GazVF500

Have you got the hole in the outer edge of the diaphragm properly around the very small brass tube in the top of the carb? You can see the part I mean in your picture of the slide, at the top left next to the small spring.

Hi Keny, the fuel tap issue affects non-fuel pump bikes too. Definitely worth a check.

Regarding the condition of the frame, make sure the drain holes are clear in the lower rails, and that they're not thin with rust. Easy to see when it's been blasted, but make sure you do it BEFORE the frame gets powder coated or painted! Its a shame to have to grind back fresh coating to repair the frame. The swing arm does indeed need a 14mm allen socket (I made one out of an old long Honda rear engine mount bolt, by bending it through 90degrees along its length) and a spanner. The only special tool required for the frame from memory is a C-spanner for the headstock. Good luck with the rebuild - have fun!

The fan on mine comes on when stood in traffic, but not during normal riding. I'd agree with the gauge running about halfway when doing normal speeds, and then climbing to 2/3rds before the fan comes on.

Hi All, I need the collective wisdom of the forum once again! Did about 125 miles on the bike today on a charity bike ride from my home to Harwich, a south-eastern seaside town. So I filled the tank on my way out this morning. The journey was all highway riding, at normal (i.e. legal) speeds, and I got most of the way back when the bike wanted me to switch to reserve tank. As far as I could tell the bike is running absolutely fine, the engine felt responsive, smooth and behaved itself very well. Does 125 miles sound a touch low to anyone else? I'm sure I've had closer to 150 normally. What should I be looking for - I guess a carb cleaning session is in my near future!

No the lead in fuel was to stop valve seat recession caused by micro-welding on soft materials for valve seats - e.g. soft cast iron heads. See your local BMC mini or MG B for details. The lead works as a lubricant. As the Hondas have aluminium heads, Honda fitted hardened ferrous (iron-based) exhaust valve seats so that enable the bikes to run on Unleaded - because the materials used meant that valve seat recession was not an issue. Dropped valves are usually caused by valve spring weakening, allowing the valve to bounce against the seat, weakening the narrowest part - the stem. Does anyone if this is more or less likely in engines that have sat in the same position for a while (says he who owns a VF that was last registered on the road in 1994....) - an anecdotal story says that privateers with formula 1 engines used to have to turn the engines to a different position every day to avoid valve spring "set".

One point on the brakes not releasing - before spending any money and stripping and rebuilding anything, make sure the very small return hole in the master cylinder is not blocked. It's under the little metal plate in the bottom of the reservoir, and needs poking through with a fine wire. If this gets blocked, the brakes won't release. Does it happen on both calipers or just one? If it's both, the problem could just be dirt in this return hole. Hope that helps!

So some hasty Googling has turned up this:- http://www.nrp-carbs.co.uk/shop/index.php?route=product/product&keyword=VF500&product_id=697 and from the same site these:- http://www.nrp-carbs.co.uk/shop/index.php?route=product/product&keyword=VF500&product_id=696 I think I know what I'm getting the bike for Christmas......

Thanks Yoshi, Its definitely the selector seal in the tap - I can blow through the outlet with the tap set to main tank only, and feel air coming out of the reserve port. Do you have a link to the Chinese taps?

OK, so after the carburettor diaphragm troubles here:- http://www.vfrdiscussion.com/forum/index.php/topic/76132-vf500f2f-5k-misfire/ I want to tackle the only other niggle that I've got with the bike. Just recently, the Main and Reserve sections of the tank have been working as one - meaning that the tank runs fully empty when its on Main and leaves me with no reserve, which has made riding the bike long distances with uncertain availability of fuel stops a bit anxious. I'm struggling to find a replacement tap, and with them all being about the same age, I'm thinking that its likely that they'll all suffer the same fate eventually. So I have some questions:- Has anyone stripped down the tap to see what's dividing the inlets on the tap? Is it sealed by O-rings, gaskets, etc Can I drill the rivets out and replace them with small nuts and bolts? Any information anyone can provide would be gratefully received, as usual.

So I finally got a day to get to the bottom of this issue. The plan was to change one thing at a time, and then a quick road test in between to see if anything improved. Started by changing the plugs (what a mission that is!). I also checked the valve clearances while I had half the bike apart. No difference. Plugs didn't look too bad. So then I dropped the oil, and while the sump was empty I changed the pulse generators. Replaced the oil filter, filled back up with oil. No difference. As a last ditch attempt, I then removed the carbs and stripped them right down. That's when I found this! So I thought I'd swap the piston and diaphragm with one of my spares, took me 3 goes to find one that didn't have a pinhole split in it! Put the carbs back on last night, and the bike is back to normal! Need to balance them back up a bit, and tweak the idle mixture, but I think we're onto a winner. The spark scatter on the front cylinders seemed to be a red herring, it would be interesting to know if anyone else's 500 shows the same issues.

OK, the P/N for the quick release fasteners is 64507-KE8-701. You can use something like this for the parts that rivet to the fairing. http://www.ebay.co.uk/itm/6x-Genuine-Dzus-Yamaha-Ducati-Honda-Motorcycle-Fairing-Fastener-Rivet-On-Clips-/130932663176?pt=UK_Motorcycle_Parts_13&hash=item1e7c31e388#ht_1718wt_1170

I actually replaced the Dzus fasteners on mine. The screws are available from Honda, I'll dig out the P/N for you. As for the parts that rivet to the lower fairing, they are standard Dzus parts, available from eBay. I was pleasantly surprised at their availability! Looking forward to seeing pics of yours as you progress with the rebuild!

Thanks to everyone for the help. I bought some Pulse Generators from eBay yesterday, and they've turned up. Measuring the resistance, I get 397 and 415Ohms, which is not quite the spec in the manual, but it's better than my current units. I also managed to get two spark units which have the same labels as my current ones. Will plug them in at the weekend and see what happens! The plot thickens.....

Can someone kindly confirm that the correct spark units are fitted to my bike? I've seen Yellow, Blue and Red labelled ones on eBay, and would just like to check. My spark units are Red labelled, and as follows:- Small Spark Unit:- A K B Z 5 5 131100 - 4651 12V MF2 Large Spark Unit:- A K B Z 5 7 131100 - 4670 12V MF2 Do these sound right for an '86 UK VF500F2F?