Camchain and tensioner seen up close in a cutaway bike engine

Home Repair And RestorationThe Battle Of The Exhaust... - By Ren Withnell

CLR 125 Exhaust Converted - At LAST!

Blog Date - 13 January 2012

If you've read this blog regularly you'll know I had a hell of a time earlier this year trying to bodge the exhaust on the CLR to keep the beast on the road.  The bodge was a success in that it has allowed the bike to continue running legally and pass another MOT for 9 months or so.  Yet in those 9 months my heart has been getting heavier and heavier each time I've looked at the mild steel end can/silencer.  Each downpour, each salty road and each damp night is taking it's toll and small spots of rust have grown into large flakes that fall of.  I've known for a long time that the silencer is not much longer for this world.

a rusty exhaust pipe from a clr 125 city fly
The rusty and far beyond repair original exhaust from the 125

In the summer I'd purchased a CBR 125 end can from G&C Motorcycles.  I'd been regaling Callum, the lad who runs the shop, with my tales of woe, my frustrations and my desires to solve my worries.  As such he sold me the end can.  The can has been down the road, is badly scratched, dirty, cheap, stainless and complete, just the way I like my bike parts.  That can has sat in my shed for a number of months.

Christmas is supposed to be a time of joy and relaxation.  For me it can be a time of boredom.  One quiet afternoon between endless movies and eating far too much chocolate I took it upon myself to fit the CBR 125 silencer to my CLR 125.  

The CBR can is about 3 or 4 inches in diameter with 3 x 6mm threaded holes to bolt the silencer to the exhaust pipe and a plate welded on to bolt the body of the can to the bike.  Of course the CLR silencer is completely different.  The CLR exhaust is a long convoluted affair that connects to the frame in several places and to the exhaust pipe with a clamp.  First job, dig out the welder.

I needed to make a flange.  A way of taking a 30mm diameter pipe into a metal plate with 3 holes in it.  With 30mm pipe to hand I used my simple, smashing and satisfying gasless mig welder to join the pipe to a flat square piece of sheet metal I happened to have lying around.  I cannot weld well at all, yet after 1 hour of sparks, heat and grinding I had what I can only describe as an "acceptable" join between the pipe and the sheet metal. Another couple of hours saw the square piece of sheet cut and ground into a sort of round shape to match the CBR silencer and the 30mm pipe cut to a sensible length.  That's the first bodge completed.

metal plate flange connecting flexible stainless tube to an exhaust
The DIY flange. This really is a bodge, but it works well and will do for me.

Next I removed the old pipe.  It came off easily and upon removal I could see the corrosion was far worse than I believed.  The hidden bits that can't be seen are also the bits that don't get cleaned and the dirt holds the damp and the damp furthers the corrosion.  I had hoped that if my cunning and devious CBR 125 Silencer plan did not come to fruition then I could re-insert the old silencer and carry on, but looking at this feeble clump of rust before me, I realised I must be successful.  Pressure.

I did have an ace up my sleeve.  A length of 30mm inside diameter flexible stainless steel exhaust pipe.  Yes...that is FLEXIBLE exhaust pipe...amazing!  I'd used this to bodge the original CLR silencer 9 months ago and now I made use of the remaining tube.  Of course the damn CLR 125 header pipe is 29mm.  My next task was to take an old piece of tube from a set of weights, cut off an inch or so, slice in a slot, remove to excess and create a shim to link the 30mm inside diameter flexible exhaust pipe to the 29mm external diameter CLR header pipe.  There was no micrometer or even a measure in sight, I just cut, try, cut, try until the shim's about right.  Sorted.

flexible stainless exhaust tube on my clr 125
The flexi-tube.  What an amazing piece of kit!

So now I was left with a 30mm inside diameter flexible pipe venting to fresh air.  Noisy.  It sounded great but noisy pipes are bloody annoying at 0600 and on long motorway trips.  Now to fit the CBR end can.  Of course the bolt holes from the original silencer are all in the wrong place.  I rooted around my "bit's of metal" draw and produced one rusty and one quite clean strip of metal bar, and an old clamp used to bolt headlamps to fork legs.  Cutting, drilling, bolting and grinding created 3 bits of metal to bolt the silencer in place.  Another hour in the fading light saw the flange attached to the 30mm flexi pipe, the silencer to the flange and the 3 bits of metal applied to hold the silencer.

