Whoa ! Too many, 2 much at once. first, Dennis.. did you rule out the possibility of ignition failure of one system causing the loss of two cylinders ? My suspicion would be that the bike was dropping one first and then, finally two. The first one to go would have been the one that has the current flow from ground to the center electrode.(check the coil diagram and you'll see what I mean) It was just a thought. The pair out would be the ones that don't drive the tach. If you're sure that wasn't the case... Still easy to check. Like maybe a bad coil ground ? They (?) did have the tank off and all... No, I still wouldn't separate the carbs. With all the float needles out, air pressure applied to the fuel inlet would force any bits out. Just a silly question, if you knew that this might happen, why not have installed a good quality fuel filter in-line from the git-go ? To run the way you say it did, there better be a ton of rust in the bowls. Otherwise... back to the drawing board. Rust bits will plug up slow jets first and cause poor response. You sound as though it was much worse than that. Since you have the carb pack out, check for that nice whoosh that healthy diaphrams make. Lift each one and let fall. Whoosh ? All better be the same. No clunks ! Again, don't remove unless you plan on replacing. Large William.... Tell me I'm wrong and we'll procede.
--- On Mon, 5/25/09, Graham Rogers <[email protected]> wrote: From: Graham Rogers <[email protected]> Subject: [Nighthawk Lovers] Re: 700SC carbs questions To: [email protected] Date: Monday, May 25, 2009, 9:49 PM Hey Dennis, I'm at the same stage with a NH700 S, and a CB750F. So, I'll watch for answers. I haven't delinked the carbs and don't see any reason to. If you've got rust in your tank, it at least needs to be cleaned. It probably needs to be lined. I did a Suzuki GS450 tank once. It turned out okay but was a lengthy, messy job. The stuff cost $40 from JC Whitney. Since then I've taken 4 tanks to a radiator repair shop and they did them for $75.00 each. I'm glad to pay them to pressure clean, and line the tanks. One of them was my CB700 tank. Cleaning the carbs of rust I found to be simple on the CB700 and other carbs, Graham On May 25, 2009, at 9:10 PM, Dennis wrote: My bike's been running a bit off for sometime now. A year ago, when I first got it, I took it into the local shop and asked them to change all the fluids, give it a tune-up and to balance the carburetor vacuums against each other. When I got it back, they told me that they'd found junk in my carb bowls and that they were pretty sure I had a problem with rust in my tank. They wanted something like $700 to sort it out. Yow. I said, "No thanks." I hadn't dealt with these particular folks before so I didn't know if they were looking at me as a cash cow customer or if they were telling me the straight stuff. The bike did run better when I got it back from them but it still wasn't exactly right. I knew this because in addition to this '86, I've also got an '85 700SC and it runs like a German clock so I can tell the difference.About the time I got the bike back, Seafoam came up in conversation on this group and I went down and got some and ran it through my bike. It seemed to help.Well, it's been a year now that I've been riding the '86 since I got it back from the shop. As I said, it runs OK but not perfect. To me, it always feels like my carbs are not balanced against each other and so when I'm running along without much throttle, it feels like some cylinders are firing solidly and others are weaker as if they're not getting as much gas.About the potential rust problem, I thought that if the guys at the shop were right and I did have a problem, then sooner of later it would come back and the bike would get worse.Well, about three weeks ago, it did get worse. It seemed like one or two cylinders weren't hitting at all. I put more Seafoam in it and ran it but it didn't seem to get better so I decided it was time to dig into the problem.I've got a copy of the Honda Shop Manual for the 84-86 CB700SC series. Today, I pulled off the gas tank and pulled my four carbs out as a unit following the instructions in the manual. There were a couple of parts that were a bit confusing but in the end it all came out OK.So, I'm going to empty my tank and then swab around in the bottom and see if I turn up any rust. I'm going to take apart the gas valve and diaphragm and see if they look OK and I'm going to have a look at the fuel strainer and see if I find any rust there. I noted when I took the small vacuum hose off the gas valve, that it didn't have a ring clamp on it and the end of the hose was partially split. That made me wonder if maybe insufficient vacuum was getting to the fuel valve diaphragm and perhaps limiting the amount of fuel delivered? I'm also going to check the carbs themselves out. Following what the manual indicates, I'm going to check out all the stuff I can check out with the four carbs still ganged together. Vacuum chamber, float chamber, float levels, jets, etc.Talking about working on the carbs brings me to my real questions here. I have a vague memory from reading along on this group that someone (was it you, Dennis H?) said that it is unwise to pull the rack of carbs all apart unless you have a good reason for doing so.But I'm thinking that if I find any grit in the fuel strainer or in the carb bowls, I'll need to pull them apart so I can get in and blow all the internal holes out with compressed air. Does that make sense or can I do that with them still ganged?The other thing I'm wondering about is do I need to buy carb rebuilding kits or not? I just looked on EBay and I saw a kit for the 700SC for $29. http://tinyurl.com/oyyknv For four carbs, that's $116 plus shipping. Money's tight here now and I'm wondering if these are essential or just nice to have. What do folks who've rebuilt their carbs think about this? Am I foolish to not buy and use a rebuilding kits?Any and all advice will be much appreciated. I've got a sheet over the engine and the four carbs sitting on my bench and I'm ready to wade into what ever's next.Thanks! Dennis Gallagher - Seattle - '86 CB700SC --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Nighthawk Motorcycle Lovers!" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/nighthawk_lovers?hl=en -~----------~----~----~----~------~----~------~--~---
