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Messages - Aye Gee 1977
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1
« on: March 23, 2024, 09:46:53 AM »
Thanks to all. I accept the condenser is the most likely culprit, and I'll check again. It's just that having tried three separate condensers, I was looking for another possibility.
The plug caps could be renewed; at this stage I can't quite see how an issue on the HT side can cause a problem on the LT side - but maybe it can!
2
« on: March 22, 2024, 03:23:08 PM »
It's a standard battery and coil system
Points 1-4 are arcing excessively - the spark is much the same as at the plug and it causes a misfire, which clears for a while when the points are cleaned.
The condensers are new pattern DS parts; I've tried swapping them over with the 2-3 set and also returned the original (40 years old) one. Whilst you can convince yourself that there is a marginal difference, before long it's points 1-4 that are troubling.
The LT resistance of the coil is 4.2 ohms (same as the other coil). I can't yet see how it can be caused by the HT side but nevertheless it has a resistance of 30.9k ohms (only 23.4k ohms for coil 2-3). The plug caps are 8.3k & 8.6k (4.3kx2 for plug caps 2-3 - which are a longer reach type).
New set of NGK plugs.
Any thoughts on what is causing the arcing would be most welcome
3
« on: March 01, 2024, 10:31:38 PM »
The silencer supplied by DSS look good but didn't fit that well.
It sits too high and too near the bike such that it fouls the rear wheel spindle nut. Packing can get it better, but still not quite right.
4
« on: February 28, 2024, 05:24:20 PM »
Aren't the throttle and the carburettor at the same end of the cable?
The twistgrip is typically at the other end.
5
« on: February 26, 2024, 04:34:18 PM »
OK - time to report back.
It's a single outlet tap; I'm not sure I know where the second outlet would link to?
The NRP kit arrived well; you don't get a lot for your £25 (cone, two screws and a couple of rubber seals. The spring fits between the lever and the cone, which pushes the cone into it housing which is logical even if it leaves a seemingly pointless void at its other end.
It was a tight fit and when assembled, bound the lever. The cone is, I would judge, turned from stock and had a small burr on the larger end, which I then removed hoping it would press home. But the tap still passed fuel when in the off position! Neither could I find space to fit the large washer so it got replaced by an O ring. This large washer prevent a petrol leaking out of the tap - it doesn't help seal the on/off/reserve function., so that's not the problem.
Petrol must be passing between the cone and its housing. The two seem to fit reasonably well - but maybe not as snug as they should be. Whether that is because the new cone has an incorrect taper or the tap is worn, I'm not sure.
Anyway, somewhat frustrated, I had another go at moulding a new cone. It's not perfectly petrol tight, but it's the best yet. I think the problem is with the two ports that lead to the tank. When moulded two limbs are formed which need to be cut off perfectly flush.
6
« on: February 19, 2024, 06:00:31 PM »
Cables and flexes sizes are generally expressed as cross sectional area of the conductor so a 1mm wire is shorthand for one having a CSA of 1 mm sq. Therefore the copper is proportional to the number i.e. 2mm is twice the size of 1mm.
Cable sizes on motorcycles are principally determined by voltage drop rather than absolute current carrying capability. The way this works, a 6v system requires a conductor four times the CSA of a 12v to have an equal voltage drop. Keeping the conductor size a bit sensible is the reason why the National Grid transmits a high voltages (e.g 275,000 volts) and steps it down locally for domestic use.
7
« on: February 12, 2024, 07:57:28 PM »
Ahem! The DIY moulded tapered cock works a bit, but passes a little fuel even when closed. It seems an odd arrangement to me, insofar as the spring presses the cone out of its house, which can't help. Maybe I have misunderstood how it is meant to work - my cone was a strange shape following its relationship with the blowlamp. The DIY method works sufficiently well to persuade me it could be done - given sufficient patience and skill. But in the meantime I have found someone that seems to sell the innards of the fuel tap https://nrp-carbs.co.uk/shop/index.php?route=product/product&product_id=5802I have ordered a kit. It's said to be for a a 1975-76 model whereas mine is a 1977 CB400F2. I'll post an update when it arrives.
8
« on: February 10, 2024, 11:41:18 AM »
My solution, and only time will prove its worth, has been to cast a new nylon taper cock.
I tried reusing the old nylon, but it resulted in bubbles and voids as it boiled soon above its melting point. I have had more success using a petrol resistant 3d printer filament. It was cast in the ally tap casing with bungs to prevent leaks to unwanted ports. Some work with a sharp knife and files required when cast.
It seems to work but it will be tried for real later today.
The best advice is not to melt the one you have!
9
« on: February 07, 2024, 10:03:26 PM »
As a younger man on a younger CB400F I toured Ireland on honeymoon in 1982, two up and staying in hotels. In 1983 we went camping in the Swiss Alps via Belgium, Germany and Austria all within a week. It performed well and was capable of carrying the luggage in hard panniers, tank bag and rear rack. The second trip resulted in several broken spokes in the rear wheel by the time we returned.
