Hello new here need help with fuel system/carbs.

[Faltang1090]

Hello all just joined like 10 minutes ago! I have been searching and searching with no results.
But here goes it's a 79 1100 with vin/serial as 3H4 000238 no mods, nothing extra, nothing terribly special besides I love riding this bike. When it was ridable

Ok so I am running into issues after I have completely rebuilt the mechanical side of this bike. Brakes, carbs, ignition systems, all the lubricants as well. My problem started out as ignition system failure fixed that. Now as the bike starts it revs up 5k rpm and stays there. Then as soon as I touch the throttle it sticks as high as the twist sets it. Now I have removed the carbs several times making sure nothing is sticking, and bench setting the butterfly to what many of the people and threads have said to adjust to. Throttle cable is loose and freely moving. The throttle adjustment screw is backed off to just touching the lever. All vacuum lines have been checked no cracks or stiff lines. Now while redoing the carbs I did not pay attention and did unscrew the fuel mixture screws on the front top area. Then realizing that they are set by factory. Have tried the adjustments previously stated in threads 1 1/4, 2, 2 1/2 and up to 3 turns out. The rebuild kits were fully installed except for the jets I didn't move or replace them. I did make sure floats and pins were moving freely, everything that was supposed to move, moved freely. Anything that wasn't was torqued where I could find specs for. I used the Haynes manual that I got with the bike. It covers almost nothing for carb issues at least what I am dealing with. I am waiting for a manometer, to sync the carbs but can't get the rpms down enough to even attempt it.
Any help is greatly appriciated I am trying to get my dad's bike running again!!!

[Faltang1090]

I haven't checked for vacuum leaks(besides on the carbs) but I have tightened everything I can, the boots don't seem to be in bad shape no noticeable cracking but will seal them tomorrow if I find anything. Possibly could the vacuum advance line do this if its bad/not connected?

[kraigb]

Hi! I just joined recently, myself, but have been toying with my '78E for a couple years. The very first thing I did after getting it was to rebuild the carburetors. I started it up, and it ran nice and smooth...until I twisted the throttle. The RPM's shot up to about 3500 and stayed there. What fixed my issue was loosening the screws that attach the carburetors to the bottom angle iron. Everything seemed to move freely when I had first put it back together, but something in the connection between carburetors must have been off just enough for it to be binding just slightly, not allowing the butterflies to return back to the idle position. I hope your problem turns out to be as simple as this. I never had it bind up again after I tightened everything back up. When you go to test it while running, very small twists of the throttle, and guaranteed return to idle, and make sure it functions perfectly before you ride!

[mack]

Throttle action

well assuming that the carbs ARE clean and benched properly. The cable isn't bound up anyplace impeding the action of the butterfly shaft, the most common cause of hanging idles is at the gear clamps on the carb/intake manifolds. Sometimes, in order to get a better angle for the screwdriver on the #2 & #3 carbs gear clamps, we rotate the clamp down slightly. When the screw is tightened in all the way, because of the upward angle, it will contact the throttle shaft assembly and bind it. Try lossening off the clamps and see if that doesn't improve the action.

[Faltang1090]

Ok sounds good on both parts! I will remove the carbs and adjust, the carbs were cleaned by hand as I don't have a dip tank. Using small amount of carb cleaner and very fine steel wool and lot of sore fingers(I have big fingers and these carbs are small compared). Also I just remembered while doing the float bowl side of carbs that the floats were differing in color due to the green residue from the dried up gas. I scrubbed these as well then checked for leaks no leaks. I could not measure them terribly accurately for sagging or bending. They all looked relatively close to normal but next payday I'll be grabbing a micrometer.

Thanks again!!

[DiverRay]

I could not measure them terribly accurately for sagging or bending. They all looked relatively close to normal but next payday I'll be grabbing a micrometer.

