funky PO re-jet

[jimmy boots]

so the PO seems to have put the 210 size air jets into my carbs instead of 180s, and carbs 3 n 4 have 45 size pilot jets instead of 42.5. should I get the normal ones or should I leave it? AFAIK everything on the bike is stock except the rear suspension (a couple of red marzocchi jobs). i didn't had a chance to ride it much previous to this fix, but it never ran super nice, had stumbling/loss of oomph issues at 55mph+. what effects might i attribute to the larger air jets and the diff in my pilots?

thx

79 standard

[dbeardslee]

Boots - Different size jets in a '79 doesn't sound good, particularly on 3 and 4. Some carbs have different size jets on 2 and 3, but not 3 and 4. Jet sizes from different manufacturers can be totally different. I'm an advocate of genuine mikuni jets. Need more info on your setup to determine what the jetting should be. Heres a good place to start - Jetting Recommendations

[psycoreefer]

I'd say go back to stock as a starting point if your bike is really stock. I'm not real sure what the effects of the jets you've got now might be but I'd think it would run better with at least all matching jets rather then 3&4 different.

I'd think the larger air jets would mean leaner at idle, and 210 is a lot bigger then 180, thats like 12 sizes larger if they go by 2.5 increments like the other jets. That might be partially the reason for the larger idle jets to richen the mixture back up, but no reason for only 3&4.

Have you cleaned the carbs well? were they really dirty? Maybe the PO was re-jetting when the problem was dirty carbs. Have you checked the idle mixture screws? Maybe the PO changed jetting because the idle mix screws are F'ed up. Do you have the screw on the bottom of the idle jet tower? Maybe the PO removed the screws and had to lean out the mixture because of it.

[jimmy boots]

good looks guys. I must have spent over 12 hours cleaning every last crevice of my carbs, they look pretty good now. I think the PO had all the pilots at 45 b/c i just found two other old 45s left over from when i had taken my bike to a shop. I'm going to go back to stock and see what happens. I am afraid to touch the idle screws, but at this point I am sure someone has already moved them from the factory setting so ill probly just put them at 1 1/4 out.

[psycoreefer]

Don't be afraid of those pilot screws. You need to pull them out to make sure that the pilot circuit is completely clean. You also need to ensure that the ends were not broken off by the PO and are now stuck in the carb bodies.

Make sure to use a small screw driver when putting them back, its a lot harder to over tighten them and cause problems when you use the smallest screw driver you own then when you use a great big one.

Tuning them by ear really isn't that hard, I find for me that the key is to set the idle really low, otherwise its easy to miss the speed increase when you hit the sweet spot.

[jimmy boots]

whoa - broken tip on number 2, and a nasty little scratch on the inside of the carb body venturi area probly from someone slipping when they tried to remove it. it's in there good too. i saw the links on getting it out...lemme find a thumbtack n try this out

[dbeardslee]

Boots - I'd try compressed air from the back side of the hole first if you've got access to an air compressor. Should be able to put a little piece of vacuum line of the end of the air nozzle and the other end over the hole. There's another post running around here somewhere about an xser trying to get a stuck tip out and enlarging the hole - not a good idea.

[Espiritus]

Go ahead and snitch me out!

Hey, Boots, don't listen that dbeardslee guy. . .no one, least of all ME, enlarged that tiny little hole when I was determined and frustrated to get that D#@* thing out!

Seriously, I was never able to get the push pin thing to work, nor was I able to find those wire gauge tools, and I suspect that this tip had been broken off for longer than my youngest child has been on this earth (16 years). I finally was able to locate a set of tiny hook and pick tools, with cushioned handles, at Home Depot, looked like dental tools for $4.49, and got it out without causing further damage.

I have the JB Weld to fix the problem but haven't gotten my courage up yet. But my rebuild kit is due to arrive tomorrow, so I will get it done soon.

Good luck!

Cam

[dbeardslee]

Cam - I was trying to keep you annonymous, but you let the Cam out of the bag

[red bandit]

#45 pilot jets were stock for the 78. Some carbs use 180's and some use 210's. Can't remember which carbs use what. Will have to look on the shelf.

[jimmy boots]

yeh i've got a 79F like you tho mate, i think my book says 42.5s and 180s. i don't have access to compressed air and i've already destroyed 5 or 6 pushpins, but luckily haven't added any more scratches to my carb. going to try the sewing needle /home depot dentist kit tomorrow, i've got to keep up the tempo on this repair as my bike has lots of other fun things i need to fix (broken float post [goin with jb weld], rusty kreem tank [gonna try Porcan], leaky petcocks [spooge holer], frozen brakes, basically everything listed in the tech tips). my chrome is still pretty shiny tho, the bike looks mean next to the garden tools in my garage

[skids]

Check on those pilot air jets again. I think the 78 and 79's need 210's. The later carbs used 180's.

Originally posted by jimmy boots
yeh i've got a 79F like you tho mate, i think my book says 42.5s and 180s.

[red bandit]

I think the 78's with 45 pilots take the 210. I don't have one to check. The 79's I have with 42.5 have 180's and the 80's with 42.5 have 185's. Not saying there are all this way.

[jimmy boots]

shall i try heating my carb to pop this chunk out?

i've been stuck with this pilot screw tip in my carb for the past week. been jamming all manner of pushpins and sewing needles and pick tools into my carb to force this stubborn little guy out to no avail. can i throw the afflicted portion of the carb body on the stove for a minute to maybe temporarily expand the hole so that the offending chunk of brass will be easier to push out? or is that madness? every smooth-running motorcycle engine i hear coming down the pike is like a slap in the face at this point, i've got to get mine going asap

boots

[TopCatGr58]

Hey Jimmy,

Take a look at THIS THREAD , MRO provides a nifty variation to try. Others have taken a brad nail in a pair of lock vice grips.

You could try a heat gun, or even a blow dryer. A search will reveal many threads, and suggestions. JOHN drilled his out with a drill press from the TOP, very slowly, using a bright light and magnifying glass or such to be able to see down in there.
T.C.