opinions on 'sort of' plug chop pic

[Colin Green]

Hi.

I took these out warm after a 60 mile plus run at different speeds. After playing around with the idle mix I got the engine to run ok but was starving and coughing when the throttle was pinned back (low and high revs) It only experienced this problem when the throttle was turned hard on. However after about 50 miles she started to do the same thing with just a bit of throttle.

I got a replacement fuel hose to install 'shortly' (to get rid of the fuel filter) and some new plugs.

Took the old ones out when she cooled a bit and from what I can see they look ok for 60+ miles.. or might it be a bit lean??? Click the link and tell me what you think.

Cheers

Colin

http://s251.photobucket.com/albums/gg305/flyingcrocodile46/?action=view&current=IMG_0011.jpg

 

[Guest]

to me the plugs look ok (or a bit on the lean side)

 

[Colin Green]

to me the plugs look ok (or a bit on the lean side)

Cool. I might wind all the screws out a third of a turn to see if it makes any difference (when I'm done with below and tested it.)

You must have bloody long needle nose pliers (>200mm needle I reckon) to be able to get through the frame down between them carbs to hold onto the fuel line.. I can get my little 75mm needle nose pliers in there but cant seem to be able to operate them to grip the smaller hose that is in there now (all thumbs). getting desperate now.. have cut one of the kids felt tip pens up to use the <1mm thin plastic walled tube to connect the hoses and take the fuel filter out of the equation. testing off cut in petrol to see if it goes soft b4 I try it out.

Damn... Soft and gooey. I'll try Micos for me little bit of pipe tomorrow.... In the mean time I'm gonna give up and try a little pipe myself

 

[Guest]

Cool. I might wind all the screws out a third of a turn to see if it makes any difference (when I'm done with below and tested it.)

your mixture is likely ok, so i dont expect a richer mix to solve your prob

 

[Guest]

You must have bloody long needle nose pliers...

as i used the thick/stiff hose i didnt need to get to the very bottom. holding it 50mm or so above the carb nipple with the pliers worked fine

 

[Colin Green]

as i used the thick/stiff hose i didnt need to get to the very bottom. holding it 50mm or so above the carb nipple with the pliers worked fine

I got thick hose (14 to 15mm outer dia) Maybe in daylight ...Awww F**k it.. I'm gonna go down and rip off the old one and give it a try.

 

[tkent02]

Can't see anything in the pics, is that blue or gray? You need to read them your self. But what was the running condition when you chopped the engine? Full throttle/high RPM to test the main jets? Just off idle to test the pilots? 1/3 or so to test out the needles? reads are meaningless without doing the chops correctly. Kieth Krause has written several lengthy and informative comments about this subject.

 

[Zooks]

Agreed, Keith is the absolute expert on this subject. Do a search or send him a PM. He hasn't been around here much lately.

 

[Colin Green]

I got thick hose (14 to 15mm outer dia) Maybe in daylight ...Awww F**k it.. I'm gonna go down and rip off the old one and give it a try.

Wasn't 14 - 15 mm. It's 13mm and the Repco salesman told a fib when he said it was 6.5mm internal dia. It's 5.5mm. The nipple on my carb is 9.2mm (which is why I asked for 7mm internal dia). I told myself that 9.2 into 5.5 don't fit and set out to disprove it. and after I took the airbox out, I did.

Took her for a spin sans petrol filter and it was exactly the same as when I got home.

What's next guys??

 

[Colin Green]

Can't see anything in the pics, is that blue or gray? You need to read them your self. But what was the running condition when you chopped the engine? Full throttle/high RPM to test the main jets? Just off idle to test the pilots? 1/3 or so to test out the needles? reads are meaningless without doing the chops correctly. Kieth Krause has written several lengthy and informative comments about this subject.

Agreed, Keith is the absolute expert on this subject. Do a search or send him a PM. He hasn't been around here much lately.

Thanks,

I'll start reading tomorrow, but I'm starting to think my problems may lie in the electrics. I just don't see how such a subtle difference in idle mix can be causing the problems and it doesn't appear to be the petrol flow into the carbs or vacuum hose or petcock.

