250ED float level

[Hosk1956]

Hello isolated chaps, I'm giving my carb some maintenance to hopefully cure an idling issue, but I am seeing conflicting info regard the float level, can somebody tell me what the float level is supposed to be (not the fuel level).

Wayne from Oz

[matt glascock]

The general rule for Mikuni carburetors is that the float arm should be parallel to the carburetor body/float chamber gasket mounting surface. I'd bet someone has a more scientific method, but this one will get you in the ball park.

[Bullfrog]

I think setting up the float arms parallel to the gasket surface IS the "scientific method" for setting Mikuni floats - and (so far as I know) is perfectly correct for all Mikuni carbs which came as standard equipment on Hodaka motorcycles.
Ed

[Bobv07662]

That big Mikuni has the stepped float arm in it. I had some issues with them being a bit rich when set up that high. I dropped mine down about an 1/8th from there and the problem went away.
Your results may vary.

[Hosk1956]

Those answers are all part of the problem, the arm has a dogleg in it, the manual shows that dogleg going down, eyeballing the arm puts it about 27mm float level.
But my arm shows wear (scuff mark) from the needle/seat on both sides of the arm, so at one time the arm was set up with the dog leg up, eyeballing the arm like that puts it about 18mm float level.
So I got on the internet and the Mikuni site says the float level should be 18mm, but I am sure I read somewhere that it should be 26mm.
My arm was in the down position when I stripped it down so thought I would come here for some clarification.
I am cleaning it as I have an idling issue, I have difficulty getting it to idle nicely and reliably when first start up (with engine warm), I can get it sort of ok, but once I get out on a ride the idle goes to crap and I find I have to wind the idle screw in and bump the idle up high to keep it idling and even then it doesn't idle well.
The next time I take it out the idle is crap at the start (won't idle) so I go thru the whole process again.
It is that much of a pain that I am not taking it riding, so I have gone back to basics and ultra sonic cleaning the carby and try again, very frustrating.
Of course this is made more frustrating as I can walk up to the little Fuji motored Deckson I had bought and it starts first kick and idles all day every time, with only just a carb clean!

Wayne from Oz

[Bullfrog]

Two thoughts:
1. Upon peeking at the Illustrated Parts List for the 250ED, the "dog-leg in the float arms seems to bend "away" from the float valve. (So "down" when bolted up normally . . . and "up" when the carb is inverted and you are doing float level checks) The Illustrated Parts Lists have a pretty good history of showing how things should be, so I think we know which way the float arms should "dog-leg". And I'm still sticking with the concept of float arm(s) parallel with the gasket surface. Though I wouldn't ignore the tip about a small adjustment from the "parallel" setting.
2. I'm not convinced that float level has anything to do with the idle issue you report - perhaps the float valve isn't doing its job reliably? Do you have an in-line fuel filter (clean fuel at float valve)? ?Heat related very small air leak?? (ie, rubber carb spigot mount gets warm, sags, opens teensy-weensy air leak? Cools off - goes back to "normal"?)
Sorry I'm not of more assistance.
Ed

[viclioce]

Following. I have a 30mm carb I bought from Bruce to use with my reeded Combat Wombat. At least it appears to have floats more consistent with the smaller carbs. Victor

[Bobv07662]

I agree with Bullfrog. The float arm step should face away from the carb body and towards the float bowl. At that point the float arm will be parallel with the gasket surface. Like I posted earlier, my bike ran cleaner on the low end with the tips of the float arm bent down 1/8" from that point.
That being said, I would not look for this bit of "fine tuning" to be the cure for your inconsistent idle problem. Keep looking at the idle circuit and any intake air leaks. How is the intake manifold boot?

[Hosk1956]

Yes agree with all regard the float arm level, just as I had some some conflicting info I thought I would put the question out there.
Also not expecting the float level to improve my idling issue, just that it came to my eye while cleaning and inspecting carby.
I have given the carby a thorough deep ultra sonic clean in the cleaner at work, now to reassemble it and double check gaskets, seals and even the oil pump cable adjustment.
The situation is better as I did discover that the manifold 'boot' had split and could see that being open at idle but sucked closed at speed by engine vacuum, replacing that did improve the idle but there is still something not quite right, I shall have another go and see what happens.
I may disconnect the oil pump and run premix if things don't improve just to check all avenues.
The only issue after that may be electrical.
Stay safe and see you all on the other side.

Wayne from Oz