Boring out stock exhaust

[timberwolfmadcat]

Might just be heresay, but when i was talking to one of the guys at Blackfoot motorsports out here in calgary when i was ordering a new exhuast gasket, he said the exhausts on scooters were very restrictive, and that a chick who used to work there bored out the stocker, and was going 65-70. Possible?? I woulda asked for her #, but well..........

[ace1969]

The guy at Blackfoot is talking out his butt. Our exhaust is actually tuned to our stock ride. 2 strokes can achieve a horse power boost from opening up the exhaust. The only way for that to work for us is to increase air flow into the bike switch to a HO cam and widen the valve ports to create less resistance then a more open exhaust would help us out but I don't know how much, Dan can give some in-site on that, as he has opened his ports a bit.

[Dandy Dan]

Ace is right that you aren't going to gain anything. Most scooters are 2-strokes and because a lot of manufacturers want them to fall under moped legislation they restrict them. The Yama Vino/BWS/Zuma scooters are like this. However a 4-stroke engine of equal size to a 2-stroke makes quite a bit less power so their is no need for restrictions (unless they are going for very restrictive top speed requirements of 30mph/50km/hr like the Met II) Our scooters are pretty much maxed out in terms of power and Honda has in no way restricted our power. That's a big part of why making the Ruckus faster is so much harder than a lot of other scooters.

Everything in our engines works perfectly together and it's all tuned just right so in order to gain power you really need to increase one area (ie. H.O. cam) but then remove all the other bottlenecks this causes (carb, exhaust, airbox, ports etc). Stock everything works together perfectly but the biggest bottleneck is the valves. The solution is a 4-valve conversion, a H.O. cam or both. This gets rid of this bottleneck but then airbox and exhaust become the tightest bottlenecks. Once you do something about that then your ports and exhaust become the bottleneck. The reason the gain per mod seems so little on the Ruckus is because everything is very closely matched so you just run into the next bottleneck.

In my opinion mods like adding a aftermarket Pod filter or just an exhaust are bad ideas from a performance standpoint if that's all you do. You'll spend 500$ and be barely faster than stock. They both raise the flow very little cuz there is still a bigger bottleneck (the valves). Plus, it's difficult to tune the carb back in perfectly so even if your potential power is now 110% of what it used to be, because your carb isn't perfect you end up running about the same speed but using more fuel.

If you want your Ruckus to go faster the first mod to do is the variator and if you aren't happy with that then I'd say do the full H.O. cam, air intake, exhaust, porting and CDI swap because if you just to 1 or 2 of these you aren't going to come out ahead much. Porting is probably the last bottleneck in my opinion and I don't think it hurts you much unless you're on to mods like big bore pistons. If you do a big bore piston you'll basically need to do the following mods to get the full potential out of it:
- 4-valve conversion, H.O. cam or both
- Bigger Carb
- Aftermarket exhaust
- Pod filter (with LONG intake hose)
- Variator
- CDI (maybe not on 2006 models)
- Porting

You'll still benefit if you don't do all of these but you'll be missing out on a lot too.

Aftermarket exhausts, like the Yoshimura, are meant for higher flowing engines so it's assumed that you've already done mods like the cam. The Yosh is aimed towards higher flows and at lower flows the stocker will slightly out perform it. Then again, the Yosh is sexy and if that alone is worth 375$ to you then go for it. By the way, my Yosh was shipped out from Yosh USA today and I should have it in a couple weeks. I think I'm gonna let it sit for a few months though until I get my 2006. I'm converted my 2003 back to stock to be sold and then I'll do the cam, pod filter, porting and exhaust to my 06 and we'll see how things go. I'm planning to have a Veypor VR2 unit by that time as well so I can view hp and torque graphs as well as all my times so I'll have some nice quantitative data on what works.

