My GS850G ongoing issues and maintenance.

[Grimly]

Ouch, indeed.
However, it's working quite well, but I have a cheapo copy of that K&N filter that I've cut down shorter, still fitting on the MGB flange and leaving plenty of breathing room through the pleats. Only have to find or make a suitable cap for it.
The MBG intake plate is definitely better than the skeletal stub-stack I had in there beforehand. That in itself was better than a hard 90* edge to the intake.
Put in the red spring (4.5oz) to the dashpot and took it out for a wazz around and a shopping trip.
AFR readings are pretty much near right, now, but I didn't take it on the motorway for a high-speed run.
I'll keep the AAA needle in it for now, to see how things pan out.

The recent aquisition of a lathe (yet to be delivered) will make the hunt for a better stub-stack plate unnecessary - I can make one up.

[Grimly]

Finally got around to fitting the proper Delkovic silencer.
I'd been using a modified HD Dyna unit for the past year, and had put off buying this one as I thought I didn't need it. Turns out the Delko pipes and collector have an unpleasant wave-front pattern which their own silencer copes with and I had a bit of a struggle trying to tame it with the HD unit.
Not quite finished yet with the mixture adjustment, so had to weld in a bung for the O2 sensor.
Neat and clean freaks can look away now.

[Rob S.]

I'm late to the party, but what is that rig on the bottom going to the back??

Don't worry about the neat and clean, but silencer? I just don't like the sound of that. Can't you call it something else?

[Grimly]

I'm late to the party, but what is that rig on the bottom going to the back??

Don't worry about the neat and clean, but silencer? I just don't like the sound of that. Can't you call it something else?

Bracketry for the tow-bar.
Hmm... alright, 'muffler' if you like.
I appreciate 'silencer', while perfectly acceptable British English, has somewhat different connotations over there.

[Rob S.]

Bracketry for the tow-bar.

Tow-bar? You mean the bike tows something?

Oh, God. What's worse is I can't say I haven't encountered this before. Right here on this sight. People pulling things behind their motorcycles.

And BBQ-shaped vessels, way up high and way out back. On V-Max's!

I almost expect Mel Gibson to zoom by in a supercharged AMC, chasing a bunch of KZ1000's.

[Grimly]

I almost expect Mel Gibson to zoom by in a supercharged AMC, chasing a bunch of KZ1000's.

The Gremlin and Pacer, now there were some cars.

[Rob S.]

The movie was just on. I only watched "Goose" crash his faired, silver KZ1000. Then get burned by the misfits.

They may have been nasty guys, but they had the coolest bikes available. KZ1000's, Z1 & KZ900's and one CB750 (how'd that guy get in the gang?!?).

[Big T]

I almost expect Mel Gibson to zoom by in a supercharged AMC, chasing a bunch of KZ1000's.

AMC ????

That's a Ford

[Grimly]

First run out with the Delkovic complete pipework, with its proper silencer on. I was taking it easy at first, because this is also the first run out with a different SU needle and the Darkside tyre.

It was soon obvious that the pipe was a bit on the noisy side, and coupled with the ratio increase in overal engine gearing caused by the 15" wheel, it tends to get to the noisy band a bit quicker too. The SU is working well today, with the cold air.

Took the long way around to the shops, and by the time I got there the tyre was getting nicely scrubbed in. I wasn't pushing my luck with it, as I didn't know what it would behave like, but honestly it's not a bit different from anything else I've had on the back - I've had some right shonky crap tyres, and it's far far better than some of that rubbish that's totally legal and approved to fit, that's for sure.

Anyway, shopping done and wazzed up the by-pass. As mentioned, because of the gearing change it goes like a rat up a drainpipe.

By 'eck, it sounds absolutely bleedin' lovely, but it's TOO DAMNED LOUD.

I must take the baffle out to see if there's any baffle material in there, as it sounds like there's nothing.

There's a physical baffle directly in the way of the exhaust gas stream, and as I suspected it's got a rounded end-on to the gas flow. This helps disperse the nasty pulse I was getting from the pipes and collector on their own, but feeding the H-D muffler. Without doubt, the Delko muffler is a better match, but it's TOO DAMNED LOUD.

As well as adding some baffle wool (I've still got half of the blanket of Acousta-FIl which worked bloody well in the H-D muffler) I might look into adding a couple of inches of perforated labyrinth pipe to the end - or even copy the Supertrapp idea; that seems to work.

That was yesterday; today I put a stainless steel pot scourer in front of the baffle, to help a bit. Internally, the baffle isn't rebuildable, so once the factory wadding is done, it's done. No matter, whenever that happens I'll rebuild it myself.
I'll see how it goes.

