interesting bikes found randomly..

JackyJoll · Post by **JackyJoll** » Fri Jul 23, 2021 12:32 pm

The Spin Doctor wrote: Fri Jul 23, 2021 11:22 am

What's with the tape round the downpipes?

Have you not seen that before?

Popular on the “hipster” style of modern cafe bike.

In theory, keeping heat in the exhaust has performance benefits.

The Spin Doctor · Post by **The Spin Doctor** » Fri Jul 23, 2021 2:40 pm

JackyJoll wrote: Fri Jul 23, 2021 12:32 pm Have you not seen that before?

Popular on the “hipster” style of modern cafe bike.

In theory, keeping heat in the exhaust has performance benefits.

I've seen it... I even remember it from the 70s! But I've never known why!

One explanation was that it helps performance by keeping heat in the exhaust, but I'm struggling to figure out any rationale for that.

Post by **Mr. Dazzle** » Fri Jul 23, 2021 3:15 pm

It changes the speed of sound in the gas and therefore changes the harmonics. Whether or not that is a benefit or just 'different' is often lost in the details.

Turbochargers can benefit from having higher inlet temps too, ultimately turbos extract work from the hot gas so hotter gas in means more available work.

You see it a lot in cars too, but thats mostly about underbonnet temperature.

Also helps prevent burning of your leg!

The Spin Doctor · Post by **The Spin Doctor** » Fri Jul 23, 2021 3:25 pm

Mr. Dazzle wrote: Fri Jul 23, 2021 3:15 pm It changes the speed of sound in the gas and therefore changes the harmonics. Whether or not that is a benefit or just 'different' is often lost in the details.

Turbochargers can benefit from having higher inlet temps too, ultimately turbos extract work from the hot gas so hotter gas in means more available work.

You see it a lot in cars too, but thats mostly about underbonnet temperature.

Also helps prevent burning of your leg!

Yebbut... I don't ride with my legs stuck out in front dangling alongside the downpipes

Yorick will be along in a moment to tell me I'm weird like that.

cheb · Post by **cheb** » Fri Jul 23, 2021 4:42 pm

I've read that it was Dr Joe Erlich and his work on 2ts that started it. The reasoning is that they got more power on the dyno that on the track and surmised that the pipes ran hotter on the dyno because of a lack of a cooling flow. Insulating the pipes on the track kept them at dyno temperature and got the missing power back.

I have no way of verifying if this it true so use your own judgement.

Post by **Rockburner** » Fri Jul 23, 2021 4:48 pm

cheb wrote: Fri Jul 23, 2021 4:42 pm so use your own judgement.

Is that genuinely a good idea?

cheb · Post by **cheb** » Fri Jul 23, 2021 6:09 pm

That depends on the user.

Post by **Taipan** » Fri Jul 23, 2021 7:06 pm

The Spin Doctor wrote: Fri Jul 23, 2021 11:24 am
v8-powered wrote: Fri Jul 23, 2021 11:06 am Quite like this - based on a Triumph Sprint 1997 vintage. https://www.returnofthecaferacers.com/t ... print-900/

I'll probably get lynched now but I rather like that too - improves on the original, I think.

I do like the right way up forks, as well.

The Triumph purists soon caught up with Spin...

JackyJoll · Post by **JackyJoll** » Fri Jul 23, 2021 8:14 pm

Taipan wrote: Fri Jul 23, 2021 7:06 pm
The Spin Doctor wrote: Fri Jul 23, 2021 11:24 am
v8-powered wrote: Fri Jul 23, 2021 11:06 am Quite like this - based on a Triumph Sprint 1997 vintage. https://www.returnofthecaferacers.com/t ... print-900/

I'll probably get lynched now but I rather like that too - improves on the original, I think.

I do like the right way up forks, as well.

The Triumph purists soon caught up with Spin...

There are Hinckley (and Thailand) Triumph purists now??

derek badger · Post by **derek badger** » Sat Jul 24, 2021 8:02 am

500cc Jawa single with a supercharger and nitrous. It's not the prettiest, but I like it because it's been built using 'why the hell not?' school of thought and it looks fun.

http://caferacersunited.com/supercharge ... KQPSByh1L0

JackyJoll · Post by **JackyJoll** » Sat Jul 24, 2021 9:35 am

Am I wrong to think about trying to ride it?

I don’t see it getting far with an unfiltered air intake pointing at the back tyre. Am I seeing that wrong?

I can’t see what keeps your leg out of the blower drive. Wouldn’t need a huge tin guard, just a bar across it.

Post by **rodbargee** » Sat Jul 24, 2021 10:16 am

Ebay at the moment 22K

Post by **weeksy** » Sat Jul 24, 2021 10:23 am

Don't like it. Not at all. Funny how different people value different things

JackyJoll · Post by **JackyJoll** » Sat Jul 24, 2021 10:24 am

It’s not even finished if you have to park on a block of wood!

Post by **rodbargee** » Sat Jul 24, 2021 10:45 am

I wonder if the"occasion" of riding such a thing offsets the probable total pain in the arse it is to ride....

3 days to go place bets now My guess 42 K

Post by **Taipan** » Sat Jul 24, 2021 11:04 am

weeksy wrote: Sat Jul 24, 2021 10:23 am Don't like it. Not at all. Funny how different people value different things

FWIW, me neither!

The Spin Doctor · Post by **The Spin Doctor** » Sat Jul 24, 2021 11:10 am

derek badger wrote: Sat Jul 24, 2021 8:02 am 500cc Jawa single with a supercharger and nitrous. It's not the prettiest, but I like it because it's been built using 'why the hell not?' school of thought and it looks fun.

Madness... in a good sense!

David · Post by **David** » Sat Jul 24, 2021 11:27 am

rodbargee wrote: Sat Jul 24, 2021 10:16 am

Ebay at the moment 22K

That is seriously nice!!!

Post by **Skub** » Sat Jul 24, 2021 7:49 pm

An interesting stroker project close to me and for not a lot of money. I daresay parts will be like hen's teeth.

https://www.facebook.com/marketplace/it ... 864320"%7D

Post by **mangocrazy** » Sun Jul 25, 2021 12:05 am

rodbargee wrote: Sat Jul 24, 2021 10:16 am

Ebay at the moment 22K

In the late 60s/early 70s that would have been the coolest of the cool. Now it's more a case of 'why did you vandalise a motorcycling icon, you moron?'

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interesting bikes found randomly..

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