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first time starting since carb rebuild/cleaning

  • Thread starter Thread starter growler
  • Start date Start date
G

growler

Guest
i'm a person that checks. and then checks again.

-carbs dipped, new o-rings
-airbox resealed, new airbox boots to carb
-bench sync done
-pilot screws seated lightly, then backed out 2.5 turns
-everything reinstalled

i'm getting some extra fuel line tonight so i can run a longer line from the tank (will set on stool next to bike) for the first start up.

this is where i get a little foggy. where does the highest idle method come in? right when i start it up? i also have my vacuum sync tool ready to use.

i'm taking a look at this right now....just want to make sure i continue in the right order. thank you in advance.

http://members.dslextreme.com/users/bikecliff/images/highest_rpm_plug_chop.html
 
Do the vacuum sync first then adjust the idle mix. I start with the screws out 3 turns. Then turn them in 1 at a time (slowly and carefully) the engine speed will start to raise a little then it will start to slow down as you turn it in. You are looking for the highest speed possible then that is your adjustment. Use the idle speed adjustment knob and set the idle speed back to 1000 then move on to the next carb until they are all done. Check out this video

https://www.youtube.com/watch?v=zm5mB3R8Ucw

He does a good job explaining it. That is a 1 cylinder bike but the adjustment is the same. Make sure you run a fan in front of your engine to keep it cool during the adjustment process. The plug chops are for checking fuel mixtures during specific operating conditions like idle, mid or high speed. It is usually used for dialing in jetting but it wouldn't hurt to check. Check out this video if you do the plug chops. It will help you with reading the plugs.

https://www.youtube.com/watch?v=saCDmyiBmb0
 
Last edited:
Sounds like you are proceeding correctly... don't forget to plug the vacuum port on the carbs (put a screw in the end of the vacuum line to plug it off) when using an isolated tank set-up like you've described. Run the petcock on Prime & you won't need to run the vacuum line back to the petcock.

For my carb syncing I use an old fuel tank I scavenged off a snow-blower I junked a few years ago. Bought a fuel shutoff valve at the hardware store in the lawn mower section & simply ran a length of fuel line from the tank to the carbs. That way you don't have to worry about dropping your MC tank by accident. Others here have modified various containers/jugs by drilling a hole through the screw cap, inserting a short piece of rigid tubing, then sealing around the tube with epoxy (you get the idea).

Also, be sure to position a box fan in front of the engine to keep it cool while you tune the carbs. !!! VERY IMPORTANT STEP !!!

Not sure there's a proper sequence of the idle setting vs. carb syncing. It's a little like the chicken & the egg game. The sync has to be good to set the idle correctly, and the idle has to be good to set the sync correctly.

If you've done a good job with your bench sync, then set the idle screws using the highest RPM method, then sync it up. You may want to do the process a couple of times to be sure you got it right.

BTW - those sync screws/lock nuts are a PITA to get exactly where you want them - the screw moves when you go to tighten the lock nut (don't over tighten the nuts)

Make sure the bike is warmed up & off choke before adjusting.
 
Hey that's cool. I was just thinking wouldn't it be cool to have a tool for that....
 
The first one you posted is the correct one, growler. I have used a friend's more than once. Works great.
 
2.5 turns out should get it running...adjust idle and synch the carbs ...

Steve showed me how he likes to use the vacuum gauges as an adjustment tool as well..the idea is that once the carb is running the best it can ...the vacuum will at the highest point as well...so leaving the gauge attached and the vac line plugged you can get a near perfect idle jet adjustment ....

try it by turning a screw in or out while you observe the vac gauges and see ...

