Hitchcocks Forum

Hi All
New on here,bought a 2016 C5 Classic last week of E.bay with only 173 mile,s on it, when I picked it up he had it warming up ready for me to ride home,it ran fine on the way home but next day when started it made a funny knocking noise when warming up,not in rythem but ramdon for about 2 mins then stopped and ran fine,i have found that this only happens when starting from cold and if I raise the revs slightly it stops,any idea,s.My nearest Enfield dealer is 75 mile,s away

Thanks in advance for any idea,s

Thanks Tony

It could well be normal. Being air-cooled and of rather crude design and manufacture, these engines are very noisy compared to modern Japanese stuff.



Two things might be causing the noise. The first is the decompressor, which operates below 750rpm or thereabouts. In reality some of them operate at somewhat higher revs. The sound is a harsh and worrying "clack clack clack" noise. If the clacking noise disappears when you rev the engine above idle, then it is almost certainly that. The decompressor is a hideous piece of design, and some people advocate removing it altogether.



The second possibility is valve gear noise. From the din they make, you wouldn't believe these engines have hydraulic lifters. The valve gear noise is horrendous. Also, it seems to come and go without any obvious pattern. If your noise occurs regardless of revs, and comes and goes, it is most likely normal valve gear noise.



There are countless other possibilities for sources of noise, as you will see in due course from other posts to this thread. But from what you've written, I'm almost certain it is the decompressor making the noise, and as such it is pretty normal. If you are moderately competent with spanners, I'd recommend disabling it. Otherwise, just live with it.

With only 173 miles on the clock your bike is very far from run in. Below 300 miles (first service) it is going to make a lot of strange noises.



Run it in carefully below 45mph to 300 miles. Read the booklet. To 600 miles gradually increase load on the motor but don't strain it, you should be able to feel what it wants to do. It is possible to run in a motor too gently, it needs some work put into it to bed it in and loosen it up, but not thrash it.



The ticking noise of the decompressor should disappear within 2 seconds of starting. Being new it may stick in a bit longer. Idle should be 1050rpm and the decompressor should cut off at 350rpm on the cam which it run s off i.e. 700rpm on the crankshaft. Compression is 8.5:1 so removing it probably not a brilliant idea as it would strain the starter motor.



From cold the idle can be irregular. A new engine is going to take longer to settle down than one that has been run in. It is air cooled so it will overheat if left idling whilst stationary too long. A new engine has more friction and so it produces more heat.

Mine, a 2010 Electra EFI makes all sorts of odd noises. They vary with the weather, how much fuel is in the tank, whether it has been parked on the side stand or the centre stand etc. etc. The best way to deal with the noises is to wear earplugs. Occasionally I forget and think terminal mechanical failure is imminent, but it is just normal. Put the earplugs back in and all is well again! I'm up to 21,000 miles now and any problems have been due to poor electrics, not mechanical issues. Relax and enjoy.

My 3 month old B5 made a noise similar to what you are describing. It only did it a few times when the odometer was reading less than 600kms (375 miles) and I initially thought it may have been the tappets. It only made the noise just after starting and when the revs were low and went away with a rev so I now believe it was the decompressor (the experienced folks on this forum helped me with this suggestion). I have since adjusted the idling speed a little with the large brass screw on the throttle body (actually the dealer did initially but I thought he'd overdone it so I reduced it). The bike has now done 1200 kms (750 miles) and I haven't heard the noise again. Interestingly, as suggested by other experienced folks on this forum, the bikes performance seems to have improved and it is running well.

I would not describe the decompressor as loud although it can easily be heard over the exhaust note. It make a kind of suck-click noise, "shlack" about three times before it closes and the idle picks up. Logically the idle won't pick up with the decompressor valve open. If the idle drops too low e.g. I practically stall it getting it up into the shed without shooting through the back wall, the decomp can open and kill the engine. That happens at about 700rpm but varies from one motor to the next. It's a centripetal cam/key on a spring widget, actually very simple which usually means a good reliable idiot-proof design.



On a new bike everything is stiff and tight inside. It needs a bit of wear to loosen up, the right kind of wear. But that includes the auto-decompressor. During the running in there will come a stage when the vibration lessens and the motor starts to produce a lot more torque, then you can and should open it up gradually and briefly. How long it takes to run in depends, some 500-600 miles, some 1000-1200 miles.



The throttle body can be rotated (one jubillee clip) to get at the idle screw. It is supposed to be 1050rpm. If you experience a flat spot near zero throttle (on or off sensation on tight corners), increase idle to about 1100rpm (without tacho, guess). On a new engine the idle will be all over the place anyway and need a couple of tweaks as it beds in.

Poor electrics - every single one of the fuses in my then-new C5 were corroded, they're aluminium and they were powdery. Replace one, replace the lot, sorted. There are two sizes of these car 'spade' fuses but they cost pennies. A few of the bulbs blew, poor quality, poor fit in sockets; they're all off the shelf car bulbs, replace one, replace the lot. The Minda headlamp is actually extremely good, with a good H4 bulb in it. The spade connectors are low quality and thin metal but are well crimped on by a gorilla (better than Mercedes do it) but can need pulling apart and putting back together to scrape oxide off. One of the connectors on the battery snapped off, the metal was too thin for the job, snapped on the bend but easily fixed. Some of the outer insulation sheaths are too short, if you get a tuit add some shrink sleeving. The choc-block multi-way connectors and the actual wire used in the wiring are pretty good.

Hi
And thank you all for your very quick replies and putting my mind at ease.The bike went in for its first service today and as it was a nice evening a went out for a ride out,the bike ran well and I did about 30 mile,s.

Again thanks for your help

Cheers Tony

All very normal for a new. Engine just run it in as jefrrs says and it will ease up by 3000 I miles. An extra oil change over and above schedule is a good plan.