My VF500 rebuild

[InvisibleCities]

For reference, from Factory Pro's website:

The main advantage of a jet kit is the ability to alter the needle "height" to dial in carburetion for various applications. Note that the aftermarket needle (top) has a circlip, which can be set in any of the grooves in the top portion of the needle, while the stock needle (bottom) has no adjustment. Check your jet-kit instructions for proper "base" clip setting. Note that the positions are counted from the top of the needle down: The "number three position" is the third groove from the top. The easiest method for installation/removal of the circlip is to place it in the desired groove, and gently force it in, by pressing the needle and clip against a flat surface. Place the open end of the circlip against a flat surface to remove. Be careful while handling the needles, as they are precision-machined pieces; bending them even the slightest amount renders them useless.

http://www.factorypro.com/index.htm

You can adjust the height on the stock jet needles by shimming:

http://www.motorcyclecarbs.com/Jet_Needle_Shim_Pack_12__P10478C7.cfm

Good luck!

[GazVF500]

So this weekend's task is to balance the carbs, now that its had some running and everything should have settled down.

So with the bike thoroughly warm (fan cutting in and out) I connected the Carbtune and got this:-

Not to worry, I thought. A bit of balance screw twiddling should have that sorted. But here's where I'm struggling.

I've got 1, 3 and 4 balanced, but can't get 2 to behave. When I adjust the screw for 2 (Left Front), number 1 vacuum goes up and 2 doesn't move. When I adjust number 1, number 1 and number 2 change.

I don't want to throw in the towel on this just yet - can anyone shed any light, or point me in the direction where I'm going wrong?

Also, I have a question - there is a balance screw on the number 1 cylinder, which I thought shouldn't have been adjustable. What's going on?

[timmythecop]

You are not turning the idle mixture screws are you?

You have to balance 1 and 2 and then 3 and 4. Then you balance 1-2 with 3-4.

[GazVF500]

Thanks Timmy. The manual I have doesn't say in which order to tackle it.

I think it's possibly that far out that I need to take the carbs off and do a "bench sync", and then start again.

I'm definitely not turning the idle screws. I wish the sync screws were as easy as those to reach, however!

[jeremyr62]

When I did mine I made some notes. I have a Mityvac and the Honda OEM synch tool.

Use a Mityvac to pull a vacuum to keep the fuel petcock open.
Turn up the idle to about 3000rpm

Jump the radiator so its always on! Important! engine gets really hot and fan switches can stick!

From the left side use the synch tool

First synch 2 to 4 (4 is black knob, 2 is the hex nut). This is the hardest to get to.
This synchs the front two carbs

Then move to rear two
Do furthest away from left side hex screw first which is 3
Then do the nearest which is 1

Now these numbers are consistent with the cylinder numbers in the FSM but differ from some interweb documents which transpose 4 for 1.

You can get them close but not perfect. If you press too hard when adjustting you are moving the butterflies so will get a bogus reading.

Don't forget you can turn the Carbtune upside down to change sensitivity.

[GazVF500]

Thanks for all the inputs guys!
So I took the carbs off and made myself more familiar with the workings of the screws.

Each adjuster works directly on the master linkage - so each cylinder can be adjusted without affecting its neighbour. Its just that mine were so far out, adjusting one carburettor allowed all the rest to close further, knocking out the readings.

Put them back on after the bench sync, and had to adjust number 2 slightly, which as you've said, Jeremy, is a pig to get at!

Just got to set the idle speed after a quick ride out, and then her bodywork can go back on.

Much better!

[InvisibleCities]

Glad this worked out!

For ref:

When I did mine I made some notes. I have a Mityvac and the Honda OEM synch tool.

Use a Mityvac to pull a vacuum to keep the fuel petcock open.

Turn up the idle to about 3000rpm

Jump the radiator so its always on! Important! engine gets really hot and fan switches can stick!

From the left side use the synch tool

First synch 2 to 4 (4 is black knob, 2 is the hex nut). This is the hardest to get to.

This synchs the front two carbs

Then move to rear two

Do furthest away from left side hex screw first which is 3

Then do the nearest which is 1

Now these numbers are consistent with the cylinder numbers in the FSM but differ from some interweb documents which transpose 4 for 1.

You can get them close but not perfect. If you press too hard when adjustting you are moving the butterflies so will get a bogus reading.

Don't forget you can turn the Carbtune upside down to change sensitivity.

Well noted!

[timmythecop]

Nice! Like IC said in my thread, a well tuned 500 motor is a thing of beauty. She should go like buttah now.

[GazVF500]

OK so I've been riding the ol' girl for a while now and it seems to be going great! I went on a trip to North Yorkshire (250miles each way), across motorways, main roads, and the (much more fun) tiny winding roads around the Dales.

It runs great, I can't feel any flat spots or anything other than a fantastically linear power delivery, so it doesn't look as if the exhaust has upset it at all - which is nice given all the hearsay and "it can't be done" that was banded about in the other thread!

However, to repay me for leaving her in the garage for a week while I went away on business, I came back to a strong smell in the garage like household emulsion. Yep, the tank had sprung a massive fuel leak!

So a radiator repair shop has fixed it for me, testing it to 1 bar pressure afterwards - but in doing so they've completely wrecked the paint! Good job I have some left.

As my dad commented "ah, its good practice for you".....

One step forwards.........

[GazVF500]

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:-

1. Has anyone stripped down the tap to see what's dividing the inlets on the tap?
2. Is it sealed by O-rings, gaskets, etc
3. 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.

[YoshiHNS]

You can drill the rivets out and tap them with small screws (#4 I think). Most of the people on the VTR forums are going to the chinese petcock since they're half the price of the replacement parts. I have one on the track bike and it works just as well.

I think the reserve works where when it is switched to on, it takes in fuel through the brass tube which sticks up into the tank. When you switch to reserve, it allows fuel to flow through the orifice between the petcock and the brass tube. All is still covered by the in tank filter. You may have a bad brass tube, or a bad selector seal on the petcock. The brass tube is easy enough to have made. If it's the selector seal, go the dubious chinese route.

[GazVF500]

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?

[YoshiHNS]

I don't remember the specific seller. If your filter and tube are still good it shouldn't matter which you get.

[GazVF500]

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......

[Roebling3]

+1 using Caswell tank sealer. As in all painting and especially coating the inside of a fuel tank; Dedicated, careful preparation and application are critical. Do not even spend a moment imagining there's a better way than what the directions describe. Good fortune, R3~

[YoshiHNS]

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......

http://jbmindustries.com/K-72-S.html

13GBP instead of 38. You should replace all four at once so they operate the same. That's 100GBP saved, minus shipping.

I'm pretty sure they are the same. I would check honda part numbers, but the VTR250 and VF500 should use the same piston diaphragm.

[InvisibleCities]

Very good intel here on rebuilding the 500's petcock:

http://vfrworld.com/forums/showthread.php/29316-1986-interceptor-500-fuel-petcock?p=267354&viewfull=1#post267354

Good luck! Let us know how you make out.

[GazVF500]

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!

[tbzep]

iirc the tank is 4.1 US gallons and reserve is supposed to kick in at 1.1 US gallons. That would give you around 41 mpg US, which isn't bad, but I think I got a little better mileage back in the day.