Topic: Need help with my 550k motor rebuild!

[fmctm1sw]

But I'm engine dumb and need some input as to what to replace, etc.

 
(machineshop in my basement..)

Those are usually mutually exclusive thoughts right there.  What has helped me is having spare parts laying around.  Exploded parts bikes, eBay, etc.  Anything I've messed up, I've been lucky enough to have a backup.  Sometimes inexperience can be offset with replacement parts (like the time I cracked my oil pan because I was tightening it instead of loosening)...

[A Grove]

AH!! I cracked my oil pan as well.. but it was bec. i over-tightened kinda intentionally.  But lucky for me (this is where the machineshop comes in handy), it was nothing that my tig and mill couldn't make happy again...

But being only 17, and having very little engine experience, thats where the lack of knowledge comes from   Agree'd on the spare parts, though.  They've come in handy time and time again. 

[paulages]

OK. so pistons are now accounted for, thanks spikey!

Anyone have input on the 126-20 cam?

i'm running it in the 718cc overbore, so it's hard to say exactly what's doing what, but i'd recommend it. good numbers on that profile.

[A Grove]

Thanks..

Still am super curious what they mean when they say modified pistons.  Taking a stab in the dark I would GUESS it has to do with needing higher compression due to valves time open being prolonged or shortened... but thats the best I can guess...

[Spikeybike]

good guess.... they're talking about the pockets in the tops of the pistons

[A Grove]

Lucky guess... I'll give megacycle a call tomorrow and get more details on what exactly I need to make this set-up worthwhile.

[moham]

The "modified" 750 pistons in the Express article had material removed from the skirt also, if memory serves. The article details the mods with pics and measurements.

[Spikeybike]

gentleman's express article