OK, first problem. ALL FLOATS NEED TO BE THE SAME TO START! You do not need the mic to do this. Get a bit of plastic from the top of a dairy container( cottage cheese, etc.) and cut an "L" from it. the long part should be narrow, and will sit on the base of the carb, the short part is cut to 27mm from the base of the long part. What you should have is 27mm as measured on the INSIDE from the top of the "L" to the inside top of the leg of the "L". Use this tool to set all the floats to the same height.
Problem #2, you MUST pull the idle adjustment screws from the front of the carbs and clean them! Also, inspect all 4 screws and make SURE the tips look the same. It's VERY EASY to break a tip off inside the carb body When you install the screws, use a screw driver wit ha small diameter handle and LIGHTLY seat the screws, then turn out 1 1/2 turns to start with.
While the carbs are off, it would not hurt to remove the carb holders and use a thin smear of yamabond #4, or another non hardening gasket sealer on the face of the holder that bolts to the head. Stock they had an "O" ring type seal molded into them. I've seen most of these be bad over the last few years, and it can cause an air leak.
Welcome to the site!

[TopCatGr58]

Hey Faltang,

You don't need a micrometer...just get a nice piece of carb board, or thin plastic sheet, measure a rectangular/U shape that is ~25.7mm high and wide enough to clear the float sides, but still reach the carb body recessed flat, and then use that to measure and set your float height. This will also allow you to verify that both ends of the float are the same height...not just the middle, you may need to "adjust" the float pontoons along with the main float height tang.

Next....just want to make sure that the vac. adv. hose it attached to the #2 carb brass nipple....NOT to the Intake Boot nipple....the carb nipple is metered and only active when throttle butterfly is open....there should be no vac. at idle from that port....or at least not enough to rotate the timing plate.

Thirdly, you say you did NOT remove the pilot jets??? You need to remove them to proper clean both the jets and the passageways. Same thing for the main jet needle/emulsion tube....needs to be removed/cleaned!!!

T.C.

[Faltang1090]

Ok I will make plastic sheet gauge, the vacuum line is on the carb nipple, I will remove the screws I still have them in the rebuild kits. I was just going by what the book had said on those, I will replace them though. I took the jets, tubes and all that apart and rebuilt/replaced everything else from the kits. I just didn't adjust the jets or change them. I was worried about them being the wrong size. Was just going by other threads,if all else fails I will swap those too.

[TopCatGr58]

Hey again,

Okay, reading your reply, you're confusing me a little!? The Pilot JETs like the MAIN jets are accessed thru the bottom of the carb under the float bowl. The Pilot Jet/idle SCREW is the screw/spring assembly on the top front of the carb body.

You say you used carb KITS, did you use the JETS(pilot/main) from the kits..if so, then that is probably a big part of the problem since they use K&L jets or some other generic jet, but not MIKUNI.

Ray suggested the 27mm height because he told me that it has worked for him....remember, he's in CA, Sea Level, California Fuel/Ethanol....that value is ~1.3mm leaner.....YMMV, but the spec does say 25.7 +/-1.0 mm!

T.C.

[Faltang1090]

Well I tried everything suggested after having time tonight. Sealed anything I can find on the carb boots/holders. Replaced the pilot jet/idle screws, checked the floats nothing seemed to be out of place. Now the Rpms start off around 3500 and climb up to 4000+. Backed off the idle screw, that helped a bit more but not much. As soon as I touch the throttle it doesn't return at all just keeps climbing. Thinking this may be putting me off my game. I also left the original jets in being told they will be different.

[kraigb]

I bought a 3-quart can of 'Berryman's Carb and Parts Cleaner' for less than $20 at Walmart when I cleaned my carbs, and it works great. It has a plastic bucket with strainer holes inside to set your parts in. About 30-45 minutes of soaking, then a thorough rinse under running water, and everything inside and out was spotless. Make sure you remove all rubber parts before you start soaking. Tear them down as far as you can and it makes things easiest. You absolutely have to get all the gunk out of the passages inside if you hope to get your carbs operating correctly. For the rubber diaphragms, I used a small amount on a cloth to wipe them clean, then rinsed the off with water immediately. They are somewhat fragile, rare, and spendy if you can even find replacements, so you want to be careful with them.

