Float level...

Just waiting on my float level gauge and I will be checking and adjusting my floats per the service manual specs.

The service manual shows 7mm for 1987 and 9mm for 1986. I've checked a couple of mine so far with a makeshift measuring tool and they are both around 9mm. I know floats can need adjustment over time, but I'm wondering if mine were set at 9mm from the factory.

My bike is a 1987, but shows manuafactured in 01/86. I believe the carbs are the same for 86/87. Does anyone know exactly why the float height change to 7mm for '87? Should I just set them all to 7mm like the book says and feel confident it will be ok? I'm hoping to not have to pull these carbs again for a LONG time.

Thanks :smile:

 

I'm starting to think you and I are the only people who like talking about carburetors! :shocked:

I got curious, so I looked in the Service Honda parts fiche. 86-87 have the same float bowls, and floats.

The difference is the needle and seat assemblies. There are two different part numbers. I'd bet their installed height (needle resting in seat, in relation to bottom edge of carb body) are 2mm apart.

I've never seen a properly adjusted float in a CV carb that when viewed from the side, with the bottom edge of the carb body level, wasn't also sitting level. In other words, if increasing float height to 9mm would cause the float to sit higher than level, I'd bet my last dollar that it was wrong.

One other thing worth mentioning, that you may already know...only adjust the float tab with your fingers, or a pair of needlenoses. Pushing down hard on the needle can ruin it.

 

Na, I gots Carbs, thing is to have right in the first place. On that model I ended up getting another set. The individual parts were one hard to find via Honda then there was the cost, you see what the rebuild kit goes for? Sheesh I got my extra set of carbs for less than half that. then went and found O ring material to build new float bowl gaskets.

 

Hey Ferris thanks for the info! Got carbs on my brain right now as that's what's holding up my project.

The different float assemblies would make sense. I didn't think to check that. This mystery should be revealing itself real soon. I actually found one float valve (not the seat) that was different than the other 3. Guess the previous owner replaced it with one off a different bike. I ordered one new float valve set using the '87 part number. So once I get this part in my hand and can compare it to the other 3 I will know more.

I'm going to go take a look at the carbs again real quick. Maybe I'll try to take a pic so you can help me understand what you are talking about in regards to the float sitting level.

RVFR, you don't have to tell me about the cost of rebuilding carbs. I've already spent a pretty penny! I needed the gasket kits for sure, but I also wanted all 4 float valve sets. Waaaay too much moola! The float valves look ok, just had the problem with the one odd one.

I'll be back with a picture...

 

Alright I took another peek and I'm not feeling so confused after all. I checked the #4 carb which I had not yet checked. It actually came in around 7mm. That makes me feel better about the other two actually being out of adjustment.

Here are some pics of the #4 carb float. One with the float sitting at an angle so the float arm is just touching the tip of the valve and another with the carb body sitting horizontal and level.





Got a call when I was out in the shop too. My parts are in at the Honda dealer. I can finally make some more progress! :smile:

 

Good news and bad news. First the good - the float level gauge arrived. All the way from Japan. Nice little tool, should be able to use it on all the bikes.



Bad news is that the new float valve set is a different part number than what I ordered. It's still listed for my year VFR, but the fiche lists two part numbers. I did not notice this when I ordered. The only difference is the float seat. The new one is stamped 2.6 while all the others in my bike are stamped 2.4. I'm thinking this is the inner diameter of the valve seat. For some reason they offered a different flow rate. I'm sure I don't want to mix them up as I really only needed the valve and not the seat. As long as the valve matches up (which it appears to so far) then I should be good.

Can anyone confirm that the stamping on the Keihin valve seats denotes the diameter or flow rate?

Thanks

 

Mea Culpa. When I drew the carburetor picture in my head this morning, I forgot to account for the angle that the VFR's carb bowl hangs down at.

Looking at the last carb pic you posted: look at the two arms that stick up, that the float pin is pressed into. If you hold the carb so that those arms are vertical, the float should form a roughly 90 degree angle to the arms. If that doesn't make sense, I'll try to come up with a better way to explain it.

