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Enduro Engine - 2 stroke Cylinder, Piston, Tranny, Bearings, Clutch, Pipes & Silencers, etc.


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Old 10-21-2010, 12:10 PM
Gasgasogeros Gasgasogeros is offline
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Default ec 300 sub port

hi on my gasgas ec300 the piston its not openull the sub ports by 4 mm with cylinder gasket 0,15 is normal this, or its must make a gasket 4 mm to open the subs ports?
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Old 10-23-2010, 03:20 AM
thespice thespice is offline
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top of piston should be level with bottom of exhaust port thats usually the correct spec
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Old 10-23-2010, 06:09 AM
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As a general rule of thumb for raising transfers.If the design has them opening @ 118deg ATDC with an exhaust set @ 88deg ATDC,This would be suited for "enduro" type power- wide torque .Most euro bikes have this set up.
If you raise the opening timing to lets say 116deg and leave the exhaust alone the power will be even flatter on top with a moderate gain from 3500 rpm -5600 rpm.If you raise the exhaust and transfer timing to lets say 84 deg and 116 deg then a slightly narrower power band with a much higher rpm peak is the result

If the transfers are too big or too small to begin with then cylinder filling capibilities are a big problem.These issues influence the power output the most.

As with most 2 cycle designs go ,the many comprimises that have to be made so most people can ride them can cause a good bike to be a pile once it hits the dealers so keep in mind that relative small internal changes might show no gains or loses at all.

There are many SEA papers written to clarify this.
And as many ways to skin the same cat.
Keep in mind the easiest way to raise ports is with gaskets
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Old 10-23-2010, 02:46 PM
Gasgasogeros Gasgasogeros is offline
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[IMG][/IMG]
[IMG][/IMG]
After the case mods
[IMG][/IMG]
Now i know why the gasgas dont make respect horsepower bad port disegn end bad case casting
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Old 10-23-2010, 05:52 PM
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With the piston at top dead center, how far down is it from the top of the cylinder?

The transfer port gasses are pressurized, so some mismatching might be a non-issue. By the time the piston has reached bottom dead center, the gas mixture would have already been expelled anyway.
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Old 10-24-2010, 12:19 AM
Gasgasogeros Gasgasogeros is offline
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With the piston at top dead center, how far down is it from the top of the cylinder? About 3.8mm
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Old 10-24-2010, 07:43 AM
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Reason I asked.
If you get the transfer ports to match up with the top of the piston, you can affect the compression and make it to where it's too low.
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Old 10-24-2010, 07:55 AM
Gasgasogeros Gasgasogeros is offline
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My question is this its comon on gasgas or something mistake on my bike ? because the piston is not oem but a vertex i know the heed must cutting on laxte the same as the gasket on base of cylinder
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Old 10-24-2010, 08:44 AM
lankydoug lankydoug is offline
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Quote:
Originally Posted by Gasgasogeros View Post
My question is this its comon on gasgas or something mistake on my bike ? because the piston is not oem but a vertex i know the heed must cutting on laxte the same as the gasket on base of cylinder
There is more than one mistake in play here because if you spaced the cyl further up to completely uncover the port you would end up with a lot less compression. If the piston deck to pin height was wrong and it was changed to uncover the port you would have so much less squish it may not even run.

I have seen casting flaws combined with the mass production machining tolerances being on the safe side to the extent that simply milling the parts to take away the excess safe factor results in big horsepower increases. This may be a case where unluckily all the parts were fudged on the safe side too add up to a big error end the end. I would be curious to know what the measurements would come out with a different cylinder in place.
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Old 10-24-2010, 01:39 PM
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I would'nt call the production tolerences mistakes. The bikes have more than enough power for the average rider and the 250's and especially the 300's seem to run very good with the cylinder lower rather than higher. The 200 is another story. Here are some pics of the preliminary port matching on a very strong running 200 I built.Notice how much expoxy was required on the one case half!



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