Topic: Bogs down upon take off

[slipnot]

Hello all matic fans...I'm new here and recently bought a 77 750A which I drove from Denver to Sacramento (1200 miles) it performed well for the most part and I made the trip in 3 days.  Since being home I changed the oil and oil filter as well as the air filter, both were nasty.  I took it to a local shop and had him install new plugs, points and condenser.  He also synced the carbs and adjusted the timing and valves.  I also put on new tires as I noticed the date when I got home of being either 1984 or 1994 (three digit number with a 4 at the end) they looked good when I bought it and I should have checked the date then  .  My issue now is accelerating from stop.  The bike just wants to take off slow, if I give it too much throttle it just bogs down, it's a little more responsive in low gear but I hardly use that gear to drive in.  The same thing happens when just giving it throttle at rest.  It just does not respond quickly, it is slow to rev up.  The mechanic says it's most likely the carbs since it has low miles and obviously sat a lot.  I've also noticed that the idle drops when put in gear and actually will stall now after the tune up was performed.  I took it back to the shop and he re-cynced the carbs and double checked the timing but it's not any better.  I noticed that the stall preventer (throttle opener) does not move when I put it in gear but I'm totally unfamiliar with this system and haven't got a clue what to do to fix it.  The other thing that's happened since taking it in to the shop is the exhaust pipes are bluing at the exhaust manifold, which irritates me to no end!!!  Sorry to be so long winded..Any suggestions on any of these issues would be greatly appreciated.  I didn't really find any posts with similar postings..

[slipnot]

Okay, well, gee I guess your supposed to twiddle your thumbs before any replies here.  Same problem on other sites so didn't really expect much more here.  Seems like a bunch of good ole boys who like to dick around with each other more than really know much about fixing bikes.  Anyway, I had to vent so if you can't handle it then just grow up. 

So I increased the idle a tad and the bike runs much better although it still is sluggish when jacking on the throttle.  Must be these old 750's with eensy carbs are not only cold blooded but doggie as well.  Runs great at high speeds and will not stall any more when idling at stop in gear.  Although, the stall preventer system is still not operating.  Maybe some carb cleaner on the diaphram and solenoid shafts will help.  Played with the wiring harness that is stuffed in a bag up in the fairing and now thw turn signals work better, they still tend to slow down a bit when slowing down on the bike.  Couldn't figure out what that God awful sound was when turning on the signals then saw a set of turn signal horns for a 750A on EBAY.  Are those Japanese people really that anal?  If I wasn't a purist and believed that ALL bikes should be kept stock and original, I would disconnect the horn but at 58 I can't hear all that well anymore anyway so I'll get used to it. 

Seems parts for these bikes are scarce and mechanics who know anything about working on them are even rarer.  Guess I'll have to become an expert or else sell it to some other sucker. 

Well thanks for reading my rants and good luck to you guys as you sit at your computers and think about riding.  Me?  I'm off for another ride and away from this contraption which doesn't give me the thrill I get on the open road...  At my age I can't be just sitting around, I have more life to live...If I don't crash first...Okay defibrilator don't go off on me while I'm riding!!!!

[raymond10078]

My first thought is that your accelerator pump is not working.

Your description isn't that clear - but that is my guess.  Honda kept leaning out the carbs over the years, and if you whacked open the throttle, the bike would kind of fall on itself, then respond - maybe a second or so delay.  I've heard others described it as like turbo lag.

The accelerator pump is supposed to (actually is does) help when the throttle is whacked open.

What happens if the throttle is slowly opened?  Roll open the throttle taking a second or two from closed to open.  Does the bike accelerate better?

If not the accelerator pump - then I'd first question your carbs - and maybe the air filter.  If you don't know the history of the bike, and its carbs, they may need a good cleaning.  As for the filter - there are some filters being sold that are TOO restrictive.  The item description makes it sound like it is a stock replacement, but is trash.  I'd put in a K&N filter.

I wouldn't knock the expertise on this site - I'd bet that most are out riding or racing - fall is coming fast, and riding days are too few to waste.

[chubbs105]

I have a similar problem w/ my '78. Usually happens when the bike is cold (which with mine is in about 2 hours it not running.) and I have to run the choke when I take off from stops so I don't kill it. After about 5-10 minutes (depending on outside temperature) of riding it finally warms up and I can stop using the choke at stops and takes off just fine.

I don't have much experience in the wonderful world of automotive equipment, so I may have a bigger problem I need to take care of. I think it just takes forever to warm up.

