Cafe racer loss power, exhaust issue? ***SOLVED***

[ileumi]

Terve kaverit!

 Finaly its ready, my 16 valve cafe racer. Everything is fine, exept my bike loss about 80hp....

 What I make? Air intake system is original, also fuel supply. ABS is removed, instrument dash is changed etc... What I have tuned, is muffler...

 In follow link you can see images, what I do. Text is finnish but please check images.

http://www.matkaendurot.com/phpBB/v...hp?f=8&t=40572

 Short explain...

 I cut the original muffler. As you see those two thin pipes, they coming for cylinder head (1+2) (3+4)

 I weld a hat and now gas returns to midle mufler, and turn back to end via thicker pipe. In the end i make noise killer.

 Sound is VERY interesting. No exhaust sound, bike just squeal like wasp, but VERY smooth.

 When I get it road, no power. Only, what I can challenge, is -70 diesel mercedes...

 What are you thinking? Is problem on muffler, and/or something else....

 Thanks!

 Ike

[ileumi]

http://www.matkaendurot.com/phpBB/viewtopic.php?f=8&t=40572

Sorry, this link works.

[johnny]

wtf bra... post up your photos in this thread instead of posting up a link to another site.. sheese... this place is whack...

[Laitch]

Only, what I can challenge, is -70 diesel mercedes...
What are you thinking? Is problem on muffler, and/or something else....

wtf bra... post up your photos in this thread instead of posting up a link to another site.. sheese... this place is whack...

Please put the model and year in your profile, too, Ike. Judging from the exhaust, it is a 1990-1992 RS but you need to tell us here so we don't need to ask you.

Pull off the whole exhaust system and run straight pipes. You will find out right quick if your exhaust system engineering sucks. Have the '70s Mercedes ready for the run. :giggles

[Martin]

All the dyno tests that I have seen on exhausts comparisons show that the OEM exhausts are better for power. All that seems to be achieved by fitting an aftermarket exhaust is more noise at the expense of power. It also seems that a quieter than OEM exhaust also depletes power.
Regards Martin.

[ileumi]

Moro taas!


Here some images of muffler.

[Laitch]

My guess is exhaust gas turbulence and restriction are playing major roles in your close contests with the '70s Mercedes diesel. It looks like you are trying to play a tuba using a soda straw. :giggles  That might be possible though; I'll scan YouTube.

[The Mighty Gryphon]

Inhale deeply, then close your mouth tightly and pinch your nose.  Exhale.
That is why your bike runs like shit...

[Nine80seven]

Nice welding, but, there's a reason engineers design, test and manufacture stuff that gets a vehicle or bike on down the the road with the least drama and most tractability.  Or, it may have nothing to do with poor running?  Once engine stuff gets heavily modified ya never know why it doesn't exactly run right. 


Buy or borrow a stock unit and see if it makes a difference.  Eliminate one thing at a time.  It may not be exhaust?


An early K exhaust dumps runners into large collector, then back into another baffled chamber, into perforated final pipe.  Genius except for the weight.  Two scents, FWIW.

[timewolf]

you may think your helping the exhaust breath. but your cutting off the main airway.
the engineers knew what they were going ... its way to short and has no reticulation. the length helps the gasses slow down = back pressure!
heat retention is also a key component for back pressure. remember as molecules heat up they move faster and gasses expand, and slow down as they cool.


there is alot of science involved here.


if you're looking for cleaner option . try this
https://cafe4racer.eu/en/55-k100-exhasut-parts-collectors-4to1
they have some less expensive options. that are quite well made.


just a thought.

[ileumi]

Back to business...

My friend borrow me original exhaust and that not solve problem. Maybe I get 3hp more but bike not work....

On center stand engine runs fine and take rpm. Also idle is very smooth, runs like always before customing.

What now?

Compression in cylinders fine. Air filter not blocket. Gasoline filter is new.

What have done?

Removing all ABS-components and original instrument cluster is changed Koso. But I think those kills power.

Tank? In winter I remove tank to paint and remove also fuel pump and lines. Is there some problems?

ANY other answers!

-Ike-

[ileumi]

Bless that I got two other bikes so I can enjoy....

Some I have to do Brick....

- Injectors tested in Bosch service, all FINE
- Fuel pressure tested, FINE
- Air temperature sensor measured in Motronic connector, FINE
- Motor temperature sensor measured in Motronic connector, FINE

Bike just wont work.....

[ileumi]

One pin in motronic connector was turn worn. That pin feed ICU and bike runs only 2/3 cylinder....

Sometimes its long, long way to find problem....

[Laitch]

One pin in motronic connector was turn worn. That pin feed ICU and bike runs only 2/3 cylinder....

Sometimes its long, long way to find problem....

:yippee: How did you find it?

[ileumi]

The breaking point was, when my friend came check ignition timing with strobo > no spark in 1. cylinder. Then check coils, ICU, Hall-sensors... Finaly, when I clean Motronic I found worn pin...

In fact, I would be check sparks in summer... But I did not do that, becouse k100 runs fine, even 2 cylinders are out of order.

Okay. Summer is past in Finland, so now I have time to finish job. Find new place to cooler expansion tank and maybe mudguards too.

But first... make service to Xchallenge, change tyres with hard studs and take some COOL winter cruising...

[natalena]

Nice build from the land of Bottas and Raikinnen.

[Nine80seven]

Nice work ileumi.  It's the little things that make a bike run right.