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how to use the tune/use adjuster screw on a Keihin carb 064A ANA Carb with pods

Jodangler

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Hello everyone, it has been fun restoring/mod my 750k7 but I have been stuck at the tuning stage. I been tweaking my points and valves, and with some time I finally got it in specs and shes running better know but it bogs down at the beginning of acceleration and if I use the choke she sound great.

I have Keihin 064A ANA Carbs.
wrapped 4 into 1 mac exhaust.
Pod filters.

IMG_1718.jpg
 
Sounds like she's runnin' lean if she opens up as she should with the choke. Does she run better when choked? Does she run as good as she should in mid and top range?

Are your carbs properly synched?

Your float hight should be 26 mm, main jet 105, slow jet #38, needle at the second slot and your a/f screw should be at one turn out (if I'm correct - your carbs should be the same as the ones on the CB750F -76 according to the numbers you provided and the picture.) Mind you this is with stock air filter and stock exhaust. What have you got in your carbs now if she runs good in mid and top? Bigger mains? Another needle position?

Let us know and we'll try and help out.
 
Yeah, it's a tease. She sound great with the choke on and yes the mid and top range sound great but once in a while I get a pop around 2k-3krpms. Anyways I have been going over it in my head and I'm starting to think my regulator might be going wrong and the electric juice from the battery is not enough or like you said my gas lines might not be up to snuff but I'm also thinking the little filter I got is holding the gas back. I'm not sure what to think but I'm hoping it's something stupid/simple.
I'm not sure what I have in the carbs, i got it from a guy who got it from an old timer and I think the altimeter new what he was doing, he torqued everything down like it was a Harley. I had to clean off a ton of gunk off every bolt and nut. If he was that paranoid with bolts coming off, he had to up date carbs with the exhaust and pods. The holidays are creeping up but
I'm going to double check my reg/rec and tweak the fuel lines, and seafoam and hope for a miracle but If that doesn't work I'm going to read anything and everything, and get familiar with my carbs...
 
If the oldtimer torqued everything down like that, he probably didn't know much about Hondas inline fours.
The popping indicates a lean condition to me. Have you checked for air leaks?

I don't think your voltage is the issue here at all. If your charging were off (and the battery low), it wouldn't run great on the choke.

You keep writing that it sounds great. Have you ridden it? How it sounds and how it rides could be two different things. You need to ride it to make sure.

Make sure your fuel gets to the carbs as it should - no blocked of fuel filter or kinks on the fuel line. If that does nothing, tear into the carbs. I'll guide you if need be.
 
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Finally the weather is warm enough to get back out in the garage and the holidays are out of the way, I was really starting get anxious thinking what was going on and your right the electrical was fine.
Ok, I just got done checking the electrical and spending countless hours and days metering, reviewing and reading what te "h---" was going on with my wires, and finally last night I found out why my oil pressure and neutral light went out. don't yank on old wires, lesson learn.

So back to carbs and after using seafoam to clean out the jets, needles ect, now I have to much gas and more problems. know I'm dripping gas and the bike doesn't want to start. The thing I didn't want to do is now unavoidable. I'm going to have to take the carbs out change gaskets and do a good cleaning. I guess it's better this way... So, do you have any suggestions you know that might become a headache or make things progress in a positive way or what I should look out for because I'm thinking I just need new gaskets and to level the floats? Do you think there's something else I should look at because I would rather change/take care of it know and not mess with the carbs, other than tuning...
 
Got done taking one carb apart the main jets (105), slow jet (40) they are stock. The carbs are not realy dirty just gunky but after inspecting the jets some of the gunk deposited in the slow jet pin hole, not pins, so I'm just thinking its just a matter of cleaning the jets/carb and leveling the floats. Even though I don't know how it rides I'm wondering if I need to change the jets with what I got 4to1 exhaust, air pods. I have read in other forums people usually go up one but I'm not sure I don't have a lot of experience with bikes or bikes in general. Any advice would help.
 
I'd just clean 'em really careful first, before concerning about jetting. "Gunk can be stuck in other passages as well, not just the jets. You could try and use wire string to clean them all out, but I prefer to take them to someone that can ultrasonic wash them for ya. Remove the float bowls, slides and all jets, o-rings and washers. No need to separate the rack, they can go in the bath as one piece apart from the parts mentioned before. But let the jets and float bowls (all hardware) get in that bath together.
Once you KNOW everything is clean put them back together and have at it. Oh - look for wear on your float needles and seats, those might need changing out to seal.
Even though you got pods and a 4-1 system, you should get it to run good enough to start doing plugchops to tune it in. Set it to factory settings and go from there. You will be needing bigger main jets and repositioning the slide needles, but get it running before you start to buy new parts. These are my .02

Johnny
 
Even though the carbs aren't that bad it would have been nice to have them ultrasonically cleaned if only I couldn't fine someone to do it, instead I had them dipped in a carb clean solution. I'm hoping it will clear out the gunk inside the carbs passageways or make it easy when I use a wire cleaner.

Im guessing the main problem were the floats. I have been trying to figure out why the floats caused such an issue and the only thing I could find that could explain it, was that it messed with the venturi effect, compile that with my exhaust and air pods I was probably trying to run my bike on pure air/to lean... I probably won't know for sure until I get her running and go through the plugchop process.
 
