S3 Race Custom Modified EC250 Complete Rebuild

[Jakobi]

Originally Posted by GMP

So your going back to the PWK, no Lectron or SmartCarb?

Good call!

I am on the preorder list for the SmartCarb. Not sure when they'll roll out to Australia though. I was advised I'll need to pay more postage than the original deposit and they would contact me to make this before shipping. In the meantime Dave is letting me hold on to the Lectron and on Kevins (Lectron) advice we're going to sample a few more needles to see if we can clean up the bottom end. At some point I may run the PWK just for a back to back comparison. I'd also like to give Dave a play with the SmartCarb to return the favour.

[Jakobi]

Checked my spares box. I have everything I need to get the rebuild done. Now I just need to decide to run 1 x 05.mm base gasket, or more likely 2 x 0.3mm gaskets.

[Jakobi]

Decided to spend the afternoon relaxing and cleaning the cylinder and powervalve. One of my favourite jobs. The PV actually didn't look too bad and I only did a half baked job of cleaning it up. I couldn't be bothered bringing it back to a polished finish again this time around. I still need to hit the cylinder with some scotchbright or the likes. So far just washed down with some kero, and then carb cleaner. Next stop will be the dishwasher (when the missus isn't watching!) Also cleaned up all the gasket surfaces on the cases. Ready to rumble. And the dealer left a message. Crank has been done and ready to be picked up again. Same day service!

[Jakobi]

More of inside the cylinder.






And of course. The nice cleaned up cases, which are ready for bearing removal.

[Jakobi]

And last pics for the day.. The transmission and gear set. Please let me know if anything strikes you as worn or damaged.

[Jakobi]

Crunched a few numbers working backwards from where we were.

With Daves previous calculations of 14:1 with a 21cc dome, and 1.25mm squish (4.3cc), we'd have a 6.1cc dome volume. This doesn't sound right though and I believe we had a dome volume of 6.6mm in the 250's. Anyway, without filling this thread with a heap of numbers, I did the maths both ways, and by going from 1.25mm squish up to 1.35mm I will see about 0.3 less UCCR.

So if I'm at approx 14:1 it should drop down to 13.7:1 (or if prev at 14.3:1 it'll drop back to 14:1). Pretty much decided I'm going to run the extra bit of gasket this time around.

Dave do you have a record of your numbers somewhere? I remember I never sent you the piston, so I'm not sure if you were using one you'd previously cc'd, or working backwards from when I cc'd the full trapped volume. The later makes sense to me.

[pscook]

Regarding the gears, you need to inspect the leading and trailing edge of the gears where they mesh, known as "dogs."



These are the dogs, you just want to look at the engagement side on the drive gear and the receiving side on the driven gear. Once you spend some time figuring how the transmission works (moving stuff side to side and front and back), it's easy to determine where the wear should be. The concern is when the edges are worn or rounded at the interface. The wear will be on the leading edge. If you are not having problems you won't see any issues.

Here's a bad one-


Here's a heavily undercut gear to prevent slipping-


Spend some time searching for "undercut gears" and you will find good info regarding inspecting your gears. You do need to separate the gears from the shaft for a full inspection, but a cursory glance should let you know how deep to go.

If I dig around a bit I might find my worn gears to give you a reasonable view of what I have seen. Otherwise, if you don't have any trans problems, you should be good as you are.

[Jakobi]

Cheers Phil. Not sure I want to be pull the gearbox apart too much. I'll never get it back together. Hahah! I would but I can see it being a headache. I'll check it all out. Great info re the dogs too. I had heard the terminology but never really knew what they were.

[Jakobi]

Today was just one of those days. I had planned to do very little and take my time. You could say it went to plan, as I did very little and it took most my time.

It was just one of those days where nothing seemed to go right. Old bearings proved to be a pain to get out. A few dropped out really easily, a few didnt. The needle rollers for the tranny seemed to be the tightest fit by far. One needed to some assistance on the outer race from the other side. The other was a blind press and I needed to get my mate to drop his blind bearing puller off to get that one out.

Next up I decided I'd clean the cases in the dishwasher. All good. An hour passes. They don't really look that much cleaner, so decide to go old fashioned. Scrubbing away all good. Letting the truck wash have a soak, I went to get the pressure washer ready. Hose blows off the back and sprays water everywhere. Get it back on, and then bleed the air bubbles out and turn it on. Nothing. Motor not engaging. Check the power point. Yep its live! POS Karcher pressure washer. It failed once under warranty, got repaired and I have used it once since. It worked briefly when I kicked it Move it back to the tap. Blow the hose of it again. Still won't work... So hose it is. Hosing everything down. Waters going everywhere. Splashing back at me. I'm wet! Its wet.. We're all wet.. but at least we're clean!

Back up to the house and start warming the cases up. The bearings had spent all day in the freezer. Just like when taking them out... Some went in easy, others didn't. If you even slighlty dropped it in on an angle the heat of the case would exchange to the bearing and it would lock up on me. Had to heat the lot to get it back out and start over. This was a bit of a trend. I don't want to know how many hours the oven was running today between getting bearings out and putting bearings in. Again on fitment some where tight and needed some help on the outer race with a socket. Some pushed in beatifully by hand. The mains seemed to push in well. Most the smaller ball bearings were no issue. The large caged bearing was a bit of a stubborn one, and both needle rollers for the transmission felt like virgins.

Today is now over. My cases are now clean, and have new bearings in them. Everythings been lubed up with some 2T oil. The sealed main bearings (as per stock) still seem to pass 2T oil through them too, and feel tighter than the old ones. Should be like a new bike!

Back to school tomorrow. So no updates for a few days.

[Jakobi]

Dirty cases


Clean cases - NO! The dishwasher didn't do this.. Good old fashioned elbow grease did


New bearings dropped in