Shed some light here speakerfritz, how did you tune your setup? Thats a high dollar setup. I agree, I hate having bike on dyno but unless I choose to do an auto tune unit I dont have a whole lot of choice. Ive tried the PC auto tune and wasnt happy. I really dont understand why bikes are tune so much in the high revs? Why not tune the bike in the rpms we really run (no higher than 4.5 - 5K!) and be done?? Luckily my bike was just about done with the tune so once I get everything back together I should be good to go. Unfortunately like you say I now have a blown motor in my lap. I have had every bike tune on dyno and all have been ok. Anything associated with Harley = cash cow IMHO

 

Here is a Manley beehive spring.

 

Oh man, thats reassuring!! thanks ;-) What did the Manley get replaced with??

 

A stock beehive spring that will travel .710. It has a distance between the upper collar and valve seal of .660 with a seat pressure of 140 lb. Those springs will support all "bolt in" cams and many of the higher lift cams under most circumstances. Heavy spring pressures contribute to valve train noise and are not necessary in most "street" buids but everybody is tuned into the "bigger is better" thought process.

 

My money's still on the seat. It doesn't happen very often but core shift in the casting, factory tolerances and high heat such as the head was under at the point of the last dyno run could and has caused valve seats to shift and/or drop out of a cylnder head. IMHO, assembly was not an issue, there was nothing anyone could have done about it and if it hadn't happened on the dyno it would have happened down the road; mark it up to bad luck and **** happens.

If you continue to run a cam like the SnS 583, the OEM beehive springs are adequate as are the OEM valve seats and guides. If budget allows, send the heads to the head porter of your choice for a basic street port; some street port work includes replacing guides with better material but most include larger intake valve, new seals, setting compression for the cam and a SERDI valve job. Cost will range from $400-$500 but will worth it.

Bore your cylinders to .010" OS and fit a set of OEM cast flat top pistons. Put her back together and retune. Should be able to get it all done for about $2000-$2500; less if you can do the work yourself. You will need to get any metal that wound up in the crankcase out and may need to replace oil pump and/or cam plate.

Don't over compensate and spend a bunch of money. There are a gazillion dyno suffessful dyno tunes that did not result in a grenaded engine; the dyno tune was not the problem. Like I said, chalk it up to bad luck and move on.

 

Old thread but exact same thing just happened to me. New 106 build, Andrews 57H cams, only difference is my heads were ported. New valves, guides, seals. Re-used beehive springs and retainers. Front intake valve smacked the piston and bent, valve guide cracked. Damage wasn't as bad but the valve spring retainer split in two just like yours when tuning the front cylinder on the dyno. We don't know what happened either.