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Author Topic: jetting  (Read 10974 times)

Offline marshalljohnson307

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Re: jetting
« Reply #15 on: May 03, 2012, 09:23:58 PM »
omr thanks again, i think i may owe ya a couple of cold one's

also i found the size of o-ring needed is 2mm x 5mm which 2mm is the thickness of the rubber, 5mm is the inner diameter, and outter diameter should be 9mm

its almost 10:30pm here i leave work in a half hour, guess where im going....to the garage!


Offline marshalljohnson307

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Re: jetting
« Reply #16 on: May 07, 2012, 03:52:35 PM »
well i had a busy weekend but found some time for the ds.....of course. so i was able to get into the carb and that o-ring was dried out and wasnt stoping anything, the brass fitting that it was wraped around slid right out once i removed the retainer screw. at auto parts store i bought an assortment of metric rubber o-rings, used the 2mm x 5mm ring, and it went on the fitting with little problem. now that it had a  fatter o-ring it was a little harder to get the fitting back in, had to use some fenese and dw-40. got that in and that took care of the carb leaking problem.
but it still ran like crap.....i started with the dj needle in second grove from top and a 175 dj needle, i couldnt get it to run good enough to ride it for a bit. i changed the jets a few times, almost made no difference. i could get it to run and idle, but would bog down on the throttle, higher thottle it would run, but going from an idle to throttle it would die half the time, and bog the other half. i thought maybe the float was set wrong, so i ended up adjusting that 3 times. and still ran like crap, i had bought 3 new plugs to put in, but i thought i would wait to its running so i could try to tune it in more. i almost felt like giving up. but i decided to pull one plug to look at it....it was pancake brown....looked like it had never be rich since that plug was in.....keep in mind it was running pretty good on those plugs, before i did all those mods. so really it was running lean before. so instead of using the recommended starting point, i used where the carb was before as a starting point. before i did the omr mods, or cdi, or exhaust.....the carb was pretty much stock except the stock needle was in the 5th grove, the last one, and had the stock 165 jet. so i compaired the dj needle i had, which was a little longer and had an extra grove. so i went with the 5th down, had to grind the end of the dj needle down to make it fit. and put in a dj 185 jet. started it up and BAM i hit the spot, took it for the first real spin, and i could feel a MONSTEROUS amount of low end torque, just what i wanted.....no hesitasion anywhere in the throttle range, but it did POP when little off heavy throttle. but i feel i now can put the plug in and try and tune it in, now that im in the ballpark.

i also got the size 40 traxxtor air jet in today, havnt installed yet, but that should help the top end more right? and also im thinking i need to go with a bigger pilot jet? maybe a size 47.5, or 50?

somthing else, i did vent the clear breather tube, that goes back into the airbox, that should stay that way right? even with the lid off the airbox?

i just thought i would post my progress and see what you guys thought or had anything to add?



« Last Edit: May 07, 2012, 05:23:39 PM by marshalljohnson307 »

Offline BigRay800

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Re: jetting
« Reply #17 on: May 07, 2012, 09:16:29 PM »
 :) if it poped when you  let off you are a little lean on the pilot or raise the neddle 1
  read the atachment i have
Ds650 powered by Suzuki GSXR 1000 [sold]
Girl made me buy a damn RZR

Offline marshalljohnson307

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Re: jetting
« Reply #18 on: May 07, 2012, 09:52:47 PM »
big ray thanks for the info....the attachment was good, i think ill save it for later reference...

but i was a little confused about a few things, i got the theroy concept down, but confused about some of the terms and such...

in the attachment....it said there 4 main adjustments #4main jet, #3pilot jet, then needle jet, and jet needle....

im confused about that i was thinking along the lines of #4main jet, in the slide you have the needle, #3pilot jet, and #2starter jet

so could you clear that up for me? is what im thinking the starter jet, really the main jet? adjusting #2 does that effect the 3/4 to wot?

also i thought from reading here turning the mixture screw out if it pops, which according to the attachment would be making it leaner? so i should be turning it in? i should be tryin to richin the pilot?

im glad for your input, and you guys are helping me out alot. thanks

Offline Oldmanracing

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Re: jetting
« Reply #19 on: May 08, 2012, 07:02:49 AM »
If the screw is in the back of the carburetor, screwing it out will lean the mixture while screwing it in will richen it. If the adjustment screw is in the front of the carburetor, it will be the opposite.