[Grimly]

Decided to tackle the noise and scored one of these Supertrapp end pieces.
Fitting it will be a challenge.

[Steve]

I have found that most "mufflers" in the aftermarket world tend to have a section of perforated pipe down the middle. The chamber between that perforated pipe and the outer shell is what usually gets filled by wrapping the perforated tube. It is my opinion that the overall noise level is directly related to the diameter of the tube. The wrapping only serves to control the echo in that chamber. It might change the overall TONE a bit, but not the overall VOLUME. A smaller-diameter pipe would be a bit more 'streetable', but might cost a couple of ponies in the process.

I like your idea of the Supertrapp disks. Keep us informed.

.

[Grimly]

I was having some success with taming the pulse, using the heavily-modded H-D muffler, but decided to use the silencer that matched the downpipes and collector just to see if they'd managed to do it. A couple other users of Delko 4-1 systems had complained about a similar pulsation, too.
The cone section of the muffler is filled with a cone-section baffle internally filled with absorbent wool, and running centrally through that is a tube with a dome on the end, the dome facing into the gas stream. The gas passes over the dome and is forced into close contact with the inside of the baffle liner.
From first start, it was loud, and out on the road it was damned loud. However, if not actually giving it welly, it wasn't obnoxiously loud.
First thing I noticed was the noise pulse had gone, the engine was smoother all the way up its range. This remained so for the duration of the test.
So, nasty pulse gone, engine smoother, but bloody noisy.
Given the gases are now flowing through the Delko system as they were designed to, I'm reluctant to interfere with the internal workings, and adding on something to simply rob them of some acoustic power at the exit is what I hope might work, without causing too much obstruction or resistance to flow.
The Supertrapp unit might do exactly that - I don't expect it to restore factory quietness, but if I can achieve a level of noise which doesn't attract attention from LEO or annoy the neighbours or citizens, I'll be happy with it.

[Steve]

I don't expect it to restore factory quietness, but if I can achieve a level of noise which doesn't attract attention from LEO or annoy the neighbours or citizens, I'll be happy with it.

I have a pipe on my 850, about which I have posted several times. It is of unknown origin, so I have no idea to whom to give credit. If Photobucket is playing nicely, you can click on the link in my signature to see it. The collector dumps into a straight-edged silencer area that is low enough to go under the saddlebags, which is the primary reason it's on the bike. The afore-mentioned 'perforated tube' exists in that area, but it's a bit different. It's about 1 1/2" in diameter and just over a foot long, but has a disk in the center that makes all the exhaust go through the perforations in the front half of the tube, through the outer chamber (where packing would normally reside), then finally through the perforations in the rear half of the tube and out the back. Having all the exhaust go through the perforations instead of going straight through the tube does reduce the noise level to just about stock levels. I have spent many a day going hundreds of miles without having my ears ringing at the end of the day.

.

[Grimly]

I have a pipe on my 850, about which I have posted several times. It is of unknown origin, so I have no idea to whom to give credit. If Photobucket is playing nicely, you can click on the link in my signature to see it. The collector dumps into a straight-edged silencer area that is low enough to go under the saddlebags, which is the primary reason it's on the bike. The afore-mentioned 'perforated tube' exists in that area, but it's a bit different. It's about 1 1/2" in diameter and just over a foot long, but has a disk in the center that makes all the exhaust go through the perforations in the front half of the tube, through the outer chamber (where packing would normally reside), then finally through the perforations in the rear half of the tube and out the back. Having all the exhaust go through the perforations instead of going straight through the tube does reduce the noise level to just about stock levels. I have spent many a day going hundreds of miles without having my ears ringing at the end of the day.

.

That's pretty much the solution I adopted for the Dyna mufflers on the XJ900F. I saw that H-D had used a simple baffle disc in the centre of the main baffle tube and then noticed the distance from the front of the muffler was different in each - to account for the different length downpipes. Once I equalised them, they worked quite well.

[Grimly]

Supertrapp abomination - pass.
Last week I fitted the 3" Supertrapp disc pack to the end of the Delko silencer, and while it did knock off some of the worst, most penetrating noise, it was still bloody loud.
Today I took out half the discs, leaving 5 or 6 in (don't recall) and gave it a whirl.
Pleased to hear that it's now quite tolerable and has a nasty snarl at 6k upwards.
More farting about needed to make sure of the effect on the mixtures up the rev range, but it does work. The AFR gauge seemed to be tracking things fine and it's not showing anything off the wall.
However, I did notice that wazzing through the gears it wasn't quite as quick as last week.
You don't get something for nothing, after all.