Opening the exhaust port on DrEvo

[CoolvetteTopic starterBerichten: 107]

I will open the exhaust port on my 43 mm DrEvo, I have been adviced to rise the port by 1,5 mm but not more.

The outlet takes a funny bend around the tube containing one of the three bolt for the cylinder and the head.
To straighten the outlet should be good for the exhaust flow but it will probably go thru the wall to the tube.

Has anyone any experience from that and is there a problem to grind thru the wall?
The tube is closed in both ends so I don´t see any thing else that can be a problem.

Has anyone anything to tell and is it worth the effort?

[MartinoModeratorBerichten: 7384]

Keep in mind there are many cylinders who have also the hole opened from what you described as the tube containing one of the three bolts for the cylinder and head. For instance the Eurocilindro.

It’s not to see directly but you can imagine the exhaust port opens up in the “tube”.

Also, when working on your exhaust port it’s almost impossible not to break through. Most of the tuned cylinders you see have this opened.

So I will say this is not that greater problem, but personally I’d like to see no exhaust gasses passing through the “tube”.

Link naar Mijn collectie / Projecten.

[CoolvetteTopic starterBerichten: 107]

Thanks, I supposed that was the case.
If there was ways to open the exhaust canal without breaking thru that would be the best to do.
But by looking at the outlet it´s easy to see that the exhaust gasses takes a bend around the bolt.

Will I get any improvement by straightening the canal as much as possible, talking about exhaust flow=power?
Is it worth the effort?

[ritzeBijdragerBerichten: 3421]

1.5 mm is a lot i think.

my stock dr evo ran 88km/h with 10.120 rpm on a reedvalve case .
i think you should take an other dr evo for tuning and testing.

for the modification you will need some dremel or milling tools

De budget beun tjoener: geen geld is te duur of het werkt nog niet
Link naar Mijn collectie / Projecten.

[CoolvetteTopic starterBerichten: 107]

OK, thanks for the reply.

The DrEvos are quite cheap so I may buy another one to do the tuning or to keep in stock.

[Gebruiker]

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