Help me!! Using Rb25de bottom end to replace rb25det

[Vicrbmw]

Ok everyone and anyone... I need some help!!

ive got a rb25de bottom end I was planning on using to replace my det after spinning a bearing and ring failure. I’ve had a fair look online and I’m getting a lot of conflicting info about this. 

I understand I need oil and water lines tapped into block, which is done. .from what I have read it’s not absolutely necessary to fit oil squirters- and I wasn’t planning on it. 

What I cannot find is a solid and answer about pistons.  Do I need to replace the de pistons with the det ones. I’m using the head from det but have read a few things about valve clearances. I’m also not sure how this will effect compression 

 

if if someone knows what I need to do I’d appreciate some guidance

 

thanks 

[Murray_Calavera]

Your questions are something that you can measure yourself. Piston to valve clearance can be measured and the compression ratio can also be calculated after you guessed it, taking the correct measurements. 

After going through this nightmare of a failed ringland and spun bearing, do you really want to use another cast piston and risk another ringland failure? I'd strongly consider picking up some forged pistons, they really aren't that expensive in the grand scheme of things. 

[GTSBoy]

Yes, you have the opportunity to do it right. Do it right.

Having said that....The compression will go up, which may not be a great thing considering how you've gotten to this point in the first place. But I wouldn't worry about valve-piston clearances. It's not like the turbo valves do anything different to the NA valves.  Up-down at the same times, etc.

[Vicrbmw]

Your both completelyright.. unfortunately in the past 4 weeks I’ve had my bike stolen and my patrol rolled so this is the last of my vehicles...

i was planning on taking a few months to rebuild other bottom end while it’s out: forged rods and pistons/ new sets of bearings and all that jazz:: but I need this thing back on the road before Tuesday... 

[Murray_Calavera]

Not sure if this is an option;

1. drop in a good wrecker motor. get yourself up and running again. 

2. build the original motor in spare time. 

3. sell wrecker motor, hopefully reclaim most of the original money invested.

4. drop in forged motor.  

Pretty shitty run of luck you've had lately, hopefully things pick up for you and the bike it found in one piece. 

[AngryRB]

Option 5- drop an RB30 bottom end in and gain bulk torque ?

[Vicrbmw]

The option has been on my mind.. however I don’t know how I’ll go with height restriction under the bonnet.. it’s already pretty tight in there 

[Dose Pipe Sutututu]

Drop n a stock motor, quickest and cheapest solution to be honest.