Y Pieces

[Rob Farmer]

I'm not a great fan of Y pieces on Paralevers. My 100PD has one fitted at the minute. Before I bin it and fit a proper collecter box I thought I'd ask if anybody has actually got their bike to run well with one fitted?
I'm swapping my engine over to a full RS spec so thought I'd give the Y a chance before bining it.

 

[judge]

All mine used to do was pop and fart and lacked mid-range power, the exact oppposite effect of what putting a Y-piece on my 1150 did.

Oilers = y-piece
Airys = collector box

 

[Rob Farmer]

I had a forlorn hope that there may have been a little known trick to getting it to work half decently with the Y piece. Looks like another £180 needs spending

 

[(RIP) pastyman]

Yup, I binned mine and got one on fleabay for £25, proper stainless and all . Bike does sound better now.

 

[Archie Adv]

Rob,

I have 2 Paralevers both fitted with Y piece and have never experienced anything but joy from fitting them. However I would add that I have also fully adapted systems rather than just the Y piece.

My 80GS with Siebenrock conversion Keihan down pipes , to Y piece to intermediate riser pipe to a Honda CBR600 sport end can and fitted with Dellortos took me a long time to sort but that was mainly due to the carbs in the first place. Farts and pops and is loud.....

Secundo, 100 GSPD again Keihan down pipes onto Y piece, onto Scorpion inter and end can. This was a direct swap for brand new standard system with no adjustments to carbs and runs like a dream. Obviously with the exception that if I remove the end can baffle which is designed to be taken out if you want..... It farts and Pops loudly on the over run.

Personally I would perservere but it's always down to what your comfortable with in the end.

Regards

Archie

I'm not a great fan of Y pieces on Paralevers. My 100PD has one fitted at the minute. Before I bin it and fit a proper collecter box I thought I'd ask if anybody has actually got their bike to run well with one fitted?
I'm swapping my engine over to a full RS spec so thought I'd give the Y a chance before bining it.

 

[Sylvester]

My Y pipe causes no problems. The bike is an 80 with a seibenrock 1000 kit. It is louder but not much. I have a collector box that looks like new but all it will do is collect dust as its not gonna go back on. The Y pipe is not like any of the commercial items, it was made by a guy here who advertises the odd y pipe on flea bay.de. Both "arms" of the Y are the same length. Not sure of the jetting fitted, but having the 80 carbs might help. They certainly seem to stay in sync longer than my old 1000 used to.

 

[Garry H]

You can tweak the mixture to get them to run fine...
But i still think the bike is better with the standard collector box
People think the bike is faster with a y piece but i am sure it's slower just sounds faster and because you lose low down power it makes it feel faster at the top

 

[brassmonkey001]

Mine seems alright

 

[Rob Farmer]

I've had a go at the mixture but it still seems flat at low revs. I'm also convinced I've got a flat spot in the mid range. It may be too much time tweaking instead of riding though.

I'm off work next week. I'll try and get a dyno run in with the Y piece fitted and then another at a later date with the collector on

 

[brassmonkey001]

I'm off work next week. I'll try and get a dyno run in with the Y piece fitted and then another at a later date with the collector on

Now that will be interesting to see.

 

[Sylvester]

Deff no flat spots on mine, picks up smoothly from very low down and pulls hard all the way up to and through the redline in top if I'd let it. Hearing all your comments though I'm temped to fit the collector just to see if there is any difference. Sylvester rule #1 prevents me from doing this.
Rule 1= If its running really good don't feck with it!

 

[Rob Farmer]

Dyno booked for Monday morning...hope the bike stays together

 

[Sylvester]

I'd be more concerned for the bike after the dyno run!!!

 

[Beemerboff]

Any dyno runs I have seen for a stock R100 GS has shown a dip between 2800 and about 3500 revs.

If the bike is in fine tune it is much less noticeable but it is still there.

It is possible that the Y piece will upset your fine tune making the dip more noticeable again.

It is also possible that the Y piece improves things outside the flat spot , making it more noticeable.

