FCS Crank Install Instructions

New crank vs Old, if you cant tell which is which don't try this install

1. Start with your pretty bike

2. Remove Rear Wheel

3. Remove front Farings

4. Unbolt Exhaust

5. Unbolt top engine mount

6. Unbolt bottom engine mount

7. Engine should come right out. Remove pull starter

8. Remove clutch bell assebly

9. Remove reed block

10 remove clutch

11. Pull it

12. Same thing with fan

13. Remove coil and timing key

14 remove cylinder

15. Remove crank case bolts

16. Remove springs(one on each side) of piston

17. Split case

18. Pull old crank out put new on in, take note where the timing key side goes. Time to grind

19. I installed the crank and rotated it and marked all the places it dragged, then grinded a bit off and repeated until it didn't drag anymore

20 Repeat for both halves

21. Setting squish

From MFO RACING:

Before you bolt it all together, do a squish test and adjust base gasket for a .5mm squish. This is EXTREMELY important!

Use a piece of lead solder and place it on the piston over the wrist pin.
Turn motor over by hand slowly.
Remove solder and measure it with calipers.
Target .5mm

In order for me to get .5mm, I had to remove the spacer and double up two gaskets I made which are thicker than stock.

This was a HUGE difference in performance.

With the spacer I had 1.2mm squish and 120 lbs compression.

Without the spacer and using two gaskets I made, I have .5mm squish and 180 lbs compression.

22. I found a piece of solder and cut it to cover the whole piston. Put some grease in the middle to keep it there. Bolt it together, rotate the crank, remove and repeat. Best I could get is .68mm with the spacer only. If I used two gaskets I was below .5mm.

From IP2

variety of cylinders out there made by different companies so squish clearance can vary
squish band must be set at 0.5mm :
less than that means piston hit the head , any more will reduce compression and engine will not make any power or may not even run ..
on most engines 2mm spacer should not be used , instead stack 3 to 4 base gaskets , each gasket is 0.3 mm so 5 will be 1.5mm .. some guys used only 3 gaskets ..
if more than 5 required then must use 2mm spacer and no gaskets ..use yamahbond 3 to seal ..
never use any type of sealant or paste on paper gasket , because when stacked the sealant may cause it to slide sideways
you may use smallest amount on case joints only

23. Porting (optional)

Big Bore KIT porting only done on exhaust port;
with stock crank:
widen to 31 mm
raise roof 2mm
=============
with SFC
exhaust port :
widen to 31 mm
raise roof 4mm
lower floor 1mm
==
warning :don't try to match exhaust channel with port size or channel can bust open (holed) , so you can taper cut only

SFC instructions:

1- case must be trimmed to make 0.5 clearance between crank and case,. can trim with half moon hand file , must trim at 45 degree angle , only cut from case centers

2-must install spacer supplied or gaskets under cylinder

3-must remove the washer on 4 cylinder bolt so bolts can reach deeper

4-it maybe possible to run without base gasket as long as piston dont hit the head , in this case use small amount of yamabond 3 to seal ..check all clearances , 0.5 clearance on all parts required , if piston hit the head add one or 2 base gaskets till it clear

5-stroker crank increase displacement to up to 54 cc so is vibration , make sure there is rubber mount on pipes mount and all fasters torqued down

6- must port cylinder and install pipe and jet kit

7- my pipe sold out so you can modify stock pipe as follows:

cut 1inch from header , add 1inch to belly , such mods make more torque than my pipe for indoor but fall short in outdoor tracks