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Messages - K2-K6
1
« on: May 08, 2026, 04:02:24 PM »
Yes agree with your thoughts Ken, it should show with wet feet though  out through the overflow tubes, if they are letting by. Interesting to hear if there's any improvement after the checks done and work on carbs.
2
« on: May 08, 2026, 02:04:02 PM »
If float valves (controlling fill from tank) are a OK, then it shouldn't matter how long the tap is left on prior to start.
As most things are checked, and carbs cleaned too, then if it persists a check of compression psi would be helpful in establishing whether anything is out of range there.
3
« on: May 08, 2026, 10:01:03 AM »
Its now fairly routine in bigger MTB forks to do tbe same in packing the preload to get ride height correct.
They're called "tokens" in there, and proprietary hard plastic that can be clicked together in addition for gaining more distance. There's general use of fork stanchion @ 40mm diameter too for racing purposes.
Some also use internal spacer that screws inside the spring coil to change the rate of spring by making section of coil incompressible, gives effectively a shorter wire length, which lifts the spring poundage without changing the spring.
Looks here that maybe previous owner was in need of jacking the front generally with the longer spring + spacers fitted.
4
« on: May 07, 2026, 08:17:43 AM »
Thats not a "later" one its an aftermarket one, they can be very unreliable and it only take a fraction of a second of reversed polarity to wreck them
It's not from SOHC F2 but later twin cam 750 (not the 70s replacement for SOHC motor either) that was original fit "OEM" and Japanese supplied component.
5
« on: May 06, 2026, 10:35:01 PM »
Perhaps one from a later Honda https://www.ebay.co.uk/itm/277950477570 combined unit from OEM supply, would need individual "adopted" loom end into existing SOHC plug.
6
« on: May 06, 2026, 12:31:41 PM »
The problem with them screws is that there is very little contact area between the screw head and the carb body, essentially a ring 0.2 mm around the screw head making contact and no friction as you tighten them which in the wrong hands could easily result in stripped threads or them working loose.
A heads up for anyone else thinking of buying these, check that the head diameter 12mm. I didn't loose much with these ay £3.50 for 2 , I just added a couple onto an existing order get above the free postage threshold.
NRP have the Keyster ones back in stock now at just over a fiver each. Might have to bite the bullet. I'll hold off for now until I have sorted through all the spare brassware to see what else I might need.
Does anyone have any good tips for cutting neat screw slots, I have seen something somewhere about folk grinding the set off a hacksaw blade to get the right thickness? Machining the threads and holes be easy enough and I have enough round brass bar laying around.
Regards
Dave
Something like this https://www.ebay.co.uk/itm/336154261880 available in 0.5mm thickness, but would need rudimentary mount to drill etc and some method of holding brass bar and moving across this, thinking lathe cross slide and dremel ? A woodworking mortise hand saw will cut brass more accurately than trying to hold a hacksaw blade straight enough, could be utilised.
7
« on: May 05, 2026, 07:28:27 AM »
There are two small ports on my F1 front master cylinder that allow the brake fluid to enter the piston bore.
The little tiny one appears to be blocked.
I've tried poking it with a sewing needle etc, but so far no luck.
Thinking about drilling it now, but unsure of what size to drill.
Anyone know ?
I'm thinking too big a hole is going to have a bad effect on the master cylinder.
A dressmakers Pin is usually thinner than a needle and with less taper from tip into shank, they often pass through smaller holes but helpful with pliers to hold them ordinarily such that you can gently wiggle them.
8
« on: May 05, 2026, 07:16:17 AM »
The bore size effect controls different aspect, the one nearest to line output has to be fully closed to build line pressure. With an increase above std, that would delay closing and increase lever travel before caliper "activation" but once past that, the master seal would operate the same as system to line is fully isolated from reservoir.
You can get 0.3mm pcb hand drill bits that should be under that size, but check initially to see if it's OK.
Have you got the mastercylinder apart, or trying to clear in situ ?
9
« on: May 04, 2026, 12:53:39 PM »
Thanks Tricky Mick for the seat info. I managed to undo the lock and open the seat. The air Filter looks brand new, so I will have to investigate further.