[trueblue]

If it is bluing the pipes it is running too lean. I would fiddle with the idle mixtures and see if that helps, if not then a carb clean sounds like it is in order. I don't know much about the A's but I think there is a switch which turns on a vacuum solenoid which in turn moves the idle up mechanism for when you put it in gear. 

[raymond10078]

I missed the pipe bluing part . . . and yes, I'd also agree that your carbs need cleaning.

The in gear idle - you've identified the symptom (dies in gear, idle positioner not working), next is the troubleshooting.  There's a solenoid mounted on the carbs - it connects to the dashpot (the flat, round part that has a plunger connecting to the carbs) via a vacuum hose.  The other side of the solenoid runs to the left carb (I think) for vacuum.  Make sure that the hoses are intact.  There's also a check valve in the path, too - don't remember which side of the solenoid it is on.

Electrically, the solenoid is energized with the bike in gear, and the circuit includes a "speed sensor" intended to turn off the solenoid above 20 mph or so.  The solenoid is hard to hear - it is easier to "feel".  Try this - engine stop switch to off/kill, key off, bike in gear, while turning the key on/off, should be able to hear or feel the solenoid klick.  Beyond this, there's a number of points to test (electrically) - and the service manual (available on this site for download) provides instructions to test the solenoid off of the bike.

[05c50]

Whoo, your evaluation of the folks on this site might be a little harsh. There's not very many 'matic guys here, and fewer that are completely familiar with the carbs on these bikes........and some us do like to ride, so let me appoligize for not getting back to you sooner. 

That being said, you said that you replaced the air filter after your trip. If it was as dirty as you said, a new filter may be adding to the lean problem.....hesitation, stalling, blue pipes. Also if the bike was sitting for awhile before your trip, it's quite possible  that you now have clogged slow jets. These carbs do have an accelerator pump that works quite well if the orifice isn't clogged. Also the idle kicker (as described by kandrtech) needs to be in working order to get the most out of these bikes. Most likely, you will need to remove and clean the carbs to get get satisfactory results and you will need to become familiar with the idle kicker system (or find someone to do it for $$$).

By the way, welcome to the site......and if this is true "If I wasn't a purist and believed that ALL bikes should be kept stock and original", you'd yank that fairing and rats nest of wiring off and throw them away......because they aint "factory".

Remember, we'll be happy to help, just give us a little time.

..............Paul

ps, that nasty turn signal beeper is there because Honda knew that someday these bikes would be ridden by old farts like me, and we need all the help we can get.

[slipnot]

Thanks all for the feedback.  Sorry, am not good in the patience department and they say you can't teach old dogs new tricks so not sure that's ever going to change.  Anyway, I had read up on the stall prevention system from the manual posted on this site (thanks to whoever did that, what a help) and then checked to see if it was operating.  I put the bike on the center stand, set the parking brake and started her up.  As I put the bike in gear I watched the diaphragm linkage and as suspected no movement.  So I'm thinking, okay the fuel gauge was disconnected so MAYBE the solenoid valve was also.  (I always start with the simple things first.  Process of elimination I learned as a kid, has saved my butt many times).  I pulled the tank so I could get to the solenoid easier and traced the wires to behind the left side cover.  Removed the side cover and pulled out the wires and guess what?  Yep, one of the wires was disconnected.  Looked for the other end, found it and hooked it up.  Cleaned the mess under the tank (silt and dust from all the years sitting) hooked up the overflow tube which was unhooked also.  Put it all back together and started her up.  Guess what?  Yep, she worked perfectly.  I adjusted the idle down a tad as I had set it up to help prevent the stalling when in gear and took her for a ride (10 pm by now).  She ran great.  Idle increased at stops just as designed and she takes off pretty damn good.  Still a little hesitation if I accelerate too quickly but not a big deal.  Not sure I want to mess with the accelerator pump as it requires pulling one of the carbs and the hesitation is not that big of a deal.  I'm going to reset the pilot screws according to the procedure in the manual as they weren't done fully when tuned at the shop.  Hoping that helps a bit too. 

So here's what I think happened.  Bike was probably stalling at stops for the previous owner, probably many years ago as I was told it sat for 16 years?  He must have pulled the tank and disconnected one side of the solenoid and hooked up a test lite as mentioned in the manual to see if it was operating correctly.  I suspect it wasn't and he couldn't figure it out.  Why? because the vacuum line going from the valve into the #2 carb was cracked as we found out when cyncing the carbs.  This would never have been found if the carbs weren't cynced.  Lucky on my part.  I suspect the previous owner got frustrated and just left it as it was thus the wires to the fuel gauge, the overflow tube and the solenoid wires weren't hooked back up.  So it ended up sitting until sold to the guy I got it from who also probably got frustrated with it, but at least got it running well enough to sell it with the caveat that a tune up would make it run better.  So here we are many years later and after a bit of frustration, a little luck  and some perseverance I have a great running classic.  I'm now a happy camper.  Just a little more tweaking (a lifetime affair) and then decide whether to get rid of the bulky fairing and king/queen seat and repair a small indent on the side of the fuel tank and this bike will look and run like new. Now, with four bikes in the garage I need to decide which ones to keep and which to sell.  That's always the hardest decision.

