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Author Topic: Need help  (Read 5464 times)

Offline Kris

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Need help
« on: August 07, 2018, 10:15:47 am »
 250 breaks so every time I try to hit power band.
 I replaced spark plugs new read cage cleans carb
 Idles  good low and mid range is perfect.  I ordered a new coil but it comes tomorrow.  I bought this used compression is 188  38 mm PWK carburetor pod filter for .20 over Paul Turner pipe and silencer
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Offline Q2W

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Re: Need help
« Reply #1 on: August 08, 2018, 07:08:32 am »
could be electrical.  Likely a jetting issue with the main jet.  Compression is a bit on the low side but should be fine.

Offline Kris

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Re: Need help
« Reply #2 on: August 08, 2018, 11:56:14 am »
 Any recommendations for the jetting?
I thought 188 was good for compression what should it be?

Offline Kris

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Re: Need help
« Reply #3 on: August 08, 2018, 11:57:26 am »
Itís 172 main and 58 pilot

Offline Q2W

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Re: Need help
« Reply #4 on: August 08, 2018, 01:55:53 pm »
180 is great for a 500.  250's around 220.

When you tested, did you hold the throttle wide open?

We'll need a lot more info for figuring your jetting but i can tell you that 172 in that small carb on a 250 seems really really massive.  I ran the 39pwk bored to 40.5 on a slightly ported 500 and i think I ran mid to upper 170 main. 180 main.

Might buy a few genuine Keihin jets and start stepping down the main until you get your powerband back.  Maybe do a plug chops at full throttle to be sure you dont get too lean. 

Do you know if your motor is air tight?  have you done a leakdown test?

***Edit:  I remembered i ran a 185ish main.  So maybe 172 isnt far off?  Either way, do some plug chops and see if you're lean/just right/rich on the main and go from there.

Offline Kris

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Re: Need help
« Reply #5 on: August 08, 2018, 02:23:53 pm »
Yes I held it open
No I didnít do a leak down test

Offline Kris

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Re: Need help
« Reply #6 on: August 08, 2018, 02:25:49 pm »
How do you do a plug chopmif it breaks up and wonít clear out in any gear. Sound like I have a stutter box stuck at like 7000 rpm

Offline All American

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Re: Need help
« Reply #7 on: August 09, 2018, 05:50:31 am »
Just simply instal a new plug, start up and give throttle, then quickly turn it off and take out spark plug....  cut away the threads portion of the spark plug to reveal the inside of the white ceramic electrode.  It should be light tan to brown I believe... but donít quote me, I may be a little off in this post
1-1985 SUZUKI LT250R
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Offline Q2W

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Re: Need help
« Reply #8 on: August 09, 2018, 11:27:51 am »
How do you do a plug chopmif it breaks up and wonít clear out in any gear. Sound like I have a stutter box stuck at like 7000 rpm

Drive down the road, hold it wide open for a bit and kill the motor while doing so.  Pull the clutch in and coast to a stop.  Check the plug. 

I believe there is a sticky post about plug chops i copied from the interwebs.

does it just break up when wide open?  or will it do it at other throttle positions?

Offline Kris

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Re: Need help
« Reply #9 on: August 09, 2018, 11:57:19 am »
Just wide open idle low and mid works great no breaking up.

Offline Kris

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Re: Need help
« Reply #10 on: August 09, 2018, 11:58:54 am »
Plug looks wet and dark

Offline Q2W

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Re: Need help
« Reply #11 on: August 09, 2018, 01:11:43 pm »
Buy a few smaller genuine Keihin main jets.  Start stepping down the jet sizes until she stops loading up.

Offline Kris

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Re: Need help
« Reply #12 on: August 09, 2018, 02:50:31 pm »
Donít know if this matters but idle screw is all the way tight and air screw is 1 1/2 out.  Seems weird that idle is all the way in?

Offline Q2W

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Re: Need help
« Reply #13 on: August 10, 2018, 06:59:26 am »
yea.  The idle screw sets the slide height.  Slide height should be set to about 3mm high then never touched again.

Once you set it correctly, it will probably start loading up down low too.

It's worth mentioning to make sure your throttle cable is adjusted so that your slide sits perfectly on the bottom of your carb and has no slack.  Unscrew the idle screw to allow slide to go all the way down then adjust the cable as needed.  then set the slide height.

Offline Kris

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Re: Need help
« Reply #14 on: August 10, 2018, 02:49:36 pm »
Any possibility of stator cutting in and out to make it sputter?
I put new Oem coil on today and no difference.
Also put needle on 1st clip to 5th clip no difference seems stronger on low end in 5th position

Offline Kris

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Re: Need help
« Reply #15 on: August 12, 2018, 05:39:44 pm »
Went from 172 main to 178 ran worse then 168 165 162 now 160 its a lot better but still sputters some any ideas?

Offline Q2W

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Re: Need help
« Reply #16 on: August 13, 2018, 11:02:44 am »
You definitely could have electrical issues.  It can cause your bike to sputter.  Check for bad grounds.   I also suggest putting a volt meter on your pickup (also make sure it and your flywheel are both clean and rust free)  Test your coil and cdi.  There is a downloadable manual on this site that has all the resistances.  What spark plug are you using?  Check your plug wire and boot and make sure there isnt corrosion where the boot connects to the wire and at plug.  Is the boot stock?

Here is how the circuits in your carb work.  Keep below in mind when jetting and only adjust 1 circuit at a time:

idle - 1/4 throttle = pilot

1/4 - 3/4  =  Needle   --  (Raising the needle = Rich)   ( Lowering the needle = Lean)

3/4 - full  =  Main


Offline Kris

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Re: Need help
« Reply #17 on: August 13, 2018, 05:59:15 pm »
Iíve only found 1 ground and thatís the kill switch grounded to frame the other end goes to cdi
I have no lights at all.
New Oem coil only other wires is stator to cdi
I see no grounds on cdi?

Offline Q2W

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Re: Need help
« Reply #18 on: August 14, 2018, 01:59:52 pm »
Here's a diagram for the 500 electrical system.  Should be identical to the 250.

Gonna need some more grounds.


Offline Kris

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Re: Need help
« Reply #19 on: August 14, 2018, 02:40:29 pm »
Isnít the coil grounded by the two bolts that hold it to the frame?

Offline Kris

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Re: Need help
« Reply #20 on: August 14, 2018, 02:42:12 pm »
And far as the stator goes I see no ground? Three bolts hold it on.

Offline Kris

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Re: Need help
« Reply #21 on: August 14, 2018, 02:47:42 pm »
My new Ricky stator has no mark on it to align with factory mark. What do I do?

Offline El Diablo

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Re: Need help
« Reply #22 on: August 14, 2018, 07:56:32 pm »
Isnít the coil grounded by the two bolts that hold it to the frame?

Yes. Make sure the contact spot is bare metal, not rusty, painted or powder coated.
Brian
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1987 Suzuki LT-500R
1990 Suzuki LT-500R
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1982 Honda ATC-250R

Offline Kris

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Re: Need help
« Reply #23 on: August 15, 2018, 12:40:00 pm »
So today I put in new stator no difference
I put the smallest jet I had 160 was 172 and it ran the best so far vey little breaking up I think I need 158 or 155

Offline Kris

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Re: Need help
« Reply #24 on: August 15, 2018, 12:45:43 pm »
The jets just seem small when the carb came wit 172 from factory. Itís a 38 mm pwk air striker from 15 years ago but it looks really clean

 

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