Arrow 71662 Exhaust - it does have an O2 senson!

Hey all, just a little FYI. I've been looking at getting a new pipe for the Swing, and had a look at Arrow cans, code 71662. The pictures and description and model-years on their website all say that the link pipe has no place for the O2 sensor. But the Swing 400 exhaust has the same model code, covers all years, and shares the same spare parts (like gaskets), and is even pictured with the 02 sensor mount. So I emailed Arrow this morning, and got a reply from their tech guy this afternoon, confirming that the link pipes all have o2 sensor mounts. He explained that the website for the 600 shows an older version of the can on an older version of the bike.




So we can actually fit these cans to the newer bikes with O2 sensors. Price is typically about £270-280 on fleabay....

but avoid the 'mototopgun' seller - last time I used him, he sent out the wrong part, spent most of the returns window dithering about what to do, then while still exchanging emails with me requested that ebay close the case behind my back... which actually succeeded! So no refund and no returns! So I then had to resort to paypal, and succeeded in getting a measly 25% off for being sent the exhaust can for a different bike! Luckily all it needed was a couple of new flat plate brackets making up, but it's the principle of the thing!

I have a Delkevic stubby oval SS. It comes with the link pipe for the O2 sensor. Sounds good (street legal) and at only £120 a bargain.

JB

Yes, I'm very tempted with a Delkevic system. They also do a 350mm pipe with a conical end cap (as opposed to flat with a pipe sticking out) that looks more like the arrow system for about £200. Most of the stubby delkevic cans I looked at weren't road legal.

Just thought I'd update on the Arrow one since I seem to recall a few peeps ruling them out since they didn't at the time appear to have an o2 sensor mount.

Delkevic product code Kit04AZ

Loud pipes save lives. OLD Harley Davidson saying.

If I could get 5 more HP from a muffler than it might be worth it. I'm sure its lighter than OE muffler its heavy.

Ride on.

doubt you'd get 5hp more just from a muffler, even the manufacturers only claim 2-3, and they're normally very optimistic. But I'd head that combining the muffler with a freer flowing air filter and a new air temp sensor or a Power Commander can get it up to +5hp. can't recall when I saw the info though.

5 HP on a larger engine yeah a muffler its easy. SW no.
All those MODS. $500-750 later who knows.

Air flow is the key biggest restriction is the throttle body size. Very small.

What size are they? Can't seem to find it online?

Throttle body size is 1.3 inch  or 32mm for each cylinder.  Its a part that is cast aluminum and has the throttle position sensor attached . Could be enlarged but only slightly and new throttle blades would need to be made.  

Engine is just an air pump. Air in -fuel-exhaust. BUT there are many more factors. This engine is built to be efficient and make power at a lower RPM where it it is most used.

There a few on Ebay now. Complete one with airbox and all parts $24 TPMs and Wax idle valve thats a great price.

32mm isn't too bad, but it's close to the limit. The Kawasaki ER5 (500 twin) makes a stated 50hp with 34mm carbs, a GPZ500 (same engine, slightly hotter cams and higher CR) makes a stated 60hp from the same 34mm CVKs. The Honda CB500 twin with 32mm CVs makes a claimed 58hp. This compared against our bike's claimed 50hp with 32mm injection throttle bodies.

So there might be room for a little more (maybe 5), but I guess you're approaching the choke point. Could improve torque though at lower rpms, which would help.

So then the CB500 has a higher compression ratio?

Ultimately the problem we face is than any significant mod to the engine will necessitate a remapping of the ECU. A Power Commander will only tweak the EFI pulses. 

Tim

Cosmic_Jumper wrote:

So then the CB500 has a higher compression ratio?

Marginally Tim, CB500 is 10.5 - 1 while fjs/fcs600 is 10.2 - 1

I would hazard a guess that the extra horsepower comes from significantly better matching of the header pipes to the exhaust ports.

The Bern wrote:

I would hazard a guess that the extra horsepower comes from significantly better matching of the header pipes to the exhaust ports.

I thought that the FJS/FSC exhaust header was a tuned length. And if so then, are you suggesting that by blueprinting the exhaust ports to the header an extra 5-8 hp can be achieved?

Cosmic_Jumper wrote:

The Bern wrote:

I would hazard a guess that the extra horsepower comes from significantly better matching of the header pipes to the exhaust ports.

I thought that the FJS/FSC exhaust header was a tuned length. And if so then, are you suggesting that by blueprinting the exhaust ports to the header an extra 5-8 hp can be achieved?