I don't know enough about these things. Could float levels or the slide diaphragms or the main jet needle height be causing these sorts of issues?
Could it be the jet sizes? http://s251.photobucket.com/albums/g...IMG_0008-1.jpg My main jet appears stock at 115 but my pilot air jet appears to be 150 rather than 170. What difference would this make? btw, my bike has standard pipes and air cleaner
Thanks for your interest

 

[Zooks]

Thanks,
I don't know enough about these things. Could float levels or the slide diaphragms or the main jet needle height be causing these sorts of issues?
Could it be the jet sizes? http://s251.photobucket.com/albums/g...IMG_0008-1.jpg My main jet appears stock at 115 but my pilot air jet appears to be 150 rather than 170. What difference would this make? btw, my bike has standard pipes and air cleaner

The difference between running well and running badly.
Jetting / mixture is one of the main reasons that these bikes 'miss' when they are being ridden. Getting it right is somewhat of a 'black art' but once you do you will be amazed at how sweet that little 'zuki engine is. Again, this is Keiths specialty.

 

[Dave8338]

Sorry...but which bike are you working on and has it been modded? I may have a suggestion or two.

 

[Colin Green]

Sorry...but which bike are you working on and has it been modded? I may have a suggestion or two.

Hi,

It's a GS1100GF made in 1985 for the New Zealand market. No mods. Thanks

 

[Guest]

may not seem that way to you after all the time you've put in but i think you are making good progress :-D

i would continue with the basic
- sync the carbs
- test the compression

(your problem seems beyond a minute difference in the mixture setting)

if you have no mods then i would also consider making sure that all the jets are the factory standard sizes

 

[Colin Green]

may not seem that way to you after all the time you've put in but i think you are making good progress :-D

i would continue with the basic
- sync the carbs
- test the compression

(your problem seems beyond a minute difference in the mixture setting)

if you have no mods then i would also consider making sure that all the jets are the factory standard sizes

Cheers, I do think the bike is potentially running a lot better. She idles so sweetly at 850 to 900 rpm (doesn't quite manage to live at 800 rpm) But she sure is quiet.. can hear the cam chain whirring slowly and not a rattle or clank to be heard... even after a 40 km trip she's still idling sweet.

I posted the following earlier;
"I don't know enough about these things. Could float levels or the slide diaphragms or the main jet needle height be causing these sorts of issues?
Could it be the jet sizes? http://s251.photobucket.com/albums/g...IMG_0008-1.jpg My main jet appears stock at 115 but my pilot air jet appears to be 150 rather than 170. What difference would this make? btw, my bike has standard pipes and air cleaner"

I have identified that the pilot air jets are not as per the manual but I'm not sure what effect that would have. Do you have any ideas?

I have decided (as I have a full set of spare parts) that I'll put them to good use by replacing (one at a time between road tests) the coils, Ignition ignitor and Regulator rectifier to see if there might be an electrical issue at play.

I had a quick read up in the manuals about the ATU and how to test, so will test and swap that out as well if need be.

Thanks for the encouragement. I prolly won't get anything done tonight as I have other chores, but will post an update when I have something to report.

 

[Guest]

check this out
http://www.factorypro.com/tech_tuning_procedures/tuning_carbtune,CV,high_rpm_engines.html

(i'm no carb expert, you really want to hear from some other guys on the forum - i think it pays to post a new thread every time you have one thing on your list sorted - so it's more focuse and easier for people to reply)

 

[Guest]

She idles so sweetly at 850 to 900 rpm

you may want to check your service manual for the correct rpm idle
too low and the oil pump doesnt deliver enough lubrication where its needed
(850rpm would be your very bottom line, i would think)

 

[Guest]

Take a pic of the plugs from the top so I can see the electrode and the head range on the threads.

 

[Nessism]

If the air jet is larger than stock won't that make the bike run leaner? Not sure if that's the way you want to go but stock usually is best for a stock bike.

 

[Guest]

If the air jet is larger than stock won't that make the bike run leaner? Not sure if that's the way you want to go but stock usually is best for a stock bike.

True. The pilot air jet goes directly to the pilot jet where it mixes the fuel and air. Then the premixed air and fuel goes through the idle mixture screws. The bigger the pilot air jet the more fuel is required. No mods means you need to go back to stock.