Y Pieces

[Beemerboff]

I'll second the need for air tightness with the Y piece, I ended up swelling the pipe ends with an expander and sealing with high temp silicone, and it made a noticable difference to the way the bike goes.

The stock aluminum gaskets between the exhaust sections eventually disintegrate, and they can block up the inlet and outlets into the the muffler. Cleaning the bits out , and enlarging the holes, improved things too.

As did removing the snorkels, adding a Unifilter and removing the engine breather pipes from the intakes.

Still a bit rich , but I am loath to interfere as it is going so well.

It has no trouble outrunning a F800s and they are reputed to have 86 HP, and the flat spot the bike had in stock trim around 3000 RPM has gone too.

 

[nick.ct]

Rob, any chance of a picture of the actual Y Piece you have used for these tests?

I ask because when I visited OS Pipes to have a Y Piece made for my 650, the guy was very particular on how the 2 pipes joined together to increase the gas flow. He said many after market Y Pieces were more like T Pieces and that the gas flow as a result was crap and that the engine produced less power than before.

Nick

 

[Wreford Miles]

I must get mine on the dyno again as Bernie spent some time setting the carbs up and it seemed to have more punch than normal and now that Richie has fitted the airfilter it pulls harder at high revs - Before you get the intial low down punch but the power would suddenly drop off at high revs, now it's happy to rev out.

As mentioned in another thread I was following Bakerman (1150) on a busy A road and he was doing a lot of those 45-95mph overtakes and the old girl was sitting on his tail and it was the power at higher revs that was enabling it IMHO

 

[Rob Farmer]

Rob, any chance of a picture of the actual Y Piece you have used for these tests?

It's a Keihan Nick. The same as the one in Ali Babas picture Linky

The Dyno chap I used said exactly the same. The gas flow through the T piece effectively interrupts the gas flow from the other exhaust. It really needs the downpipes to come in together or use a small collector like the Mono g/s.

Of course a standard collector box would render all of this mucking about superfluous and give more power

 

[(RIP) Kaister]

The gas flow through the T piece effectively interrupts the gas flow from the other exhaust. It really needs the downpipes to come in together or use a small collector like the Mono g/s.

Of course a standard collector box would render all of this mucking about superfluous and give more power

only if its not set up right.

more torque for a given amount of fuel at a certain point in the rev range - maybe ?

you never see a race bike with a collector box

 

[SJRoome]

Dyno plots

Rob

I will start by saying I have never used a dynometer but I am puzzled about your plots.

On your original dynorun you did two runs. From your text it seems that the lower power and torque figures were from a run with the throttle not fully open. Would you not expect to get lower power and torque then? The plots with the throttle fully open and the bike operating against a load are higher and nice and straight. Assuming the light blue plot is power in bhp, if you extrapolate it to 6500 you get a peak power in the high 50s, which is close to the design figure of 60bhp. Also if there was an effect from removing the collection box you would expect it to be a resonant effect and there is no trace of that in your plot. The plot of mixture is a lovely straight line (but too rich) so dropping the needle on the bike as it was then looks like a better place to be. Unless the line is straight because the sensor or plotter is at the end of its range - if so you were running really rich!

It also looks like there is something wrong with the revs scale in your later plot. This shows no torque below 3750 revs. Can this be true? Mine feels nothing like that and the Riders handbook says that this is the revs at which you should get maximum torque.


Steve

 

[Rob Farmer]

Hi Steve,

The first plots show a run of 37 BHP which was under the bikes own steam and was a full throttle run. The higher plot was a back to front run where the bike was revved to the max and assisted by the dyno and then slowed down by the dyno. I think it was supposed to give some indication of where the power was going to be (it turned out to be reasonably accurate).

The Fuel air ratio on that first dyno chart is terrible. It was so rich it was off the bottom of the scale. I had no idea what was wrong at the time. It turned out to be the cam timing out one tooth. It's nice and flat because that is the lowest figure the air sensor will read (10.5:1) It just starts to appear again around 6000 rpm as the carbs start to come onto main jet only the little peaks that appear on the readouts are misfires caused by too rich a mixture.
If you look on the chart I posted from yesterdays run there is a peak just below 5500, directly above that on the torque and bhp plots is a dip that corresponds.

the shape of the start of the plot depends at what revs the operator winds the throttle open. The bikes already running on the rolling road when they open them up.

I'm really pleased with the way the bikes running now. Goes like billyo. It does seem strange dropping the needles to get more power though

This was Wrefords going through it's paces to produce the graph he posted on one of the earlier posts.

