Camchain and tensioner seen up close in a cutaway bike engine

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

Battle Of The Exhaust - Day 4

Stuff it...the motor's back together so I decided to chuck it in the frame and see if it would start.  Using the back box and a lump of wood to get the motor to the right height it wasn't too difficult to get just 2 of the engine bolts in place.  That's all I needed to hold the motor in place enough to wire it up, slap in the carb and see if it will run.

The blooming battery was dead!  Not completely, but it wasn't turning the motor crisply.  I've also got the half dead battery from the 600 that wasn't allowing the 600 to start, so rather than take the battery off the car (again) I jumpered the old 600 battery into the loop.  The motor turned a bit sharper but it still didn't seem to be cranking at the normal speed.  To be honest, it just seemed that it wasn't just low batteries, but the motor seemed tight too.

I removed the spark plug to see an acceptable if not fat spark, but I guess you can't expect much from a 125.  I placed my finger over the plug hole and cranked the motor.  There seemed to be an acceptable amount of comression and suction too.  So I replaced the plug and left it for a smoke.  Eventually I tried again.  Harumph harumph harumph harumph harumph harumph harumph harumph harumph from the motor... harumph harumph harumph harumph harumph pop harumph harumph harumph harumph pop...there's promise in that there motor.

Another few cranks, a few more pops then BANG, the motor coughed and started.  It's not a pleasant noise, even from a tiddly 125, a motor with no exhaust at all.  I started it a couple of times then decided to put the pipe on.  Well, the header pipe at least.

I needed to make the new exhaust studs.  Fortunately about 8 years ago I inherited from a deceased friend a collection of nuts, bolts, clamps and threaded bar.  That's 6mm threaded bar, in stainless, just what I needed.  So with hacksaw and a 6mm tap I cust some new studs and cleaned the threads.  I inserted them and tightened them, carefully, I still don't trust these helicoil thingies.   The header was then carfully and gingerly fitted and I restarted the bike.

It's still a noisy bugger with no silencer.  It's too loud for me so I'm very loathed to disturb all the neighbours and make enemies so I only ran the bike for a minute or so.  So far so good. 

Now the next part of the plan is to create some kind of silencer.  I still don't want to spend any money for 2 reasons.  Firstly I'm tight, secondly I don't want to throw money at the bike incase the damn motor gives up or something else fails.  So far I've cut out the bad part of the existing silencer, but that leaves me with a 4 inch gap between the header and the silencer.  I've ordered some 30mm flexible exhaust.  I've never heard of it before so I'll be interested in how it works and if will solve my problem.  It cost a tenner for half a metre, not so bad so far.

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!

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

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