For the 2010 season we are rebuilding Ian's Helmke's race bike. Ian will be running in Heavyweight Superbike and Supertwins in CCS Atlantic for our ECS Racing effort, so we wanted to give him as strong a bike as possible. Here are some of the improvements we are making:
Ian's 996 motor was in need of a rebuild, and a performance boost. Last year we had added Pistal high compression pistons, and for this season we are adding a 900ss crank for 2mm greater stroke and a displacement increase to 1026 and we are adding 748R intake cams. The heads have stock valves, but we cleaned up the intake ports a bit which should help. And, to allow for the extra stroke, we are adding an additional 1mm thick base gasket.
We thought we'd show you the bottom end of the motor going together - there's plenty of pictures of heads and valves online already, but you don't see split cases very often. Enjoy this, and check back - as we get the bike together, we'll show you all the other interesting stuff about this bike!
It all comes down to the crank - on the left is the 900ss crank nicely polished and knife edged, with radiused oil holes, and a micro polished journal. The crank is balanced for the new rods and the Pistal pistons. On the right is Ian's old 996 crank.
To handle the power we needed to upgrade to Carillo Rods - they are stronger an lighter than the stock units.
You an see in this picture the bearing in his old rod beginning to fail.
These cases really need a bath!! And while we were in there we found the busted off end of the shifter mechanism stuffed in behind a bearing. Yikes! Glad we tore this one apart.
The cases get a little love - no grime or gasket material anywhere - and then the crank goes in and we bolt them together to check the crank end play - this will tell us if we are correctly pre-loaded or not.
As you can see we've only got .0005" of runout and we want to see around .0015". The crank has two 2.20mm shims so we will go to two 2.25mm shim to add .05mm. This gives us about .0012" on the gauge.
The next step is to shim up the transmission. We are using the 996 transmission rather than a close ratio 748 gearbox because this motor is going to make so much torque that a close ratio box would be pointless. In go the gears, forks, selector drum, and the fork pins.
Next we check shaft endplay for the transmission. On the output shaft we have .008", the selector drum has .012" and the input shaft has .006" - we will need to snug up the output shaft to .002" because it is floating - the input shaft can stay at .006" because with the clutch bolted up it gets pulled snug in its bearing. While we have it all together we check that the dogs are equally spaced when they are disengaged, and then we shift through each gear and check to feel the the play between the gears to make sure they all are engaging the same and that there isn't one ratio with too much play.
Rods, and shells and Clevite 77 Plastigauge. Lovely.
On goes the Plastigauge and we bolt up everything to double check our clearance. Looks perfect.
Now that we are going ahead with final assembly, we green locktite and stake in the oil passage plug - these have a tendency to come out otherwise...
Next up is a little assembly lube to keep everything happy as it goes together.
Bolts get snugged but not torqued yet - there is a 40 ftlb spec as well as a spec for stretch on these bolts - .0004" to .0006", so we need to measure them first. Once we have that, we torque them and check to make sure our stretch is correct - bolts get anti seize too.
With everything situated, it's time for a little sealant and then back together!
We ran the bike on the dyno when it was all back together and here's the result. Look at the torque!
We'll have more on Ian's bike as we go along. It's happening pretty fast so we may just cover the rest of the basics on getting a 996 ready for the track and then you'll have to follow it over on ECS Racing!