what could have caused this?

[ToKwik]

Quick questions?

Did you verify there was no other damage? When that rod broke, it was because it was the weakest point when the failure occurred.

You stated that you replaced the crankshaft. Did you replace the bearings that were worn and clearanced for the old crank? Was the crank replaced because of a spun bearing?

If you are asking where TDC is for reassembly, then you may need to have someone else there who is more experienced take a look. I can probably think of a dozen things that could be wrong, but it's hard to make an educated guess on something you might have missed on your reassembly. For instance, what is the condition of the pistons? Are you reusing the old ones? Is the head on yet? What is the condition of the cylinders? Did you check them or just wipe the oil out with a rag? You replaced the rods, but what do the wrist pins look like? Are you using the old bearings, Bearings from the donor motor, Or did you purchase new ones?

I'm not trying to be an asshole, but you may need some assistance personally with reassembly. It is just a bunch of nuts and bolt, but there is a certain way it needs to go together in order for it to work properly. Finding help online may not be your best solution.

Hope you get it figured out.

[chino12]

Originally Posted by ToKwik

Quick questions?

Did you verify there was no other damage? When that rod broke, it was because it was the weakest point when the failure occurred.

You stated that you replaced the crankshaft. Did you replace the bearings that were worn and clearanced for the old crank? Was the crank replaced because of a spun bearing?

If you are asking where TDC is for reassembly, then you may need to have someone else there who is more experienced take a look. I can probably think of a dozen things that could be wrong, but it's hard to make an educated guess on something you might have missed on your reassembly. For instance, what is the condition of the pistons? Are you reusing the old ones? Is the head on yet? What is the condition of the cylinders? Did you check them or just wipe the oil out with a rag? You replaced the rods, but what do the wrist pins look like? Are you using the old bearings, Bearings from the donor motor, Or did you purchase new ones?

I'm not trying to be an asshole, but you may need some assistance personally with reassembly. It is just a bunch of nuts and bolt, but there is a certain way it needs to go together in order for it to work properly. Finding help online may not be your best solution.

Hope you get it figured out.

thanks for the checklist dude, i do however like to fix my own stuff even though its my first time when dealing with an engine - worst case scenario i cannot fix it and buy a new one and lose a couple of euros, fuck that

i replaced the crankshaft because it was damaged where the rod which snapped is attached - dunno how its called

i didnt replace the bearings as they all looked the same and good to me

i am using a new set of pistons with a new set of rods - i didnt check the cylinders, just cleaned them and installed the pistons - they were sliding smooth when the rods were not attached to the shaft

so you are saying - judging by your answer - after the rods are installed and tightened the pistons should move when rotating the crankshaft?

quote from wikipedia

More generally, the dead centre is any position of a crank where the applied force is straight along its axis, meaning no turning force can be applied.

[KingJafeJoe]

Question: Are you planning on putting the T-Shirt back in the pan?

[old man roger]

Originally Posted by adichino

thanks for the checklist dude, i do however like to fix my own stuff even though its my first time when dealing with an engine - worst case scenario i cannot fix it and buy a new one and lose a couple of euros, fuck that

i replaced the crankshaft because it was damaged where the rod which snapped is attached - dunno how its called

i didnt replace the bearings as they all looked the same and good to me

i am using a new set of pistons with a new set of rods - i didnt check the cylinders, just cleaned them and installed the pistons - they were sliding smooth when the rods were not attached to the shaft

so you are saying - judging by your answer - after the rods are installed and tightened the pistons should move when rotating the crankshaft?

quote from wikipedia

OH BOY!!!! I'm going to keep this short because I'm not about to type out every thing you need to know to rebuild an engine.

The bearings need to match the size of the crank and rods, there is a certain amount of clearance required because the crank, rods, and the bearings expand when they get hot.

There also needs to be a certain amount of piston to cylinder wall clearance because the pistons expand when they get hot.

If you haven't checked these clearances then you have not correctly installed the parts.

[JohnnyP]

Originally Posted by adichino

thanks for the checklist dude, i do however like to fix my own stuff even though its my first time when dealing with an engine - worst case scenario i cannot fix it and buy a new one and lose a couple of euros, fuck that

i replaced the crankshaft because it was damaged where the rod which snapped is attached - dunno how its called

i didnt replace the bearings as they all looked the same and good to me

i am using a new set of pistons with a new set of rods - i didnt check the cylinders, just cleaned them and installed the pistons - they were sliding smooth when the rods were not attached to the shaft

so you are saying - judging by your answer - after the rods are installed and tightened the pistons should move when rotating the crankshaft?

quote from wikipedia

If you didnt change your case and rod bearings to match your new crank you engine will not last long....The chances that you got the exact same journal sizes on your new crank are a million to one....

[chino12]

i know i should have measured and checked everything as written in the service manual .. i didnt though

too much of a hassle, you guys convinced me, and i just wanna ride ..i think im gonna go with a new motor ... the bearings are too expansive so that this engine rebuild is still worth it

so i got F4i motor parts for sale, who wants some ?

[TRICKY]

Amazing story and funny to read, even though I feel bad for you for braking that motor, but I agree and you should spend 600-800 bucks on a new motor.
Painting a Honda green was mistake number one, second mistake was to remove the T-shirt, I think it was kind of a special super hot top secret oil filter

[TRICKY]

Originally Posted by B-rup

Its cuz you painted your f4i Kawi green......bike started acting like one

You Sir are absofuckinglutely correct!

[TRICKY]

Originally Posted by StuntNick

Again it was manbearpig!!!

The tshirt could have only be left by mistake. I could see that happening if your drunk and high and working in pitch black.

...the dutch experience

[chino12]

Originally Posted by TRICKY

...the dutch experience

haha been there but wasnt working on the engine at that time

i decided to give it another shot and today i made the crank spin freely ... it was because of a bearing

i think i have a good chance to rebuild this engine, and if its gonna blow again in one month oh well .. fuck it!

i've noticed something weird though .. when i was assembling back the crankcase, there are 6x7mm bolts which need to be torqued at 18nm .. and i barely torqued them at 7-8ish nm and they broke everytime, everyone of them ... from the half of the thread they were stretching

oh well i guess i will apply some special lock solution on the bolts or whatever its called, throw back a tshirt in and ride the bitch untll it blows again