[3Phase]

Regular carburetor cleaner can destroy the throttle shaft seals and they're a pain in the you-know-what to replace.

It depends on the formula you bought -- MEK, Toluene or whatever -- but you can use regular cleaner if you partially submerge the carburetors and reposition them while they're soaking the clean the fuel/air passages. Be careful and don't soak the carburetors for too long. The fumes from some of the solvents can melt the shaft seals or make them swell up tear when you move the throttle.

Yamaha makes a water-based carburetor cleaner that you can order from Parker Yamaha if your local dealership can't find it. I've been to Parker Yamaha and they're good people to work with:-


www.parkeryamaha.com, Parker, AZ: ACC-CARBC-LE-NR


.

[yamtom]

good luck with brand name Pine Sol

Ive had real good luck with brand name pine sol for cleaning carbs. Ive used it on four or five sets o carbs, total soaking, for two to three days. Ten bucks worth will get you enough to soak the whole rack, unlike that ten bux a quart stuff from yamaha. But dont use the generic stuff, for whatever reason it doesnt seem to work on carbs right. Some people have said on another list,,,,,,, that rubber and plastic should not be put in pine sol, but I have had no problem. Just open the enrichments up,, let them totally soak,, use the hard chemical cleaners for hard parts only, and use a tiny plastic wand to clean the passages in jets,, such as a cutting from a hair brush. Every passage in those carbs must flow air or carb cleaner ,,,the three tiny ones at the throttle flapper,, must be open. I had trouble with the copper tubes that feed the enricheners on my bandit carbs, I ended up using,, a tiny insulin syringe with the needle so small and filled the syringe with strong carb cleaner stuck it in the hole, and over two days, I did get the thing cleared out. On the third day, it was a great feeling to see the stuff shoot thru that passage. I also have had trouble on my 80, with the carb clamps interfering with the throttle cable like someone said, in my case it was stuck holding the carbs closed, but yours may be holding it open, check that out. You may have to rotate the clamp a bit. Re the diaphragms, be extremely careful to get the slides etc back on with the diaphragms precisely where they are sposed to be, Ive had them out of place, I find that if you massage those rubber pieces at the edges where they sit in the groove at the top of the carb, use a tiny bit of vaseline in the groove, it will help hold them in, and of course the diaphragms have to be free of holes too, you cant always see the smaller holes until you hold them in a bright light. I use liquid elec tape, the spray stuff on mine to fix the holes unless you want to buy new ones, which of course would be better.

[3Phase]

Tom, like Pine Sol you can't use the Yamaha cleaner straight out of the bottle, you have to mix it with water, I think it's 2 to 1, so you get a lot more than a quart.

Unlike Pine Sol it's made to clean carburetors, not floors.

.

[Faltang1090]

Ok well I removed the carbs for the 20th odd time, getting fairly good at it now. Separated them down to individual pieces, completely checked all passages and flow throughs. Nothing is visibly blocked everything flows. Then soaked and scrubbed and cleared anything left over, from the previous cleaning. The reinforced rubber on the tubes have some rubbing but no holes. Checked with my mag light as well. Also when the tube were out I checked the jets. I lowered the jet one clip up to bring the jet down. On all of them, this bike was last jetted at our old place on the prairies. I am now 3500 feet higher. I could be wrong on that but I looked online and looked at the graph. So if that's backwards I will change that back(dyslexia kicking in hard tonight). I also removed the exhaust pipes need to weld them back together found out tonight I have cracked pipes. The carbs are not sticking open or closed at any point. Everything is freely moving back into position. I also used gaskets from the 2.3 ford engine thermostat housing for the carb boots. Sealed every area that could be leaking, so tomorrow when everything is sealed and cured I will try again to start it. Again thank you all for the help!!!!! It is getting better!!