If the weather holds today I will try some further tests. I have compared the speedo with a Sat-Nav and they are within 2 mph of each other.
Mine is a Red bike, but I have several litres of JCB Yellow Paint, if all else fails. . . !
Something that may need double checking, some years ago I had a honda that had stood for a while, that air filter looked new, but just would not flow properly, giving rich mixture and "capped" power output. Whether it had been damp and possibly compromised, or something else that I couldn't readily explain, the result was clear and when swapped it was fine. Tenuous link, but a possibility to consider.
10
« on: May 04, 2026, 12:19:56 PM »
I noticed yesterday that no 2 exhaust pipe warmed up a little slower than the test although it seemed to start OK so I believe the cable / plug on no 2 is occasionally breaking down.
The leads on all plugs are a bit short like they have been shorted a number of times so time for new hardware .
That rings alarm bells for a poor running cylinder. Given that your other investigations have not given anything confirmed as probable cause, that partially missing cylinder needs investigating for both ignition and idle circuit fuel supply. If you have a borescope it would be worthwhile looking in there to see if there's anything untoward. The cheap type for phone, with front & side facing camera are really good value to get decent inspection. Hope you have a good holiday, anywhere interesting ?
11
« on: May 03, 2026, 03:52:30 PM »
Thanks for the replies..
I'm putting two and two together here...
I am unable to get the seat to open, as the lock is stuck. Also the plugs are a bit sooty.
So maybe my air cleaners need cleaning, as it is most likely running too rich.
Thanks for all the replies so far..
When contemporary, a few friends completed the "I left something under the seat" routine, that to restrict the air intake. Notably a pair of waterproof overtrouser that his bike shop removed for him when he put it in for service because of the poor running He was suitably embarrassed about that one 
12
« on: May 03, 2026, 10:17:30 AM »
The CB200 is much more of a grunty little motor and tuned more for that torque in low range, to quite good effect.
The 400 really needs to be revved out to get the higher end performance. Generally low torque but productive high rev performance. Youd probably need to ring it right out to red line in forth before even thinking about fith if wanting to see how fast it'll go. It just won't reward early upchanged ratios with much in the way of ultimate pace.
You've got to let the four sing its head off for extraction of absolutely speed.
13
« on: May 03, 2026, 08:27:42 AM »
From the experience with my 400F over the past few years, the bike will run great on E10 fuel with totally stock settings on everything - jet size, needle position, airscrew turns, STOCK type muffler and stock air filter/airbox. As noted, leaving untreated fuel (without some sort of fuel storage additive) in the tank and especially in the carbs for extended period will have bad results.
I don't see particular problems either, but here with possibly lean mixture (flat spot etc) it could help compound any effects by containing more oxygen in fuel mix. There's reasonable margin (there usually is on non accelerator pumped slide carbs) as they have to be set with bias to slightly rich to run correctly (the bog std setup) but with needles dropped plus E10, there's some measure of compound effect that eats the margin provided by standard settings. My view is that these engine are very sensitive to being run in the correct air fuel range, when everything is fine. Outside that though, unintended consequential problems quickly build.
14
« on: May 03, 2026, 08:15:56 AM »
From this "Just to clarity when the bike died it would not even turn over until it had cooled down" do I understand correctly that it had partially seized, which stopped you turning the engine over ken4004 ?
That sets alarm bells ringing especially after a recent engine rebuild.
A partially blocked oil pump strainer gauze screen (possibly with surplus gasket
sealer etc) can cause restricted oil flow to the cylinder head, over heating and eventual camshaft seizure.
I'd pull the sump pan off and inspect the strainer gauze and check the oil filter at the same time.
Good luck
It does for me too, and similarly feel caution in checking possible cause is time well spent. My thoughts also go into running lean, the situation described with high heat long hill, flat spot (classic lean consequence) and motor coming to a stop. Then not re starting but free when cooled .... suggest "nipped up" to me, if no poor oil supply etc that points to classic partial bore seizure.
15
« on: May 02, 2026, 08:42:27 PM »
From this "Just to clarity when the bike died it would not even turn over until it had cooled down" do I understand correctly that it had partially seized, which stopped you turning the engine over ken4004 ?
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