The float in that pic looks a teeny bit high. High, as in the level it will rise to when the bowl fills up with fuel. This can actually be beneficial performance wise, and I think that is about where I would set it and leave it, even if it is a little beyond spec. The risk you run with a float that is too high is fuel venting through the overflow tube.

Here's how you make sure: fill the carbs BEFORE you put them back on the bike. Shake 'em. Tilt 'em side - to - side. Let them sit on the bench for a while, full of fuel, and look for leaks. While you are at it, if you have access to compressed air, use an air blower across the vent above the carb inlet to make sure the slides work properly. I can't tell you how many mechanics refuse to take this little extra step, and end up having to pull them back off.

 

T-Bone - I thank God there are guys like you that are willing to work on Diesel engines. I think I'd rather spend an eternity in Hell rebuilding Hodaka Road Toad carburetors than face the stinking / knocking / puking / farting / every bolt weighs 200 lbs stuff you fix every day.

 

Good tips Ferris. I get what you are saying about the 90 degrees. If you look at my second pic that is basically the same thing. I should be able to dial them in spot on with my new tool!

Filling the carbs on the bench might be the way to go. I hate the anticipation of wondering if they will be ok once everything is back together. And I would be REALLY bummed to pull those suckers back off after all this work.

Anyhow, in regards to the part number business. I called a couple parts places and checked with them. They are telling me that there are 3 part numbers and all should be the same part. The part I received would be the newest version. I asked if they could explain the difference between the stamping on the 2.6 and 2.4, but they didn't know why.

I'm just going to play it safe and reuse all my 2.4 seats and just use the float valve I needed from the new set in the first place.

 

I wonder....if they are all the same part, why the different numbers? The online fiche won't let me cut and paste or screen shot what I was looking at. I didn't see any notes about supercession, either.

Truthfully, I have never paid any attention to the numbers stamped on needle seats - normally, it's a non-issue, since there is only one part available! I'm sure it has some significance, but I have no idea what.

 

I did a quick Google search to see what I could come up with for the float valve sizing. Sure enough, I found a page (while not specific to VFR's) that shows a chart with the different float valve sizing measured in mm. You need to scroll down the page quite a ways and look for a smaller chart. There is one at the very bottom too.

So for whatever reason it appears Honda went to a larger (2.6mm) float valve seat.

http://www.factorypro.com/tech/carbkei.html

 

Today was a good day. I got the carbs back together! :smile:

I took Ferris' advice and filled them with gas before installing and they are bone dry, not leaking a drop. Thanks for the tip Ferris!

I am letting them sit overnight and will be attempting to reinstall tomorrow. This carb rebuild has been a mission and has taken a lot of patience so far. I think I've hit my stride, hopefully I'll have things buttoned up soon. I'm amazed it even ran after seeing what was going on in these carbs. It should be a beast when I get it back on the road. :car:

 

:biggrin: :first: eace: :dance: Hooray!!!

Of course, you know once it's running, you owe us a burnout pic or something.

 

I just wish my float height troubles were so easily solved. I still can't Honda, Keihin, nor anyone else on the net to figure out where to set them :-(

1986 VFR from Japan. 9mm's caused the fuel to pump out of the carbs as fast as the fuel pump could send it through. 7mm's doesn't leak, but I don't know if it is right??? The bitch is the rack id: VD-BOA. It doesn't show up in any service manual or search. The best info I found was that the A on the end usually means a Japanese home-market only and has something "different" then the regular VD-BOB (according what little help Keihin was).

So, sorry to hi-jack But if anyone can find specs on this rack, I'd appreciate it a bunch!!

Wal

 

Wal - if the spec isn't readily available, why worry over it? If you know 9mm is too high, set them lower, say 1mm down, then bench test test them as described above.

To me, optimum float height is within a hair of the maximum that won't cause them to vent. Not having enough fuel to keep the jets immersed will lean the engine and fuel starve it. Having more in the bowl than is needed really has no downside.

 

Let me tell you guys. Since I've got this thing back together and running it is running spot on and fast! No leaks or heavy fuel smell to the exhaust. Did I mention it is torquey and FAST!?