What size pilots? The issues seem to be on the pilot circut, so remove air/ fuel screw, pilot jet, and blow compressed air through all orfices!
Check the needles, should be 24231, clip in second groove from bottom.
Make sure the floats don't have any holes in them, remove and shake and listen.
Davo
Plugs foulingThanks Davo. I went thru the carbs the first winter after buying the bike. I'm pretty sure all was to spec except the mains. I actually found a pair of NOS mains in the std size (135) and installed them and the engine could not take the gas when I would accelerate. Definite bog and then fine. I think it has 130 or 125 mains in it now. Put those in and the bog went away. When I was trying the new 135 mains, I also tinkered with the needle setting to lean it out. Did not help. I know the main feeds thru the needle jet.
It could have the wrong needle in it. I seem to remember it did have the K on it for Keihin. Looked good under a 10x loupe. But I'll review all this stuff again, hopefully starting tonight. I might have left the needle in the bottom groove when I put the smaller mains back in. Don't remember. I tend to err on the side of rich. That's an easy check. I think, and it may have been on my S90, I fixed a leak in one of the floats. Could be I have a new one. Will check that as well. I know all the usual suspects. I was hoping this might be a common issue and there would be a common cause/solution. regards, Rob Okay Gents, I started on this last night and finished up tonight. Here's the blow by blow report.
Last night. Pulled the seat and tank off and first check was for a loose ground. Found one. But I don't think it is related. The small ground wire that comes out of the bundle under the tank and lands on the coil bracket was loose. Bolt was backed out a bit. I had the coils off the bike last year and I may have simply not tightened that bolt. I think that wire is for one of the accessories. I scraped the paint off the frame at both coil bracket attachments points, cleaned up the bracket and the wire ring terminal and tightened up the bolts. Checked with DMM and no resistance to ground thru the terminal. I also checked the main ground lead between the battery and the engine/frame and have a rock solid ground with zero resistance. I don't think that a loose ground is related to what was happening, but still good to have it corrected. Pulled the tops off the carbs to check needle position. It was in the second from the bottom, per spec. I raised it to the 3rd groove to see if it would lean out the rich low speed problem. Put the bike back together and and fired her up. Started hard, but idled once warm. But it had a definite flat spot off of idle as I tried to accelerate. I rode it around the yard and tried various rates of adding throttle and it was the same in all cases. Flat from zero throttle until it started to take gas at probably 1/2 throttle or so. Called it quits for the night. Today Today was pull the carbs and recheck everything. Here were my findings Right carb Main Jet - 130 Pilot Jet - 38 Needle - no markings but remnants of the Keihin K. No wear on metering section. Some wear at point where needle passes thru slide. Needle jet - looked fine, no wear. No markings Float setting - per spec 22.5mm. No apparent signs of leakage. Left carb Same as right with exception of pilot jet and the float. As I inspectded the pilot jet I thought it was partially plugged. I put a piece of fine wire thru it and it was clear. I looked thru it with my magnifying visor and it did not look right. When I looked thru the non-slotted end, it looked like the hole was not centered. So I put a straight piece of wire thru it and sure enough, drilled crooked. Not sure how much that would effect running. Probably nil. But I will pick up another jet if it makes itself available. The float sounded like it had liquid in it when I shook it. It also felt heavier. I put both floats on my digital reloading scale set to grains and the right float weighed 158.1 grains. The left weighed 177.4 grains. That's a big difference. I shook it while holding one lobe in my hand to dampen sound and could hear liquid. I shook it again with the other lobe in my hand and nothing. So, only one lobe appeared to be leaking. I then did Davo's boiling water test. I put a glass measuring cup of water in the m'wave until it boiled and then submerged the left float. Here is a tip for those trying this. Even if the float is dry, it has gasoline still on the surface. When it hits the hot water, it flashes to gas vapor. This means bubbles galore. Gives the impression the float is loaded with leaks. You have to boil that stuff off and wipe the float with a clean paper towel a couple of times for this to stop. Then put the float in and look for bubbles for form on the surface and then float up. You have to look closely. It could take a few seconds for the bubble to form on the surface. I was putting the float in the freezer for a few minutes and then putting it in the boiling water. This would