Do the Ton - CAFE RACERS What's in a name ?

I got my bike to perform worse than stock, still it seems faster because of all the noise. No way im turning that throttle wide open again though. Nearly shat myself last time.
 
datadavid said:
I got my bike to perform worse than stock, still it seems faster because of all the noise. No way im turning that throttle wide open again though. Nearly shat myself last time.
I managed that with a YZF750 by fitting an expensive and very well known race silencer, the bike was louder but at least 10 mph slower.
 
Back about a million years ago, if you'll pardon the hyperbole, Performance Bikes did a comparison of exhausts for a CB900. All made more noise than stock. Some gave a hole in the middle which made the bike FEEL stronger but few made any more power and IIRC none were better overall.

If you look at Dyno charts for modern expensive exhausts, the improvement is typically tiny over stock and that's after many dyno runs and different designs. All the hacked off/drilled out crappy designs on cafe racers are extremely unlikely to improve performance and yet we keep buying them. I am on the 4th or 5th design of a 2 stroke muffler and am planning to gut a pair of CB160 pipes to improve performance with different internals. I should know better :)
 
Speak to Pete Gibson in Southend or if you can find him Alan Baker (I think) who started Motad, both are very knowledgeable about exhausts.
I remember the Performance Bikes exhaust test, I can't remember which exhaust one though.
 
It depends on at what point we're talking about an improvement in performance. If stock is setup up for better overall performance, in other words finding the moderate numbers from 0 to 10k, then maybe an overall improvement can't be found. But, an exhaust could be designed to find better torque at low rpm, or better top end speed. I've played the game of trading pipes on an Elsinore that made it go from "hard to keep the front wheel on the ground" to "hard to do a wheelie if you tried." Just the exhaust made a significant difference in low-end torque.
 
That was on a two stroke yes? Different sort of beast.

Yes there were some changes to the power curve compared to stock but little to no actual improvement for a street bike and all made lots more noise. That's not to say that some exhausts can't be improved upon, but most changes will create more noise and less power.
 
On my RD350YPVS I had Allspeeds which gave a good spread of power and a small top end increase, I changed these for Jim Lomas pipes which gave a huge top end increase at the expense of the midrange - you have to look at what you want and buy/build an exhaust according to that.
 
My point is that you guys are speaking in way too general terms. Not every aftermarket exhaust is for every engine. That's where people go wrong. Sure you can dump random big exhausts on CB900 and manipulate your data to prove a point. It's all about creating an exhaust that has the greatest volume along with the greatest velocity. Sometimes a 1 1/2" pipe does this more than a 2" pipe. It's all about eliminating reversion and where your power band is is key. Generally speaking, lower power bands need narrower pipes. Some high performance cars run 2 different pipe diameters for different rpm ranges. The reality is, the headers are the most important function of exhaust flow. Guys running 4-into-1 headers without proper consideration can choose whatever muffler they want and it won't matter because they've screwed up the system halfway down the line. Length is another ingredient that can cancel out reversion. As far as noise, the greatest factor is the tip. Going up on tip size makes it louder, but unless you've altered the exhaust ahead of the tip, you're not going to see a notable performance change- good or bad.
 
Au contraire mon ami.
We have used specific examples that cannot necessarily be extrapolated for all conditions. In teh example of the 900 I referenced, those were all expensive aftermarket systems offered by major aftermarket companies and all specifically designed and offered for the CB900F of the time.

I agree totally that just changing parts randomly has a high probability of making more noise and low probability of making any power. I think was are arguing the same point but using slightly different examples to do so.
 
teazer said:
I think was are arguing the same point but using slightly different examples to do so.
You're right. I think we're on the same page.
 
Talking of exhaust / silencers, I picked up a pair of BMW Rennsport loooong tapering meggas at one of the Brands Hatch test days. The Continental Sidecar Circus were in town for an event and were having a final test and tune on the Wednesday before the meeting. At the end of the day virtually everyone had gone home [ we'd gone to the Brands Club House ] when I came across this pair of meggas and some odd tools. I handed them in to the Brands officials as they obviously belonged to one of the sidecar racers. One of the meggas had a large ding and the other a smaller one, and I suspect that the pair were replaced and maybe even deliberately left as scrap.

Anyway the next Wednesday - said official came up to me and said that as nobody had claimed the parts, they were mine if I wanted them ! My road outfit at the time had a Siamese exhaust, so I fitted the least damaged of the two and used that for a week or two, until the bellow from the exhaust became hurtful to the ears ! Yes - even for me.

Was there any performance increase ??? Well yes, in the mid-range power band and top end with a trade off at the bottom end.

However, the noise alone must have added 20bhp !
 
Oh at the very least Beach.

In some way it's like a drug that surly enhances your ability to corner at top speed with a cliff at your side... Or for me a Rorer/Lemon 714 was magical in my absurdly stoopid youth, mix that with a KZ900 and an unplugged Kerker... 2nd gear 8000 rpm and 45mph up and down A1A then park at the pier with the guys leaned against the seat smokin Marlboro's talking shit whilst trolling for skanks, then off to Homestead fully amped up for drag racing at the air force base, I ran a flat slick so just before headin to the line, I pulled a set of shortened tie downs out of the tail and cinched the forks to the stops... you loos a little grip but the bike would pull straight and stay on the ground... whomped a lota Z1R's and CB1100F's on that old 900 Kaw!

Wonder how many more I could of won with a properly tuned pipe and carbs :p
 
I've been doing a lot of trawling through the posts lately [ banned from garage ! :'( ] and it's encouraging to see the amount of peeps building now with "unlikely" donors and small capacity machines.

Most of these will be hard put to break the magic Ton - but does it matter ?

In the good old days, here in the UK there was no capacity limit for learners and newly licensed riders, so it was quite natural to start modifying what you had. That could be a BSA Bantam or a Vincent Black Shadow.

This new intake of builders are here because they are on the first steps to what ? - maybe that Bike of the Month slot in a few years time.

Long live the Cafe Racer - of all generations.
 
http://vancouver.craigslist.ca/van/mcy/5666897710.html

Not a Cafe but looks like a nice bike, might be a good deal for you Yanks with you dollar the way it is against ours.

Brian
 
Still did not crack the ton on the rolling road. 87.?? Mph 140 kph.
Ran in a dyno shootout . Was some wonderful store bought hp on show . H2r Kawasaki was scary powerful. 228 rwhp compared to my 12.42 rwhp.


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