Cold blood and weak push start

[Serialboyscout]

Hi guys, I'm new to the site and CBs but I'm enjoying getting my hands dirty and sorting through all the awesome information on this site.

I recently purchased a 1978 cb750 Super Sport with 28k miles. I noticed a gas leak out of the float bowls shortly after the purchases so I took the carbs off and replaced the float bowl gaskets, the old ones were just that, old and brittle. I cleaned the carbs as best I know how (they were very clean to begin with) and put them back on. Bike ran great and still does when warmed up.

Unfortunately the bike is a pain in the A$$ to start. The push start is only good for a couple of attempts then it dies down to nothing, almost as if it needs to charge the starter solenoid before it can give it another go. Is this normal? The batter is holding a good charge and the water levels are good. The kick start is my secondary option after the pathetic attempt by the push start. This again works great if the bike has recently been run and is warm. But if the bike has sat over night and is cold it takes forever to start, if I'm lucky.

I know with the plethora of intelligent cb enthusiasts on here there are some recommendations.


Thanks in advance,

the humble newb,

Dane  

[Re-run]

Have you had the battery tested? It might charge ok and hold charge but might be on its last leg.
Easy way to check it charge batt, take voltage read. hook it up and hit starter till it dies. take read again. If the voltage has tanked, you need a new battery.

As for hard starting, it is hard to say. Without knowing what type of ignition you have(points or elect), if you have the stock air filter, or any other tune up stuff; it could be anything.

Also when you cleaned the carbs, did you pull the jets out? If not, then they are not truly clean.
Unscrew the mains and then use a pliers and wrap cloth or rubber around the idle jet, grip with the pliers and twist and pull. Out they come. Crap builds up in there pretty good.

Now to make you jealous! My 78K starts on 1 kick on a 60 degree morning!

[Serialboyscout]

I'll test the battery out tonight and get that out of the equation once and for all.

Not sure on the ignition, it's a stock 78 f2 super sport. Is there an easy way to tell one from the other? I'll do some more research this evening. I have the stock air filter and no other tune up stuff.

I didn't clean the jets but I can do that as well. I did run some cleaner through the gas tank but I know that doesn't mean they're clean.

Are there any other adjustments on the carbs that should be done? I'm planning on syncing them up after I get the starting issue resolved.


On an addition side note I've heard a ticking coming from the engine. Sounds like it could be a valve issue from surfing the forums. Any experience with something of that nature?


Thanks for the response! And for making me jealous, now I know what I have to look forward to after some time and effort. :)

[Re-run]

Now you will hate me. How many miles are on the engine? Did any maintenance records come with the ride?
The F3 engines had valve issues. The guides wore out fast from the angle. In most cases, new guides usually worked to fix it as long as the valve stems are not work too badly.
Do you have smoke on start up? if not, then they should be ok yet.

To check your ignition, pull off the points cover on the right side and look. you cant miss points.
A valve could be out of adjustment and causing the tick. Those should be adjusted. When using feeler gauges, bend the last 3/8th inch of the gauge, makes it easier to use. Also up the valve clearance .01 on both sides. This allows the vales a bit more room and makes wear less and allows for heat expansion. Slightly more noise is the only downfall.

Does the clutch rattle badly in neutral and then go away if you pull it in? If not, I would not worry too much about that. Also, pulling jets will not change the sync really. AS long as you do not remove the slides, it should be fine.

When cleaning the jets, be careful. They are not steel, just brass. You can use a wire to clean them. DO not let others fear you about this. Just use a thin strand of copper wire and go at it easy.

[Serialboyscout]

No smoke at start up just a ticking noise that doesn't sound normal. Sounds like it could just be a valve adjustment issue. The clutch doesn't rattle at all in neutral and that makes me happy!

I'll pull the carbs tonight and clean the jets thoroughly. I'm also going to replace the carb boots. When I pulled the carbs off the first time I noticed some cracking on the boots but didn't think it would be that big of a deal. As I've read more this can actually have a large impact on how the engine runs. Do you know a good place to order these? My local Honda dealership said they would be about 50-60 bucks a piece!

BTW I went and gave the girl another shot at starting and she came right to life with the first push start. Although, weather has warmed up significantly!

[Re-run]

I think I know a place ti get them for like 20 each or so but I have to see if I can find it again.

[cbrydr]

check your fuel pump in #2 carb . make sure it sprays fuel when you twist throttle . they become stiff with age and do not work very well.  2 or 3 twist before cranking will give you a little extra fuel when starting cold . pump should spray in all 4 carbs

[Re-run]

Age isnt so much an issue as is the gunk that builds up over time. I replaced my pump 4 years ago, I just thought I should. Well that old unit still works. Crud builds up around edges and then comes off and clogs the nozzles. More important are the passageways that this fuel goes through. Spray carb cleaner in those passages and you should see gas come out of the brass nozzles.

[Re-run]

http://www.davidsilverspares.co.uk/parts/

This site is uk but they ship to US. The manifolds are about 16 each or so. From what I hear, shipping is not too bad either.

[Serialboyscout]

Awesome information guys. Thanks for all the help. Looks like I will be playing with the carbs this weekend! I'll have to pull out my Clymers manual and track down some fuel pump information. I wouldn't mind replacing it if I can gain some benefits.

[cbRider]

A quick and easy way to eliminate the ignition system is to spray some starting fluid into the carburetors.
I she fires up your ignition is not the problem.
My 81 CB750F had a vacuum petcock which prevented the carbs from filling, so I eliminated it.
You might not have one.

[woodsrider250-2]

Yeah, that's only the DOHC's, and I 2nd the elimination of the vacuum 'safety valve!'

[woodsrider250-2]

Yeah, that's only the DOHC's, and I 2nd the elimination of the vacuum 'safety valve!'