79 Special won't run after needle replacement

[Solonys]

I'm back after finally getting another XS! This time, the bike had sat for 2 years and came with a stuck float needle in the #2 float, which caused gas to flow into the airbox when running. I removed the carbs and replaced all 4 needles/slides, then reset the float height to the OEM spec; now the bike won't start on fuel. The carbs are definitely getting fuel, since if I unscrew a bowl plug, it drains a whole bowl of gas. The bike will start if I spray carb cleaner into the airbox, but won't run once I stop.

Anyone got any idea what's going on? I did not touch anything inside the carbs except the floats and float needle/slides.

[shutchis]

The jets are dirty; clean the carbs.

[DiverRay]

+1 on clean the carbs!!!!
The fuel you get now is crap! Carbs are probably green inside from the Ethanol they call gas now. You need to pull ALL the jets, spray a GOOD carb cleaner through the carbs, and re-assemble, sync, and run. If you cannot get ethanol free gas, you will need to drain the carbs and tank if it sits for more than two months. Welcome to "modern" "gas".

[Bonz]

To add to Ray's post above, if you spray carb cleaner into the carburetor bodies, be sure it gets flushed out quickly. Carb cleaner will do bad things to o-rings such as needle seats if the 79 has o-rings there, and fuel rail o-rings. An SF should have the brass needle tips, however if you have rubber needle tips carb cleaner will ruin those as well. Reality is, carb cleaner was designed to clean off the exterior of carburetors as they would accumulate that light gunky film back in the day. It's been adapted to spraying the inside of carburetors as a cleaner however not meant to mix with rubber.

[Solonys]

I was hoping to avoid tearing down the carbs; there was no green goo in the carb bowls because the PO had drained them when he parked it, and it ran when I gave it gas (aside from the stuck float causing gas leakage. I figured I knocked something out of whack while replacing the needle assembly. Ah well, guess no such luck.

[Solonys]

Well, I replaced all the jets (since they are cheap, although the existing jets were fine) and now it no longer leaks gas; took it for a test run and it appears I have a sticking front left brake caliper, so I get to tear that down and rebuild it.

Who said old bikes are boring?!

[DiverRay]

Do BOTH front brakes! Then put in the new braided brake lines as well.

[cajun31]

Do BOTH front brakes! Then put in the new braided brake lines as well.

I would redo the rear caliper as well.

[BillyRok]

Better to have a bike that will stop but not go than a bike that will go but not stop (often becomes apparent at the worst times). Get her to do both and you'll have it licked! A few years back I did what others have just advocated here, rebuilt the calipers - new fluid - AND SS lines, couldn't believe the difference...not cheap but you won't regret it, promise!

[Solonys]

Thankfully the bike has SS lines already, so that wasn't required; I rebuilt both front calipers and replaced the fluid/pads, but it appears that the stuck caliper caused it's rotor to warp. Awesome.

What's everyone using for rotors these days? I am having a bit of a problem locating the correct rotor because according to MikesXS, Partzilla, and EBC, the 79 special didn't exist, so I can't find the correct OEM P/N to cross-reference. Are the 79 special rotors the same as the 79 standard?

[bikerphil]

Yes they are. There are 2 types of OEM rotors, solid and slotted. The 79 Specials and the 78-80 Standards all use the same solid rotor, left, right, and rear.

[cajun31]

Thankfully the bike has SS lines already, so that wasn't required; I rebuilt both front calipers and replaced the fluid/pads, but it appears that the stuck caliper caused it's rotor to warp. Awesome.

What's everyone using for rotors these days? I am having a bit of a problem locating the correct rotor because according to MikesXS, Partzilla, and EBC, the 79 special didn't exist, so I can't find the correct OEM P/N to cross-reference. Are the 79 special rotors the same as the 79 standard?

Are you absolutely sure that the rotors are warped? I am not saying they can't be... just like they can warp on automobiles, however I have never seen them warp on these bikes. Second question is how badly are they warped ... meaning if not bad you might be better off taking them to have them turned. If that can be done within tolerances you might actually save a couple of bucks.

[bikerphil]

The runout limit on these rotors is .005", they can't be turned, the material is too hard. Sometimes when upgrading to SS brake lines, the warped rotor problem will show up and you will feel a pulse in the lever. The rubber lines will mask this. If the rotors have been remover from wheel, make sure there is no debris between the wheel and rotor to cause runout.

[cajun31]

posted to wrong post... apologies

[Solonys]

Are you absolutely sure that the rotors are warped? I am not saying they can't be... just like they can warp on automobiles, however I have never seen them warp on these bikes. Second question is how badly are they warped ... meaning if not bad you might be better off taking them to have them turned. If that can be done within tolerances you might actually save a couple of bucks.

I'm quite sure the rotor was warped, I could see the runout with the naked eye lol. I picked one up from a local salvage place that was flat and has good life left to get me by until I am sure everything else is working properly for 5 bucks, and the problem is resolved lol