DISPLACEMENT 800-900cc engine correctly done with a stroker crank and big bore, with "only" 85 MM style pistons and please report back with your results.

I doubt you will think "stock stroke 90MM big bore engine" is still a good idea.

Brian

I have to agree strongly. The benefits of a stroker are not always understood.

 

[kevbo]

One thing that has always been missing is how the product benefits the end user. The fact that its bigger or makes more power may be enough for most buyers but that doesnt always translate into the thrust increase that I want. I know that I can get an instant 600 pounds of thrust with stock parts. How much instant thrust is your engine going to provide and at what price.

 

[BombThreat]

I love how a large majority of people here "debating" against engine builders such as dasa and brian have no clue about high performance motors, never has built a high performance motor, will never be able to afford a high performance motor, will never have the skills to use a high performance motor.

Have a merry christmas everyone :newangel:

Thats a helluva assumption.

 

[waxhead]

I have covered this subject 20 times already in the other threads.

Buy one for yourself and compare it to an EQUIVALENT DISPLACEMENT 800-900cc engine correctly done with a stroker crank and big bore, with "only" 85 MM style pistons and please report back with your results.

I doubt you will think "stock stroke 90MM big bore engine" is still a good idea.

Brian

Finially some one making sense
Does anyone wonder why they try and make two strokes a square bore to stroke ratio in all the gp bikes ??
Better power the tz 125 was never able to get a look in when it came to racing until they went square bore stroke ratio

To over bore an engine to hell makes it very undersquare not a good option in my mind

Brian your right on , ride a fast stroker and see the difference between a big bore with the same cc

 

[GIL]

I am not retying to stir anything up here. but, Chuckie is running some STUPID compression on his big motors and is not breaking stainless bolts.
I DO realize that ADA had some girdle bolt issues due to the threads being cut instead of rolled. (Keep in mind this was a loooooong time ago).
Again-not trying to fuel a fire, I simply don't understand the issues w/stainless bolts, and I do appreciate the fact that u guys do think there is a problem and created a solution.

 

[demolition_x]

and just another thought but by adding a few more bolts to the head the load on each bolt would be less. I still have never heard of a stainless bolt breaking.

 

[CARBONX2]

As far as I have been told the s/s bolts don't relly stretch when torqued so they don't have the same clamping force as a regular bolt, which is the essential factor to prevent leaks during heat cycling of the motor

 

[2XLR8]

In the old days of mod Kawasaki 650's you had to use a girdled head if you made horsepower. The girdled heads for the 650 and 750 used long 8mm bolts. You would break those occasionally. When we went to Yamaha engines with stroker mods using oem cylinders many people ran MRD heads. They had good squish band width and chamber design. They also used 8mm girdle bolts. I broke a few and once broke my cylinder because of it. I then switched to a good grade non stinless bolt and I never broke one. Later the ADA head came out so I drilled the head and used the 10 mm studs from ADA on the MRD. I have never heard of anyone breaking a 10mm stud.
In those days the pipes available meant less than 150 REAL Horsepower even with a stroker. It is the HORSEPOWER and not the COMPRESSION that broke the bolts. You can have an engine cranking massive compression like 260 PSI but there could be onother engine cranking less than 200 pounds and it makes more power and it would be that one that breaks the bolts. This is assuming that neither one of them is getting into detonation. You have to wonder at what rpm point the (too high of a) compression is actually hurting you. I would say it is lower than most people think.

 

[Matt_E]

150 REAL Horsepower

:lmao:

:haha:

 

[Millertime]

Getting further off topic here but we are already headed that way.

I broke a girdle bolt on a SXR this year. very hard to find a stainless replacement through a local bolt store. So I took a 3 foot section of 8x1.25 allthread that I had laying around and cut a section to be my girdle bolt and put a nut on. I figured it would break because it is low grade, but after about 40 gallons it is still doing good.

by the way did someone say 16mm stroker? WOW thats cool chit.

 

[rkm]

Rod pin breaks on Pto end typically are due to the shock loading from not enough bearing support.

 

[wsuwrhr]

Where have you been? I posted pictures of the billet 16MM case I made probably close to two years ago.

Brian

by the way did someone say 16mm stroker? WOW thats cool chit.

 

[Millertime]

Yeah I know --- I have pics printed and hanging on my office wall. It just seemed like everyone was getting away from the initial fact that there are cases and cranks out there to do a 16mm stroker the right way without having to get differant pipes, intake manifolds ect.

 

[wsuwrhr]

ancake: