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Tuning up the Super Sport

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Easy-X
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PostPosted: 21:13 - 25 Mar 2021    Post subject: Tuning up the Super Sport Reply with quote

It's running but the low-down power is a bit disappointing. Over 4k is fine. Idles at ~1k, seems okay. I'm going to start with resetting all the mixture screws to the factory setting and go from there. After that I'm thinking as it has an aftermarket exhaust and pod filters the main jets were changed but not the pilots Thinking

Obviously with a 4 carb bike you can't just fiddle with the mixture screws and guess from the revs but is there a method beyond sending it to a garage with some sort of exhaust gas analyser? e.g. Colortune.

The only other issue is the front brake feel is wooden. Seems a previous owner swapped in the master from an XS650 - no wonder Honda levers wouldn't fit Rolling Eyes Probably go back to an OEM one and get some new brake hoses.

Contemplating steel braided but the front brake is a bit odd on this: master with a standard banjo bolt then an inline pressure switch (also standard banjos) and finally a 10mm threaded fitting for a hardline. AN fittings aren't too hard to sort out for a custom made line are they?
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stevo123
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PostPosted: 22:39 - 26 Mar 2021    Post subject: Reply with quote

NOT an expert but I would start by cleaning the carbs, jets and small galleries within.
Then balance them with a carb balancing tool if more than one carb on your machine.
If you have added aftermarket bits then best consult the tinternetz for advice on up-jetting for your chosen mods. Plugs should tell you how you are tuning wise.
At least that's the way I would go about it..
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Easy-X
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PostPosted: 00:39 - 27 Mar 2021    Post subject: Reply with quote

stevo123 wrote:
NOT an expert but I would start by cleaning the carbs, jets and small galleries within.
Then balance them with a carb balancing tool if more than one carb on your machine.
If you have added aftermarket bits then best consult the tinternetz for advice on up-jetting for your chosen mods. Plugs should tell you how you are tuning wise.
At least that's the way I would go about it..


Soz, should have mentioned explicitly here (it was in the "wot have you done to your bike today" thread) that the carbs have been off, cleaned and balanced. The pods and an exhaust were already on the bike so are the carbs correctly jetted? Who knows.

The old plugs in there say "rich" but again, who knows how long they've been in there. I don't really want to get into the whole "read the tea leaves" of plug chops but it'll probably head that way Neutral
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A100man
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PostPosted: 08:27 - 27 Mar 2021    Post subject: Reply with quote

Never owned one, never used one, but from what I've read Colourtune is used to set the idle mixture only. Also before you set of down the carbs rabbit hole you need to ensure valve clearancse are set good. without that all refernece points are lost.
Finally I understand that intake mods have more effect on jetting than exhaust and most folk recommend retainingstock air box.
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redeem ouzzer
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PostPosted: 09:21 - 27 Mar 2021    Post subject: Reply with quote

Not sure what the bike is, you mention it all over the place without actually saying what it is and I can’t be arsed to troll through all your old posts. Put the original airbox back on or pay a man with a dyno for a few hours work to sort it. I’m betting it needs stronger slide springs and that’s why it’s rich as fuck at bottom end.
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Robby
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PostPosted: 11:09 - 27 Mar 2021    Post subject: Reply with quote

As said, no idea what the bike is. If it's one of the old grey import 400s then being gutless below 4k rpm is quite normal.

For the front brake, a braided line won't make it feel less wooden. Common causes for a wooden feel are the wrong size master cylinder, or a lot of corrosion in the caliper between the caliper body and piston seal. This makes the piston bind a bit. Solution is to pump out the piston(s), remove the seals, scrape out the fluffy alloy corrosion from behind them.
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Easy-X
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PostPosted: 13:06 - 27 Mar 2021    Post subject: Reply with quote

Robby wrote:
As said, no idea what the bike is. If it's one of the old grey import 400s then being gutless below 4k rpm is quite normal.


Honda CB400F0 Super Sport 1975. And yes, imported from US. So they were never up to much?

Robby wrote:
For the front brake, a braided line won't make it feel less wooden. Common causes for a wooden feel are the wrong size master cylinder, or a lot of corrosion in the caliper between the caliper body and piston seal. This makes the piston bind a bit. Solution is to pump out the piston(s), remove the seals, scrape out the fluffy alloy corrosion from behind them.


Thanks, I'll continue with the plan: put back the braking system to OEM. And it actually works out cheaper to make custom brake lines than buy a set .
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A100man
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PostPosted: 23:00 - 28 Mar 2021    Post subject: Reply with quote

So it's a Honda 400/4. Why didn't you say? I thought yo were talking about that CBR1000 you were working on .

Valve clearance and airbox tip still appliies. Easy on those too - no shims.
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Ste
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PostPosted: 00:09 - 29 Mar 2021    Post subject: Reply with quote

Easy-X wrote:
Honda CB400

Thinking

Completely off topic; but when I was at high-school, we had a very wizened old tortoise of a woodwork teacher; he drove a rather old Mini Traveler (you remember the estate car version, with the feaux 'woody' back?) and should have retired five years before, but no-one had the heart to tell him to stop coming to work! His successor was a young chap straight out of teacher-training school, who rode one of them, and thought that and his leather jacket would make him seem 'cool' to us.... I recall a conversation about 'bikes' he was party to, in which he offered ridicule of an ER50, and that we'd know what he meant when we'd tried something with an engine over 350cc, and that HIS bike had an engine as big as Swinnies Mini!

I am slightly embarrassed by the retort I offered that it also had a shaft drive like Swinnes mini, and for how much it weighed might as well have been Swinnies mini.. at least he could cart his tool shed about with him, in that! (He wasn't particularly enamored when his ultimate rebuke to a 14 year old, "So what do YOU ride then?" was answered by "XT500" lol)

Old GS 850's make useful trikes I believe...... think I'd still prefer the Mini Traveler, though.......

On topic, though, its a bit of a skew argument; I'd suffer a 400N..... and I'd find the 'fun' I could have with it.. crikey, found some fun in the 250 Lardy-Dreams, and HAVE fun with 125 Pooper-Dreams!

Some-one once asked why I didn't 'commute' on my Cota trails bike.... That's a lot of fun to ride.... where mountain goats fear to tread... I cant nightmare how painful it would have been trying to commute 25 miles a day on... without some-where to 'sit' though! (Let alone it being want to nip up if asked to sustain more than 30 for the length of a field!) Wouldn't imagine there to be much fun trying to wrestle a GL1000 through a trials section, either! Though was quite 'fun' riding the VF-Tho out of a water-logged, hill-side rally field, over tractor ruts, fully loaded, 'feet-up' in the face of folk trying to wrestle adventure sports out the mud and hand-cart luggage to the farm drive to load'em..... but probably not at the time!!! Bit of a laugh when back o hard-standing... rather arse twitching during the act, ISTR!!

B-U-T... all something of a detraction.

CB400N may, as bikes go be pretty much as dull as ditch-water, and as un-aspirational a motorcycle as you can imagine.. but, with the right approach and attitude, not expecting the bike to serve the fun for you.. if that was what I had? The places it could take me; the things I could see, the things I could do 'with' rather than on it?
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A100man
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PostPosted: 09:43 - 29 Mar 2021    Post subject: Reply with quote

Ste wrote:
Easy-X wrote:
Honda CB400

Thinking

Completely off topic; but when I was at high-school, we had a very wizened old tortoise of a woodwork teacher; he drove a rather old Mini Traveler (you remember the estate car version, with the feaux 'woody' back?) and should have retired five years before, but no-one had the heart to tell him to stop coming to work! His successor was a young chap straight out of teacher-training school, who rode one of them, and thought that and his leather jacket would make him seem 'cool' to us.... I recall a conversation about 'bikes' he was party to, in which he offered ridicule of an ER50, and that we'd know what he meant when we'd tried something with an engine over 350cc, and that HIS bike had an engine as big as Swinnies Mini!

I am slightly embarrassed by the retort I offered that it also had a shaft drive like Swinnes mini, and for how much it weighed might as well have been Swinnies mini.. at least he could cart his tool shed about with him, in that! (He wasn't particularly enamored when his ultimate rebuke to a 14 year old, "So what do YOU ride then?" was answered by "XT500" lol)

Old GS 850's make useful trikes I believe...... think I'd still prefer the Mini Traveler, though.......

On topic, though, its a bit of a skew argument; I'd suffer a 400N..... and I'd find the 'fun' I could have with it.. crikey, found some fun in the 250 Lardy-Dreams, and HAVE fun with 125 Pooper-Dreams!

Some-one once asked why I didn't 'commute' on my Cota trails bike.... That's a lot of fun to ride.... where mountain goats fear to tread... I cant nightmare how painful it would have been trying to commute 25 miles a day on... without some-where to 'sit' though! (Let alone it being want to nip up if asked to sustain more than 30 for the length of a field!) Wouldn't imagine there to be much fun trying to wrestle a GL1000 through a trials section, either! Though was quite 'fun' riding the VF-Tho out of a water-logged, hill-side rally field, over tractor ruts, fully loaded, 'feet-up' in the face of folk trying to wrestle adventure sports out the mud and hand-cart luggage to the farm drive to load'em..... but probably not at the time!!! Bit of a laugh when back o hard-standing... rather arse twitching during the act, ISTR!!

B-U-T... all something of a detraction.