cause the air to expand and provide a better chance of leaking out at a rate I could see. It worked. I kept seeing this lone bubble on the side. I looked at the float with a 10x loupe and found a crack. There appeared to be two other smaller ones next to it too. No bubbles, but visible lines. The other lobe and the right float did not produce any bubbles. To get the gas out of the bad lobe I used a dental pick to remove the solder plug in the center of the convex end of the float. Using the opposite side like a pump, I pumped the gas thru the small hole. There was a lot in there. And it stunk. It was really old gas. The cracks were tiny and probably temperature changes caused the gas to get sucked in over time. To get all the gas out, I put the float in the freezer, hole side down and then with the hole side still down, hit it with a hair dryer on high. The fuel would get forced out the hole by the expanding air. I repeated this many times until there was no more gas. I cleaned the cracks under a magifier with a dental pick then wire brushed it with a brass brush and cleaned it with acetone. I hit it a few more times with the hair dryer. I'd wipe the cracks with acetone and then hit it with the dryer. When it did not appear anything was coming out of the cracks, I soldered them shut. I cleaned the small hole the same way and then plugged the hole with a dab of solder. I tested the float in boiling water. Went thru the same flurry of bubbles when the gas that came out of the float and got in to the pores off-gassed in the boiling water. Once that was done, the float was tested several times, each time being put into the freezer to cool it down and then into the boiling water. NO BUBBLES!! Success!! Knocking on wood here. I weighed the left float and it now weighed 155.1 grains. That's 13% lighter than it was before being drained and repaired. The floats repaired, I returned both needles to the 2nd groove from the bottom. I also compared the stock float height to the suggested trick of setting it to the top of the jet holder. They were both below the end of the holder. So, I bent the tang on each to put them at the end of the holder which resulted in a 24.5mm float height, 2mm above spec. This will lower the fuel level a bit. A side problem I was having was the carbs would spill a little fuel when I would part the bike after riding. It would spill out the overflow tubes. I figured it might be heat/expansion related. Now I'm thinking it was more related to float height in both carbs and even more so in left one with the heavy float. When I got the bike back together I fired it up and it idled nicely. Warmed it up and took it around the yard. It was like a new bike. No flat spot at all. Took throttle like it had an accelerator pump. I think we fixed the problem. I did leave the 130 mains in the carbs. I need to do a throttle chop tomorrow to see if I might be running on the lean side when on the mains. It will also be interesting to see if that rich bog I experienced when I put the 135's in this spring will be gone. I suspect it will. I know this post was long, but I figured it would help the next guy work thru a similar problem. My suspicion is I had two things in play here. Fuel level was too high in both carbs and the left was flooding worse due to the one heavy lobe. Hopefully tomorrow will prove the issue to be cured. The problem of the bike only running on the right cylinder when first started was most likely caused by that heavy float. That would explain why changing plugs at the fall giro did not solve the problem, but running the bike and warming it up and apparently clearing that flooded cylinder did get it to run on both cylinders again. When you back into the problem starting with the evidence, it all starts to make sense. What appeared to be an intermittent electrical issue was fuel all along. As I sit here typing this, I don't think I'll even test ride it until I put the 135 mains back into the carbs. No sense taking a chance of holing a piston. If it runs rich or still bogs, I'll put the 130's back in. That's an easy swap. Thanks for the tips, suggestions and assistance, guys. 48, I have to admit that when you said to raise the float height, I thought youj meant with the carb in operating position. This is why I thought you were suggesting this in reference to the smaller main jet. It dawned on me tonight as I re-read the posts before heading into the garage you were referring to the float height spec for setting it. Doing what you suggested actually lowers the float height when in operation and hence the fuel level. I know you know this. Just stating this so it is clear for the next guy that might use this thread as a reference. Thanks again. I'll report back tomorrow after the shake down ride. Best regards, Rob More feedback from Motogiro this past weekendI ran in the Motogiro on Sat and Sunday and wanted to post my observations/experiences with reference to this problem (and same issue thought to be ignition in the Ignition forum section).
