Problem - can anyone help diagnose this please?

[Minimoto]

Rough running RVF engine. Revs all over the place... Video here:

https://goo.gl/photos/6g4jwWV4hFhefpAR7

I've just got my carbs back together and had a go at visually balancing them until I can get some vacuum gauges on it. I took the plugs out last night and cleaned them up and set the gap to 0.6 - 0.7 mm as per Haynes. Today's the revs are all over the place going up and down on their own and then staying high after blipping the throttle. I've sealed off the vacuum pipe to the fuel tap. I'd be surprised if it's an air leak around the carb attachment rubbers, but could be. The fuel is going in via a temporary container and pipe to the carbs.

I hope the video works to shows you. Any help or advice greatly appreciated :-)

Dave

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[Minimoto]

Jets are 112 F/R and needles have 2 x 0.5mm washers under them.

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[Minimoto]

Can anyone post a video of the slides operating as the engine is revved please to compare what mine are doing?

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[Morespeedvicar]

Have you checked your float levels? I didn't think the nc35 needed and extra washer under the needles but I could be wrong.
Are all the mixture screws set ok?
From what I can remember the slides don't move much just from blipping the throttle.
Cheers
Ian

[Minimoto]

Hi Ian. I have the pilot screw out 1 5/8 as per the Haynes manual. I have the extra washers in.

I'll check the float heights. They are all stock floats and not touched before, so should be 12.5mm. Will see...

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[skinnydog0_0]

trying to balance by eye is nearly impossible. I use a feeler gauge to set them prior to getting the vac gauge on them. Most of the time they are 90% sorted. I have tried setting them by eye and they can be way off.
If you have kept the settign as before when it was running (i.e. float heigts, jet sizes, A/F settings) & there are no air leaks its likely its the balancing.

[Minimoto]

Hi skinny, I have been trying to do it by eye, trying to set the butterfly's to the same point against the holes in the sidewall of the carbs. Hadn't thought about trying to use feeler guages. The pilot jet is set to 1 and 5/8 turns. Do you think I should change this to more or less to take account of the larger jets and needle height? Or leave as is...?

Cheers,
Dave

I've split the carbs right down and re-built them which is why they need balancing. I've not changed the float heights, but have but in 112 jets all round and raised all the needles by 1 washer.

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[richyrd5]

I'd say air leak as well as out of balance carbs.get some gauge's on them and a tin of wd40 to spray around carb rubbers...also I'd put only 1 washer under needles,2 is to much with a standard(?)exhaust...good luck bud

[Minimoto]

Hi Rich, thanks for the advice, I'll check the rubbers tonight. Has anyone any experience of using the cheaper version available on eBay?

Here's the exhaust...

What do you reckon for jet and needle settings? Where do you think I should set the pilot jet screw to?

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[richyrd5]

OK,now we might get somewhere. I'd be going up a bit with the jetting if you got twin stacks on..maybe start at 118/120 and one shim under needles..pilots at 2 turns out...what airbox are u using?..also rubbers on eBay are OK to use,but rick Oliver for genuine ones.