Not changing the lrngth Tim, It's the diameters not matching that's the problem, it was a 'passing observation' I made last summer when I had occasion to change the gaskets.
The gaskets sit in a recess in the 'head, the bore of the gasket is close in size to the port, but is way bigger than the bore of the header, the error is quite pronounced.
Gas flow would be greatly improved by either bigger bore headers or an initial conical section on the original headers.
It's only half a dozen nuts, so next time I have it on the bike bench I'll nip it off, take some pictures & dimensions & post here, you'll see what I mean bud
Back in the day when I built engines for rally/hill climb/stock car racing/circuit racing we would bolt up manifold & gasket assemblies to the head, the drill though the lot, drive in a roll pin, then match the ports, gasket & manifold to each other, this was done to both inlet & exhaust.

I think the reason the CB500 makes more power is a) a slightly larger bore by 1mm, and b) the ability to rev a lot higher. I suspect the cam timing will be higher lift, longer duration to match. More highly strung basically.

Interesting observation on the exhaust ports / pipe matching. Did you note if they were double skinned?

gavinfdavies wrote:

Interesting observation on the exhaust ports / pipe matching. Did you note if they were double skinned?

Deffo single skinned bud

I think the silverwing is 22mm bore, the gasket is 35mm bore, so the gases are trying to overcome a flow restriction in the area of 13mm bore, not only that but restriction is made worse by it being an instant reduction in diameter rather than a gradual one.
If you want to get a pipe size which gives better flow measure a 600 Thundercat (it's same gasket )
Larger diameter pipe married to an Integra silencer should see a worthwhile power increase, without upsetting peeps (loud pipes save lives is IMHO a load of bollocks)

I wonder if rather than getting some new headers made, if Thunderpussy pipes are the better sized bore, if one could cut off their first few inches, and weld them onto the Swing headers with a conical joiner if required? Flow matching could give a good gain.

Regarding fuelling, a PCV does remap the whole fuel and ignition map, for all RPM and throttle opening. Can also bypass the o2 sensor to avoid buggeirng about with that.

However, I do recall some one finding a thermocouple that has the same curve as the stoke air intake sensor, but offset by the right amount to trick the ecu into thinking its a certain amount colder than it actually is, and hence richening the fuelling. Since the sensor is non-linear, one can't just drop in a plain resistor, you need something else non-linear to get it to work for all temps. I recall it cost him about £12 or something from an inductrial air-con supplier, and once fitted and combined with his exhaust and air filter, it gained about 5hp on the dyno at the back wheel, which is about 1/6th more power! I'll have to find and save a copy of that info at some point.

http://silverwing.org/cgi-bin/topic_show.pl?tid=5449

Found the link! Don't know where I got the power guesses from, but pretty pleased at my memory overall. Only read it once 6 months ago before I had the bike and was still looking around at options.

gavinfdavies wrote:

I wonder if rather than getting some new headers made, if Thunderpussy pipes are the better sized bore, if one could cut off their first few inches, and weld them onto the Swing headers with a conical joiner if required? Flow matching could give a good gain

Could well work bud would certainly be an improvement over OEM, but there would be larger gains from full length bigger bore then increase by (iirc from calculations by Geoff Howe) 20-22% at the collector box.

I was thinking of buying a scrap head to use as a jig, but 'being under the doctor' for a while last Autumn I got no further than the thinking stage

Port matching and some cylinder head flow improvements could get more HP from this engine. Port and polish. It would be in a usable RPM range that matches the CVT type trans. Manual trans bikes use larger throttle bodies because its easy to REV to redline in any gear. Free flowing muffler a plus. Header pipes are small more for torque.

Modifying or changing the air temp. sensor fools the ECU into thinking its colder and adds more fuel. That can be a good thing on a lean running engine. O/2 sensor is always switching lean to rich adjusting mixture at a preset map from ECU.

Somebody is making a box that plugs into air intake sensor and changes the reading. AUS. company I think.

gavinfdavies wrote:

< > However, I do recall some one finding a thermocouple that has the same curve as the stoke air intake sensor, but offset by the right amount to trick the ecu into thinking its a certain amount colder than it actually is, and hence richening the fuelling. Since the sensor is non-linear, one can't just drop in a plain resistor, you need something else non-linear to get it to work for all temps. I recall it cost him about £12 or something from an inductrial air-con supplier, and once fitted and combined with his exhaust and air filter, it gained about 5hp on the dyno at the back wheel, which is about 1/6th more power! I'll have to find and save a copy of that info at some point.

This could be the info you're referring to:
https://www.silverwing600.com/t9912-enriching-fuel-mixture-iat-hacking

Thanks Cosmic. Knew I'd seen it somewhere.

Regarding those boxes, I've seen them... and they're expensive.

