S3 Race Custom Modified EC250 Complete Rebuild

[Jakobi]

Hello everyone. Here I go again on another learning curve following on from the last one HERE. 110 hours or there abouts has passed since I changed the EC300R to a 250 and I must say I've loved every second of it. The Gasser has been as reliable as a stone and now has 260hrs on the bottom end. I figured it was time for a complete rebuild. I have a large assortment of parts ready which I will probably photograph and post tonight. I may add costings too if anyone shows interest.

Stage 1: Engine Removal

All went to plan here. No real issues. Dropped the fluids and went about removing what had to come off to get the engine out. I had planned to remove the engine complete with flywheel however it appeared to be a whole lot of work to unwire everything so just left everything connected and removed the flywheel and stator. No rust or corrosion on the flywheel at all which was fanstastic.



The 2K3 doesn't allow you to modify the timing. I will discuss this with Dave and may look at drilling this out a bit and advancing the timing just a tad.


It looks like the main seal might have been leaking slightly. There appears to be a bit of oil and dust in below the seal. The bike hadn't shown any dangerous signs of running lean but it did feel a bit flat in the top end at the end of the last ride.


Out of the bike and on the bench. I need to go and fab up a jig to hold the engine in the vice this afternoon. I think that will be the easiest way to work on it. If I'm lazy I'll just use some timber offcuts and tack up a box.

[Jakobi]

Empty Chasis. It had been washed prior to pull down. Amazing how much dirt and crap is still on the engine and frame.


And a quick peek in the exhaust port.

[dmcca]

Good work... With the ignition timing just remove the little curved plate with the 'T' stamped on it and you'll get the adjustment you're after.

[Jakobi]

Originally Posted by dmcca

Good work... With the ignition timing just remove the little curved plate with the 'T' stamped on it and you'll get the adjustment you're after.

How much advance would you look at adding Dave?

[Jakobi]

And continuing with the pull down.

RHS engine cover bolts backed out, water pump, impeller and seal removed.


Side removed. Everything looks pretty good. Clutch basket shows no notching in the fingers on first inspection which is a bonus. Bit of rust by the looks on the PV governor spring. Thats a bit odd. A close up to follow.


Powervalve covers removed. Not too much spooge but enough to know everythings been lubed up well. I'm very happy with the Amsoil Dominator.

[Jakobi]

How good does the head look. Nothing has been wiped down yet. Just as they are as I strip it down. Daves magic is a winner!


The piston wash. What do you all think? Its hard to know what was from the Lectron and what was my previous settings. Overall I think it looks pretty good. Some wash around the transfers. Not much carbon build up. Appears to be some in the middle but I have been toying around lately too. The dot in the middle is from the plastic piston stop I used during pull down.


More pics will come of the piston once its been removed along with cylinder and ring end gaps etc.

[GMP]

I don't know, my setup is pretty tight and on the edge for pump fuel and piston looked perfect when I had the jug off. Perhaps it's just a result of jetting being a bit crisp for the setup.


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[Jakobi]

Originally Posted by GMP

I don't know, my setup is pretty tight and on the edge for pump fuel and piston looked perfect when I had the jug off. Perhaps it's just a result of jetting being a bit crisp for the setup.

I think this plays a part too Glenn. I think that the 175 main with the Yamaha needle was cutting it really fine. Couple that up with my riding continuing to improve and more time spent in that rev range and its pretty likely. The needle clip position is definitely in its ideal position. At half a clip richer the bike loses snap and doesn't want to stand up as much when coming onto the pipe. Noticably decreased performance. The pilot circuit I have been running a bit on the richer side for torque.

The other consideration is that the bike fell totally flat in the top end coming home at the end of the last ride. Enough to make me decide I wanted to pull it down. It was having issues idling, either stalling or racing when adjusting the idle speed. On pull down I noticed a weeping main seal on the stator side. Was this enough to allow for a hot run? Who knows? If you know a way to ascertain which it was I'm happy to investigate further, otherwise I'm going to assume it was a result of all of the above. I'll probably drop comp a touch more, as well as fattening up the main jet a size or two.

[GMP]

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


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[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.