Some strange issues...

Hey all. my bike isn't running properly.
wondering if y'all had some trouble shooting advice

The good:

Valves good/clearances in spec
timing dead on
compression good
carbs clean
fuel level set to 3mm +/- 1mm
fresh gas
good battery
vacuum present when syncing carbs
no vac leaks

The bad:

tried to colortune: 2+3 three rich and firing well, but 1+ 4 firing only intermittently with lots of popping (backfire) #1 exhaust pipe cold

tried to sync: vacuum present but all over the place


my question/thoughts:

spent some time chatting with my bike mechanic buddy trying to figure out why one and four aren't firing properly.

we came up with:

bad coil/bad plug caps/bad tci/bad electrical connection
OR
carbs so far out of sync that 1+4 aren't firing properly

i was wondering if one of you fine people could give me a step by step on how to test the aforementioned electrics, bearing in mind that i'm not very well versed in the use of the multimeter

I would just do the carbs to eliminate that, but i have to borrow my mechanics sync sticks and he needs them this week.

 

Well Id say for sure you have a bad coil or bad plug caps. So remove the caps and check the resistance, also check the resistance on one and two anything over 4.5 ohms need new caps same for coil leads.

 

my BRAND NEW Dyna coil (only 1 of the 2 new ones) checked out OK with the Ohm meter but would only fire 1 & 4 intermitantly. I found this using the Colortune. Switch the white connectors going to the coils and switch the 1&4 wires w/ 2&3 holes and see if the problem fires. let us know. P.S. using a Volt meter, just turn the dial to the Ohm setting and touch the leads to whatever your testing. compare the value on the display to the value the manual says you need and Viola! you now know how to use one. don't be scared, it's easier than a calculator.

 

did you mean OR instead of AND where underlined below?

Switch the white connectors going to the coils and switch the 1&4 wires w/ 2&3 holes

if or, that's awesome coz i was going to just switch the cables from 1&4 to 2&3 and see if it worked but they're not long enough.


my multimeter has many ohm settings

20m
200k
2k
200

which do i use?

i lost the instructions, guessing that m is mega and k is kilo but that's just a guess

note that i didn't buy any tnt and am now checking electronics ; )

 

2k, the word is 'and'

 

thanks yamaman!

im still a little confused though... wouldn't switching the connectors and the cables make the problem just move to 2&3?

 

if you've bench synced and all mixture screws are set the same on the carbs, i would say it very well could be an ignition issue. it could be any one of a bad plug coil, pickup coil or TCI (or an electrical connection somewhere between). here is a troubleshooting guide to help you figure it out:

Ignition Troubleshooting Guide

follow the troubleshooting steps and let us know how you make out.

cheers,

Trev

 

so i tried to use my multimeter to test the coil, but I'm having issues. I'm really bad with electronics.

I set the multimeter to the 2K setting, and did the "primary coil check" as specified in my haynes manual. desired value is 2.5 Ohms +/- 10%, but all i get is a 1. as if its not reading anything. same for both coils, and i know one is working.

did the secondary coil check and same result.

wanna help the special kid? im sticking one probe in one side of the connector and one in the other, just like the picture in the manual...

 

try setting the multimeter to the lower 200 ohm scale

 

the idea IS to move the problem around to differentially isolate it. If you move the wires and the problem follows then the problem is in the wires or coils or something. If you move the wires and the problem stays put then it's in the plugs, compression, mix or some such.

 

@ tibor... did that, same thing. no reading on any setting

my spark plug cables aren't long enough to switch 1&4 to 2&3; can I just switch the coil connectors with the same results?