1976 CB550F1 (what have I let myself in for) Project

[eight0]

The air filters from Steeldragon performance finally arrived and I think they look great.

The intakes are actually velocity stacks with the 'airbox' built around them. they fix to the carbs with a rubber seal recessed inside and are held firmly in place with gudgeon screws.

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[taysidedragon]

Those airfilters are beautiful work. 👍

In my weird Welsh world those screws are grub screws. 🤪

[eight0]

You are totally right. I had Gudgeon pin stuck in my head for some reason. Sent pre-coffee.

[taysidedragon]

You are totally right. I had Gudgeon pin stuck in my head for some reason. Sent pre-coffee.

Coffee's essential.  I can't operate without caffeine.  ☕

[eight0]

It holds in place and has a feeling of sealing when you push them on but yes the grub screws are needed to keep them from coming off again. Let's see.

[eight0]

So the bike has a bit of a bad oil leak.

It appears to be coming from the base gasket, it leaks all around it when it's been running. You can just see it in this photo where it's leaked over the top case. It also leaked from both sides and dropped around the alternator cover and points cover.

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When it's cold and sitting it still leaks but not from the base gasket, it comes from the left side off the bottom of the oil pan.

Tackling the base gasket first, should I re-torque the head?

[Bryanj]

You can try but i doubt it will cure it

[eight0]

Oh that's not good. What usually causes that then and what's the fix?

[Bryanj]

Hadnt magnified it enough to see that, yes there is an O ring in a groove but i think that washer is steel, its the one on the top bolt that is soft. Either way it should not have a spring washer and the bolt slotlooks chewed

[eight0]

Well I found the cause of the major oil leak, the drain on the oil pump wasn't snugged up completely. I was still getting oil pressure so I hope it hasn't starved the engine at all.

There doesn't appear to be any oil leaking from the top tensioner nut but I've replaced the bottom spring washer with a copper one and it seems to be better. It's possible I've missed the rubber O ring on the inside, I really can't remember. I'll have to live with it until I can bring myself to dive back into the top end.

[eight0]

Also, I've just hit 100 miles on it. What's the consensus on when to do the first oil change?

Bikes been getting a lot of attention which is nice. The air filters seem fine too, I don't have a benchmark as I never rode it with the airbox but it pulls smoothly through the revs with power throughout and idles well.

[eight0]

It's been a while since I've posted, I hope everyone is enjoying some nice rides between the downpours.

I've been riding the bike quite a lot and it has decent revs throughout the range and pulls well. It stumbles a bit when warm from idle but as I'm not running the original airbox I'm not going to open a can of worms there.
The bike is running very rich though. All the plugs are quite sooty and I can turn the choke off just after starting it without it being unhappy. I believe I've set the float levels correctly.

I'm running the original 38 pilot jets I got with the bike but looking through the jets at a light, the holes seem inconsistent. I think it may be possible they've been drilled previously or carelessly cleaned with some wire.

The needle is dropped down one clip from standard.

To rule it out I need some original 38's known to be good, I don't want to go aftermarket as they may not be good either. I don't suppose anyone has any they would be willing to sell me??

[K2-K6]

Think I'd be inclined to buy new and test it with them to gauge effect as it's not a std setup anyway.

You can compare your current jet with new by plugging it into a length of clear plastic pipe and filling with petrol to time them as it drains to give reference to compare new one. It would at least give you an informed view before running them to give real combustion experience.

The idle jets should, I  believe, affect the whole rpm range too. It's just that we can adjust them up until they reach full flow but they don't stop there in continuously working as additional to main jet.

If yours have been "bored out" then it's probably realistic to get a accurate set point with new to give clear direction from here.

[eight0]

Solid advice, hadn't thought of using a tube to compare. I'll have to order some from NRP as screw in pilots for the 069A's are unobtanium new. Allens performance only sell push in.

[K2-K6]

It's very interesting to see what you get with the filters you are using.

I thought they looked impressive when you got them, and to me seem to have a decent % of key attributes that replicate the std system.

Specifically they don't delete the bellmouth,  this effectively controls the air stream condition heading into the carb venturi and highly influence the flow accuracy.
In addition,  having them paired rather than individual also has important influence on mixture. Intake systems have quite alot of fuel misting back out of the intakes due to inverse pulsing among intake dynamics, and with pods critically losing this aspect. The fuel mist is part of the mixture total,  but travels from one cylinder to another depending on pulsing,  which doesn't appear to have been discarded with this setup.

It must be of interest to others on here that don't run an airbox, looking pretty competent to me. Certainly interesting to see what jets you end up with as anything close to standard would suggest air management performance similar to original specification.

If you find yourself with any concern about running lean , then raise the plug range by #1 in NGK terms to give yourself more safety margin.