Does anyone know if the VT250 rods are forged or shot peened?

**328FTW** · 29th September 2013, 14:17

Because I can tell you with 100% certainty it was rod failure in my motors that made them explode. The previous couple were so mangled I was having trouble deciphering if it dropped a valve grenading the rod or the other way around but this latest one the rod is split in the same place however the head is completely intact; not even a bent valve. So it kinda concludes my suspicion the rods are failing. There is zero signs of detonation on the piston tops and besides that it failed on a neutral rev after I'd warmed it up this time and was just messing around, I'd only expect detonation under load. It seems like tensional stresses causing failure, makes sense it's always at revs.

So given all this does anyone know if the rods are surface hardened in any way? Because I'm tempted to polish, balance and shot peen a set. Make sure all marking is parallel to to the load axis and try minimize my chances of crack propagation. Cause I'm running out of ideas to fix the fucking thing.

**spanner spinner** · 29th September 2013, 21:25

Forged, the factories don't bother to shot peen unless it's something special there building. usually these things throw rods cause there is a big end problem, check the crank pin for out of round and set the rod clearance to the minimum clearance as per the factory clearance. This helps keep them alive a little longer but all vt250's have weak rods. My advice would be to source a late model VTR250 engine as the later engines have a bigger crank pin diameter and better rods to stop the explosion of rods through the crank case that the early models suffered from.

**ducatilover** · 29th September 2013, 23:48

Spada motor... Rods can't be that weak with the way I treated mine

**Drew** · 30th September 2013, 05:04

This is all very interesting and all, and I know you're trying to make all the time you've spent add up to a running bike. I just can't help but wonder if it isn't time to quit the bike for sanity's sake.

Or, bolt a balance weight to the crank pin and make a single cylinder out of the motor and sell it as a bucket racer.

**haydes55** · 30th September 2013, 07:28

Remove the motor, weld in some pedals. Make a pretty cool push bike. Buy a gn250. It'll suck your love of motorbikes out of you, but it shouldn't blow up.

**328FTW** · 30th September 2013, 12:44

Originally Posted by haydes55

Remove the motor, weld in some pedals. Make a pretty cool push bike. Buy a gn250. It'll suck your love of motorbikes out of you, but it shouldn't blow up.

It's funny because that's exactly what I did and you're right rofl.

http://i536.photobucket.com/albums/f...2-28175925.jpg

I have a VTR motor, that's my spare one. I just need to open it to get the correct bearing code (pink, brown, blue etc) for clearances. I was asking about the shot peening because if I have it apart then it's an option to just do it and hope. I only spend time on this piece of shit when I can be bothered, most of my time has been on the prelude and selling my E30. Plus I have one spare motor left, it's going in the bike and if it blows up then at least I got rid of it the right way.

**328FTW** · 6th October 2013, 01:25

I pulled it down today, the mains had started to go. One of the journals was showing gold and I could feel the marks with my fingernail so it's not worth it to try fix. One of the rods I inspected and it's looks like it has some damage.

I was thinking of buying this motor

http://www.trademe.co.nz/Browse/List...x?id=646358679

I'm little more ok with putting money at this because it turns out the "burned valve" on my 2005 maxima was broken coil pack and I was readying up for a hell of a repair bill. The head gaskets are cost enough on their own and it all went up from there. I was kind of hoping it would be around $400 though, not 600.