As the CB400F was becoming rather worn-out, it was retired in favour of a CX500B which was a better touring bike, but not something you could love so much. Quite how either bike would feel today in such circumstances in hard to know
I have just finished restoring the CB400F - and started the engine only yesterday, for the first time in 40 years. Looking back at my contemporary records, I have been surprised how much time and effort was required to keep a comparatively new bike running well. Maybe I'll post the various problems and issues sometime.
10
« on: January 14, 2024, 09:22:54 PM »
I fitted a Cibie headlamp to my 1977 CB400F2 after a year or so. The glass was concave then and remains so to this day!
It was a great improvement to the standard fitting but I can't remember whether it was a Z beam or whether that name was reserved for the 7" diameter version
11
« on: January 04, 2024, 07:00:31 PM »
I bought a tap repair kit from David Silver a few years ago and I'm sure that it included the nylon bush thingy.
I just had a look at DS and the repair kit doesn't include the nylon Bush. ☹
I kept an old note of some problems with the bike that included need for a new filter etc. And joy of joys, I recently found a brand new refurb kit that I must have bought 40 years ago and had quite forgotten. It all went downhill when I put the blowlamp on the tap. For those that like details, the large nut on the kit is plated whereas the one on the bike is plain brass
12
« on: January 04, 2024, 06:54:06 PM »
I suspect it's unlikely that innards from a new aftermarket tap will be interchangeable.
Many now have rivets holding them together.
I would try & source an original used one I'd start with Steve at 400 bits.
I bought one off e-bay but the thread was wrong so had a refund, it also differed from the photo that showed screws, there are a couple of different sized threads iirc where it fits the petrol tank.
What confused me was there is only one part number listed in the parts book 16951-377-005 like this one below.
.https://www.ebay.co.uk/itm/115828691611
I have a dented early 400 petrol tank & the tap is a different size fitting to my later 400.
Thank you. I will ask if 400bits has anything to help. It does seem that there is more than one fitting size
13
« on: January 04, 2024, 04:19:11 PM »
After a mere 40 years on non-use, I thought now was the time to restore my beloved 400 - bought new when 1 was 17 years of age and then ridden to death before being retired at 65,000 miles
I have had a few problems - the rear hub housing was worn due to the bearing turning within; this was a recurring issue when in regular use. Not noted previously, the sleeve between bearing and axle on the drive side has worn - presumably it was turning on the axle rather than the bearing; fortunately the spindle is unscathed. Anyway, all stripped down including splitting the crankcases (for the second time in my ownership) and now being reassembled. The chrome plating seems to be taking an age - it won't be long before it is holding things up. I just hope they haven't lost anything.
Parts are not too hard - but I can't find a rear mudguard (so had to patch the holes with fibreglass(!). I managed to dismantle the horn such that it now makes a noise of sort - and only broke the plastic a little when reassembling.
Anyway, I did a silly thing and applied some heat to the petrol tap to loosen its screws - which was successful! I now know there is a tapered nylon bush inside - with a low melting point. Does anyone have a spare bush or bustd tap, please? If it matters, it has a 20mm thread.
If not, can anyone speculate whether (and which ideally which) of the cheapo petrol taps on ebay might yield a suitable innard
Thanks
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14
« on: January 04, 2024, 04:02:47 PM »
After a mere 40 years on non-use, I thought now was the time to restore my beloved 400 - bought new when 1 was 17 years of age and then ridden to death before being retired at 65,000 miles
I have had a few problems - the rear hub housing was worn due to the bearing turning within; this was a recurring issue when in regular use. Not noted previously, the sleeve between bearing and axle on the drive side has worn - presumably it was turning on the axle rather than the bearing; fortunately the spindle is unscathed. Anyway, all stripped down including splitting the crankcases (for the second time in my ownership) and now being reassembled. The chrome plating seems to be taking an age - it won't be long before it is holding things up. I just hope they haven't lost anything.
Parts are not too hard - but I can't find a rear mudguard (so had to patch the holes with fibreglass(!). I managed to dismantle the horn such that it now makes a noise of sort - and only broke the plastic a little when reassembling.
Anyway, I did a silly thing and applied some heat to the petrol tap to loosen its screws - which was successful! I now know there is a tapered nylon bush inside - with a low melting point. Does anyone have a spare bush or bustd tap, please? If it matters, it has a 20mm thread.
If not, can anyone speculate whether (and which ideally which) of the cheapo petrol taps on ebay might yield a suitable innard
Thanks
15
« on: December 05, 2023, 03:43:09 PM »
On my 1977 F2 the cover was finished in silver enamel, same as upper crankcase.
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