CB400N may, as bikes go be pretty much as dull as ditch-water, and as un-aspirational a motorcycle as you can imagine.. but, with the right approach and attitude, not expecting the bike to serve the fun for you.. if that was what I had? The places it could take me; the things I could see, the things I could do 'with' rather than on it?


Ste. Teff has hacked your account and I claim my five pounds.
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Easy-X
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PostPosted: 18:42 - 30 Mar 2021    Post subject: Reply with quote

The pod filters got a good clean today and actually made a bit difference!

Idle to ~2.5k is smooth then up to ~3.5k it's a bit rough but over 4k it's lovely; TBF a perfectly usable bike now. Might still piss about with the pilot jets / needle position unless an airbox turns up cheap on eBay.
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stinkwheel
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PostPosted: 19:15 - 30 Mar 2021    Post subject: Reply with quote

A company called 6-Sigma do jet kits for the CB400F. Stages 1,2,3 and 7.

Stage 3 is for pod filters with a loud pipe.

They will also be new, not ovalled or worn jets and needles.

https://www.6sigmajetkit.com/honda-cb400f-jet-kit.html
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Fizzer Thou
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PostPosted: 11:14 - 31 Mar 2021    Post subject: Reply with quote

I first encountered the Honda CB400F back in 1977 when a bloke at Navy College bought one.He had thrashed it around Brands Hatch and found that the standard exhaust reduced the ground clearance by quite a bit,so fitted a Devil complete system.He messed with the jets and air filters but it was never easy to remove the carbs quickly or easily,similar to the CB550F1 that I bought the following year.

What we did find was that the overheated engine and blown head gasket from prolonged over revving of the liitle four had also caused the 'O' rings between the inlet manifolds and the cylinder head to shrink and one had split,with the other three going that way.After those had been replaced it was a lot easier to adjust the running of the mixture.

Part 108 on the fiche

https://www.cmsnl.com/honda-cb400f-england_model14639/partslist/E01-1.html#.YGRJfZrTXIU

Dave Silvers also hold a good stock of CB400F parts Wink which is a lot better than buying similar parts from an eu country

https://www.davidsilverspares.co.uk/CB400F-SUPER-SPORT-FOUR/
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Easy-X
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PostPosted: 14:45 - 31 Mar 2021    Post subject: Reply with quote

If anything it's a bit rich rather than lean (air leaks) if cleaning the pod filters makes any odds but I'll take a peek at the aforementioned O-rings next time it's apart.

I'm starting to see the benefit of a single carb thumper or twin versus a whole bank of four Shocked Even just changing the needle clip one notch would be a major undertaking - actually harder than changing out jets.

Oh, and Dave Silver's a godsend Thumbs Up
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Easy-X
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PostPosted: 14:51 - 31 Mar 2021    Post subject: Reply with quote

BTW it seems the NOVA and dating paperwork might be wrong. It's meant to be a 1975 CB400F (colloquially known as a CB400F0 to distinguish between the CB400F1, CB400F2 later variants) but the pillion pegs are attached to the frame which wasn't a thing till 1976...

That's the calibre of Classic Bike Autism required at bike meet ups Laughing
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Robby
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PostPosted: 10:35 - 01 Apr 2021    Post subject: Reply with quote

Ok, so not what would be typically thought of as a 400c grey import - that usually refers to the mid 80s - mid 90s Japanese 4 cylinder 400s, imported from Japan. Well known for having power outputs of around 60hp, and achieving that by revving quite high and being gutless and low revs.

This is not that. This is a 45 year old bike that could have all manner of little problems, not helped by running on pod filters.

My preferred method to get it running right would be to fit a standard airbox, and do all I can to ensure a good seal between carbs and engine. Also looking at anything that could cause an air leak on the carbs, like throttle shaft seals. More of a problem at tickover, but seeing as it's a pain in arse to do anything on the carbs you really want to take them off once and do a proper job, rather than keep removing and refitting.

Start from the assumption that it never ran right on pods, people have cocked around with every carb setting there is, and the jets and needles are worn. So four carb rebuild kits and an airbox will get it running right.
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Easy-X
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PostPosted: 18:30 - 11 Apr 2021    Post subject: Reply with quote

Good news! An airbox has turned up on eBay with a job lot of other spares, should be able to drop the stupid pod filters Very Happy
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Easy-X
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PostPosted: 19:28 - 05 May 2021    Post subject: Reply with quote

Bad news! The seller of the airbox (+ associated bits) didn't hand out the tracking information till way too late and seemingly didn't think of slapping on a return address so it's all sitting in a depot somewhere Sad

Good news! A fella with a full vacuum-gauge setup has fine tuned the bench-balance I did and now the low to mid RPM stumble is barely noticeable Smile For pod filters I'd call that a win and job done.
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