Lightweight Crank, Rods and Pistons - Ducati.ms

Sputniks · Jan 29th, 2012, 11:20 am

A mechanic recommends a full engine blueprint at the time a stock crankshaft/rods/pistons replaced with the lightweight ones. But the blueprinting would triple the labor cost. From what I know the blueprinting is performed to turn a stock motor to a race one. I ride the bike on the street as much as I ride it on a track (trackdays only, no racing). I made an attempt to educate myself on the blueprinting. But all the information on the subject is very technical and the discussions deal with the terms I have no idea about: "valve porting", "ceramic coating", "compression ration" and etc. A year ago I have installed a lightweight flywheel. And it made a subtle difference on a bike's acceleration. Installing the lightweight crankshaft and rods likely would have a similar impact: a faster acceleration, reduced inertia and rotation momentum. Is it absolutely necessarily to blueprint the engine for the lightweight rods and crank to work?
P.s. The engine is Streetfighter 1098 with 12.5K miles.

nine16 · Jan 29th, 2012, 11:43 am

First, the lightweight flywheel made zero difference in acceleration. Now, if you are going to do any new spinny parts in the motor (and it sounds like you're doing all of them), you need the extra labor of balancing the crank anyway. Full blueprinting may be a bit overkill but it will make the engine more reliable. A comfort on the street, but definitely more of an asset on the track. Ask your builder how much addition money for blueprinting vs just crank balance and assembly and then weigh the benefits/cost for yourself.

Sputniks · Jan 29th, 2012, 2:02 pm

Quote:

Originally Posted by nine16

First, the lightweight flywheel made zero difference in acceleration. Now, if you are going to do any new spinny parts in the motor (and it sounds like you're doing all of them), you need the extra labor of balancing the crank anyway. Full blueprinting may be a bit overkill but it will make the engine more reliable. A comfort on the street, but definitely more of an asset on the track. Ask your builder how much addition money for blueprinting vs just crank balance and assembly and then weigh the benefits/cost for yourself.

The crank is already pre-balanced for the rods and the pistons to be used. The mechanic doesn't have to balance it.
It is hard to weight the benefits/cost of the blueprinting since I don't know what to expect from the blueprinted motor. It would be great to hear from those who has a first hand experience riding the bike before and after the blueprint job was performed.

desmo11 · Jan 29th, 2012, 2:24 pm

What is this guy telling you is 'blueprinting'? If the crank/rods/pistons have been balanced that should be most of it. Other than that it is straightforward assembly. If you're being sold a deal that setting bearing clearances, squish, valve lash, cam timing, etc. is 'special' you might want to shop around a bit for someone to assemble your engine.

wdietz186 · Jan 29th, 2012, 2:27 pm

Blueprinting refers to making sure the clearances etc. are in spec with the mfgr's design tolerances. If you aren't racing the bike and it is ridden mostly on the street doing a full blueprint on the engine is a waste of money.Lighter crank,rods,pistons,etc. are a benefit in a race engine but when you get down to it most if not all street riders don't use the performance offered by the stock engine. Careful assembly of the stock pieces are all you need,most critically the rod bearing selection.

Bella749 · Jan 29th, 2012, 3:43 pm

I would'nt call blueprinitng a waste of money, unless you strictly doing it to a fresh engine for street use. Like stated, "blueprinting" is nothing more than careful assembly of the engine to precise tolerances as opposed to mass-production tolerances. A well-balanced engine is smoother and more reliable, but not necesarily more powerful (that comes with tuning.

If the engine is apart to replace the crank, blueprinting is a logical choice, since the engine is already apart. I don't understand why the labor costs are tripled, though. Generally, a full blueprint job will run about $2-2.5k plus the cost of parts.

ZDM · Jan 29th, 2012, 4:42 pm

I understand that to balance and blueprint a motor was to match a parts designed spec tolerances as best as possible. For instance an engineer designs two parts to fit together at a certain tolerance. When an engine is B&B they mechanic measures these two tolerances and if one is outside spec he'll need to replace that part with another until the parts fall within designed tolerances. I always thought this could only be properly done at the factory where the engine builder had access to hundreds of parts so they could pick and choose the parts that fit together within spec. Not sure how it's done at FBF or the Ducshop. I guess they machine the part until it fits with in spec. Not sure if I'm right about this...it is interesting as it's a time consuming and labor intensive process.
I just had my stock crank balanced by FBF after having my cases split to replace a bad main bearing. The difference that balancing made was pretty significant as my engine is so smooth now vs before....I wasn't expecting much, but as it turned out I was shocked with regards to the before and after. It really was $$ well spent. I also had all the bearings replaced which might be a good idea as your cases are split anyway. We discussed crank lightening, blueprinting, lighter rods ad nauseum I'm sure FBF felt. But in the long run I decided to stick with new bearings throughout and crank balancing-worked out very, very well!

Mr R · Jan 29th, 2012, 5:01 pm

anyone ever used Wossner pistons ?

nine16 · Jan 29th, 2012, 6:00 pm

Not very common in the US, but they have a good reputation as I recall. Pistals are great. Domestically, JE are good but I've hear very mixed reviews about Wiseco.

froggert · Jan 30th, 2012, 10:06 am

i had my 1098 blueprinted for greater reliability. it came from the factory with too much preload on the crank. while it was apart, i had the crank lightened, polished and knife-edged and the whole assembly balanced. kept the stock pistons since stock compression is already pretty high and i had to draw a line somewhere cost-wise.

does the streetfighter use the same main bearing as the 1098? if so, definitely get that checked out while everything is apart.