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45mm Nc cast cylinder

: lør 8. okt 2011 11:33
af allspeed
Hi all
For myself for christmas :oops: i was thinking of buying the New Competition 45mm cast iron kit. I am sure you guys have tried these,any thoughts please.
Currently running a grunty expansion chamber and nc 43 alu kit.Bike runs well and reliable with 80 85kmh on the flat in good conditions.
i was hoping the 45mm would offer the same sort of speed but with more low end torque ?

Or am i expecting to much

Re: 45mm Nc cast cylinder

: søn 9. okt 2011 21:48
af allspeed
60 views :whew
Has no one fitted and ran one of these, you must have some input ? It may only be £80 but i dont like to waste my money !

Re: 45mm Nc cast cylinder

: man 10. okt 2011 02:07
af kreidlerhansen
I don't ride a Yamaha, I'll admit, but...


You'll only feel a slight increase in low-end power (if any - port design is essential and hardly consistent within this price range) and I'll bet you'd gain the same from optimizing the ports in your present 43mm cylinder. I'm not very keen on the NC product to begin with though the alu/nicasil cylinders are OK, generally speaking. The tiny cylinder design really benifits from an alloy/nicasil combo!

What you're asking for is probably beyond the limit of an engine with such a short stroke and you'd be much better off fitting a crank shaft with 42mm stroke! This will affect low-end power to suit your needs. These crank shafts are not easy to come by, unfortunately.


I'd spend my money on a good 45-46mm piston with a single chrome-ring and send an aluminium cylinder to Airsal in Spain to have it bored and replated to a 4/100mm clearance. This is an expensive solution but if you like the cylinder's "personlity" so to speak, this will bring you the best result along with a properly designed squish band. Depending on the ring opening you might even have room for a couple og booster ports.
Add to this that a nicasil plated cylinder with a good quality piston will last for ages when broken in correctly.

If you've got tonnes of patience you can go for a 3/100mm clearance and break it in over ~600 Miles letting the engine work primarily around 5-7.000rpm. This will maximize piston/cylinder longievity but also increase the risk of a seized piston during break-in.
Run it in properly and you should see 20.000 Miles easily from such a setup... if not twice that.

£80 is about the price of the replating. Of course, you'd have to add the cost of a piston (Vertex has a good price/quality ratio at ~£65) and postage to and from Spain.


It may seem a bit over the top but it's the way I'd go to have that one, nearly perfect setup rather than buying 10 different cylinder kits and never getting what I want. That way you end up spending the same money or more with no guarantee of success.

Re: 45mm Nc cast cylinder

: søn 29. jan 2012 18:28
af allspeed
Can i please ask you guys for some advice on your standard two peice exhausts. Can anyone say how this exhaust performs with a 32mm down pipe added and the front cone restrictor removed. We tend to just fit the full power one peice exhaust here as they are cheap and work well but i would like the standard 1979 look two peice exhaust. I have removed the restriction ok and the downpipe is coming but can anyone say how they go like this in compariosn to the one peice exhaust.Are they comparible ?

Re: 45mm Nc cast cylinder

: søn 29. jan 2012 19:03
af Morten - Webmaster
I'm listening on this one......

Re: 45mm Nc cast cylinder

: søn 29. jan 2012 21:39
af Kai
I've owned several one piece exhausts during my time with the Fizzie (the one we know here in DK as 5.3hp exhaust with 32mm downpipe)
They work ok, earlier versions seems to work better than the new crap you can buy cheap from "Protuna" and others..

I don't know exactly what or where the difference is, but the old one piece exhaust revved higher and had a decent bottom end.

But, what i do know, is that if you can manage to get the restrictor pipe out of the two-piece exhaust, and remove the 1'st exhaust baffle inside, and shorten the little muffler pipe/thingie accordingly, it will outperform both the 5.3hp exhaust and even the good old 8.5hp straight cut exhaust. Even with the 28mm downpipe.
As long as you dont push it to hard with big bore cylinders. They tend to overheat because the exhaust flow is a little more restricted with the 2piece exhaust.

I don't know if there is any difference between the Danish street legal exhaust, and the ones sold in other countries.

Don't blame me, if it won't work for you.

Re: 45mm Nc cast cylinder

: tors 2. feb 2012 16:48
af allspeed
Very good thanks for that, i have a two peice limitation uk pipe that i have removed the restrictor on, and another from a french fs1 that appears to never have had a limitation tube fitted. They sound very nice,better than a 5.3 pipe,almost like half of a rd125/200 air cooled twin. The sound alone makes me want to try it as although i dont mind a loud exhaust a quiter one that sounds nice and looks standard would be great in my book.

I now have the 32mm downpipe but am still waiting for the 32mm gland seal, when this comes soon, and the english weather warms up a little i will test it and report back. The 5-3 is a pretty good pipe for a uk rotary as it gives a good spread of power but it sounds horrid (standard) and snap at the mounting point too easy.Ours are made by Luhac ,we dont get bose just the luhac brand.

It may be a little while but i wll report back.

Re: 45mm Nc cast cylinder

: tors 2. feb 2012 17:08
af allspeed
Can someone post a pic of the 8.5 staright cut exhaust as i am not familier with which one this is ?

Re: 45mm Nc cast cylinder

: tors 2. feb 2012 17:29
af M.Ruseng
Here :-)
http://postimage.org/image/5njlxjveb/" onclick="window.open(this.href);return false;

Re: 45mm Nc cast cylinder

: tors 2. feb 2012 22:39
af allspeed
Thank you, we dont have those.I have never seen one over here before.