Just got my replacement cylinder today, so was hoping to have the bike ready for the weekend's racing. Anyway, the cylinder arrives and despite not being really clean, and the base face being scratched to sh*t .... the thing has been ported (mostly exhaust side). My other cylinder has not been ported.

Should I
(A) Stick it in, should be fine if the jetting is OK.
(B) Put it in temporarily until I can get the old one fixed. If it blows it blows.
(C) Port the the other one so that they match each other. Ulp!

J

And if (A) or (B), should it go in the top or the bottom?
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MC28 SE -sold-
MC21 with RS250 engine -for sale-
MC21 race bike -soon for sale-

Ported how? If you mean the exhaust window in the cylinder wall, then it is probably on track to where it needs to be. If they machined the EXIT of the exhaust port, they screwed the cylinder and killed a bit of power.

The proper way is to open the outer/upper edges of the exhaust port, so the roof of the port is more flat or straight across. The NSR suffers from too little blow-down exhaust port timing and this fixes it.

It is pretty easy to port these if you are handy with a dremel. You have to be real careful not to cause the plating to peel, and round/taper the edges of the plating to keep the rings from catching.
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Paul Herr
'88 FZR4/GSXR/YZF Frankenbike
MY BIKE PICS

Bastards! They did open up the exit, and not the cylinder wall side I don't think.

So can I run this at the same time as a stock one? Would you put it top or bottom?

I'm thinking I'll put it in the bottom and be aware that I'm going to need different jetting for each cylinder. Then try and pick up another cylinder sometime or get my old one fixed.
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MC28 SE -sold-
MC21 with RS250 engine -for sale-
MC21 race bike -soon for sale-

Urrgh (grimace)

You just know it's going to end in tears

Ahh, you should be fine - please don't forget to add to the 'Blow Up's' thread after you've cained the thing to hell and back

Good luck.
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These aren't the droids you're looking for.

It's starting to feel like I assemble my top end from time to time to take out for a seizure.
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MC28 SE -sold-
MC21 with RS250 engine -for sale-
MC21 race bike -soon for sale-

I dunno if this may be of any help but you can get stick on thermo-readers that helped me out when messing around with the YPVS.

They cost about £1 each - I guess that's about a billion yen but they are an adhesive plastic patch about the size of a small match box. You attach them to the engine part and run the bike. They change colour (very distinctively) with tepm and you read off the colour against a chart. They help to give you an idea of running temp differences. The don't last too well on pipes as the adhesive burns and the leave a nasty mess as they slide off but are a real bonus when designing your own pipe for your bike.

I used one on each pipe and 1 on the front of each barrel, one on the rear of each barrel and one on each head. You'd think the engine would be the same temp all over, especially on a paralell twin but ohhh no.

The NSR would be a really interesting bike to accurately monitor engine temp and especially when using the 300cc kit.


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These aren't the droids you're looking for.