After posting my last followup, I rode the bike several times and it ran great and started great each time. On Friday I offloaded the bike, rode it around town, gassed in up in prep for the next's day's event and parked it for the night. That Saturday morning, she fired right up and ran like a top all day. Idled perfectly, pulled hard and flew when I cranked up the wick. Event was in the mountains of VT and NH and based at the foot of Bromley Mt.. So there were plenty of steep hills to climb and she performed flawlessly. There are several stops during the event, some involve parking for an hour or so, some slow speed agility tests and such and the bike started on first kick each time and ran perfect. So, not much to report from the first day other than a good run and a reliable engine. That Saturday night and well into early Sunday morning it poured rain and my bike was parked in the parking lot thru it all. Rain was over before the riders wandered out of their rooms, but it was chilly and damp out to say the least. So, the rain was the primary change from the day before. I tried to start my bike and it was reluctant. I tried various combinations of choke and it would pop, run a few RPM and quit. I gave up and put new plugs in the bike. Plugs in the bike were black with dry carbon, just like they have been all along thru this issue. Bike still did not want to fire up, but finally did. It ran on one cylinder. I turned the choke on and off, tried moving to reserve in case there was a petcock feed issue. No difference. I figured it might be wet somewhere so shot the plug caps with WD40. No change. So I started it and let it warm up and then started to raise the revs and the other cylinder would fire. As rev were brought higher, it would fire, albeit somewhat erratic on both cylinders, one very smooth the other erratic. I was not going to pull the tank and spray the coils with WD40 so decided to take it for a ride since in the fall giro, riding it cleared the problem and she ran on both cylinders. I took a ride into town. I flogged her pretty hard and she would run on both, but that same cylinder was still missing. After about a 5 mile round trip, she was back to running well on both cylinders and I was pretty sure she'd get me thru the second day. I parked her to let the heat soak up into coil area and perhaps dry out any moisture in the coils and/or condensors. There were a lot of bikes having similar issues, guys were pushing bikes all over the place trying to get them started. Most were Honda twins. A CB77 a few bikes over was running really rough. But he ran the event that day so assume his problem cleared up to. When the event started, bike started fine, idled fine and ran perfectly all day for the entire event. I have not started it today, but will shortly. I suspect it will be fine. I suspect the problem was moisture. The question is where? Here are my susipicions. Not sure how I can confirm them except to just start replacing parts or hosing the bike down and seeing if it does it again. 1. Moisture invading the plug wire to coil connection and shorting to ground. 2. Moisture invading the condensor on the bad running cylinder and causing it to short to ground. 3. Moisture affecting the points on that bad cylinder. - This is a weak possiblity in my opinion because I put new points on both side after the spring giro. Yet the problem persists. 4. Plug wires are absorbing moisture and shorting to ground. All three of the above are based on the problem seeming to be related to moisture/rain. Fall giro was very wet on the first day and I trailer the bike on an open trailer in a downpour to the event the first morning. But I'm leaning more towards the first two with #4 following closely behind. The black fouled plugs is still a concern. The exhaust pops a bit on decel so that would tell me the closed throttle at higher revs is lean, which would be expected due to the higher air flow thru the cut-out so the idle mixture should not be too rich. My oil level does not go down although she does puff a bit, a very small bit of blue smoke. Perhaps this is oil fouling and it is just so slight that it does not appear to be greasy. This could play a roll in the hard start, but cannot be sure. I guess what I should do is get the bike running well and then changed the plugs for a set that are fouled (I have not cleaned the set taken out on Sunday morning) and see if it still starts and runs well. The solution here might be moving to the next hotter plug range to burn off the carbon, knowing that even saying "burning carbon" is a dopey statement. But I know a hotter plug is better for plugs that are fouling. I suppose my repaired float is leaking again and that is a simple check that will be done. I probably should bite the bullet and just buy a new float. So, that's it, guys. I know, another long winded post. But I figure if noodling thru these problems is fun for you like it is for me, the details make the process more accurate than a guessing game. I don't think I left anything out. I'm giving you all my observations. One a completely different topic, yet still related to the CL77, I truly wish my 2nd and 3rd gears were swapped. The ratio steps between 3rd and 4th and 1st and 2nd are just too high and you are either screaming up a hill or chugging up a hill at some speeds. That mod is #1 on the list when the engine comes apart some day. I probbably should ask this in a separate thread, but is it possible to split the bottom cases and swap the gears without disturbing the top end? I'd actually consider that if it could be done. regards, Rob Additional follow upStarted the bike today. Gas on, choke on, two priming kicks, ignition on, fired on first kick and died. Choke off, fired on first kick and ran perfectly on both cylinders.
This is another vote for moisture. Tomorrow, will put fouled plugs back in bike from Saturdays problems and try to start it. Will report back with results. regards, Rob
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