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[SJRoome]

Reading the spark plugs

Hi

I tried putting a brand new pair of NGK BP6ES spark plugs into my y piece equipped R100GS. I started it with only half choke, immediately rode off and aplied no choke within seconds. I did not stop at all and as soon as I got to open road I held a constant 70mph in 4th gear for about a mile. I then killed the ingition and disengaged the clutch and glided to a halt and replaced the plugs.

Left

Right

Looking at them under a magnifying glass and trying to follow the method given here http://www.strappe.com/plugs.html. I came to the conclusion that the ignition advance is correct, the plugs may be a little cold, and there is no evidence of the bike running rich.

Any expert plug readers out there?


Steve


Steve

 

[Voyager]

Hi

Any expert plug readers out there?

Steve

I suspect 'Plug Chopping' is a dying art.

Only people like Proff and I will remember doing that in our youth




Bob.

 

[Redboots]

I held a constant 70mph in 4th gear for about a mile. I then killed the ingition and disengaged the clutch and glided to a halt and replaced the plugs.

Steve, plug chopping should be done flat out! Pick a gear and pin it. Hold it flat out for some seconds and then kill it. You need about a 15 min ride to warm it up properly first.

70 in 4th will not have the needle all the way out of the main jet.

John

 

[gee-yes]

I have an R 100 GS PD with the Y piece fitted - no problems at all - runs much the same as the collector box just a bit noisier - the odd pop but nothing of concern.

Lovely graphs though chaps.

 

[Redboots]

I have an R 100 GS PD with the Y piece fitted - no problems at all - runs much the same as the collector box just a bit noisier - the odd pop

Just put one on mine, so I hope I have the same result when its finished.

John

 

[SJRoome]

Hi Redboots

Hi Redboots

I wanted the needle to be partially in the needle jet. I was deliberately not running flat out as I was testing Rob Farmer's theory that Y pieces caused the bike to run rich in the middle region of the carb's operation.

I also suspect that that the plug would have got hotter after being used for longer. If true, this would lead to the conclusion that the standard carbs (if in really good condition and tuned) and the standard plugs are right for the bike and that the Y piece (if fitted so as to eliminate leaks and with no blockages) has no effect.

Steve

 

[(RIP) ugg]

look at any haynes manual, they give yer pug colours.

its hard to see on a photo, it looks weak to me , but its not in true day light.

is this what they call a plug chop






































ugg

 

[Rob Farmer]

Steve,

Those plugs look like the mixture is weak. Do you know what jets you have and what the needle is currently set to. I tried my needle on the top notch. It ran well at low throttle positions but I could feel the lack of power when cracking the throttle open. The plugs looked like yours after I did a plug chop after a run up a gentle hill.

I'm currently on the 2nd notch from the top. I suspect that the ideal would be making a spacer to get half way between the 1st and 2nd notches. I think the CV carbs will always run a little rich on the midrange if you get the top end right.

 

[John Armstrong]

Only a slight thread hijack but what front brake set up do you have? Is it the €800 Spiegler set-up?

 

[Sean Kelly]

Hi

Plugs look different using leaded/unleaded, make sure you don't try and match the wrong colours.

My Sexton motor 'y-piece' bike on the dyno was a bit rich on the needle so we dropped it a half notch using a spacer. But then the carbs were old and the needles/jets were probably a bit baggy. If doing it again, I'd fit new parts first.

Cheers

Sean

 

[AliBaba]

Here is my “R80”, standard exhaust, Siebenrock, a few other modifications.

78.5Nm=58Ft/lb

 

[John Armstrong]

That's exactly what in needs. My bike is completely standard apart from the Y piece and hasn't been running too well. The dyno run today showed that the mixture was very rich across the midrange section of the rev range controlled by the needle. I've dropped the needle down one notch to the second notch from the top. The difference is amazing. I'm not chasing horsepower but do want the bike running as well as it possibly can.
like.

What sort of fuel consumption were / are you getting Rob with varied riding? I'm guessing mine is around 45mpg.

Plus while I'm asking is there much to be gained from dropping the needle when up in the higher Alps passes. Not thinking about changing half way up the Grossglockner ....

My set up, stainless headers without cross piece, y-piece but not a Keihan, Laser exhaust and 2nd needle from the top.

 

[Redboots]

what front brake set up do you have? Is it the €800 Spiegler set-up?

Nooooo... to rich for me. Its the HE disk and caliper from Motoren Israel - link - Israel make the caliper adaptor. When I spoke to HE they said they do not make an adaptor for the GS.
Currently €465 but that's way better than €800

I put the Spiegler caliper (which was new) and disk on the bike I sold.....

John