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Author Topic: carb jetting/plug chop  (Read 498 times)

guss,guss

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Re: carb jetting/plug chop
« Reply #15 on: June 25, 2015, 07:19:00 PM »
i put  2.5 slide in.  the plug is white hot in 1/4 throttle.
        P-6  needle jet
        30 pilot
     pilot air screw 1-1/4 out.
    regular paper air filter( not a high flow K&N)
  small can opener baffle .
how could it possibly run so Lean only in 1/4 range. should i put RTV between the rubber manifold and the plate?
    it also has a 6DH2 needle and a 2.0 air jet.that's what they said it can with. i never hear anybody talk about the air jet. i don't know where that is.
  should i go to a 2.0 slide? that's all i can think of to do.
kill em all.  let God sort them out.

DanB

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Re: carb jetting/plug chop
« Reply #16 on: June 25, 2015, 10:30:18 PM »
Did you try the P8 as Ace suggested?  Thats the move I would make and not mess with the tiny air jet
Suppose I were an idiot, and suppose I were a member of Congress; but I repeat myself. ... Mark Twain
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guss,guss

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Re: carb jetting/plug chop
« Reply #17 on: June 25, 2015, 11:12:28 PM »
no, dammit. i flaked. I'm not going to let this carb kick my butt. right. P-8, drop the needle low, got it. thanks for reminding me.
kill em all.  let God sort them out.

ace.cafe

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Re: carb jetting/plug chop
« Reply #18 on: June 26, 2015, 07:54:10 AM »
i put  2.5 slide in.  the plug is white hot in 1/4 throttle.
        P-6  needle jet
        30 pilot
     pilot air screw 1-1/4 out.
    regular paper air filter( not a high flow K&N)
  small can opener baffle .
how could it possibly run so Lean only in 1/4 range. should i put RTV between the rubber manifold and the plate?
    it also has a 6DH2 needle and a 2.0 air jet.that's what they said it can with. i never hear anybody talk about the air jet. i don't know where that is.
  should i go to a 2.0 slide? that's all i can think of to do.
If you don't have a proper manifold gasket between the rubber manifold and the head, or if there is any chance that gasket is compromised, then you should definitely put some RTV gasket maker on that joint, and let it cure 24 hours before starting the bike back up.
Manifold air leak will  make carb tuning impossible.

guss,guss

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Re: carb jetting/plug chop
« Reply #19 on: June 26, 2015, 09:08:10 AM »
i know.
 i was sort of grasping at straws. it doesn't make sense to me that it would have an air leak in just the lower range. but i thought i would ask.
 i remmember why at first i didn't think the P-8 would help. its because i had already gone to Q-2 and it still ran hot at 1/4 but bogged down above that.
 this is baffling.      i will try a 2.0 slide.
« Last Edit: June 26, 2015, 10:39:26 AM by guss,guss »
kill em all.  let God sort them out.

Mike_D

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Re: carb jetting/plug chop
« Reply #20 on: June 26, 2015, 09:21:39 PM »
I've experienced a bike with a manifold leak that rode OK but idled like crap.  Check the manifold and seal it well with good silicone.  Just take the time to rule it out.  It is worth it.

ace.cafe

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Re: carb jetting/plug chop
« Reply #21 on: June 27, 2015, 06:58:06 PM »
i know.
 i was sort of grasping at straws. it doesn't make sense to me that it would have an air leak in just the lower range. but i thought i would ask.
 i remmember why at first i didn't think the P-8 would help. its because i had already gone to Q-2 and it still ran hot at 1/4 but bogged down above that.
 this is baffling.      i will try a 2.0 slide.
Air leaks are most troublesome at small throttle positions because that is a high vacuum condition with the slide mostly closed. That is when the air leak is going to leak the most.

guss,guss

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Re: carb jetting/plug chop
« Reply #22 on: June 28, 2015, 12:39:35 PM »
you guys convinced me it must be an intake or exhaust leak. even though i can't detect an exhaust leak and the idle doesn't change when i spray WD40 around the intake manifold.
 is there a better spray to use? like the old starting spray, either.
 my first attempt did not fix it. i pulled the rubber manifold and put a thin coat of rtv. let it cure more than 24hrs. still hot.
next i am going to pull the rubber manifold and the aluminum adapter block,. i think i will use one of the factor paper gaskets and trim the inner hole to match the block and put that between the block and head with rtv on both sides. and clean the rubber manifold and rtv it and put the whole thing together. please let me know if there is anything wrong with this idea.  thanks.
« Last Edit: June 28, 2015, 07:49:40 PM by guss,guss »
kill em all.  let God sort them out.