It is also possible that the thin aluminium gaskets between the various pipe can fall apart, and the bits partially block the inlet to the muffler - like mine did.

I always seem to do more than one thing at a time when I work on the bike , so I cant be certain what did what, but after fitting the Y piece it was not good.

I checked and set everything, fuel level , plugs , timing, carb balance, etc to no avail . Then I noticed the heat band round the muffler at the intake position.
The muffler was removed , most of the bits of the old aluminium fell out but there was a large piece which was still rattling around inside.

I enlarged the small inlet hole out to 1/2 " but it still wouldn't come out, so I resorted to to the 1970s schoolboys tuning trick and tried to knock a hole in the baffle at the back of the silencer with a sharpened steel rod .

Success - the back baffle bent over and a large, fused lump of aluminium fell out. I hooked the baffle back a bit straighter ,but there was still a decent gap at the edge.

To complete the schoolboy tuning I unclipped the snorkels from the air box.

Eureka - the flat spot was gone , there engine is much livelier all the way through but especially over 4500 revs , there is a pleasing burble from the exhaust and fuel consumption has decreased slightly.

FWIW there was an article somewhere where the muffler was replaced with a Supertrapp, the snorkels removed and the carbs tuned , and they got good results on the dyno - 5% power increase and and more than 5% decrease in consumption. They had started with a lean tuned US spec motor , so a European spec PD may not replicate the results.

They started with around 71 hp and ended up with nearer 75 - let us know how you go.

 

[Sean Kelly]

Hiya

I ran my Sexton built motor on the dyno )1000c RT bottom end, 800cc GS top end) with Y piece. Got quite a nice flat curve if I remember right. I'll try and dig out the chart and post it if I can.

Dyno man used spacers to adjust the needle height and get the right mixture for cruising speed. The steps in the needle are too wide for subtle adjustment.

Cheers

Sean

 

[Rob Farmer]

Well. It ain't too good. The mixture is a country mile out, the good news is it's linear and all down to the needle position. I may need a longer needle though. The poor mixture's preventing the bike making good BHP. The jet sizes are good apparently.

The midrange flat spot I could feel is there and more than likely caused by the Y piece. The Dyno chap wasn't impressed by the Y piece at all, it's too crude and doesn't give a proper airflow.

I had two runs. A standard rev it up and read the torque, BHP and mixture - the bike was putting out 37 BHP. Not good at all but the rich mixture prevented the bike from making it's full power. If I sort the jetting I should be able to see 60 BHP at the back wheel.

The 2nd run was a step response where the throttle is whacked full open and the dyno controls the rpm by varying the load. The bike made 47 BHP with this test. Still not good.

The bottom line is the Y piece puts a hole in the midrange and the needles need replacing with longer ones. I've got them set to the standard RS position at the moment. The Air ratio graph shows the mixture going as low as 10.2

The Speedo is 12 Mph out at 100MPH as well.

This is going to get expensive Common sense says put a standard cam in and fit a collector box.

 

[Wreford Miles]

For comparison

Mines all torque ;-)

 

[Rob Farmer]

Thats a much healthier looking chart than mine Wreford

I need to bin this cam and fit a collector box.

 

[Sylvester]

Rob, r u sure it's the y piece and not the cam? I procured a "race" cam for my DR 600. The dyno graph looked like the cross section of an Alpine stage of the Tour de France. With exactly the same set up (supertrap/bigbore headers/gas flowed head/modified airbox) except a minor change to the jetting and another cam which was to quote "not so racey" MAJOR improvement. I was still p*ssed off to have to chuck the special cam though. Spent a small fortune on that motor in the end but got 15,000 mile of big smiles out of it. At least that's what my rose tinted specs say. Sold it before I came sausageside after owning it for 12 years. Still miss it (sniff...sniff).

 

[Wreford Miles]

Thats a much healthier looking chart than mine Wreford

I need to bin this cam and fit a collector box.

Mine got a 320 degree cam - whatever that is, some sort of high torque thing ;-)