With great trepidation I get the keys and start the bike.  I expected to hear a roar, instead I heard a motorcycle.  It's a bit louder than the original and I can hear a few leaks from the flange and the shim but nothing that can't be bashed into submission.  I took the bike out for a ride and confirmed that all is well, if a little noisier than before.  I looked at pedestrians as I passed by and none of them were covering their ears or running away.  I think the additional noise is acceptable, the bike's gone from very quiet to simply quiet.  The silencer is E stamped anyhow, so it must be legal officer...?

the finished project showing the new end can and the flexi tube
The final product.  It's not pretty but it's functional, legal and I love the way it looks so...bodged

I can now report after a couple of weeks of riding the exhaust remains a success.  In fact riding the bike has made it quieter.  As the exhaust heats and cools it is settling and sealing itself, I've not needed to bash the flange or the shim they've just settled in and all is normal and acceptable.  After all this work, I only hope and prey the motor and the rest of the bike don't let me down.  

Battle Of The Exhaust - Day 1
Battle Of The Exhaust - Day 2
Battle Of The Exhaust - Day 3
Battle Of The Exhaust - Day 4
Battle Of The Exhaust - Day 5
Battle Of The Exhaust - Day 6 - Success!
CLR 125 Exhaust Converted - At LAST!

Reader's Comments

kieran said :-
Hi where did you get the flexible tubing from?
01/01/2000 00:00:00 UTC
Jo said :-
Hi there

i'm just starting to experience the trials of owning a cityfly- nice bikes for pootling around on, good height for the engine size...but a real pain to find spares for. Just had to replace the tyres (which pirelli no longer seem to make!), will soon have to find new fork legs and possibly an exhaust- both of which are also no longer made! Can't figure out why honda would go to the rouble of making a decent bike and then not provide spares support for...Anyway, desperation has forced me to consider making a muffler for my cityfly- where did you get your flexible exhaust from? Any probs using the cbr exhaust?

many thanks

01/01/2000 00:00:00 UTC
Ren - The Editor said :-
Hi Jo!

I can actually source a brand new exhaust for the bike, you need to find a local dealer with an account at Fowlers of Bristol. I was quoted £195 for a new silencer.

You should also be able to get fork legs, but if not then

Wemoto have the fork legs, not cheap again though.

If you happen to want to try my bodge then the flexible pipe was purchased from E-Bay. Just do a search for "Flexible Exhaust". I've used 30mm inside diameter.

The CLR is an ace bike. It was never popular though hence the lack of spares.
01/01/2000 00:00:00 UTC
said :-
Ouch!...not looking forward to finding £195 for the muffler- i keep checking on fleabay just in case a decent 2nd hand one pops up- luckily its not long gone through its MoT with a bit of exhaust filler keeping it legal...but i'm going to have to stop avoiding doing something about it soon! I know the engine in the CLR is the same as the old (1980's?) XL125r- do you reckon the fork legs from that'll fit?- oddly there seesm to be loads of spares floating about for that!

take care

01/01/2000 00:00:00 UTC
Ed said :-
I've got the same issue - I blew a hole the size of a 1p piece in my silencer on my CLR125 today on the way home, the hot exhaust gases then melted a hole in the plastic air intake (behind the air filter) so it was basically blowing exhaust straight back into the carburettor!!! Amazingly I still limped home and have patched it up with some steel can cut into a square and wired around and exhaust putty all over it but suspect it won't last. I too love a bodge! Not as good as yours though. Now the search for a replacement silencer. Also not looking forward to £195...! Also looking on Ebay!! Love the bike though still.
01/01/2000 00:00:00 UTC
Ren - The Ed said :-
Nick Wheels Wood on facebook posted up his own exhaust conversion. With his kind permission he's sent me some pictures. Cheers Nick!

The first pic is the completed system. The exhaust is from a Lextec but he warns, be careful as this one is almost too long. Sounds great though.

Lextec exhaust on a Honda CLR 125 city fly
01/01/2000 00:00:00 UTC
Ren - The Ed said :-
The second image shows the rear end looking very smart indeed.

Shiny exhaust at the rear of the city fly
01/01/2000 00:00:00 UTC
Ren - The Ed said :-
He's still working on the join between the header and the flexible tubing. It's a bit rough at the moment but I'm sure he'll get it looking a lot smarter when he find the right clamp.

The join between the header and the flexi pipe, filled with gloop to create a seal
01/01/2000 00:00:00 UTC
Essexalien said :-
Made mine up myself and also unrestricted it too it goes really well with crf150 barrel piston and cam with 26mm carb lol
24/07/2016 10:14:37 UTC
Ren - The Ed said :-
Hi Essexalien. Bet it goes well de-restricted and with a 150 barrel. Got an pictures for people to see? I hope you've also got a full licence for that unrestricted bike :-)
25/07/2016 07:29:11 UTC
Essexalien said :-
Yes this is my winter bike also have a zx9r Yamaha fz600/fzx750/yzf1000 1070cc and reworked engine it's an animal and a cx500 lol

