VFR750 1990-93 To 1994-97 Carb Swap (3rd Gen to 4th Gen)

[smallfrowne]

Not sure why I'm doing it now, other than it's something to do, and my set of carbs is missing a trumpet which saddens me.

Original carbs on the right from the 90-93 era and on the left the 94-97 era carbs to go on.

(Note the missing trumpet on the older set, which wiggled its way loose and snapped its locating tabs off somewhere on a trip to the bottom of Spain)

The later carbs are flat slide, and have a smaller gob (34mm vs 36mm) which is sad as bigger is better. Nevermind. Might make up for it with huge jets though. Heh heh. OK they have different attributes so can be smaller and flow alright.

To do this swap you need:

• A set of carbs, durrrr

And also off the later bike:

• Airbox, they are different although the filter and filter cover is the same (the snorkel is different too)

• Throttle pull and push cables (old ones are shorter, because it uses the front carb as the master, later uses the rear)

• Probably choke cable, though mine was knackered anyway. But the later one is definitely a smidge longer

• Intake mounting rubbers, these are slightly different.

Additional annoyance is the throttle stop adjuster. This is longer on the later bike and 'cobbles up' when you fit it in the position of the early bike and try to make an adjustment. This would be fine if you could simply use the shorter adjuster off the early carbs, but the old uses M4x0. 7 and the new, M5x0.8. Hmmm

Pull cables on the bottom, throttle stops in the middle and the new close/push cable at top but I didn't yet get the old one out for comparison. Later cables at bottom, old above.

Later snorkel on the left, old on right.

I've just fitted the cables for now but am waiting for a set of float bowl seals before I crack on because they were a bit perished.

[fastbob]

I've just figured out what those connecting strip things are on the bolts . I'm guessing it's a super safe way of ensuring that a loose bolt can't find it's way into the engine . Very thoughtful of Honda .

[Snod Blatter]

Smaller carbs? Doing it wrong.

A cable tie will sort out the idle speed adjuster shirley?

[fastbob]

Smaller carbs? Doing it wrong.

A cable tie will sort out the idle speed adjuster shirley?

[smallfrowne]

Bugger. Had the issue with the mix screws but after that plainish sailing, or so I thought. Got to the point where everything was hooked up, cables, fuel hose, air filter. Larvely jubbly. Key turned in the ignition, fuel pump pumping, starter motor motoring... Blub blub lub blub lubbbbblublblbub... Alright she works. And pisses petrol out all over the top of the engine, wooo.

Rigged up the carbs off the bike in hope of getting a better view of the leak. Set the pump up with an extra battery to fill the bowls again but they didn't leak :/ So, back on the bike and try again. Pissed fuel out. Interesting.

Split up the carbs time, nice.

[Gerontious]

Tick Tock.

[smallfrowne]

... goes the clock.

Might as well give them a bath then.

[Mr Fro]

Now that's a proper size sonicator.

[smallfrowne]

It's not bad, wish it was mine but my mate doesn't seem to mind lending it out. I'll get him some chips

Cleaned up well. The problem was a dry o ring on one of the plastic fuel inlet T pipes. But actually they were all ready to go. Soo new ones of those on, and it should all be OK...

At this point I was thinking I hope this is how it's meant to go. But I didnt realise the games to come, the fun of getting the stacks in place whilst simultaneously trying to get the top plate back on was a good finisher to the game of squishing the carbs together, aligning some spacers and 3 different T pipes. Then I still had to squish the carbs onto the bike. Anyway, all that behind me...

Not that badly out of sync to say theyve had a good fettle.

Some melted knuckles later and voilà.

Next: 150mph test ride