If you need help ..let me know ...I am not far away ...
 
growler said:
Just picked up one of these off of Ebay. After seeing how they adjust, I didn't want to get super frustrated. $20 is worth that. :)

http://www.ebay.com/itm/MOTION-PRO-...0878431895&pt=Motors_Automotive_Tools&vxp=mtr
Click to expand...
That is a nice-enough tool (I kinda wish I had one :-\\\), but it will be "fun" trying to fit it on the center adjuster. :D



growler said:
right? they also have this one, but don't say what carbs it fits.
http://www.ebay.com/itm/Motion-Pro-...Parts_Accessories&hash=item41659ae8aa&vxp=mtr
Click to expand...
That tool is for reaching under the VM carbs (1979 and older bikes) to adjust the fuel screw. You won't need it for your bike.

.
 
hah! i agree, i took a long socket extension just to see how i'd get at the adjusters, and it will be a small (hopefully) challenge to work around the frame.

Steve said:
That is a nice-enough tool (I kinda wish I had one :-\\\), but it will be "fun" trying to fit it on the center adjuster. :D
Click to expand...
 
I just checked amazon.ca. They have the Motion Pro Tool for $23.10 but want $57 for shipping! WTF?

I ordered mine from amazon.com and had it shipped to detroitmailbox.com free. If you are close to the border there may be similar places you can ship to. Even a UPS store would work.

K
 
Well, the tool I paid priority shipping for didn't show up, so I didn't get too far on synching the carbs. :(

I did, however, start it up. Happy to report she started right away, and then the idle surged to 5000 rpm. Played with idle adjustment screw and got it warmed up to where it would idle at 1000 rpms steady. Put a big garage fan on it to keep things cool and breezy on the engine. Snapped the throttle a couple times and rpms surged again, sounding like the throttle was sticking. It definitely is, the grip doesn't snap back at all. Maybe new throttle cable? Or grease it?

The air mixture screws are set at 2.5 turns out from lightly seated. Right when I started to adjust them using the highest idle method, I thought I should check to make sure all the cylinders were firing, just because. Good thing I did, because cylinder #2's exhaust pipe wasn't nearly as hot as the other three. I could touch my finger to it when the bike was running. Pulled the plug, it was a little wet on tip. Wiped it down, reinstalled, ran it again, checked plug again, wet again. Could this be from my carbs not being synced yet? As soon as I get my darn tool I can do them.

Frustrated, so I took a break. At least it started right up.
 
nastyjones said:
Ha Ha, shipping to me in Canada by Priority post $27.13. No thanks.
Click to expand...

Skinner said:
I just checked amazon.ca. They have the Motion Pro Tool for $23.10 but want $57 for shipping! WTF?

I ordered mine from amazon.com and had it shipped to detroitmailbox.com free. If you are close to the border there may be similar places you can ship to. Even a UPS store would work.

K
Click to expand...

get the carbtune and the screwdriver from here

http://www.carbtune.co.uk/carbdtls.html


http://www.carbtune.co.uk/carbtool.html

you can't beat his prices....

http://www.carbtune.co.uk/carbpric.html

.



sorry for the HighJack......

.
 
found some good info after searching "wet plug.

http://www.thegsresources.com/_forum/showpost.php?p=2014608&postcount=28

maybe 2 1/2 turns is too much for cylinder two. gonna pull all the plugs and see if any others are wet. after i get my carbtool (hopefully today) i can get the mixture set correctly and carbs synched....would that possibily eliminate the issue and get #2 working again? spark is bluish. just put four new NGKs in there.
 
crap. i forgot to plug the vacuum line.

i'll do that and begin the steps all over again. :oops: newbie mistake!

hikermikem said:
Sounds like you are proceeding correctly... don't forget to plug the vacuum port on the carbs (put a screw in the end of the vacuum line to plug it off) when using an isolated tank set-up like you've described. Run the petcock on Prime & you won't need to run the vacuum line back to the petcock.
Click to expand...
 
growler said:
crap. i forgot to plug the vacuum line.

i'll do that and begin the steps all over again. :oops: newbie mistake!
Click to expand...

Ha, not necessarily a newbie mistake, I still forget to plug it off myself on occasion... :rolleyes:
 
Just add a little 3in1 or graphite oil to the throttle shaft where they go into and out of each carb. Should help things slide along better.
 
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