Arizoni

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Re: carb jetting/plug chop
« Reply #23 on: June 28, 2015, 01:32:48 PM »
The only thing that might not be the best depends on the type of RTV** you use.

Some people reading that RTV is being used think, "Oh.  I have some of that stuff left over from sealing my bathtub.".

That's not a good plan.

If the RTV smells like vinegar when it cures it is giving off acetic acid that will attack any aluminum part it  touches.
The RTV made for bathtubs and the like also is not fuel or oil resistant.

Always use a RTV that is made to be used around aluminum parts and is oil/fuel resistant.
Permatex Ultra Black and several others specifically made for these applications will work fine.

** For the newbie to working on their motorcycle:
RTV = Room Temperature Vulcanizing.  It cures at room temperature. 
The term is usually applied to silicone rubber sealants.
Jim
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guss,guss

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Re: carb jetting/plug chop
« Reply #24 on: June 29, 2015, 07:24:34 PM »
thanks for asking. i am using ultra black.
 i took the rubber manfold and block off, cleaned up resealed. still runs hot in 1/4 range. checked for exhaust and intake leaks again. no leaks.
 i got the 2.0 slide and P-8 in the mail today. put those in with the needle lowest setting(clip highest)  and currently have 30 pilot in there. still runs hot in the 1/4 throttle range. plug looks new.i can see the heat waves from the engine and the exhaust pipe tics after a short ride of a couple miles.
when i go higher than 1/4 it gets a little color but not too dark. 
the other day i was sure (hoping)it must be an intake leak. now, i am at a loss.
i was really hoping to ride this weekend.
 i think i will put the 35 pilot in and raise the needle a notch, and see what happens. any other suggestions are welcome.
kill em all.  let God sort them out.

Blltrdr

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Re: carb jetting/plug chop
« Reply #25 on: June 29, 2015, 10:20:03 PM »
Have you checked your slide height? Should just click at the end of it's travel.
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ace.cafe

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Re: carb jetting/plug chop
« Reply #26 on: June 30, 2015, 06:58:30 AM »
Something is not right. This is outside the usual carb jetting numbers for this kind of carb on these engines
Is this a used carb, or worn out, or anything like that?
What about float level? Is it too low?
« Last Edit: June 30, 2015, 07:01:30 AM by ace.cafe »

rep_movsd

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Re: carb jetting/plug chop
« Reply #27 on: June 30, 2015, 08:11:18 AM »
thanks for asking. i am using ultra black.
 i took the rubber manfold and block off, cleaned up resealed. still runs hot in 1/4 range. checked for exhaust and intake leaks again. no leaks.
 i got the 2.0 slide and P-8 in the mail today. put those in with the needle lowest setting(clip highest)  and currently have 30 pilot in there. still runs hot in the 1/4 throttle range. plug looks new.i can see the heat waves from the engine and the exhaust pipe tics after a short ride of a couple miles.
when i go higher than 1/4 it gets a little color but not too dark. 
the other day i was sure (hoping)it must be an intake leak. now, i am at a loss.
i was really hoping to ride this weekend.
 i think i will put the 35 pilot in and raise the needle a notch, and see what happens. any other suggestions are welcome.

When you say ity runs hot, how hot do you mean?
Bullets do run hot, being air cooled, especially when you are pottering around at low speeds in summer (or in traffic) and there's not enough speed for the air-cooling to happen
You know it's _really_ hot when you get that "burnt metal" smell which comes from paint on the barrel outgassing.
Note that if the engine gets too hot, the carb body itself will be really hot even if you have a rubber manifold.

rep_movsd

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Re: carb jetting/plug chop
« Reply #28 on: June 30, 2015, 08:14:44 AM »
One symptom of leanness is lack of engine braking, the engine is happy to "run away" a bit even with closed throttle. Have you dialed out your air screw way out of the limit?
The engine note also sounds a bit tinny rather than bassy when its lean and idling.
Usually, more than 2 turns out on the air screw is too lean.

cafeman

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Re: carb jetting/plug chop
« Reply #29 on: June 30, 2015, 09:27:44 AM »
Pull the carb, and do a thorough cleaning with carb spray and compressed air. Back flush all pilot/air ports: cover the pilot screw hole and the jets threaded hole with fingers and flush from the pilot inlet port so cleaner comes out the hole in the main bore, then cover the hole in the carb bore and the inlet hole and flush from the jet threaded hole so cleaner comes out the screw hole. Back and forth forcing cleaner and air out all the holes by alternately covering two holes at a time in the  pilot circuit. Straight forward and the proper way to clean ports. If you can, drain the tank and use race fuel or at least the same grade and brand of premium for jetting runs. Establish a clean tank, fuel and good flow, clean fuel filter and petcock filter if it has one, floats not hanging up, etc.
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