ntake porting.......

nq50KillingSpree · Post by **nq50KillingSpree** » Wed Aug 20, 2008 6:50 am

why should one leave the walls rough from grinding it out? wouldnt that create more air resistance? seems to me smooth would let air flow more spreely i mean freely........pleaze explain..........

keithw · Post by **keithw** » Wed Aug 20, 2008 7:08 am

The carb atomizes the fuel. The manifold vaporizes the fuel. A fair number of the tiny fuel droplets hit the manifold walls. If the wall is polished they just roll along and don't get vaporized very well. If the wall is rough the droplets stick, spread out over the greater surface area of the rough wall, and vaporize. You don't want sharp corners or big lumps and bumps in the manifold but you do want a rough surface.

The reason you need enrichment on starting is that the cold manifold and engine don't vaporize the fuel very well. In order to get the proper amound of vaporized fuel a lot of extra fuel is added. Most of it goes out the tail pipe unburned.

keithw

nq50KillingSpree · Post by **nq50KillingSpree** » Wed Aug 20, 2008 3:26 pm

thanx for that info..it helped explain it so a dummy like me can understand..
so i thought i saw(could be mistaken) a few pics of 85-86 spree that you rebuilt.....how do i get a tuned exhaust pipe? im not much on resources as far as a welder and other things...although i can weld..what is the best tuned pipe for a stock nq50 spree? is there another model of honda i can swap it with? or do i need to go to my local powersports store and buy an aftermarket? i know id get raped on the price but im tired of this ugly az stock muff.. any tips or pointers coming from a pro like yer self would be greatly appreciated.. can you send me pics of the engine you rebuilt to my email addy? so i can use as a base line to start from?
thnx nq50 killinspree

keithw · Post by **keithw** » Wed Aug 20, 2008 4:54 pm

All a pro is is someone who gets paid to do a job. Sorry, I'm not a pro just a dedicated amateur. Go to the advanced tech section and check out the Jennings book and the tuned pipe calculator. I added an inch to the center section of the pipe to get it like I wanted it. It isn't bad to weld one up. It will no doubt take a few days of spare time for the first one. I can't really reccoment any aftermarket one as I haven't tested any of them. They really need to be built for the specific engine model so rolling your own is the best answer.

According to UPS my stock muffler will be here any day. Once I get it I'll do the baseline testing on my stock Spree. After that I'll start doing mods. I'll post lots of pictures allong the way. The idea is to document and test various mods and actually measure what they do.

keithw