after reading through many pages here i'm beginning to understand that once you mod past a stage 1 setup the life span appears to drop of drastically. technically what is the common weak point? cracked block? thrown rod? valves dropping out? is the common cause the higher rpm's or are the motors unable to process out the added heat causing fatigue on internals of the cylinder sleeves themselves?

how many hours are the guys running stage 2 and stage 3 motors actually getting out of them?

The blocks can't seem to handle the compression. But there is no one reason being how they are modded so many different ways.

i noticed the new vangaurds have a sleeved block. i built turbo'd 4 bangers for a while. blocks not handling compression is nothing new. i know air cooled vs water cooled in apples and oranges but we'd sleeve sleeve open deck honda blocks before we'd slap a big turbo setup on it. in theory, since vanguard blocks are already sleeved, could the factory sleeve be pushed out, the block reamed and a thicker, stronger sleeve be pressed in?

have the blocks always been sleeved or is this something knew with the onset of the CDI era motors?

Depends on the recipe used for the mods. You can get 100's of hours on motors with cams, pistons, c-rods, etc... The MB45 is a very reliable motor. Running race oil in them is recommended.

What kind of race oil do you recommend deadbird? I have a mb 45 .

Seems like as soon as the compression starts getting over the 190's the issues arrive, that and as soon as you start running over 4600rpm's........ I put my 2nd 45mag through the paces and she did fine....... just keep her running under 4600rpms and you should be good..

As far as oil goes, a high zinc racing oil is what you want....anything that says "not for road use" racing oil...........10W30