This write-up is confusing.

OMR Explanation:
If the pilot screw is between the slide/venturi and the motor - it is a Fuel Jet.
To richen: Turn Out
To lean: Turn In

If the pilot screw is between the slide/venturi and the front of carb - it is a Air Jet.
To richen: Turn In
To Lean:  Turn Out

The stock carburetor has the pilot screw between the slide/venturi and the motor.
It is a Fuel Jet.

Offline Oldmanracing

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Re: jetting
« Reply #20 on: May 08, 2012, 07:56:52 AM »
More Thoughts.

#1-Do you have the needle assembly in correct order.

3-Needle Assembly Into Slide:
The injection molding of the vacuum slide sometimes had a slight mismatch in its production.
With the needle and washers removed from slide, look down with good light and where the washer will rest, does your bottom look round or can you see a slight flat lip that is raised and thus looks like like the bottom is D shaped. Many slides seem to have a D shaped bottom.
If you have a D bottom:
Take the thick metal washer and grind a flat. Usually about half the width to the inner hole is find.
Install the thick washer first to align in the D.
Then install thick nylon washer.
Then needle with clip in 4th or 5th(stock needle) or 2nd or 3rd(DJ needle) from top groove, and thinner washer on top of clip.
Press in plunger with small spring attached.
When assembled and you turn the slide over and look at the needle going into the slide, you will notice that the needle is positioned in the middle and has equal space around the needle. This is important otherwise the needle will be dragging in jet needle and wear out of round. Also the better it is positioned, the better fuel will be drawn up the jet needle and the fuel will atomize better.
Final Check:
Push needle lightly up into slide body. There should be a slight movement. Spring will return needle when released. If running in the 5th(Stock) or 5th/6th(DJ), you may find that there is no movement.
Warning: If no movement, the assembly may come apart while riding.
Fix: Grind 1/32-1/16 off top of needle and re-assemble. Check again for movement.
I have found that the slide length varies. Excess shrinkage is the issue.

#2-Because you went to extremes, it appears that you do not have enough atmospheric pressure to raise the fuel adequately.

I would install the #40 air jet.
This will add the needed pressure to the emulsion tube and draw up fuel better.
Your high altitude and running withour airbox has degraded the pressure required to draw up fuel.

OMR

Offline marshalljohnson307

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Re: jetting
« Reply #21 on: May 08, 2012, 08:22:20 PM »
omr ok sounds good....just to let you know i have been studying your mods for a bit now and have completed them....my spring was right length and number of coils, left it alone. yep had the d-shaped bottom where the needle goes into the slide.....i grounded the ring and installed it, needle doesnt rub on the jet. im running with dj in the 5th grove, and yep i had to grind a bit off the top down, to where there was a little play on the needle so it wouldnt come out. i drilled out the 2 holes in the slide and added 2 more. i removed the clear breather tube going to the airbox, vented it with a filter on the carb, and pluged the one on the airbox.....now as far as i can tell, alls i have to do is install the size 40 traxxtor air jet (hard to find btw) which is sitting on the bench right now, then ill be completed with the stock carb mods. maybe ill get it in tomorrow.......omr thanks alot for sharing your info with the world.......you probably could have went into business modding carbs?..........the only other thing is the modded emolsion tube, but i cant find any info on that.....so you wanna let me in on that info? hehe

now it seems to be running pretty good, it is popping, coming off high throttle, but  going to a bigger pilot jet should help with that. ill order the part in the next few days when i find some time. one question on that is, does that richen all the circuits or just the main? im wondering if that would help a little with the poping?

Offline marshalljohnson307

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Re: jetting
« Reply #22 on: May 09, 2012, 06:22:11 PM »
ok so today i installed the size 40 air jet, and it does richen things up, it was running good before i put it in, wasnt spot on, but running good with dj needle in 5th grove, with a 185 main dj jet. put in the airjet it ran like crap, i could get it to idle with the choke all the way on, for a min, then it got warm and just wouldnt run. so i raised the needle up to the 3rd notch, up 2. and it is running pretty good there, i would say its probably running better then ever before, no hesistation anywhere in the thottle, i was able to get a little...little pop coming off 2nd or 3rd, but much better.....and the crazy thing is.....when feathering the throttle, i can hear somone what of a low whistling, or swoshing sound, coming from the exhaust, kinda of a new sound, i take it as better throttle response? alot crisper? i like it, and it sounds good.....but i was only able to take a 10 min ride, and a bunch of driveway reving......pull the new plug, and it still looks new, maybe a heir on the rich side......now that im close i should be able to get it spot on......but that probably wasnt enough riding time to get a good gauge of the plug...

