What is the correct float height for an '80 Standard?

[cywelchjr]

Hi, Ken. I'm just trying to get to a starting point with this thing. Currently, I have fuel pouring out of the carburetor, filling the airbox, and possibly the crankcase. The jets are stock. I have the carbs apart again, and want to verify the float levels. The needles seem to be traveling in the seats perfectly, and I found no debris causing them to hang up. The left side petcock was leaking, and I took it apart and rebuilt it. After I have it running halfway decent, I will sync and colortune it.

With the 80 carbs, if your pouring gas all over, make sure that you replaced the o-ring on the needle valve seats. If you replaced nothing else, make sure you replace that, if it's original it is almost guaranteed to leak around the seat, and no amount of fiddling will fix that without replacing the o-rings. You can get them at any parts store that sells viton o-rings, but take them in to make sure you get the right metric ones (yes, o-rings come in both metric and sae just like nuts and bolts). If you have gas coming out of the airbox, the problem is ALWAYS in the carbs (not saying you might not have a petcock problem too, but if the carbs are right, the petcock matters not), so fix that FIRST. My 400 (has the same hybrid carbs you have) had to have the o-rings replaced and then it stopped running rich and was tunable, at least after I replaced the little tiny o-rings that go around the idle mixture screws (this is another one that is almost guaranteed to be shot after 30 years), and it's almost impossible to adjust the mixture if those o-rings are bad.

[cywelchjr]

The pic not very good indication of the later model floats as the later floats will set a bit different when correct. When close to correct the lower rounded portion of float is highest point(upsidedown orentation) and measurement is to there. Have not tried it as of yet to see what actual measurement would be, but setting all floats so they are exactly perpendicular to carb body when inverted and held level is the rule of thumb so to speak for a starting point and most of time being correct. That was suggested to me by a bike mechanic friend who has worked many years at two different dealerships. Like I say, haven't done it to see what actual millemeters are, but IMO would be sound advice for a starting point. Before your done you will become an expert pulling these carbs, specially if using stock airbox.....get fairly quick at it too. Just for curiosity, let us know here what that particular motor seemed to like for a float setting.

I will say that the 23 mm reading is to the highest (furthest from the carb body) part of the float, assuming that the float is as mentioned level from side to side. One other thing that can cause them to leak, is if the float is hanging up for some reason after you get the carbs installed. If this is happening, often tapping (sometimes a bit hard) with a non metallic object (screwdriver handle or the like) on the side of the carbs will often correct that, however if that happens something is not quite right. Additionally, there is an adjustment to control how far the floats can drop that can help this.

My PO destroyed the original engine for my bike by having a very rusty tank with no filters, and junk torn filter towers on the petcocks. I don't have filters now, but I have a VERY clean tank, with virtually no rust at all, and that just surface flash, and my petcock towers are good with no tears, so I don't run filters, but if it doubt, filter it out.

(the PO told me it would pour gas on the floor sometimes, and he just tapped the carbs with a hammer handle when it did, it was because bits of rust were getting caught in the needle valves, and the tapping made them jiggle and let the rust get through so they would close. Of course in the meantime he didn't know that the gas was in the oil and trashed the bearings, not quite enough for me to notice till the second oil change. When I pulled the tank, I found it was about to explode like a water balloon it was so bad rust wise, had multiple patches with JBWeld and such to try and keep it from leaking. I had thought it had a minor hole that I was going to braze after getting it boiled out, but after i saw the condition it's sitting on my part frame, never to go on a bike again.)

[DGXSER]

First off, I did not see the answer to Ken's question, of how many Ts are between the carbs, one or two. This differentiates the two models of carbs which determines the float heights.

If you have two Ts, the taller original dimension is appropriate, if one T, the smaller 23 +/- .5 mm is the correct height.

As to measuring, the picture Phil posted is accurate. I have set quite a few of the newer model carbs with the plastic floats, and that flat area is always the highest in the ones I have worked on. What ever point is the highest is the point of measurement.

[cywelchjr]

First off, I did not see the answer to Ken's question, of how many Ts are between the carbs, one or two. This differentiates the two models of carbs which determines the float heights.

If you have two Ts, the taller original dimension is appropriate, if one T, the smaller 23 +/- .5 mm is the correct height.

As to measuring, the picture Phil posted is accurate. I have set quite a few of the newer model carbs with the plastic floats, and that flat area is always the highest in the ones I have worked on. What ever point is the highest is the point of measurement.

Good point. My response was based on the carbs likely being stock 80 carbs, which would likely have plastic floats and the rubber plug (early carbs have a screw in there rather than the rubber plug), although I have seen 80 carbs with the rubber plug and brass floats, but the measurement is the same with plastic or brass floats in both cases.

The rubber plug was the primary reference to them being the bastard carbs for me.

[ThrottleJunky]

Thanks for all the input, guys. Yes, I only have 2 "T" fittings. My floats are the plastic type, and the highest point is the stepped up area as in the illustration provided. Thanks A LOT for that picture, BikerPhil. I did replace the O-rings, but I'm not sure of the material. My friend owns an auto repair shop, and he has thousands of them.

[ThrottleJunky]

I used green high temp hnbr o-rings, not viton. Will this be troublesome?

[cywelchjr]

I used green high temp hnbr o-rings, not viton. Will this be troublesome?

Its possible it might be a problem if they're not gas proof.

[ThrottleJunky]

Its possible it might be a problem if they're not gas proof.

They're high temp auto AC o-rings which are good for petroleum based chemicals, but I'm not sure if gasoline will harm them.

[natemoen]

They should be ok. hbnr is a nitrile based petroleum resistant product.

[petejw]

hi throttlejunky,
when u get it altogether to check that uve set the
floats at the correct level, take the bike out on a flat piece of
road, in 5th gear, with revs at 2000rpm crack the throttle wide open
the engine should pull smoothly with out any hesitation or bog.

also while u have the carbs off the bike, with the float bowls removed
and the carbs upside down, with ur mouth blow into the fuel inlet, if there
are any leaks u should be able to hear and feel it leaking, also do this
with the float bowls attached to see if there is any sticking.

hope this helps.

[Ken Talbot]

How about these pics:

[ThrottleJunky]

Hahahahaha. Nice one, Ken. It doesn't get any more clear than that. I really appreciate all the suggestions, guys. It's a big help. I'm very happy I found this forum. I plan on re-installing the carbs for the, yes, THIRD time tomorrow. My hunch is that the o-rings were leaking on the seats, because the floats were not out of adjustment much. The needles don't leak.

The only problem I can find with the carbs is that one of the vacuum slides seems to be binding a bit. When I gently push it up and down with my finger, it is sticky, whereas the others feel very smooth. I'm not sure what that would translate to in terms of performance.

[petejw]

that slide if its sticking will affect the operation,
while u have it apart check the needle is sitting correctly
in the slide, ull have to loosen the 2 small screws inside the slide
and slowly rotate the needle til it seats. hope that make sense.

[mack]

Hose fittings

Just a question here. Don't his carb bowls have the fittings to hook up a hose to check what the actual level of the gas is inside the bowls? Trouble with floats in general is they may not all have the same boyancy.

[DGXSER]

Only the 81 models came with the side outlet bowl drain to be able to hook a hose to it. All prior years just have a plug.

I have not ever used that method myself, simply set the floats to the factory setting every time. Always runs like a champ for me.