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For those with unit construction Royal Enfields.

Although fitted with hydraulic tappets there are items on the timing side that do require attention.

Firstly the decompressor, it's an automatic type controlled by a bobweight and a hair spring. The springs really are very fine metal and can loose there 'spring' or the tiny activating pin can get sticky in its slot if crappy oil has been used. either way if your getting a distinctive clank at low revs (especially when starting from cold) and it disappears as the revs increase then it's the decompressor that needs cleaning and a new spring.

Secondly if your bike is noisy at idle....



Do you hear the clackity sound?

Thats the cam gears with too much backlash so they chatter between loading in each direction. Luckily on this model the cam spindles are fitted with eccentric shafts so they are adjustable. Sadly you will need to remove the tank and rocker covers because moving the gears out of mesh means the hydraulic tappet will drop down and you will need to slacken off the rocker blocks to get them back in.

Do the adjustment in the following manner - set the engine to TDC so all the cam timing dots align, disengage the inlet cam gear by pulling it forwards (the tappet will fall down) and then unlock and adjust the exhaust tappet so the backlash is only just removed between the exhaust cam gear and the crankshaft. Then do the inlet cam; again only just enough to remove the backlash between the inlet cam gear and the exhaust cam gear that drives it. There is no adjustment for the oil pump (plastic) drive gear.

Compare the sound after (yes I know the idle speed is lower)



As always when replacing the outer cover make sure the oil feed O-ring stays in place.

Stay chipper - it's only nuts and bolts

I have a buzzing sound coming from the top end of my Bullet 500 when it's cold, lasting approximately 30 seconds. It's recently had the engine oil changed (10w50 fully synthetic) and subsequently a 1500 mile NC500 journey under its belt throughout which the buzzing still occurs when cold when starting out each day. This couldn't be the tappets, could it?

alihar07 wrote: ↑

Mon Aug 31, 2020 9:06 pm

I have a buzzing sound coming from the top end of my Bullet 500 when it's cold, lasting approximately 30 seconds. It's recently had the engine oil changed (10w50 fully synthetic) and subsequently a 1500 mile NC500 journey under its belt throughout which the buzzing still occurs when cold when starting out each day. This couldn't be the tappets, could it?

Fuel injection pump?

The fuel injection pump whines for 2 seconds after the ignition is switched on, then stops as the pressure has built up; it only kicks in again when the engine has started. This sound I'm noticing isn't a whine, it's a lower frequency buzzing that is coming out of the cylinder head for 30 seconds, lower down than the fuel pump. Perhaps it's the oil absent from the head for 30 seconds because it's all drained out over night, meaning there's metal to metal contact for a short duration? I could try heavier oil?

Could do with a little more info or a video with sound?

It won’t be the oil grade, if they did remove the outside cover during the oil service (there would be no need), then it’s possible the O ring that seals the back of the filter chamber to the pump could be missing.....if that is the case then you won’t have oil pressure for the rockers feed.

It’s worth checking.

[youtube]https://youtu.be/xyPAKcuqYbM[/youtube]

I've worked out how to create a youtube video, should be in the above link. Might need some decent headphones to hear the sound clearly .

That’s not a good sound......

Well it’s not the tappets or cam gear as the frequency is too high, (you do need to adjust the cam backlash though).

If it’s originating on that side of the engine then best pull off the primary cover and take a look inside, the primary chain adjustment is supposed to be automatic but something could be up with that or even the starter drive.

It sounds like it's the go faster lollipop stick you fitted as a kid to make it go faster

Bogger

What Dave said and have a look at the starter sprag clutch, it might be on its way out.

I've had a quick look into the inspection port on the left side crank case; primary chain tension appears to be correct (it isn't loose or really taut) and everything rotates smoothly at kick starter speed without the strange noises. I've booked it in for a service, so shall see if the garage changing oil and filters helps with the vibration. The vibration does disappear once the bike gets underway, and doesn't reappear until the bikes been restarted once it has cooled down completely. The bike is still under warranty, so will look to get the Moto GB dealership to check this vibration if it doesn't go away. And I will also to get them to look at the cam-gear back-lash while they're at it. I assume the cam-gears going loose would be covered under warranty?