i saw somewhere that the 87 cbr 1000f exhaust system goes 4 into 1 then back in to 2....
and by blocking one of the splits you get a four in to one.
is this true? i just wanna know before i go to the trouble of removing stuff.

 

You are right, but plugging one of the outlets will most probably hurt the flow and performance even if you put a better muffler at the end. Its a cheap way to improve the apperance if the stock cans look bad.

 

jOel, when i bought my '87 it was set up something like you are talking about. headers join up underneath into one, (collector box?) one side is welded up and only have one muffler (can) right hand side, had the bike 2yrs now no problem with the exhaust and it sounds good...
ps. emailed you the other day (pete - blue mtns) here are a couple of pics of my ride same year as yours, see exhaust, i you want close up pics of exhaust setup can take some, if it ever stops raining, supposed to be going to Byron next weekend, be nice if it was dry for a few days...

 

Yes, the four head pipes go into a collector under the bike and split into two. It is a 4-1-2 system. I went with a Two Brothers slip-on. To install it you pull both mufflers and they give you a plug to insert in the left side of the collector/splitter. This takes about 1/2 hour for installation. Better performance and sound.

 

Here is a picture of the stock system. It was posted in this forum earlier by member Kasaari. As one can see the splitting point is very restrictive, and the flow will not be better if one pipe is blocked.

[IMG]local://upfiles/4562/B8BF78FEB0974E99B5B990B48B4F530C.jpg[/IMG]

 

Yes and no, while the OEM system has two very small outlet holes, one for each muffler, the TB's slip-on has one large tail pipe and that diameter is followed through the muffler to the exiting point. Perhaps not as free flowing as a 4-1 system, however low and mid range power is increased with the slip-on.

[IMG]local://upfiles/8473/59DE8965CDB44456A043F8CC0637449C.jpg[/IMG]

 

thanks guys, i will have a go and see what i think!