Topic: Cb350f float height?

[Photoputz83]

I'm having a few issues getting my cb350f to run anything other than rich. The engine top end was rebuilt. New pistons after hone, using new rings and wrist pins. New gaskets, and seals. The exhaust is a 4-1 with baffle installed, and the air filter is a steel dragon performance air box which is pretty much velocity stacks with a protective shroud around them. I started with 85 mains, and 38 pilot jets, needle in stock position, and air screw 7/8 turn out. It ran rich at that point, and I mean really rich. I swapped the main jets out with 80 mains, and kept the 38 pilot jets in. I did however turn out the air screw another half turn. It still runs rich, but doesnt seem to have much in terms of flat spots when riding. My question is if the float height being at 21mm is causing this problem. I've seen many people say to say at 23-24mm, and others say keep the height at the level in the honda manual. I occassionally get gas out of the overflow tubes, and so rechecked all the floats. All brass is keihin All are at a hair over 21mm. Am I missing something here? Any help or suggestion would be wonderful. Cheers.

[maxheadflow]

I typically don't mess with float level.  21mm is what the spec calls for.   The stock jet sizes seem to be 35 / 75  needle in the middle.  If the carbs have over 35-40,000 miles on them the needles and needle jets may be worn.  They can wear out quicker.

[Photoputz83]

Carbs have 5400 miles. No noticeable wear.

[carnivorous chicken]

Can always use the "clear tube method" to verify fuel level in the bowl. Do a search and you'll find the info on the forums.

[Bodi]

Usually with pods or velocity stacks you need to go one smaller on the pilot jet to get rid of over rich low throttle. I believe I went from 40 to 38 on a 400, maybe 38 to 35 is what you need?

[maxheadflow]

Usually with pods or velocity stacks you need to go one smaller on the pilot jet to get rid of over rich low throttle. I believe I went from 40 to 38 on a 400, maybe 38 to 35 is what you need?

Right on. I was hoping the OP would notice that his pilot is one size bigger over stock.   Too many jet the bike assuming they made some change that will require more fuel when it really wasn't needed.   It would not surprise me if it needs an even smaller jet.  Short intakes before the carb seem to need less jetting. My reasoning is that there is more standoff that gets sucked back in at lower speeds.  Longer ones want more pilot. Don't jet the bike based on what you think the motor needs.  Jet the bike on what the motor wants. If it's running rich cut the fuel.  You need to tune the jets separately.  It might need more main.

Another pet peeve is that you set the pilot screw to some preset value.  With the motor has correct ignition timing, valves adjusted and new plugs, and carbs synched, you adjust each pilot to where the motor idles best. You will hear one cylinder start to burble while messing with the idle screw.  (sometimes you have to go back and resync) I thought setting the pilot screw to some fixed value was a Harley Davidson cv carb thing. 

[Photoputz83]

Setting to the factory starting point of 7/8 turn out was strictly a starting point that was in the honda manual for this model. I knew I'd have to adjust from there. Ran but not well at that point, turned in and began to stall out. Went the opposite direction and it seemed to run a bit better. Fount the sweet spot for the way it is currently jetted. Will re-sync with every change made. I have a full jet kit from 30-45 in pilot, 70-100 in mains. I'm just trying to figure out the float height that people have had luck with. That's all. There are three different numbers that I've been finding. Honda manual says 21mm which on occasion will cause a small bit to drip out of the overflow tubes. Others are saying 23mm. Once I get that answer I'll re-jet, and re-sync.

[maxheadflow]

Setting to the factory starting point of 7/8 turn out was strictly a starting point that was in the honda manual for this model. I knew I'd have to adjust from there. Ran but not well at that point, turned in and began to stall out. Went the opposite direction and it seemed to run a bit better. Fount the sweet spot for the way it is currently jetted. Will re-sync with every change made. I have a full jet kit from 30-45 in pilot, 70-100 in mains. I'm just trying to figure out the float height that people have had luck with. That's all. There are three different numbers that I've been finding. Honda manual says 21mm which on occasion will cause a small bit to drip out of the overflow tubes. Others are saying 23mm. Once I get that answer I'll re-jet, and re-sync.

If the bike idles better with the air screw turned in, you don't need to go smaller on the pilot jet.  I'd check to see if the float needles are worn.   I don't know what that air cleaner does for the jetting.   May have a bad float.. I would guess you could go a little lower if they are heavy.  When you say it's running rich, what kind if indication are you getting?  Plugs?  All of them?

[Photoputz83]

Symptoms are a little low on power, wouldn't say bogging, but not as much pep as it should have. Spark plugs are black. Not oil, but fuel. Smoke out the exhaust, not white/blue. Runs worse when less air is introduced into the idle circuit (air screw in). Choke kills bike. New carb internals.

[maxheadflow]

I'm not reading things right today.  If it ran better with the air screws out, you might want to go lower on the pilot.  I guess you could drop the needles a notch also.

[Photoputz83]

That's what I'm thinking, but still wondering about the float height. Typically the honda factory service manuals are pretty spot on with float height levels. My 550k, and 750k3 all were perfect at stock height. The 350f on the other hand seems to be off. I'll just end up rigging up a fuel reservoir and hose to do it on the bench. Getting tired of pulling them off the bike lol.

[Johnny5]

I run my 350f at 24mm float height with good results. I think at 21mm, you're going to be choking on gas.