On other bikes, usually singles, a similar trick is to replace the injector with a larger item, with a big bore kit to match the improved flow. The jump in fuelling can be quite large, but can match going from a 125cc barrel to the 155cc barrel quite nicely.

here's  pic of some thundercat headers

and here's a pair showing Swing headers.

To be honest they both look a bit crap! I think it would be best to send a spare set of headers to some one like Alldens in Lincs and get him to knock up a pair of replacement ends for the stock headers with a full bore opening to match the head, but with a more gradual taper down to stock bore in order to maintain gas velocity. One of my other bikes (an Enfield with similar RPMs to the Swing) has a stainless single-skin header option, but it actually makes it noticeably worse (and that's with a proper PCV setup) than the stock header, as the bore goes from something like 34mm up to 47mm on the stainless ones! No gas velocity for scavenging.

gavinfdavies wrote:

I think it would be best to send a spare set of headers to some one like Alldens in Lincs and get him to knock up a pair of replacement ends for the stock headers with a full bore opening to match the head, but with a more gradual taper down to stock bore in order to maintain gas velocity.

I've made a meager attempt at enlarging the headers to match the head ports on a spare set of header pipes I have. However it proved to be too tedious a job and there isn't a lot of spare meat there to prune away without weakening the mounting. Perhaps having a custom set of headers made  (or at least the first 6-8 inches as you mention) would prove to be a better option. But it wouldn't be cost effective and all but pointless unless you were making a dedicated racing engine with larger valves and throttle bodies, a reprogramed ECU and various mods to overcome transmission inefficiencies to deliver any horsepower gains to the rear wheel.

IHMO the weak link in the Silverwing is the transmission --too much energy loss between the crankshaft and the rear wheel. There are many 600cc bikes which perform better, faster and more fuel efficient than our Silverwing.

The above said, I do have an assortment of Dr Pulley sliding weights, a Dr Pulley HiT clutch and have tested Dr Pulley's new racing variator. All of which work very well.

Tim

I find one of the biggest issues seems to be that first second or two after opening the throttle, the engine seems to try to pull away while at the same time trying to sort the pulley ratio out to get high rpm. Does the HiT clutch help with this? It suggest that it starts to bite at something like 1,500rpm and then locks fully by 1,750rpm in order to minimise slip. But that strikes me as a bit premature if you're trying for acceleration which is surely the aim of getting a fancy clutch in the first place. I would have though engagement at about 2,500-3,000 and lock up at 3,500rpm would be fine. It would mean free-wheeling at lower rpms in traffic, but my 125 scoot does that any way and it's not a bother. I prefer it a bit since it means you're not slipping the clutch the whole time. A little burst of acceleration then coast.

Regarding the pipes, I suspect even just a basic blending job would pay dividends if you're fitting a new silencer/filter/re-map etc.

I hope I understand your question correctly.

The HiT clutch kit comes with an assortment of springs which allow adjustment of both clutch-in as well as full lock. Using "weaker" springs will allow clutch-in to occur at a lower rpm (so clutch-in could be adjusted at that 1700rpm or 3000rpm if you choose) and, depending on the springs selected for lock-up, the clutch will lock at a greater or lesser rpm after clutch-in. I'm told that significantly weaker lock-up springs (or none at all) will allow the scoot to wheelie. 

Basically the clutch will act "normally" at low(er) rpm but lock further in the rpm range or during rapid acceleration. It is also possible, by alternating different springs for lock-up, to "ease" the clutch into full lock --not that there is any feeling of an abrupt lock-up anyway.

Re that lag in lower rpm pulley ratio, after years of fiddling with the variator, I think that that lag is just the nature of a variator trying to find that sweet spot. HTH
Tim

That is an ugly header pipe opening is much larger than pipe diameter. It also starts to bend very quickly for ground clearance. Opening up the flange third step down will increase flow some and a small taper would help. Never going to open that to match head.

Something aftermarket could be made but whole exhaust system will be different. $$$ how many will they sell VS cost of testing etc.

Leovince made a full system called 4Road, I missed my chance to get one a year ago.

The bigger issue is the engine is a slave to the ECU! This prevents any significant gains from any intake or exhaust mods, as the engine is tuned for low stress a long life.

But I now believe the best gains can be made with CVT tuning, not smoke and mirrors, but weights and springs. This approach lets the engine operate in it's best power "sweet spot" while accelerating.

One important thing to remember is the clutch is a driven clutch, not a drive clutch. This means it is tied to rear drive pulley input rpm, not engine output rpm. The variator (gear ratio) will determine how the clutch responds to the rpm of the engine.