City fly clr125/150
01/08/2016 21:44:31 UTC
Essexalien said :-

01/08/2016 21:48:30 UTC
Essexalien said :-
I am tempted to rebuild it with the crf230 crank and top end it all fits in the 125 cases and it's only about 1cm taller in the barrel
01/08/2016 21:56:19 UTC
Ren - The Ed said :-
That looks tidy Essexalien, so tidy it looks original! I know it's not from the end can but the untrained eye wouldn't know. Now why would you want to go sticking some bigger engine bits on it? If it's your winter hack just keep it nice and simple. I guess you love tinkering so just do it :)
02/08/2016 07:29:05 UTC
Essexalien said :-
Well ed it's all a bit of fun isn't it I love my bikes and have a few rare machines my fzx750 is one of 11 bikes originally sold in the UK there are a few jap and American fazer over here now but as I said there is only 11 brit models left when I bought it it had been leanin against a wall outside for about 8 years and was a total wreck here is a picture of it now

02/08/2016 09:45:00 UTC
Ren - The Ed said :-
Ooooof! I have seen one or two of those over the years but they were probably the imports. You sir have spoiled yourself rotten and are now making us all very jealous. I take it you do all the restoration work yourself?
02/08/2016 10:58:41 UTC
Essexalien said :-
Yes ren I do most of my own work and also make a lot of my own parts too like the front brake on the fzx is a vmax 298mm disk with 6 pot busa caliper and xjr1200 master I did put a twin disk setup on there but it just kept on locking up the front wheel but single worhshop extremily efectivley and also an r6 rear caliper works well too

02/08/2016 13:39:02 UTC
Essexalien said :-
It took me about 2 years and probably about 2500 hours and a divorce lol to restore it lol
02/08/2016 13:57:53 UTC
Ren - The Ed said :-
Well I know where to go if I want my CBF125 restored and/or customised. 2,500 hours...that's a lot. That's over a year's full time work!
03/08/2016 17:31:19 UTC
Essexalien said :-
Ahh cbf125 crf150f 2007-2016 barrel and piston should bolt strait onto that little beauty lol happy days
04/08/2016 05:56:55 UTC
Ren - The Ed said :-
You don't HAVE to tune up and bore out EVERY motorcycle? 11bhp is already far too powerful for me - hehe :-)
04/08/2016 09:46:54 UTC
Essexalien said :-
I know that it's just always been something iv played arround with at 16 I had a honda ss50 which when I got it would just about do 40 and all my mates would thrash the pants off it on their fs1e's so it began c70 barrel piston and big valve head and 5 speed ss50 cam port and polish cb125s carb and it would cruise at 55-60 and topped out about 67 no more fs1e trouble and iv done it ever since
05/08/2016 00:17:13 UTC
Ren - The Ed said :-
You're a tinkerer aren't you Essexalien. Have you got any projects on the go at the moment?
05/08/2016 09:08:49 UTC
Essexalien said :-
As always yes a 1988 fz600 which I bought with no bodywork someone had started a chopper convertion on it badly but it is slowly coming into shape as a rat fighter and will replace my cx500 and clr as every day transport or that's the idea anyway lol
05/08/2016 11:55:23 UTC
Essexalien said :-

05/08/2016 12:04:57 UTC
Essexalien said :-
R6 tank and seat unit and subframe iv also filled the pockets under the top yoke with weld and seam welded a 5mm plate under that to fit bar risers so I can now fit proper bars not clip ones the bike has only done 14k from new so that's less than 500 miles a year but I think it must have been someone's track toy because it has a full yoshimura exhaust and 32mm xj600 carbs fitted and looks like it's had a fair bit of head work done too and to top the lot I only paid £75 for it happy days
05/08/2016 12:17:37 UTC
Ren - The Ed said :-
That's some serious work there Essexalien! If you ever feel the need to document your work I'd love to publish it on here :-)
06/08/2016 11:07:15 UTC
Darren G said :-
I have an old CLR125. I am lucky cos my exhast is in very good condition. I am liking my bike very much and use it off road when I can. Its not as good as my friends Yamaha motor cross bike but I can still laugh with him. Maybe I shall make my own exhaust like you when this one goes rusty.
02/07/2018 07:17:14 UTC
Ren - The Ed said :-
Good to read you're enjoying the CLR Darren. I'm wondering if your exhaust is a replacement as this model of bike hasn't been made for years now.
02/07/2018 21:13:24 UTC
ali g said :-
thanks for your tip, my city fly is 1999, with only 8k , i have been looking for replacement exhaust for a while, using your tips iI can make a replacement cheaply, keeping the bike on the road. stay safe and keep the shiny side up.

Posted Image
20/11/2020 08:54:23 UTC
Ren - The Ed¹ said :-
Great to hear ali g. I'm sure with a little work and a little fettling you'll be fine. Sometimes it just takes the inspiration to get you started.
21/11/2020 13:42:07 UTC

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Home Repair And RestorationThe Battle Of The Exhaust... - By Ren Withnell

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