Oh, by the way, the turn signals are working great now too.    Go figure.  And as far as the bluing?  Really hardly noticeable when out in the light.  Funny how when your frustrated everything always looks worse.  Or is that just me

[05c50]

Good to hear that you found some of the problems and it's running better. If it sat for 16 years and it's running that good, I'd say you're pretty lucky. You might want to add a little Seafoam to the tank and run the snot out of it. The more you ride 'em, the better they run.

One thing about the"matic. It's a good conversation starter. It seems like most people have heard of them, but have never seen one. If for no other reason, that's why I keep mine.

...................Paul

apology accepted
 

[slipnot]

Thanks Paul.  I do have some seafoam here at the house and will run some through for a while.  I did use a cheaper brand of carb cleaner when I drove it the 1200 miles from Denver, so I'm sure that helped clean the snot out of the carbs as well as driving it 65-70 miles per hour. 

I took it out for a long drive today and I'm not sure it can run much better.  These bikes really are a blast to drive.  Still going to readjust the pilot screws just to know everything will have been set to specs.  Would still like to know how to hook up a tach so I can be sure the idle is set right on. 

I do have that knocking sound others on this site have mentioned and am going to work on figuring out what the devil is causing that.  I'm a firm believer in the idea that if it didn't occur when driving off the show room floor then something just ain't right in Kansas, and I'm sure these babies didn't knock when new.  So, in my book there's always a reason for everything.  Fixing is another matter....

My kid is after me to finish the XS650 Special for him but I'm thinking of finding another one of these hondamatics.  I bet if he drove mine he'd be a convert. 

[05c50]

Yep, they are fun to ride. I usually don't ride mine very far, but earlier this year during the relay rally I gave it a good workout. I was pleasantly surprised with it's handling on the twisties and the fuel economy. Not a bad package! I'll probably never get rid of it.

The knocking noise on cold idle doesn't bother me much. When someone asks about it, I just tell them that all the motorcycles with torque convertors sound like that. Not too many people can argue with me.

............Paul 

[raymond10078]

Tach hookup?  Here are two options:


• This one connects at the points:

http://www.sears.com/actron-dwell-tach-volt-meter/p-00902165000P

• And this one clips onto a spark plug wire

http://www.antarespro.com/2662754-item-ELECTRONIC_SPECIALTIES-325--855174001083-+TACHOMETER+CORDLESS+INDUCTIVE.aspx?sgd=349d312d313d315d318

[/list]

Knock?  It is my personal experience, that when the timing is dead on, the carbs are synched AND the idle is set correctly, there is no knock (at least I can't hear it).  My bike will easily idle way below 1000 rpm, but will knock some at lower idle speeds.  When I set the idle up to specs (950 in neutral, and 1000 in gear), I can't hear it any more.  Yes - the idle is higher when in gear!

[slipnot]

I have an older Hawk analyzer and it looks like on the Sears analyzer you just double the scale reading for the 8 cyl to get readings for the 4 cyl.  My question then is where on the points to hook the lead from the analyzer.  Obviously the black is to a ground, but where to hook the other lead?   On cars you would connect to the coil, but there's two coils on the bike.  Does it matter?  Or is there some place to hook to the points as you mention?...Thanks

[raymond10078]

I connect directly to the points/points connection under the right side points cover.

[slipnot]

Right on...That worked....I was off quite a bit, and the knock improves significantly when the idle is set at 950.

[raymond10078]

did you also set your in-gear idle speed? 

[slipnot]

I did set the idle in gear to 900 and 950 at rest.  It does seem to want to take off at stops when in  gear and I have to keep pretty good pressure on the brake to hold it still.  I'm going to take it down to 800-850 even though the specs call for 1000 +/- 100 rpm.  I know, it doesn't make sense but that's what it is.  Any input is appreciated.

Oh, by the way, if your going to cut across your front lawn because you have cars parked in the driveway, be cautioned that front brakes don't grip on wet grass.  Bike needed a bath after that stunt.  These babies will take off on you when you let loose of the brake, I could have been on America's dumbest home videos!!! Darn, missed my 5 seconds of fame!!!  Needed help lifting that puppy back up, heavy sons of beaches, Huh?