What are your experiences from changing the stock system to a complete 4 to 1 system?

Will there be a good increase in power, assuming the bike is properly jetted, or is it hardly noticeable and most a show thing? May cans are already changed to lighter/louder ones and there is a KN-filter to carbs, but I will change the whole exhaust system if there will be a significant power increase.

Maybe any of you have also dynoed the bike with stock exhaust and with replaced exhaust system, I'm interested in diagrams if available.

I've also seen a cheap solution where the header connection to left muffler is plugged and a free flowing muffler is fitted to the right side. Is that worth doing or is it meaningless out of a performance perspective if one already have dual free flowing mufflers. My guess is that plugging one side would disturb the flow and could even reduce exhaust flow.

Lastly, on bikes with full 4 to 1 systems, what jet sizes do yoy have in carbs?

 

I replaced my 1000F's stock system to Yoshimura 4-2-1 system last winter. I got it dynoed & rejetted (sorry don't remember the jet sizes, I'll check if they were written in the dyno sheet), and after tuning the carbs it gave 128hp from back wheel, so there's definitely a good power gain. In reference 2002 Super Blackbird with 152hp from engine gave 133hp from back wheel in that same dyno. I have the dyno sheet somewhere, I try to find it and post it here. Air filter is still stock, don't know if K&N would give any more power. Complete aftermarket exhaust system weights ALOT less than stock system, so power-to-weight -ratio increases by that way too.

Also, think it good or bad, new system is definitely louder. As you can see from the image I attached, muffler in my system is quite small, and when giving it more throttle, it really blasts a loud sound. However it's nowhere near annoying, I'd call it more a manly roar, hah. I like it when driving on a motorway, I can still hear the exhaust and thus know in what state the engine is. In other words, I can 'feel' the engine better. All in all, I give complete aftermarket systems two thumbs up.

Cheers from Finland and surrounded by snow, waiting to ride my bike again.

 

Thanks Kaasari for the information, great figures! I'm having a Yoshi on my GSX R1000 and is quite happy with that. So, I will now try to find one for the CBR to. Perhaps they are not to easy to find since the bike has not been produced for some time. In worst case I will adapt a full race system from another litre-bike.

Where did you get the Yoshis system?

A lot of snow here to but I'm not keen at all start riding...

 

I found that dyno sheet, thought it was lost forever. I have no scanner so I took a photo from it, hope it's ok. In comments line it says for jets "125", don't know at all what that means but probably it has something to do with jet sizes.

Other picture attached is from stock exhaust. I draw a circle to where I think is the biggest problem in stock system. For my common sense, that part restricts free flowing (and those horsepowers for that matter) quite much as it has T-like shape, not straight line, and if you want to modify the stock system you should override that part somehow.

I got my Yoshi system from ebay -like net-market here in Finland, sold by fellow CBR rider. As you said they are harder to find now so I recommend searching for second-hand markets. Laser still has it's Pro d'Or 4-2-1 system for 1000F for sale brand-new and I remember I saw that Yoshi system being sold in some German net-shop (Louis maybe?), but you'll save lots of money if you find that system second-hand. Best of luck finding it, I honestly think it greatly improves already a great bike. Don't forget to readjust the carbs after fitting that new exhaust system!

Ps. Just noticed that the exhaust picture looks like some weird 4-3-1-2 exhaust system, bad camera angle I think.

 

Thanks Kaasari. I saw that Two Bros in US still have full systems to this bike, they cost a lot although.

 

i have a full yoshi system on my 87 1000f and it is reall loud, like he said, "manly", but loud!

 

I know you lose a lot of weight with aftermarket exhaust, but do you also lose the centerstand?

 

I'm happy to discard the heavy center-stand and will use the portable wheelstand.

 

I have an aftermarket Exchust and a centerstand

 

i had to take mine off, but i was happy to