G5 Carburation.

crawsue · Post by **crawsue** » Tue Apr 18, 2006 5:57 pm

I know that I have been here before,but I am now at the end of my tether trying to set up this carb'.It starts fine,ticksover O.K. pulls well ,but in the 1st 1/8th of throttle opening it "hunts" badly.All settings have been carefully checked (points,plug,adv/ret)the carb' is exactly as specified ,the manifold is well seated.I have moved the needle up and down --up makes it too rich and fouls the plug,down has no effect.I contacted a carb'supplier who suggested the throttle slide valve was worn and that replacement was the only cure,but as the machine ran well before the bottom -end work I am reluctant to fork out £160:00 or so to replace the carb'.I have little experience of "monoblocks" but those who have seen it seem to agree that looks to be in fair condition.Is a worn slide such a big deal? HELP---PLEASE!!!!!

lawrence · Post by **lawrence** » Tue Apr 18, 2006 7:55 pm

Hi crawford
I understand your frustration. Before getting a new carb why not try a Colortune plug. Beg, borrow or buy one from eBay. They give you a perfect analysis.

I bought a new set of carbs on the advice of a dealer (now defunct) for my Bonneville. The problem turned out to be frayed throttle cables. He didn't want to take the carbs back either. The slide on my 389 is very lose but the bike runs well.

crawsue · Post by **crawsue** » Tue Apr 18, 2006 8:04 pm

Thanks,local spanner-man will try with his colour tune tomorrow.I can't beleive that my slide is in such bad condition as it is a very tight fit at the top of the carb' body!CR

itma · Post by **itma** » Tue Apr 18, 2006 9:25 pm

There are a number of silly things that you might try looking at first.
The tight fit of the slide at the top is distortion most likely; the wear occurs at the bottom, it`ll show if you put your finger in and waggle the the slide; on a really bad one it will rattle in tune with the intake like a tappet. The slide should show no appreciable ridges, and not have a sharp edge at the bottom intake edge.
Back to silly things to check... is the float needle the right way up? that is point upwards? is the paper washer under the jet block the correct one? not too thick? is the throttle needle in the right hole and not getting trapped by the spring? is the pilot screw bent at the tip or shiny where its been forced home? does the needle jet match the needle? Have you put a washer under the float needle housing? if so chuck it, not needed.
Another thing that can catch out the novice is the coil connections; are they the right way round? can sound and feel like the thing is running too rich, same as a duff condenser; some barsteward pulled that stunt on me when I was on L plates, took me days to get to the bottom of it.
In my experience colour tune plugs are of little use on older bikes, especially singles with monoblocs, but Lawrence likes them
In biblical times, folk used to tune their carbs with the exhaust pipe off, and observe the colour of the flame coming out. A satisfying practice and one to be recommended if your neighbours brat continues to annoy with his/her/its loud [c]rap music.

crawsue · Post by **crawsue** » Tue Apr 18, 2006 11:07 pm

Thanks,ITMA,I've double checked just about everything on your list re' the carb',but will check out the coil connections tomorrow.I had assumed that it widnae go if they were reversed!CR.

Merlin · Post by **Merlin** » Tue Apr 18, 2006 11:56 pm

Thanks for that ITMA I love this club makes me feel at home

crawsue · Post by **crawsue** » Wed Apr 19, 2006 9:55 am

Thanks again ITMA tried the exhaust pipe off trick this morning as I couldnae' sleep.My A.S.B.O. will be here by lunch time!C.

itma · Post by **itma** » Wed Apr 19, 2006 11:23 am

Another good way to really iritate the brats next door is to turn your biggest speakers face against the wall, and put your TT sound tapes on, preferanbly the ones with 1960`s 12 speed jap two strokes doing lots of gearchangeing and acceleration; keep the commentary down but turn sound up as much as poss when the bikes are on.
It works, ask me how I know.
To vary the annoyance, try BBC sound effects tapes of WW2 battle noises; In south London heavy machine gun fire at 2 am had them jumping out the windows.
Oh happy daysEdited by - itma on 19 Apr 2006 10:25:05 AM

crawsue · Post by **crawsue** » Wed Apr 19, 2006 8:53 pm

ITMA ,you are a very disturbed person,but then you would be,you ride AMC!Had a good session on the G5 this afternoon,rechecked everything reset the valve clearances after tightening down the head to 35lbs/in.Put the needle one notch lower and it is a lot better -but not as good as it has been.After a run the plug came out and it was "wet" and "petroly"(?)I have discovered that the contact breaker spindle is all over the place ,so will replace the bearing--that can't be helping.Have been put off getting a new slide by stories of jamming open,so my pal is going to have a look round the stalls at Stafford this w/e to see whats what.If all else fails it might just have to be a replacement carb',do I buy new or try the refurb ones from the guy in "Jampot"?

Don Madden · Post by **Don Madden** » Wed Apr 19, 2006 9:18 pm

Hi ITMA, I've used your "Stereo Attack" method too, but play Mozart. Makes the younger crowd over here ill. Gunfire here is too common to notice. Not even my G80CS with open pipe can drown out the noise of a Harley. Cheers, Don.