Calling Mikuni Tuning Gurus!!!!!!

[Finnigan]

I think there is a small leak in BOTH boots on the engine side, will a thin film of yamabond work?

I'm starting off with the following settings

Idle screws out 1.5 turns
Air screws out 3 turns

That sound like a good start point?

 

[cxman]

i would do air screws out 1.5 and go from there

yes yamaha bond or even good rtv will work to seal the boots

 

[Sonreir]

Air screws on the Mikunis should be much closer to one turn. I'd use that, instead (after the air leaks are fixed).

 

[Finnigan]

Ok so I pulled the carbs and one felt like it had oil residue in the left, then I pulled the plugs and one looks greasy?! Can that happen?

 

[Sonreir]

If you're burning oil, yes. You'd probably notice the smoke from the exhaust though.

 

[Finnigan]

Took apart the carb and theres definitely oil in there... how does it get in there to begin with?

 

[Sonreir]

In the carbs? That's a tricky one. Maybe leaky intake valve seals? I would probably guess somewhere higher up, though. Maybe the valve covers and then leaking into the carbs from there? Not something I've heard of before.

 

[Finnigan]

Could it have something to do with not lapping the valves after the guides were replaced?

 

[Sonreir]

Not likely, unless your cylinders are also full of oil.

 

[Finnigan]

I'm kinda worried about that now, is the only way to check to take the top end apart?

 

[Sonreir]

Have you been blowing smoke while the bike was running?

 

[Finnigan]

not when i'm idling at normal rmp's

but above 4000 yes there is white smoke

 

[Sonreir]

Done a compression test lately?

 

[Finnigan]

No, i guess thats my next step?

 

[Sonreir]

Sounds like a good idea. If compression is good, the only place I can think of that would cause oil to burn would be leaking past the valve guides.

 

[Finnigan]

Ok, I'll pick up a tool and youtube it tonight. Thanks

 

[Finnigan]

Just picked up a cheapo HF compression test kit and both cylinders read exactly 90psi

Did it a few times on each one just to make sure

 

[Sonreir]

That's half of what you should be seeing. Did you do those readings with the throttle open?

Do the readings get better if you add a tablespoon of motor oil to each cylinder?

 

[Finnigan]

Really? I saw a few vids that said if the carbs are off its ok (which mine are at the moment)

 

[Sonreir]

Really? I saw a few vids that said if the carbs are off its ok (which mine are at the moment)

Yup. Carbs off are actually better than throttle open.

How are the numbers after adding a bit of oil to the cylinders? A tablespoon in through each spark plug hole and then wait a minute or two.