400/4 Engine noise, bodges and Primary chain

[Fourplay]

Just got my recently acquired 79 400/4 running.
My concern is the noise from the engine at tickover.
I shot a video on my phone and at 1200 revs there seems to be a rattling and lashing coming from the lower part of the engine. Please excuse the poor quality of the videos (shot lying on my back under the bike!)
https://www.youtube.com/watch?v=QWlwj_9bQik

It's definitely not ticking over smoothly and the PO said it needed the carbs stripping down and syncing.

But before attempting the carb strip down, I re-tensioned the primary chain, changed the plugs and did the tappets.
It seemed quieter less rattling sound but still the lashing.

So I decided to change the oil and filter and clean the sump to see what delights lay in store. Oil quite black but no metallic particles just some bits of gasket cement.

But what is this all about? Looks like someone has attacked the filter housing with a drill?
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Also one of the sump bolts had sheared and a fluted rod/drill was fixed into the broken stud on the sump. A double ended nut had been forced onto the end of the rod to hold the cover in place.
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Before re-fitting the filter housing and sump, thought I would have a look at the primary chain. There seems a lot of sideplay in the chain/sprocket/collar, is this correct? See video link.
https://www.youtube.com/watch?v=x5_cqHMzBuo


I've refitted the sump but dang it I managed to shear one of the Sump bolts. Haven't attempted to remove it yet. So now down to 9 bolts on the sump! I know it's bodged and hate leaving it as is. Just want to get the engine running ok and ride a few miles to see what else needs sorting.

Any advice gratefully received

Justin

[McCabe-Thiele (Ted)]

Those odd drill marks that you describe are on my crank case filter face as well I think mine has just the one from memory not certain.

As regards the stripped thread as you know Helicoil should sort it in the long term - with some sealant added to the gasket it might just be oil tight in the short term.

[Bryanj]

Looks to me like a plugged machining hole from Honda and that rod is a snap on type screw extractor that is supposed to be turned with the double ended nut, better than the tapered easyouts as its hamered into a parallel hole so the flutes bite in but still only works 50% of the time

[Fourplay]

Looks to me like a plugged machining hole from Honda and that rod is a snap on type screw extractor that is supposed to be turned with the double ended nut, better than the tapered easyouts as its hamered into a parallel hole so the flutes bite in but still only works 50% of the time

Hi Bryan,

The rod has been set in at an angle and not dead centre of the sheared bolt, its between the outer diameter and the threaded part of the crankcase. I think I'm going to have to leave this until I have to do a full engine strip as it seems risky trying to get it out lying on my back —I may do more damage that way. I'll remove the sump again and see if I can get the remains of theone I sheared out —may be easier—hopefully there may be part of the bolt sitting proud of the crankcase.

Any thoughts on the engine noise, also on the primary chain/sprocket etc play?

Thanks,

Justin

[Nurse Julie]

Those drilling marks where the filer sits are standard, we all have them to a greater or lesser degree on our engines. There are quite a few in various places all over the engine, so nothing to worry about.
There is alway a bit of side play on the primary chain and as for the engine noise, I would start with giving the carbs a thorough strip and clean, fit new Viton O rings, bench sync and then vaccum sync. How many miles has that engine done?

[Fourplay]

Those drilling marks where the filer sits are standard, we all have them to a greater or lesser degree on our engines. There are quite a few in various places all over the engine, so nothing to worry about.
There is alway a bit of side play on the primary chain and as for the engine noise, I would start with giving the carbs a thorough strip and clean, fit new Viton O rings, bench sync and then vaccum sync. How many miles has that engine done?

Hello Julie. I bought the bike in April with 39,000 miles 10,000 done in the last 30 years. (have MOTs back to 1991 and receipts for work/parts back to 2006). New pistons fitted in 2006 at 36,000 miles. Receipts for dealer servicing/new parts.

Came with carb rebuild sets, so I know the carbs need sorting. Was putting this off until I was happy that the cam chain/primary chain were okay. But I guess the uneven running at idle may be contributing to the rattle and primary chain slap.

Never owned a four before so much of this new to me.

So as advised I think I will remove the carbs, and try and reuse as much of the original jets etc as possible.

I'll be in touch about the Viton O rings once I've stripped the carbs as I see you sell the Carb screw sets as well ,

Thanks for your help.

Justin

[McCabe-Thiele (Ted)]

Listening to your noise it does have that sort of uneven running tone to it so Julies far more experienced answer looks very  sound to me.

I would also be checking the timing is spot on for both sets of points - gap/dwell.

[Nurse Julie]

OK Justin. I know removing and stripping the carbs and syncing is a bit of  faffing around but, at least it will either rule out, or not, any engine issues there may be.

[K2-K6]

"But what is this all about? Looks like someone has attacked the filter housing with a drill?"

As already indicated above they are present in various places and would seem to be there to facilitate machine clearance for critical machining during manufacturing.

[McCabe-Thiele (Ted)]

"But what is this all about? Looks like someone has attacked the filter housing with a drill?"

As already indicated above they are present in various places and would seem to be there to facilitate machine clearance for critical machining during manufacturing.

If it was a flywheel they would be balancing marks, it's probably something odd like where a robot style machine holds it whilst they stamp the casing marks on the other side during production?