I'm still trying to get my 96 magna sorted out, and I'm stuck again. I installed Dave Dodge's jet/shim kit along with Vance&Hines pipes and K&N filter. Before
this, the bike ran OK except for the usual stumble around 4k that most stock bikes seem to have. Now, under throttle, the bike goes great, but at light throttle it runs rough and pops both decel and accel. I called Dave Dodge and he said it's a vacuum leak somewhere. I removed and reinstalled carbs making sure everything was tight, and still have the same issue.
Could a small air leak in the airbox cause this much rough running? Also, there
is one hose near the hose that connects to the back of the airbox that is not
connected to anything. It comes off one of the tubes that runs between the carbs. I can't find anywhere that it could go. Maybe just some kind of breather hose?
Any ideas of probable vacuum leak areas would be appreciated. Thanks.
Don't think there should be hoses not connected. I have attached pages from the shop manual showing carbs and hoses, along with instructions for disassembling carbs.
Hope this helps.
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I agree does sound like an airleak. Places to look would be the airbox, as well as the rubber intake boots.
Also make double sure a diaphragm did not get out of its ring when putting the black plastic cover back on...
Thanks for the replies, I went ahead and ordered new carb insulators since mine are 12 years old and a bit stiff. I am still wondering about the hose near the rear of the airbox that is not
connected to anything. Does anyone have their tank off and can look? It is about a 1/2" OD
hose that runs up from the carbs and ends in a half loop next to the hose that is attached to the back of the airbox. Thanks for the picture from the repair manual, but I can't tell from that.
Its a vent line. It goes up and makes a 180° turn down?? With a "bendy" bail holding it in place at the top from the back middle airbox bolt?
If so then it vents to atmosphere.
That's it, thanks Greg. I think I'll try wrapping the airbox seam with duct tape while waiting
for the new carb insulators.
On the "D" shaped pilot jets, where did you adjust them too?? I have found that on V&H I have to put them at least 3 1/8 turns out on a setup such as yours. Matter of fact we ended up putting on a second set of shims to help on one..
3 1/8 is where I have it now as a matter of fact. I tried everywhere between 2 1/2 and 3 1/2. Right now, when you open the throttle, from 5k to redline you better hold on, but it is just not right at part throttle, very rough running.
Does it do this at any particular RPM range? Or is it when you simply hold steady at a set speed??
It's not a particular rpm. If you're not accelerating it does it. It is worse when going
say 30-40 mph versus 60-65 because I'm giving it more throttle to maintain the higher speeds.
Alright that helps a lot... I believe its too lean on the low to mid range transition, you would benefit from another shim added to the stock and DRP shim you already added.
It helps, wont completely aleviate it, not that I have found YET. I have some ideas about it but still working towards proving them.
I too had to add the extra (3rd shim) on my magna as Greg suggested, and it helped my midrange, stumble-shutter quite a bit. I can still find a little bit of "flutter" if i look for it but just going up and down the rpm range, the extra shim helped my 01 out a lot. Good luck... Lance
OK, thanks Greg and Lance, I will stop by Radio Shack and try the
extra shim set-up. Probably can't get to it until the weekend, but I
will report the results.//Matt
Something I should note Matt, Some MOOTsters thought that my k&n air filter caused me to run lean, that is why they recommended the 3rd shim, otherwise it would have probably ran fine with stock air filter and 2 shims... Good luck to ya. Lance
Well, I added the 3rd shim and started with the pilot jet out 2 3/4 turns. It runs
worse by far now. The rough running, bucking and popping is much worse. To me,
it seems rich, like it's trying to clear out the extra gas and then eventually it takes
off, although now even under heavy throttle, it runs rough. Before with one extra shim, it ran fine under throttle. I didn't have time to experiment with the pilot screw, but I
can't imagine it will cure this. On the bright side, I'm getting pretty fast at carb
removal and replacement.
I checked the plugs before starting it up, and they were damp with gas, and one of
them was very loose and very wet. So I think it was rich before adding the next
shim. If the one plug was loose enough, could that have caused the rough running at
part throttle?
At any rate, it doesn't seem that the extra shim is the answer in my case. It also
doesn't seem to me that I am leaking vacuum from the boots, carbs, or airbox.
Any ideas, thoughts?