Offline marshalljohnson307

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Re: jetting
« Reply #23 on: May 10, 2012, 07:46:37 PM »
so today i worked on the ds a bit today, i went down to a size 175 dj, thats down from 185 main, with the dj needle still in 3rd grove from the top, i did notice more poping on highspeed slow down, i did check the pilot jet, is a size 40. so tonight ill order a 47.5......to be honest its hard to notice the difference.....seemed like maybe the 185 was a little better? maybe less poping?.....anyhow i rode maybe 15min.....couple sprints up and down a field......checked the plug and it still looking pretty much new?......so i guess what im wondering is.....what range do i need to be in for it to run well? i mean jet wise.....i was at 186 now 175 how far should i be able to go, before it runs like crap? if i went to 160, it surely wouldnt run right......right?

and just to confirm those jetting sound about right? maybe a little rich? and also......if im riding it for 15 min, and plug still looks new.....that means im pretty close right?

Offline marshalljohnson307

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Re: jetting
« Reply #24 on: May 22, 2012, 07:23:32 PM »
update: after doing about a week or so of jetting, making adjustments, riding, jettin,
etc. i decided that i found that with the omr mods, exhaust tip mod, lid off the box with a
K&N, and big gun cdi, went from 40 to 47.5 pilot and went from 120 to 40 airjet.  i found
that it seems to like it in the 2nd notch from top (DJ) with a 185 main jet (DJ) and that
riding at just under 6k ft. this weekend ill be at 8.5k ft so ill see what she does then.

Offline BigFun421

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jetting
« Reply #25 on: November 16, 2017, 11:00:57 AM »
The bike started off stock that led to the OMR mods for airbox on which led to airbox off mods. Now I am on the hunt for the 120 to 40 air bleeds and a larger pilot. I installed a loony tune exhaust direct mount air filter staying with the 47.5 pilot. now I have a need for a larger pilot, even at the risky four turns out I’m still getting an aggressive backfire and off idol stumble. Currently I have soldered and re-drilled the air bleed as well as installed the DJ needle on the fourth clip down and 200 Main. I’m having trouble locally finding the air bleed in stock. Anyone have any experience drilling that can advise in drilling the pilot?
    I should also mentioned I test drive a 2800 feet but really only run it hard at sea level with high humidity and cool temps.


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« Last Edit: November 16, 2017, 11:07:49 AM by BigFun421 »

Offline BigFun421

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Re: jetting
« Reply #26 on: November 18, 2017, 05:19:41 PM »
So now I’m thinking it had a #40 pilot. I checked the original with a wire drill and it was a 76 or .020” I drilled upto a .025” in the backup I found. The results were promising. No back fire and no off idle stumble, good power and a better progression in rpm. The pilot screw is 3/4 turn out. I’ll re check once I’m on the beach.


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Offline BigFun421

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Re: jetting
« Reply #27 on: February 09, 2018, 07:00:59 AM »
UPDATE: After 2 days on the beach I have turned up my idle to 1500RPM and I have turned the pilot out a total 1.25 turns. My top end is flat and won’t overrev but I’m fearful that is due to the direct mount filter. I’m going to see if I can bend and squeeze my original filter mount in for testing. 


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Offline BigFun421

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jetting
« Reply #28 on: February 25, 2018, 08:26:58 AM »
Welp, there is no cutting that will get the stock filter even close. I was thinking some dom tube with just the right shape. But now I’m back on the hunt for a carb that can flow enough laminar air to get my top end back. The Guys at Ron woods finally picked up my call... but they are not who they once were, they said they would call me back about the tm45 and intake, but I never heard back. I’m emailing Eric at OMW about a lectron 48. We shall see.


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« Last Edit: February 25, 2018, 08:31:16 AM by BigFun421 »

Offline Oldmanracing

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Re: jetting
« Reply #29 on: March 07, 2018, 09:05:02 PM »
Can't over-rev?
Did you set the float bowl per my specs?
What does the sparkplug look like?
« Last Edit: March 07, 2018, 09:07:15 PM by Oldmanracing »

 

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