Topic: Spark plug cap resistance and whole lot more

[flybox1]

methinks someone before you has adjusted the slides.
if it bugs you, release each slide from the throttle bell, then turn all carb top vacuum adjustment nuts to the center of their total travel range.
from here, you can now re-bench sync the slides, and proceed with a vacuum sync.
Each slide is treated individually when a vacuum sync is done.  They might all be different heights again when completed

[Deltarider]

fuel delivery.

Hm, looks more like a vent tube to me.

Yesterday i opened the air screw almost 2 rounds. It pops and backfires

Could indicate too lean.

[flybox1]

Delta, you are correct.  #66 is listed as  Tube Fuel, but it should be the atm vent between carbs.
http://images.cmsnl.com/img/partslists/honda-cb750k2-four-european-direct-sales-carburetor-keihin_bigma000039e26_c6f5.gif

[topperharley]

What if thats clogged or leaks? What does it do?

[flybox1]

What if thats clogged or leaks? What does it do?

it shouldnt ever leak gas.
Its a passageway for air to move in and out of the carb bowl empty space, as fuel is used and replenished up to float level.
Blockage here and you would see inconsistent filling and flow of gas into that carb bowl.

[topperharley]

Shot in the dark. I switched carbs 1 and 4 jets together. Emulsion tubes were clean.

Cyl 1 pops when idle. That is a symptom of lean mixture or thats what iv thought. Well i found atleast 5 more reasons why it pops. Doesnt have to be lean.
Im gonna do the idle test first with new plug. Only i dont have a fan to cool it down. I have to do on sequences and let it cool a bit in between.

[flybox1]

Where in Finland are you located?

[topperharley]

Tampere.

Lähetetty minun SM-G903F laitteesta Tapatalkilla

[flybox1]

wow....looks like wonderful scenery with all the water there.

[topperharley]

Yes. I have to say that we have lots of beautifull roads on coyntry side and small villages and cities to drive around. Just like you have there in states.
Now that the weather is good +20c° and nature is starting to bloom i just cant wait to get out there.  We have a long dark winter and it really sucks the life force out of you.

The best thing i know that you can do with your bike is ride a bike with your friends all night long when the sun wont go below horizon at all

[flybox1]

The best thing i know that you can do with your bike is ride a bike with your friends all night long when the sun wont go below horizon at all

now that would be fun 

[topperharley]

Yea. Its awesome.

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[PeWe]

The best thing i know that you can do with your bike is ride a bike with your friends all night long when the sun wont go below horizon at all

now that would be fun 

Reminds me about my first years with my CB750 I still have! Just cruising around between the cafe's and where girls where, in the city as well as other cities around. We could drive 110km east to get a burger at McDonalds in central Stockholm.
Late 70 and early 80's had bad summers here except some early morings when sun rised. Went to bed with sunny blue sky, woke up withe grey rainy skies.

[topperharley]

What do you guys say?  I measured the coils spark plug wire pins and i got nothing. I mean shoult there be a resistance in between 1-4 spark plug wire connector? Please confirm this becouse i didnt get reading on secondary at all.
I got 4ohm in primary test.
Did understand this right?

PRIMARY RESISTANCE
Set the multimeter to measure ohms. Use one test lead on each of the small terminals that attach to the wiring harness. If
using stock coils, you should get a reading of approx 5 ohms. If using DOHC or most aftermarket "hot" coils the reading
should be about 3 ohms. If your readings are very far off from the given values, the coil is probably bad. If you do not get
a reading, or if it flickers in and out, then there is a broken wire and the coil is bad.


SECONDARY RESISTANCE
Set the multimeter to measure ohms. Once again we are going to isolate and de-energize the coil. Use one test lead in
each of the spark plug wire connectors. You may have to wiggle them around to get them to a spot where you are getting
a reading. Depending on the coil you should get a reading of 5Kohms to 20Kohms. I don't have a manual with me so I will
edit later for the actual cb750 specs. If you get no reading, the coil is bad. This test can also be performed with the plug
wires and caps in place. Due to the extra resistance though you should get a reading between 10Kohm to 50Kohms
depending on the coil, wires and caps. If this is done first, and there is no reading, do the test without the wires. If you get
a reading with no wires and no reading without, then the wires are most likely your problem.

[flybox1]

Got the correct setting on your ohm meter?
http://www.hondachopper.com/garage/troubleshooting_charging_system/troubleshooting_charging_system.pdf

[topperharley]

thanks Fly  I did have a wrong scale. Well it seems that coils are fine. Damn,  i gues.... Anyway we just won Belarus in hockey WC. Lets see how it goes from here.

[flybox1]

No Prob 
So, did you even out the vacuum sync screws on those carbs and do another bench sync?

[topperharley]

No i didnt even them out. Im happy about the sync and the idle on bike. I will do all those cosmetic things next winter.  God damn plug just keeps on fouling and that is my mission. I have a really busy weekend coming so i dont have time to spend with the bike. I drove a 50km route this evening. Boy ws that nice in warm summer evening. Ofcourse i replaced the fouled plug after i came home

[flybox1]

....and carry an extra one with you 

[topperharley]

Im waiting for carbtune sync gauge to arrive. I got pissed of my old mechanical vacuum gauges. Just coudnt get steady readings from them.

It just got to me. The bike used to be 900cc. The carb settings are from those days. 135 main and needle in the middle groove. What if i move the clip up a groove to get it a bit leaner. The setting that was good for 900cc cant be good for 750cc. Right?

[flybox1]

the carbs dont care what engine they are on.
you need to tune the carbs to provide the proper air/fuel ratio to the bike based on your air intake and exhaust setup.
this is why doing the series of plug chops is important.  it'll show you what you need to change.
...or pay to get on a dyno with a gas analyzer(most accurate)

[topperharley]

Before i do the plug chops im gonna check all the adjustable things and do an vacuum sync with carbtune. Hope it arrives wed- or thursday.

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[topperharley]

Well the sync gadget has not arrived yet. I wanted to test something so i lowered the needles one groove. Im a bit short right now so i didnt do the plug chops yet. Two kids sucking money out of dads wallet God bless them . Actually the biggest thing was the ignition. I found a old post from you fly! It was about shimming the point plate. I always did the "cold" setting for ignition timing and after that with timing lamp. always got it on the F. Only after i read the about the shimming i was like #$%*, no way. I always made a big mistake when i didnt check the timing after i tighten the bolts. Well this time i did. The timing was way off. Bike always ran good but after this shimming and timing it runs even better. I also took one coil off from advance unit springs. After the needle adjust and timing setting i took a 50km ride and didnt get a fouled plug. Its still black and sooty but didnt foul. I also took the ride the easy way and did not push it on highest revs. The difference when riding on the edge of idle is really big. It used to be hard, like i coudnt get it run smooth. No it does. It also starts on first stroke. All the foulings have happened after a high rev ride. Dont know if that is relevant but maybe smaller jet would do the trick. Maybe i buy the whole service kit for the carbs but the sync and plug chop is first.

[flybox1]

Hey Hey, cool stuff    I've got my plate shimmed with folded alu from a soda can 
Hold off on adjusting the main jet for now.  Get the carbs vac sync'd, and ride a bit more.
I've got 4 kids of my own     Just throw some cardboard into their shoes so they last longer, and tell them Dad will ride to get them new shoes when the bike is fixed 

[topperharley]

Thanks Fly. Will do. You know, i work in board mill so there is plenty of board in them shoes. Hope the carbtune comes this week.