My 1982 GS750E Project

[Anthony]

When I say hanging idle, when I blip the throttle, it stays high around 3-4k for 5-30 seconds. It's the weirdest thing... I do have the PVC pipe throttle mod that makes the throttle 20% less to WOT. Would that be causing an issue? I adjusted the slack properly by the carbs.

 

[Dodik]

hanging idle is a symptom of lean condition,

i am sure you read this by now but just in case its a good starting point,
http://www.factorypro.com/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html

 

[Anthony]

So I put the pilot screws at 3 turns out, and it has hanging idle bad there. I also tried to hear the upper RPM's and it won't budge above 6k RPM's. Would a lean condition cause that issue too? This is hurting my head :/

 

[Dodik]

yes if it wont rev to redline your main jet is too small, which positions is the clip on the the needles, and I am guessing you are on DJ124 mains right now? When you are doing all of this is the entire airbox assembled and connected to the filter? Do you have the endcap on the pipe or is it open.

 

[Anthony]

The needle clips are at the third position I believe, and yes I have the DJ124's installed for the main jets. The airbox is fully assembled and has no intake leaks that I could find from testing. I have a supertrapp exhaust, so the end is capped off but has the fins on the outside to let the exhaust escape in a 360 degree manner. The manual for the DJ kit said to install the 124s if you only have an after market exhaust and stock airbox setup like I do. Is that not the correct thing to do? Or maybe the needle position is off?

 

[Dodik]

no needle position is good at the moment, it may need to be changed once you figure out why it is lean, are you able to get idle speed to around a 1000rpms or at least below 2k? If you answered yes then did you try to finally synch the carbs?

 

[Anthony]

Yes I can get it to idle around 1200 healthily. It sounds good there. And I tried to vacuum sync previously with my carbtune but I was not getting any vacuum readings on anything less than 3000 rpm. I haven't checked to see if it is doing that still after the second valve clearance, but that was next on the list to test. What would that mean if it still has no readings on the carbtune below 3k rpm? Bad tool?

 

[Dodik]

i'd say yes, something would be clogged since the bike is running it means vacuum has to be there.
Try to do sync, after adjust the idle, if you still can not get it to rev to redline it means that larger main jets are required.

On monday or tuesday i will actually install DJ124 and Airbox with filter on mine i'll tell you how it goes. Not liking the pods.

 

[Anthony]

I will definitely test out the carbtune again and see if my readings are good. Might try a tad bit of sea foam as well, just for kicks. I'm really hoping I can get somewhere with this. Please let me know what your outcome for your setup is, you've been my only source of constant help for this (which I greatly appreciate!).

 

[Dodik]

Well i installed my airbox, with oem style filter, lid is closed, DJ124 mains. needle clip is at third from the bottom slots. starts fine no hanging idle or any problems thus far but I have not adjusted the idle as i ran out of time, did about a mile run to air up my front tire and it will rev all the way up. will mess more tonight with it.

So this brings us back to your issue, did you drill the slides as required per the jet kit? when you did valve adjustment did cams look original?

 

[Anthony]

Yes the slides are drilled and the cams looked original from what I could tell. I do have pictures of it I can provide. I have not hooked up the carbtune yet to see if I get vacuum. But that doesn't fix either RPM or hanging idle issue. Unless I could rule out a carb sync (which I can't do with no vacuum readings).

 

[Dodik]

took the bike to work this morning to get it warmed up, I can feel its a bit lean on the low circuit, and just a tiny bit of hanging like you describe but not as bad, which leaves me to believe that your pipe and air filter combo is probably less restrictive than mine.
Which filter do you have in there? is it reusable and does it require oil spray prior to using it by any chance?

You could try to block a bit of filter element with just masking tape and see if improves the response. If it does you know you'll need bigger jets if it makes it worst then something else is at play here.

 

[Anthony]

I have a K&N reusable filter. It comes oiled. I do have an OEM one though that I can use for testing. Would I still need to do the masking tape if I did that?

 

[Dodik]

not necessarily, my filter is from last year so im pretty sure it allows a bit less air than yours, since it takes two minutes to swap the filter I would try it and see if it changes anything. try oem filter and see if it will rev up to redline. also how many discs is on your supertrapp pipe, the more discs the less restrictive it is.

all these suggestions are only because i don't want you to have to remove the carbs again and rejet, and from your symptoms the bike is slightly lean, so reduce amount of air coming into the engine (hence the tape suggestion but its more of a temp solution, less flowing filter is a better option) or increase back pressure take a couple of discs out of the pipe.

i am starting to think that there should be a stage 2 kit, since 1 seems a bit lean and 3 a bit rich.

 

[Anthony]

So I switched out the K&N air filter for the OEM filter and it seemed to hang less and it went up to 6500 RPM. So I'm guessing I'm fighting a lean issue?

 

[Dodik]

sounds about right, I ordered myself 120 mikuni main jets, they should be here tonight. thats right inbetween stage 1 and 3, so i have a feeling that they will work. On your bike i noticed you have 12 discs on that supertrapp i only have 6, cause i like it quiet but our results will vary slightly because of that.

 

[Anthony]

Wouldn't I need bigger main jets to get the upper RPMs higher?

 

[Dodik]

mikuni and dynojet use slightly different numbering system, thats why i specifically said mikuni,
on Cliffs site there used to be a chart for the conversion but link is gone although the factor is still there and it is 0.9375.
so a DJ124 x 0.9375 = 116.5 in mikuni numbers
and DJ130x0.9375 = 121.875

mikuni jets go but 2.5 increments so 115, 117.5, 120, 122.5 thats why i went with 120s
and it runs great, still need to do plug chops to test each circuit but it runs without any hesitation and feels right where it needs to be.

if you going with k&n filter and 12 plates on the trap then install dj130 and call it a day since you already have them.

