4th Gen Carb Service

I've got a 97 VFR750 that has been sat for around 18 months since I last used it but I am intending to put it back on the road for this year. I started it up today with the intention of doing an oil and filter change but it immediately started leaking a large amount of fuel from the top of the carbs. I've pulled the carbs out the bike and traced the leak to the T shaped fuel supply pipes between 2 of the carbs, I suspect the rubber seals have dried up and perished from being sat unused.

Whilst the carbs are out the bike I'd like to give them a full clean and service to avoid any further problems and having to pull them back out in the near future. I considered doing the work myself as I have a ultrasonic cleaner and have successfully rebuilt carbs before, however these seem to be more complex and the linkages etc all look slightly more daunting! It seems like paying out a bit of money here might be well worth the time and frustration of doing it all myself.

I'm wondering if anyone has any recommendations for company's in the UK for V4 carb work? I'm hoping to have them fully cleaned and rubber seals etc all replaced. Picture of the bike below for good measure, back when it was fuel tight!

 

Probably leaking due to stuck float bowls, but if you going to go through the carbs anyway...that'll be solved.

The old FJs used to get that problem. Driving them off of a higher surface to a lower, like a curb, usually fixed it until next season.

 

Sadly it's not the float bowls. With the carbs off the bike running the fuel pump it's definitely leaking from the fuel inlet pipes.

I've been reading the how to on replacing them over on V4 Dreams and can get Viton seal kits from NRP in the UK so considering giving it a go myself.

 

The job is not "hard", it's tedious. A good work space you can lay everything out in the "exploded view", without risk of being disturbed.

 

That's good the hear!

Although I can get the seal kits here it looks significantly cheaper to order individual o-rings as I've seen mentioned elsewhere on here. Does anyone happen to have a list of sizes required? If not I guess the alternative is taking them apart and then measuring inside and outside diameters, then maybe going slightly bigger to give a snug seal?

 

Fuel tube: 7 x 2 mm

I can update later with the float bowl o-ring.

 

not a good idea, i think that won't work.

 

Great - thanks!

Ah okay - is the only real way trial and error then? Going through parts list doesn't seem to give any sizes. I'll go with the Captain's sizes anyway... it'll be better to have all the parts ready to go whilst the strip down is all fresh in my memory I think.

 

hit up magna andy he'll let you know what you need.That said striping them down isnt that bad,plus you can repair your angry enrichment systems.

 

76 x 2 mm Float Bowl o-rings

99% of the time when I get into carbs, the fuel cross-overs and float bowls are really the only things that are absolutely needed. The other stuff I do just cuz I'm in there. The vent o-rings can usually be cleaned and lubed and still install snug.

And yes, trial and error. Some that seemed so easy and I was very confident, were WAY off. The vent tube o-rings were surprisingly weird. Just did this whole process for the coolant system o-rings too.

 

Awesome - much appreciated! Is it easy enough to shape those large o-rings to the float bowl? Seems like the sort of thing that you'll constantly be pushing one bit in as the other side pops out!

If you have the sizes already for the vent tubes I might as well tag them onto the order? Also, the tabbed O-rings between the carbs and plenum... are they usually good to be reused or worth replacing whilst in there?

 

Between the carb and plenum will be OK. Clean and red rubber grease or o-ring lube. If one seems damaged (unlikely) you can Hondabond no problem.

Float bowl o-rings will stay put. You can put a dab of grease on a tight corner if it gives you grief. It won't.

 

Got the carbs apart, cleaned up and orings replaced today. It really wasn't as bad as I was expecting getting them apart/back together so thanks for the encouragement to give it a go. I followed the v4 dreams guide which helped a lot.

I was pretty relieved to find the process didn't seem to throw the carb sync out too much, I had to tweak them a little but was expecting much worse. Not sure if I just got lucky there?

Either way the bike is now back together, leak free and with a fresh oil change, ready for another years riding!