Tachometer fluctuation at stop and idle issues

[naturalphenomena]

I recently re-jetted my crabs with a buddy of mine, we put 17.5 main jets, 42 pilot jets and used 4 washers on the needle, its running great, not lean or rich at the top or mid range. When i start the bike it warms up great without the choke but the choke just help it warm up quicker, but when i rev and let go of the throttle when its warm, it stalls the tach goes up than down to 0 and stalls im not revving past 5k, on top of that when im at a stand sill the tach is fluctuating going up and down starting from 1k to 1.8k at stand still.

I have been messing with the pilot air jets making sure they are the same along with tighting them cause it causes my bike not to stall but, it still isn't helping.

The bike is also going to 3k rpm staying there and slowly dropping 1.3k

I recently replaced the Pilot Air jets with brand new ones and put new carburetor gaskets in.


Any Suggestions?

[choneofakind]

what setup do you have for the intake? 42 pilot jet sounds big. That explains the bogging and dropping idle when you blip it, and the fact that it doesn't idle right when warmed up. Here's some guidelines to tuning your carbs:

http://www.factorypro.com/tech_tunin...m_engines.html

depending on your intake setup, you might want to go back to 38 (stock) pilot jets, or down to a 40

[JLinde1339]

Sounds too rich at idle range. Have you messed with the idle mixture screws at all?
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[Skippii]

Originally Posted by naturalphenomena

I recently re-jetted my crabs with a buddy of mine, we put 17.5 main jets,

Um...stock is 105. Did you perhaps mean that you put a 117.5 in the bike? If so, take it out because that's not anywhere within a sane range for the bike.

[Skippii]

Originally Posted by naturalphenomena

I recently re-jetted my crabs with a buddy of mine, we put 17.5 main jets

What sort of measurement is that? Some companies have weird numbers that have nothing to do with the kehin numbers. Keihin stock size is 105, with full aftermaket intake and exhausts you might go as high as 112.

, 42 pilot jets

Why did you change the pilot gets? There is very rarely any reason to do so.

and used 4 washers on the needle,

That is too many shims under a needle. The only reason to do that is if something else is way wrong.

its running great, not lean or rich at the top or mid range. but when i rev and let go of the throttle when its warm, it stalls

I'm not sure I'd describe that as "running great," but you mean that you're only having problems at low throttle openings, right? What makes you think you're NOT running rich or lean at the top end?

The tach goes up than down to 0 and stalls im not revving past 5k

If you blip the throttle and it drops below where you'd previously set the idle, that indicates a rich condition.

When i start the bike it warms up great without the choke but the choke just help it warm up quicker,

That means you are running too rich at idle. You don't want your bike to start with a cold engine with no choke.

on top of that when im at a stand sill the tach is fluctuating going up and down starting from 1k to 1.8k at stand still.

The tachometer, or the engine? The tach is not accurate at very low speeds In fact, it normally reads 0 for anything below 1krpm. So, is your ENGINE fluctuating speeds, or is the tach not reading correctly?

I recently replaced the Pilot Air jets with brand new ones

Why?

I have been messing with the pilot air jets making sure they are the same along with tighting them cause it causes my bike not to stall but, it still isn't helping.

Put them back to the stock positions for now.

The bike is also going to 3k rpm staying there and slowly dropping 1.3k

This is generally something that happens just before the bike is fully warmed up. Are you saying that when it's *completely* warmed up and has been ridden, it climbs from 1-1.8kRPM to 3K by itself, and then descends without touching the throttle, or does this happen when you do something?



The problems you're describing could be anything from a leaky intake to a battery with a shorted cell. The most glaring problem, though (and the most likely cause) is that your jetting is way, way off.
What you need to do is use a systematic method of getting everything sorted, only chaning one thing at a time.

Step one will be to adjust the pilot circuit to get your bike to start when cold with the choke on, and NOT start when cold with the choke off.

Before we get that though, please describe your bike's mods in detail. Air filter condition, airbox modifications, exhaust header and muffler mods--all of that. That will give us an idea what parts of the carb should be addressed.

And, then describe/clarify all changes you've done to the carb.

Float height: Any change/Adjustment?
Pilot jet: 38 to 42 (+4) What did you do this?
Pilot Idle screw: Back to stock setting?
Needle height: +4 washers..what kind of washers? SAE #3 or #4 or metric 3mm?
Needle Taper: Did you replace or reshape the needle?
Slide hole size: Still stock?
Main Jet size: ????

Also, you're in Florida? No elevation, mild temperature?

[choneofakind]

Originally Posted by Skippii

Um...stock is 110.

105 actually

[Skippii]

Doh! I knew that. Wonder why I typed 110..


Yes, 105.