What do you guys think. Rough surface=better fuel atomization. On a polaris the reeds dump right on the crank so will a rougher surface draw the air from the reeds better? the cranks turning the right way. and if i sandblast the entire intake track and inside the cases, will the fuel be more atomized? Please NO stupid comments, just facts and opinions.

Actually, there was a company advertising "Turbo Crank" treatment in which the outer edges of the balance discs were scalloped to create turbulence toward the transfers upward. Keeping a somewhat rough finish increases the mixture velocity minimizing raw fuel drop out. A wetted port will flow as well as a polished port. Another dimension to consider is on the newer Port FI motors inlet tract finish will be more important as there will be dry air running as opposed to heavier mixture so CFM will be artificially increased. The need to help tumble the A/F mixture won't be necessary as the fuel is added upstream. This opens the door for intake tract tuning through length and volume. FFT (Food for thought) not (Fast Fourier Transform) as Dynamo^Joe would be dealing with on a Bruel & Kjaer (or better) FFT analyser.

T.D.

Makes sense if everything is in the right place.









SWRules

My friend had a CR 125 motocross bike and during the winter he took the motor apart and polished just about everything that could be done. He split the cases and polished those as well, he polished everything. When he put it back together in the spring someone told him he had wasted his time doing all that work to the motor because the fuel wouldn't atomize well, he said that the fuel atomizes in the carb not the motor. Well to get to the point that little 125 would walk my CR 250, no bull that thing absolutly ripped. I guess he was right about all the polishing he did, i'd do it to my sled but i don't have the time or the energy.

you sure he didn't slip something in the tank of your 250!!!??? there's no comparison 125 vs. 250, and now he beats you????

to get to the point that little 125 would walk my CR 250

i appreciate the response but you really got to get better at slipping the clutch.

I never said how old my CR 250 was and yes he did beat me when he was done the motor work, believe it or not.

IMO FWIW it wouldn't do anything for you. It's a virtual tornado in the case anyway, the fuel is atomized plenty. The case atmophere is changing from highpressure to lowvacume 133 times a second at 8000 rpms with with crank and rods flying around. Don't think any unsuspended fuel droplets would have a chance. This is simular to the ongoing debate about polishing or texture on the intake ports? Other than to make them look nice I say no difference, wouldn't spend much time doing it either way. Maybe if the ports were big long straight tubes some fluid dynamics might come into play, but the the (highly atomized) mixure makes loops and turns and bends and bounces off walls and is divided by edges and spills over shelves, IMO the wall texture isn't going to make that much difference in fuel seperation. Consider how the oil from the injection is just "slobbered" raw into the case, even with it's high viscosity (compared to fuel air from the carb) it has no problem being fragmented, which leads to a whole different topic (premix vs inj). Not sure I buy into the turbo crank theory either. The ones I've seen were done for a buds kx80 mini roadrace bike. It had no advantage on the other bikes in the series.

Sandblasting any internal part on a motor is bad news. If you don't get all the sand out it could chew the $hit out of your engine. :cussing:


I save sandblasting for external painted surfaces like the metal parts of the ski.
Besides I've never heard of this theory of rough surfaces in the crank before??

Originally posted by jawz@Jul 31 2003, 10:37 AM
Sandblasting any internal part on a motor is bad news.* If you don't get all the sand out it could chew the $hit out of your engine.* * :cussing:*


I save sandblasting for external painted surfaces like the metal parts of the ski.
Besides I've never heard of this theory of rough surfaces in the crank before??
Jawz would know! He dunked his sled and sucked up enough sand off the bottom to coat a desert. :doh: :withstupid: I don't think I would try anything like that unless I had tons of cash like Jawz' wallet or alot of knowledge(which I don't)

Turboing the crank does work...it is like anything else, on a certain engine a certain modification might work great and on a different engine the modification may have little or no benifit...

check out this link http://www.advancedracingtechnologies.com/snowtech.html