My RC24 resurrection

This is a picture I took of the position of the float as the tang on the float started to touch the metal wire at the top of the needle to open the float valve; not close it. Have I got that the right way round?



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the best way to clean an idle jet and gauge that it's fully clear is like this......

 

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Nope, wrong way round, the float tab touches the button on the needle to close the fuel flow.

if you connect a clean section of fuel hose and blow through it so you can hear the air passing through....then rotate the carbs so the floats touch the needles, and that should stop you blowing air thru the hose.

 

Likely OEM.

The tests mentioned earlier -- blow thought and also leaving the carbs in the washing basin attached to the fuel bottle will tell you if its F'd

If it looks damaged, best replace the needle and seat with OEM

 

Yep, did that.


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So when I do the float height check, the needle should be in the fully seated (closed) position?


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^^ yes

 

Cheers mate!


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Just to add that, the plunger on the needle shouldn't be full depressed, just lightly seated. again, if you hook up a clean fuel line and blow into it you can tell when they "just seat"

 

I was thinking that you’re unlikely to have got 2 of the 4 carbs correct and wondered about the ignition circuit diagram

Cylinders #2&4, #1&3 use different pulse triggers, so check the wiring from the pulse generator to the spark unit ….like this https://www.cmsnl.com/honda-vfr750f...andmph_model19883/pulse-gen-assy_30300ml7003/

Electrex offer single pick ups, they should be able to sort you out, you’ll probably have to send it to them though

As #1&3 ran the spark unit is OK

If #2 fired up then it’s likely a dodgy connection, you can test the triggers against each other for internal shorts or excess resistance

This is an old thread on here on the subject, lots of waffle tho ‘ https://vfrworld.com/threads/pulse-generator.47878/page-6

 

Hi mate. Thanks for this, but I’m not quite with you. When you say ‘the plunger’ do you mean the needle? Do you mean just the very top of the needle, where it touches the metal tang of the float?


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Cheers thumbs. I was wondering whether it was something to do with the pulse generator. I don’t have much time tomorrow so I will use what time I’ve got to start checking the coil resistances, continuity of ht leads, and I’ll have a look at this too.


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Hi there, on one end of the needle is the Viton rubber tip, on the other end is a spring loaded plunger and a wire hanger that hooks over the float tab. The float tab pushes on the spring loaded plunger, but the Viton tip will seat and seal in the seat BEFORE that plunger is compressed. So you want to test float height with the Viton tip sealing off in the seat, but NOT with the plunger compressed.

 

Got it! Thanks mate! Didn’t realise the top of the needle was spring loaded. Now all that makes sense! Every day’s a learning day!


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I now have a bike with 4 working cylinders. I am a bit of a numpty. Will explain.
Started off checking the resistance of the coils. All seemed ok. Not the same values as in the workshop manual but did equate to the resistances given in the Haynes manual, so all good.




Also pulled out the carbs again and re-did the float heights on carbs 2 and 4. They were both out by some way, but thanks to the advice above, I was happy with the end result.

Got the carbs back on and the front 2 cylinders were firing. Excellent. But I noticed a popping from cylinder 1, where the seal around the boot wasn’t tight. Sorted that out, only for the front 2 cylinders to stop firing. End then the penny dropped…

You now how I said that was getting good at taking the carbs on and off? I was lying! The reason I’ve had most of these problems is because I haven’t been seating the carbs correctly in the boots. Obvious when I saw it happening. At one point I was gently pushing down on the carb rack and this was causing cylinder 4 to start firing when the seal was ok; when I realised the pressure, a dead cylinder. What a numpty!

So went out and got myself a good quality ratchet strap and used this to make sure they were all seated in properly. And bingo.

It’s still running a bit rough at idle but sounds so much better when the throttle is opened up. Hopefully this will be sorted out with a carb balance. I’m not sure how to go about measuring the mixture? Any more tips gratefully received.

Still waiting for the cover gaskets to arrive, but when they come I’ll get the clearances sorted. At least I own a V4 and not a V3!




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Exactly the tool I use

 

glad you're making progress !!

 

A couple of weeks off to regroup and had a lot on at work, so will be getting stuck into the VFR for a bit. The plan is to do the following stuff, this week.

1. Drain the cooling system and remove the radiator. Straighten the bent fins, flush and check the fan over. Give it a spray. Thought I’d go for a Matt black rather than silver? The grill in front of the rad is broken at one of the mounting tabs. Looks aluminium so don’t think I can fix, so will have to source a replacement.
2. While the rad is off, get the valve covers off, clean and re spray and check and adjust all the valve clearances. Hopefully that will cure the persistent knocking I can hear, which I think is still coming from that pesky third cylinder. I’ve watched a lot of YouTube clips, and advice on the valve adjustment? Seems I just need a 10mm spanner and my feeler gauges. Anything to look out for?


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^^ don't use an open-end wrench on adjuster locknuts, box-end only. in back of the fan you can find a small hole where you can oil the rear motor bearing. if you've located noise to one cylinder, inspect the adjuster screw bottoms for damage.