cylinder damage

**Sun Nov 19, 2006 5:31 pm » Post: #1 » Download Post**

hi guys,after stripping top end today and looking closely at cylinder walls i noticed the powervalve petals have slightly dented the walls of the exhaust port where they touch.Is this normal and shall i polish them out when i clean it?Also exhaust port bridge has a slight crack on cylinder wall side do i need to get this repaired?
Thanks Rob.

**Sun Nov 19, 2006 6:01 pm » Post: #2 » Download Post**

It's quite common to see older barrels with slightly "dented" ports where the RC Valves have rubbed. You need to ensure the Valves do not open too far.

As for the crack in the bridge - that's often a give-away that it's not been warmed up sufficiently. The motor could've been like that for years, but at the same time, crack's aren't good! (Not in barrels anyway!! Very Happy

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Andy.
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**Sun Nov 19, 2006 6:06 pm » Post: #3 » Download Post**

Looking at a couple of cylinders I've got here both have slight marks, but I wouldn't call them dents, surely well adjusted powervalves don't hit the port that hard? Polish it out if you want, I doubt it's big enough to matter.

As for the crack no sane person is ever going to recommend on a forum that you run a damaged barrel but we all have.

If you can feel it at all yes, get it replated for sure, if not, well....it's up to you.
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**Sun Nov 19, 2006 6:29 pm » Post: #4 » Download Post**

thanks for the fast replies,is it the side of the port that stops the valves opening too far then and not the cable adjustment?
Im still gonna use cylinder with the cracked bridge for now.is it worth me looking for some mc18 cylinders rather than going to the trouble and expence of repairing my mc16 ones?

**Sun Nov 19, 2006 6:33 pm » Post: #5 » Download Post**

The cable adjustment is what controls the valve. The valve shouldn't touch the port when adjusted right.

MC18 barrels are much better than MC16 ones and would be a good idea if youre going to have to replate/replace the '16 ones anyway.
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If I have to take the carbs off once more...

**Sun Nov 19, 2006 6:38 pm » Post: #6 » Download Post**

do the mc18 cylinders and carbs come up for sale very often as ever mc 16 owner must want them?

**Sun Nov 19, 2006 6:42 pm » Post: #7 » Download Post**

beakergixer750cc wrote:do the mc18 cylinders and carbs come up for sale very often as ever mc 16 owner must want them?

Especially this MC16 owner!! Laughing

Mind you, I have F3 ones for mine now, so you can have first shout on the next MC18 ones that come up!! Wink

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Andy.
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**Sun Nov 19, 2006 6:48 pm » Post: #8 » Download Post**

thanks Andy,i'd definately be interested if some did come up,how much more power would i get with this mc18 set up?

**Sun Nov 19, 2006 6:56 pm » Post: #9 » Download Post**

Looking at about a 10hp gain with MC18 barrels, heads, and carbs I'd say.
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Andy.
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**Sun Nov 19, 2006 7:00 pm » Post: #10 » Download Post**

looking at all nsr model specs,interestingly they all make 45bhp apart from mc28 with 40!! Is this a back wheel or a crank figure?

**Sun Nov 19, 2006 7:35 pm » Post: #11 » Download Post**

beakergixer750cc wrote:looking at all nsr model specs,interestingly they all make 45bhp apart from mc28 with 40!! Is this a back wheel or a crank figure?

Until you delimit them.

The MC16 makes about 45hp cos it's crap! Smile

The exhaust ports and the carbs are dinky, and that's what holds it back.

The MC18 and MC21 are limited in the ignition, and will make 60hp+ easily.

The MC28 makes 40hp cos it's crap! Laughing

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Andy.
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**Sun Nov 19, 2006 7:43 pm » Post: #12 » Download Post**

that'll be the wire splice thing that keeps cropping up on here then?Doh!
Was that a crank power figure then?

**Sun Nov 19, 2006 9:30 pm » Post: #13 » Download Post**

This might sound like a knob question but wouldn't '18 barrels need '18 pipes if the ports are that much larger than the '16
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**Sun Nov 19, 2006 10:44 pm » Post: #14 » Download Post**

Andy wrote:The MC28 makes 40hp cos it's crap!

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**Mon Nov 20, 2006 8:37 pm » Post: #15 » Download Post**

never having seen a mc18 cylinder,would it be possible to open up ports on mc 16 cylinder to mc18 size?