Poor running at low revs

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Tbird
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Poor running at low revs

Post by Tbird » Mon May 07, 2018 1:58 am

Hi All, my 3yf is running like crap at low revs. Steady throttle below 3500-4000 rpm it feels very ‘jumpy’. Accelerating, or above 4K revs, runs fine. Closing throttle also causes it to jump.
I have a new air filter, carb rubbers (both sides of carbs), spark plug and coil/ ht lead. No air leak that I can find. Pilot jet is clear, set at 2.5 turns. Fuel tap and petrol cap are fine.
Also notice, when I start it (no issue there), if I rev the engine, it tends to drop off/ doesn’t respond for a second or two. This doesn’t happen when she is warm. It’s doing my head in :drugs:
Anyone have any idea what’s up? I’m no carb expert, but diaphragms seem fine. I’d imagine it’s a fuel issue?

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Mezo
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Re: Poor running at low revs

Post by Mezo » Mon May 07, 2018 5:31 am

I wonder if its a problem with your choke? you say there is no issue once the engine is warmed up yes?

Mezo.

Tbird
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Re: Poor running at low revs

Post by Tbird » Mon May 07, 2018 10:04 am

It does happen when warm Mezo. I’ve had a look at the choke, moving freely.

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Mezo
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Re: Poor running at low revs

Post by Mezo » Mon May 07, 2018 11:10 am

And you have made sure the float needle valve filter is clear right?

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Mezo.

Tbird
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Re: Poor running at low revs

Post by Tbird » Mon May 07, 2018 12:04 pm

I haven’t. Didn’t know there was a filter on it! Will take a look.

stevep10
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Re: Poor running at low revs

Post by stevep10 » Mon May 07, 2018 7:35 pm

Have you changed the slide needles and emulsion tubes? They tend to wear and go oval.

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Mezo
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Re: Poor running at low revs

Post by Mezo » Mon May 07, 2018 10:35 pm

Tbird wrote:
Mon May 07, 2018 12:04 pm
I haven’t. Didn’t know there was a filter on it! Will take a look.
Bit of a bastard to get out, remove that screw & then grab it with flat nose pliers & wiggle left & right pulling at the same time.

Mezo.

Noobsonwheels
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Re: Poor running at low revs

Post by Noobsonwheels » Thu Sep 27, 2018 10:48 am

Seems to have some what the same izzue on my bike.

Got it in May this year, and it was ok. After filling oil and 98 Oktan it started this. No clue if that has anything to do with this.
But after one day like this, the bike started for 3 sec the next day, could not start it after.

Did this things fix the izzue on your bike?

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