 

[Crankthat]

[FONT=&quot] [/FONT]
[FONT=&quot]Hole Dia”---Keihin # -- DynoJet # -- Mikuni #[/FONT]
[FONT=&quot]0.0350---- 92.5--------- 92----------- 86.3[/FONT]
[FONT=&quot]0.0360---- 95----------- 94----------- 88.1[/FONT]
[FONT=&quot]0.0370---- 97.5--------- 96----------- 90[/FONT]
[FONT=&quot]0.0380---- 100---------- 98----------- 91.9[/FONT]
[FONT=&quot]0.0390---- 102.5------- 100---------- 93.8[/FONT]
[FONT=&quot]0.0400---- 105--------- 102---------- 95.6[/FONT]
[FONT=&quot]0.0410---- 107.5------- 104---------- 97.5[/FONT]
[FONT=&quot]0.0420---- 110--------- 106---------- 99.4[/FONT]
[FONT=&quot]0.0430---- 112.5------- 108--------- 101.3[/FONT]
[FONT=&quot]0.0440---- 115--------- 110--------- 103.1[/FONT]
[FONT=&quot]0.0450---- 117.5------- 112--------- 105[/FONT]
[FONT=&quot]0.0460---- 120--------- 114--------- 106.9[/FONT]
[FONT=&quot]0.0470---- 122.5------- 116--------- 108.8[/FONT]
[FONT=&quot]0.0480---- 125--------- 118--------- 110.6[/FONT]
[FONT=&quot]0.0490---- 127.5------- 120--------- 112.5[/FONT]
[FONT=&quot]0.0500---- 130--------- 122--------- 114.4[/FONT]
[FONT=&quot]0.0510---- 132.5------- 124--------- 116.3[/FONT]
[FONT=&quot]0.0520---- 135--------- 126--------- 118.1[/FONT]
[FONT=&quot]0.0530---- 137.5------- 128--------- 120[/FONT]
[FONT=&quot]0.0540---- 140--------- 130--------- 121.9[/FONT]
[FONT=&quot]0.0550---- 142.5------- 132--------- 123.8[/FONT]
[FONT=&quot]0.0560---- 145--------- 134--------- 125.6[/FONT]
[FONT=&quot]0.0570---- 147.5------- 136--------- 127.5[/FONT]
[FONT=&quot]0.0580---- 150--------- 138--------- 129.4[/FONT]
[FONT=&quot]0.0590---- 152.5------- 140--------- 131.3[/FONT]
[FONT=&quot]0.0600---- 155--------- 142--------- 133.1[/FONT]
[FONT=&quot]0.0610---- 157.5------- 144--------- 135[/FONT]
[FONT=&quot]0.0620---- 160--------- 146--------- 136.9[/FONT]
[FONT=&quot]0.0630---- 162.5------- 148--------- 138.8[/FONT]
[FONT=&quot]0.0640---- 165--------- 150--------- 140.6[/FONT]
[FONT=&quot]0.0650---- 167.5------- 152--------- 142.5[/FONT]
[FONT=&quot]0.0660---- 170--------- 154--------- 144.4[/FONT]
[FONT=&quot]0.0670---- 172.5------- 156--------- 146.3[/FONT]
[FONT=&quot]0.0680---- 175--------- 158--------- 148.1[/FONT]
[FONT=&quot]0.0690---- 177.5------- 160--------- 150[/FONT]
[FONT=&quot]0.0700---- 180--------- 162--------- 151.9[/FONT]
[FONT=&quot]0.0710---- 182.5------- 164--------- 153.8[/FONT]
[FONT=&quot]0.0720---- 185--------- 166--------- 155.6[/FONT]
[FONT=&quot]0.0730---- 187.5------- 168--------- 1575[/FONT]
[FONT=&quot]0.0740---- 190--------- 170--------- 159.4[/FONT]
[FONT=&quot]0.0750---- 192.5------- 172--------- 161.3[/FONT]
[FONT=&quot]0.0760---- 195--------- 174--------- 163.1[/FONT]
[FONT=&quot]0.0770---- 197.5------- 176--------- 165[/FONT]
[FONT=&quot]0.0780---- 200--------- 178--------- 166.9[/FONT]
[FONT=&quot]0.0790---- 202.5------- 180--------- 168.8[/FONT]
[FONT=&quot]0.0800---- 205--------- 182--------- 170.6[/FONT]
[FONT=&quot]0.0810---- 207.5------- 184--------- 172.5[/FONT]
[FONT=&quot]0.0820---- 210--------- 186--------- 174.4[/FONT]
[FONT=&quot]0.0830---- 212.5------- 188--------- 176.3[/FONT]
[FONT=&quot]0.0840---- 215--------- 190--------- 178.1[/FONT]
[FONT=&quot]0.0850---- 217.5------- 192--------- 180[/FONT]
[FONT=&quot]0.0860---- 220--------- 194--------- 181.9[/FONT]
[FONT=&quot]0.0870---- 222.5------- 196--------- 183.7[/FONT]
[FONT=&quot]0.0880---- 225--------- 198--------- 185.6[/FONT]
[FONT=&quot]0.0890---- 227.5------- 200--------- 187.5[/FONT]

 

[Dodik]

so any luck going with stage 3 jets?