There's an ad in the for sale section about a guy in Canada doing ultrasonic washing of carb racks. Might be worth a try?
 
Alright stabler, I got the bike running (sweet!) I just don't know what to think. I thought I was running lean but know I'm starting to question it. So maybe you can help out.

At the first start the bike ran around 2k RPM with popping/backfire and noticeable spitting on cylinder 1, after a couple of minutes the RPM jumped to 4k'ish RPM, then to 6RPM with all of the original symptoms backfire/popping/spitting. After that I just turned the engine off to regroup and go through the process/analyze what was going on. I want to get her wormed up but in a manageable manner where I have time to go through the check list (and how should I go about that, "list") I'm thinking I should go back and recheck the valves (once they get cold again) than go back and check the points. I know I did a good job with it but my conscious is telling me to just go over it again. Anyways what's your though on the whole thing.....
 
Ok I went back at it and I have the little idle screw on the filter side a 4 full turns out and it looks like it did something, it brought the back the idle to 4k RPMS. I thinks its almost all the way out. I also should mention that I'm doing this without the pod filter in. ????
 
I pulled the spark plugs out, well only 1and4 for obvious reasons, both are white/light gray and one plug had a half white ring on the outer edge of the ceramic. I'm guessing I need to go up on my jets but how much and would that solve my idle problem?

I also tried tightened the air screw half a turn from settings or go back half a turn from a normal setting of a full turn out, it still revved very high. Which I thought would bring the rev down a little but no dice/luck.. Anyways there it is, any thoughts?.
 
Sounds like air leaks in your rubber manifolds. I had the same issue.
Try spraying starter gas on one intake at the time while running and listen for rev changes.
I'd start there and rulle that out first.
Get back here with the results.
 
Nope. boots and exhaust headers are sealed.

I turned the choke on, as the sleeves were bottoming out the bike calmed down and idled to manufacturers settings (900-1k ROM's) sweet!! Im in business.

Know I just need to figure out the jetting, I'm thinking pilot jet #42 but I'm also thinking #41 with one clip down on the needle? But I'm leaning towards #42 just for simplicity. my train of thought especially in this case is that I can lean it out with the air screw and (hopefully) not deviate to far from the settings (one turn out)??? It's all based on fussy logic and no experience, haha...
 
Your needle position wont affect the idle. I'm not sure as of how much effect changing from #40 to #42 will do in your carbs. Rule of thumb (from what I've gathered - and on the later carbs 77-78) is that #45 will make it easier to get it to settle at idle without turning the a/f screws out too far. I went with #42 and shoulda gone bigger. Your carbs on the other hand might respond different. I run pods and Mac 4-2.
 
I still think you may have something else going on if you are that lean at idle. I have successfully run stock carbs on bigger bore motors with the stock idle jet...wasn't perfect but it wasnt terribly lean either. Needle position will have no effect on idle. I would start over with the idle circuit...turn all four idle screws in until seated then back out 1 turn, maybe i 1/8. Then back off the idle speed screw till the slides are completely closed...make sure they are closing and not hanging up from a throttle cable adjustment issue or a linkage bind. Turn the screw in until the slides just start to move then give it another turn. Should be pretty close to base idle. If the slides are held open too far from binding no amount of idle screw adjusting will get the mixture right. Recheck and adjust carb balance...750's very picky about carb balance and unsettled idle. Also you are talking about idle increasing as it runs...you do have to adjust the idle screw down as the motor warms up, just the nature of the beast, as it starts to run more efficiently, you have to turn the speed down. Also sticking or weak springs in the ignition advancer can and will cause an unstable and erratic idle...maybe you have more then one issue...
 
Thanks S and DD, and the hondachoppers (I love pictures)...

Your right S taking my carbs apart and giving them a good cleaning was the smartes thing to do, when your knew and know nothing about carbs, it can seem a little daunting/big job but know I can say that wasn't bad at all, only if you are careful with the gas and gauges to fine tune... I actually ended up polishing the bowls and tops...

And

DD, you got me off the proverbial jet cliff and saved me $50 bones, I love it when money stays in my pocket... The idle screw and throttle sleeves did the job. I don't have the perfect mixture yet but know Its all about finding the sweet spot.

tomorrow I will clean the plugs and let the bike idle for a while and check whether I need to go richer or leaner on the little screw with the spring on the carbs, and once the weather start improving I will take the bike for a spin and see if I can fine tune it or if I need to mess around with the top end of the throttle/needle/jets...
Thanks again guys

I might have another issue with the gapping point/dwell/retard plate limit and bike timing mark lining up, and if a closer gap will give me more retard or a wider gap will give me more advance... but I will make another post for that...
 
thanx guys... interesting thread... just putting my 750 back on the road after a 3 year hiatus.. i had tried bumping the jets up a size or two with no luck after a big bore kit was done a few years before... never got it set right so i went back to the stock 105 and 40 combination (all new parts) and new needle jets... replaced what I could without taking each carb completely apart... i dont understand your comments about the "slides starting to move"... is this done without the airbox so you can see inside? you have lost me
 
Yes, that would be done while looking at them. You remove what is needed to view them. On some engines you just remove the rubber tube and leave airbox alone, I use like a little $1 child's plastic backed mirror to view the slides.
 
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