[chanito]

I hate to disagree with DD, but the muffler and the carburator can flow way more than a stock ruckus engine can, so modifying your muffler will not get you more power just a noisier one, and make you loose your top end, also i run the valve sizes and compared them to the piston size, and no, we do not need bigger valves, unless you seriously modify the head; so do not waste time or money on bigger valves, a HO cam makes sense, and a porting even more, and we need to find a CDI that will not replace the stock capacitor but add to it, that is the only part i got for Katrina that i wish i did not buy, and what makes me even more upset is that i new it will not do nothing for Katrina (my ruckus) but bought it anyways

[Dandy Dan]

What I meant in my last post is that if your Ruckus is pretty much stock then mods like the muffler won't do much for you because there are other bigger bottlenecks....the stock muffler can keep up to the current airflow. Whether you can modify your engine enough to make the muffler become a bottleneck is a question mark but Abe (from Battlescooter) told me that everyone with the H.O. cam that has later added an aftermarket has noticed a decent improvement. I imagine that if you have the H.O. cam and you've also added a big bore piston than an aftermarket pipe would really become appealing.

About the valves, I mainly meant that the whole valve setup is a restriction and the best solution for that is the H.O. cam but 4-valves also help. I was just trying to say that the breathing of our head is one of the main bottlenecks stock and the H.O. cam is the best way to help that.

I don't really understand how a H.O. cam would help if bigger valves wouldn't unless it has to do with the cam opening the valves longer because although it opens them farther it seems that 2 valves open pretty far would be similar to 4 valves that aren't open quite as far. I'm not really clear on how much the 4-valve conversion would help but I can't imagine Honda would have manufactured a whole new head, piston, valves etc if there was no advantage. I don't think the conversion is worth the money but I can't see it producing no benefit.

About porting, I still haven't really made up my mind on this issue. The ports are hooked pretty sharply and porting them is very difficult and awkward if you are going to do a good job. You definately need the right Dremel tools for the job.

The reason I suggest adding a CDI to pre-06 scoots is really just because it eliminates the redline and I feel that once you've added the H.O. cam and other mods then the peak hp falls above 8k so to get there you need the CDI and the appropriate gearing.

About the carb, yeah 18mm is huge for our 50cc 4-strokes....I think my brothers 80cc 2-stroke also uses a 18mm carb. I listed the carb to cover all the potential bottlenecks but you're right that it really isn't neccesary...I don't really know at what point our stock carb starts to rob power but Abe has said you should do it once you've done the cam but that seems like overkill to me. I think even with the big bore pistons we should be fine but maybe if we've done everything one day like the big bore piston and stroker crank etc then there might come a point in which you could benefit. I don't really know though.

[Robo-Mod]

People think the ruck is just like every other random 2-stroke, and it's not. It is not restricted, but rather engineered for it's market segment.

[chanito]

Robo knows!
the stock muffler flows pretty decent, and because is a pulse killing multichasmbered one it will actually out perform and open exhaust or a flow thru like the Yoshimura, a cam can take advantage of longer duration and overlaps, when you install bigger valves in an engine, you usally increase flow, but you also slow down the flow of the intake, so it looses inertia and stop flowing into the chamber way sooner, and believe it or not that makes the engine less efficient at low and midrange, so installing a bigger valve will give you a more top end (if dialed right), but it will kill your lower and mid range, however a cam that is set properly might give more mid range or low range, or move you power curve, so a cam can make more power in the range you desire without going for bigger valves, bigger valves on the other hands, might create a bigger problem than an increase in performance, specially with the design of our intake track

[ace1969]

Chanito you should go to work for Honda and show them how to build the Ruckus correctly. No curves in the intake and easier cylinder for rebores etc.

[chanito]

If the money is right, i will do it ;D
I doubt they are interested

[thizz13]

SO WHOS RIGHT AND WHOS WRONG??

[chanito]

The ruckus exhaust is not restricted in any way

[kentuckyrucky]

so let me get this right, the H.O Cam should be my first big mod for best instant gains across the band is that right? mods to date are: UNI drop-in high-flow air filter & Daytona Drag Variator with 6g rollers.

im considering the Kleihn Race Carb Kit from battlescooter for $235 (its complete with everything) and the Dayona Race CDI. thoughts?

[kentuckyrucky]

Daytona*