Y-Piece and Dyno Run

[Cheezee Rider]

Hi folks...

Did a dyno run before and after fitting a Y-piece to compare the bikes performance, especially the fuelling....

The bike is a 2005 R1150GS Adv, it came without a cat code plug fitted. Took the Y-piece and some tools to the dyno center. The first dyno run was with the bike as standard. After the first run was completed I dropped the cat out and fitted the Y-piece and the second run was done.

Have read a lot about Y-pieces making the bike run lean, which after looking at the fuelling chart, seems to be the case at low revs (the dyno operator said that about 90% of bikes run lean at low revs and richer higher up the rev range). But interestingly the fuelling is much better with the Y-piece than with the bike as standard. The gain in power with the Y-piece is about 5.5 bhp which is 7% of the bikes original power. Coming home from the dyno center the bike felt a little more eager and pulled easier. (The cat weighs 7Kg so the bike will a tad lighter too !)

The tests were done with the same operator and the same environmental conditions (temperature, pressure etc). Not sure how accurate the dyno is but I guess its a good comparative test....

hope the charts come out ok

 

[T900]

what make y piece did you use

 

[pomm001]

Great post,
I too have an adventure with Y pice and std can , and have wondered what a back to back test would would say
I have tried both set ups and feel the Y piece gives that bit extra
only down side is the ocassional backfire on the overun, look on the board for Steptoes mod on the CAT plug, didnt do much for mine
If you ever get the urge to go back to the dyno would be good to see if the CAT plug mod makes any difference

 

[Le singe]

Good results, the only way is to get the bike on the dyno and correct any problems if there are any.
Doing 'it worked for my bike,it must be right for yours' alterations is not the way to go.
For the cost of the check you've now got complete peace of mind that everything is as it should be.

 

[HeatedGrips]

Thanks for that Cheezee, I don't think anyone has posted this info before.

The low-end weak mixture seems to match what happened to my bike after I had a Y-piece fitted, it made the bike hopelessly rough at low revs.

I only sorted it earlier this year after adoping the Steptoe cat-code link.

 

[Cheezee Rider]

My bike as standard would occasionally backfire while blipping the throttle on downshifts but the sound was muffled, presumably by the cat. With the Y-piece fitted get the same amount of backfiring but this time its a little louder ! Think I might try the Steptoe link sometime, looks interesting...

T900 - I bought the Y-piece second hand. The guy who sold it said it was made by an engineering firm near Middlesbrough as a one off. It seems well made and robust.

 

[dicktheleg]

I'm just about to fit a Remus Y piece to a 1999 1150 GS which does not have a cat code plug, I've long suspected that it runs lean at the bottom end and now I am concerned that the Y piece will make that worse.

Does anyone fully understand the effects of the various cat code positions and if so can they explain them here. eg if I want to dial out the low end leanness what would be the best cat code link to start with?

Cheers
Richard

 

[Cheezee Rider]

With the Y-peice fitted the bike is still a bit lean at low revs but with the cat in its even worse. The dyno operator was not at all impressed by the fuelling of the bike as standard...fitting the Y-piece seems to have made it better but its still not perfect. This can be altered by the use of a Power Commander or similar device. I know this goes against popular thinking but in my case the addition of the Y-piece has improved the fuelling not made it worse....according to the dyno chart. I would be more worried about having the cat in than the Y-piece..has anyone else checked the fuel/air ratio of their bike as standard ?