3TJ Carb problem, is my set up correct? floods engine

[JonathanCox]

hi all, I'm nearly putting my 3TJ back on the road after restoring it

I have a carb problem, It's a total bugger to start from cold, and really after its hot and half cooled down again

turns out it's flooding the engine very badly, I took the carb off after cranking for a good 10 seconds to find the intake valves bubbling with fuel when they go up and down.



I need to ask any of you If my carb is correct, which I believe it is, it's all stock from looking at the manuals

My Pilot is on 32.5 (the jet sunken down?)

The main jet is #100 on cylinder 1 and 4, 97.5 on 2 and 3, as should be stock.

Is the other jet called a starter jet? Anyway, they're all #50, as stock I believe.

I'm running exup, stock air box with clean filter, new plugs, however they'll need to be cleaned as it's flooded

All air/fuel mixture screws at 2.5 turns out as stock.

I can only think, that my two jets are the wrong way around, however looking on the parts diagram for the carb it seems correct

Any ideas? Thanks

[Drunkn Munky]

If its flooding then you need to check your float height and condition of the needle valve if float height is good

[JonathanCox]

Hi, ok, I have come across float height before but I haven't tested it, nor adjusted it

Is it the silver tab you see in my picture? will it need to be bent accordingly? If so the tab is all the same in all 4 bowls, untouched..

[Drunkn Munky]

No its a ballache to set the float height on these, with the carbs on the bike you need to set the bike upright and level then attach a clear pipe to the drain nipple, undo the drain screw and check the level against the level in the workshop manual (available in the docs section)

[Drunkn Munky]

These threads might be worthwhile reading through

viewtopic.php?f=37&t=47231&p=341708&hil ... ht#p341708

viewtopic.php?f=62&t=46769&start=30

[JonathanCox]

Thanks, I've done a little test with the clear tubing tonight and did some adjusting on two carbs, I saw on a screenshot that you should level it up with the line on the float bowl face, however reading it should be 4.5 to 6.5mm below that line. So I'll adjust accordingly again tomorrow.

It seemed that all 4 tabs were not bent at all, just stood upright, allowing a huge amount of fuel in, but it was used in a different set up before I had the carbs so.

Thanks for the help

[JonathanCox]

There is a lot of conflicting information and some missing for the 3TJ model and carbs

I'm unsure what to do, I think I'm going to have to line up the fuel level in the tube to the middle line casting on the bowl, and see how it runs

Even on some information it states 21mm below the MIKUNI upper line, which is about where the casted line is on our 3TJ carbs, so I'll line it up as I said, see what happens.

[dobbslc]

If the bike has been running well in the past I would be careful how far you bend the tabs as it shouldn't have gone far out, you might find its the float needles not sealing properly that's causing the high fuel level.

[JonathanCox]

The bike is all newish to me. I've been building it from scratch, it had a 600 3HE engine and carbs before but I fitted a 400 back in..

I've balanced the carbs and they're running at the same level on any given RPM after a blip of the throttle.

However, #1 cylinder header is much colder than it's brothers, It does become hotter if you rev the engine up

I've found that I backed out the air/fuel mixture screw half a turn to 3 turns out (I have it stock to 2.5 turns) Then the header becomes as hot as the others.

Would this indicate the carbs need cleaning? I have cleaned them before but I'll have another crack at it.

While googling this I saw people use a temp gun pointing at each header, and turning each mixture screw to level the temps? Would this be a better idea?

[hunter]

It sounds like you have a blocked pilot jet or circuit or both on that cylinder.