Carb Help Needed

[djduke7]

Heres the story, my 79 special was running rough so I figured it was time for a carb cleaning ...... got some rebuilt kits on ebay for this make and model and installed them in the carbs . ok heres the problem when I crack the throttle and let it go the rpm's rise stay there for awhile then drop,also very strong smell of gas nothing i do with the mixture screws helps tryed settings from 1.25 turns to 2 turns out from a lightly seated position .Floats were set by measurement and by the sight tube method,did the wire tie presych ...the butterflys dont appear to be sticking. Heres a few things i did notice ,,,,,, the mixture screw tips on the rebuild kits arent as pointy as the ones that were in there and the float valve was a hair shorter had to adjust the floats a bit Im thinking that i should go back to the original parts and give them a try but im going to throw this out there to see if someone can save me the trouble of ripping this thing apart again ......the slide diaphrams looked good also .........tnx Duke

[CMA1]

Re: Carb Help Needed

Originally posted by djduke7
.Floats were set by measurement and by the sight tube method,

Hi Duke,
You say "sight tube method"... my 79 doesn't have the float bowl fittings for the tube method.
I set my floats at exactly 25mm... works fine.
Did you replace the Pilot Jets with ones in the kit? If so, try the OE ones back in.... worked for me.
The 79 Pilot Screws have a more 'blunt' point than the replacement ones usually. I used the 'pointy' ones from the kits, but I spent a lot of time with 12oo grit paper to wear them down to a profile more consistent with the OE screws.(my 4 were all broken off)

The Pilot jets seem to be the consistent 'buggaboo' when I searched through the archives.... maybe that's why you are not getting a response when you try to adjust the screws.

good luck, Larry

[djduke7]

Thanks Larry for the suggestion i will try that... i figure it had a lot to do with the quality of the kits.....I thought i had all the bases covered by buying new kits.....i made a adapter that fits in the bowel drain for sighting the floats....what i cant believe is the fumes they bring tears to your eyes and that aint because i got to tear it down again i guess i got a hobby now..... tnx again Duke

[Ken Talbot]

From the sound of it, you may have got some blunt-end pilot screws that are meant for the later-model (80-81) carbs, instead of the sharp-point pilot screws that are meant for the early (78-79) carbs. Were the tips broken off of your original screws?

[djduke7]

Hi Ken
No the orignal screw tips werent broke off there in good condition still i cleaned up the old internals and reinstalled it all ..have to set the floats and put em back on the bike....I think your right about being for a later bike,,,,,, Ill let you guys know how i made out thanks Duke

[Bill__Woods]

When I installed K&L carb kits on my bike, it ran very rich. I installed the original Pilot Jets and the problem was solved.
the rest of the just were numbered and correct. the pilot jets were unnumbered and incorrect, go figure.
good luck!

[djduke7]

Well I got the old parts cleaned up and the floats set but........I still have a real rich condition..... not real crisp throttle response and the once in a while backfire the pilot screw setting is 1.5 turns out...I thinking I have to check the coils and the timing.....anything else??????????????????????? tnx Duke

[Ken Talbot]

You might try setting the floats about 1mm 'leaner' than they are right now. Do this with a micrometer so you can be sure you've got all four as close as possible. Resync the carbs, set the pilots for the sweetest sond as described in some earlier posts, and see if that doesn't get you closer to where you want to be.

[skids]

Ken, I could swear you have it backwards... Both of my newer carb sets have needles that will actually lower into the ventouri bore if I screw them in all the way. My 78E had blunt tips. A rebuild kit had sharper tips and I think they were just wrong for the 78.

Originally posted by Ken Talbot
From the sound of it, you may have got some blunt-end pilot screws that are meant for the later-model (80-81) carbs, instead of the sharp-point pilot screws that are meant for the early (78-79) carbs. Were the tips broken off of your original screws?

[tab1324]

rich condition??

My bike (82' XJ1100) requires about 3 1/4 turns of the idle screw before it runs right. The backfires I was getting came from too lean a condition. One thing that seemed to make a big difference too was the timing tensioner adjustment. I was having similar problems as you mention but after making the timing adjustment and turning the screws out a bit - runs pretty well. Hasn't even been properly synched.

Tom B.

[djduke7]

Thanks guys you have givin me a lot to work with ......I 'll get a chance this weekend to get it together and make a few adjustments would like to have her on the road soon ...losing alot of crusing time.........thanks again for all the help alot of heads are better than one Duke