EC200 Cylinder Measurements
 

Does anybody have an EC200 cylinder that they could measure the base gasket surface to head gasket surface distance? I'm basically looking for the height of the cylinder to 0.001" or 0.025mm.

Wes.

I could really use some help with this, I've got a bike here with 4mm of squish and I'm trying to figure out where the problem lies, cylinder, piston, head or rod dimensions. I suspect it's the cylinder as the piston sits about 1-2mm below the exhaust port at BDC, but could be the rod's too short or the piston pin hole is too high as well. It only has one 0.020" base gasket installed.

Wes.

The piston sits below the exhuast port at BDC. Thats the first time I have read that. My 250 + 300 cylinders required 1.3mm of gasket to get them flush.

Whats the history of the bike Wes? Is this the new one you bought? Sounds like a Friday arv special. 4mm is outrageous. So so so. Lets start. Get the part numbers off the piston, and rod. Check that they are correct. If that checks out, then I'd say its probably the cyl. Warranty?

I run the thin base basket on my 200. I can't remember what it is....

If i had mine torn down i could help you out.

This is the new bike I just bought. I have been struggling to get it running decent on the bottom end, numerous jetting combos including 2 different slides and 4 different needles, tried a DEP 200 pipe, then decided to do a compression test which revealed 90psi compression. From there I pulled it apart expecting to see broken/missing rings or cylinder/piston damage but there was no obvious reasons for the low compression (ring end gap is 0.48mm). Last ditched attempt, I checked the squish and found out it was 4mm! I'm thinking the cylinder base wasn't machined enough because of the piston being below the exhaust port, but as I said, it could be a few other things. Here are pictures of the numbers on the piston and rod. Working on warranty, but I didn't buy it through a local dealer this time which is making things a bit more difficult.

Wes.

Ok. So the rod is a genuine Vesrah (same as the 250 and 300 also). I'd say its unlikely to be that, but if you wanted to measure, I have a used one on the bench beside me. The Piston is also a genuine Vertex stamped so I assume its height would be in spec, and if out it should only be minimal. Which leaves the crank offset, but I'm guessing more likely the cylinder height. The problem being that if you have to machine the cylinder, what effect will that have on the nikasil?

I could machine the base gasket surface without touching the nikasil as long as the casting is ok and the skirt of the cylinder doesn't hit anything in the case when it drops down 2.5mm. Maybe I'll check that clearance too, just to be sure.

Wes.

Good thinking. From memory you should be able to check that easily enough through the intake. If you drop that down to get the ports flush, with maybe 1mm of gasket, you can then still change the port timing to boost the bottom end if you need to.

It may come down to that, but if anyone has the cylinder height measurement I could prove that this is the problem and hopefully work this out through warranty. Biggest problem right now is that I'm less than a week from a long weekend camping/riding trip and I need this sorted before that.

Wes.

I'd be screaming for a new motor! That is ridiculous! Tell me how something like this went through the factory final dyno test? IT DIDN'T.

Lord knows I've fixed a lot of screw ups but remachining a cylinder? No Way.


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