Well if ya got wet plugs and with the symptoms you describe I say its too rich. One way to tell if you have an air/vacuum leak is to fire it up then spray carb cleaner or such around the intake boots etc. If engine speeds up when you spray it has a leak.
Oh you dont have to pull the carbs to do the shims, the rears can be reached fairly easy and the front if you unbolt the radiator and have a shorty #2 phillips screwdriver can reach them while gently pushing the radiator out of the way.
I did spray around the carb boots as well as the airbox looking for leaks, but found
none. Thanks for the tip on changing out shims without carb removal. I will try it.
It seems I have lots of experimenting left to do, but I'll get it right one of these tries.
It just occured to me why the rear two cylinders had very wet plugs, because of the small amount of gas spilled when taking off the gas tank :-?. The front two smelled
of gas and were only slightly damp. I still think I'm running rich. I'm going to go back to the original one shim and start there.
Dave told me the same thing when I had those issues. I have a '95 running k&n air filter, vance & hines, Dyna 3k Ignition module. I installed the 105 jets and one extra shim and ran with the stock filter for awhile. it was pretty good, definately better than origional setup. i added the k&n and then the trouble started. the k&n/vance &hines allows it to flow better, thus leaner. as soon as i put the old filter in, the midrange stumble got better.
i played around with various setups, and finially found a combo that works great for me. i have tried 105,108,110 and finally 112 jets. i upped the pilot two sizes from stock 40 to 42, then to 45. and i am using 3 shims on each needle, and the d screws are at 3 turns out, but it's just a tad rich at idle, i need to back them down to 2.5 or 2.75 turns out. if you need part numbers (acutal kehin/honda parts) letme know and i'll shoot them back to ya. One thing to check before you get crazy into this is to make sure you took out the two rubber o-rings on either side of the air filter box. if these are still in while putting the k&n back, there will be an air leak as the lid would not seal properly to the bottom half. hope this helps. -chad
Quote from: Magnatic on May 26, 2008, 02:13:25 PM
I'm still trying to get my 96 magna sorted out, and I'm stuck again. I installed Dave Dodge's jet/shim kit along with Vance&Hines pipes and K&N filter. Before
this, the bike ran OK except for the usual stumble around 4k that most stock bikes seem to have. Now, under throttle, the bike goes great, but at light throttle it runs rough and pops both decel and accel. I called Dave Dodge and he said it's a vacuum leak somewhere. I removed and reinstalled carbs making sure everything was tight, and still have the same issue.
Could a small air leak in the airbox cause this much rough running? Also, there
is one hose near the hose that connects to the back of the airbox that is not
connected to anything. It comes off one of the tubes that runs between the carbs. I can't find anywhere that it could go. Maybe just some kind of breather hose?
Any ideas of probable vacuum leak areas would be appreciated. Thanks.
Ok so I learned something new Orings you say Hmmmmmmmmm and thought the pilot jets could go up so thats a good thing. Thanks Chad Post the part numbers here or on the other carb post :-D :-D
JETS:
112 Main:
Mfg Product Number: 99101-GHB-1120
Description: JET (#112) for Honda
Order Quantity: 4
Unit Price: $4.83
Total Cost: $19.32
110 Main:
99101-GHB-1110
45 Slow Jet:
PRODUCT INFORMATION:
Part Number: 99103-MT2-0450
Description: JET (#45) for Honda
Order Quantity: 4
Shipped Quantity: 4
Unit Price: $7.53
Total Cost: $30.12
42 Slow Jet: 99103-MT2-0420
Thanks for that Chad, great information. It doesn't seem that I could possibly be
running rich going from your experience. I did remove the airbox o-rings, as a matter
of fact I duct taped the seam to be sure! What is your gas mileage with that set-up?
Thanks//Matt
Check out this thread, it details what I did step-by-step.
I still get between 34-42 MPG depending how I ride. I tend to be on the heavy side :) the plugs looks just as they should. (finally) they were too white for my taste.
http://forums.delphiforums.com/MagnaRider/messages?msg=14706.1
Quote from: Magnatic on June 01, 2008, 08:27:51 AM
Thanks for that Chad, great information. It doesn't seem that I could possibly be
running rich going from your experience. I did remove the airbox o-rings, as a matter
of fact I duct taped the seam to be sure! What is your gas mileage with that set-up?
Thanks//Matt