Topic: What does it indicate if the bike runs great but is a PITA to start?

[juntjoo]

Thought I recall him saying wet plugs. Bad battery, old plugs leads me down electrical path. He said he's never changed the plugs on it. Doesn't know what kind of ignition system he has either.

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Ask me about the ignition system. I'll tell you what I know. It's stock 82 nighthawk...

[evinrude7]

... carbs get cleaned before getting it right. .. on here for most that haven't done it before ,  is 3 times or more..
 That is telling something.

Huh? You read drunk lol. Are you saying most people have had to clean out their carbs several times to fix issues? That's not good news. I've cleaned these a couple times already. Between each cleaning bike sat for like 8 months.

What could I have missed? I did the two Jets. Can see right through both. Also the pilot(air) screws. Accel pump works good. Carb spray didn't help this time. A year ago that's how I had to get home at night, carb spray. Always had this hard start issue. Otherwise bike always ran good. In my garage couple days ago ran (stationary) strong. So only difference now is carb spray no work. So I'm hoping new plugs will do the trick although you guys are betting not.

I'm betting it's not only the plugs but elsewhere in the ignition including battery.

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[evinrude7]

Thought I recall him saying wet plugs. Bad battery, old plugs leads me down electrical path. He said he's never changed the plugs on it. Doesn't know what kind of ignition system he has either.

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Ask me about the ignition system. I'll tell you what I know. It's stock 82 nighthawk...

Yes and I posted a cmsnl link so you could see what it is.

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[juntjoo]

Thought I recall him saying wet plugs. Bad battery, old plugs leads me down electrical path. He said he's never changed the plugs on it. Doesn't know what kind of ignition system he has either.

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Ask me about the ignition system. I'll tell you what I know. It's stock 82 nighthawk...

Yes and I posted a cmsnl link so you could see what it is.

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Ah. I don't think your link had my model. I'm on my bicycle now, but it's so chill I can text, but I think i recall the cb650 has "magnetic" while mine is something different  sound right?

[juntjoo]

[evinrude7]

I don't know what yours has in it. According to cmsnl on your 82 650sc nighthawk you have a pulse generator. See if you can test it.

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[Stev-o]

Have you had your battery tested yet?  Your wasting time until you do this!

[evinrude7]

Have you had your battery tested yet?  Your wasting time until you do this!

+1

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[juntjoo]

Have you had your battery tested yet?  Your wasting time until you do this!

On my way home with a new one. New battery, new plugs. Guy said he could not test it. I'd charged it 100 times in the last 72 hrs so I'm guessing it was bad. Tomorrow I'll have the verdict

[evinrude7]

Have you had your battery tested yet?  Your wasting time until you do this!

On my way home with a new one. New battery, new plugs. Guy said he could not test it. I'd charged it 100 times in the last 72 hrs so I'm guessing it was bad. Tomorrow I'll have the verdict

Don't quit on it being ignition if just slapping a new battery and plugs in it doesn't do the trick. Adjust the valve lash and time it. Make sure you gap the plugs correctly and don't over tighten.

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[754]

Why is there tape over part of the carbs.... ?

[juntjoo]

Why is there tape over part of the carbs.... ?

I guess it was just too much air flow when I first took off the air box 5 back then. I forget exactly but it ran funny. So a piece of masking tape right over the middle did the trick

[754]

Well other bike start and run pretty good without any tape.
 Did you clean your jets and the passages they fit into that go inside the carb body ? Or just the jets ?

[juntjoo]

Well other bike start and run pretty good without any tape.
 Did you clean your jets and the passages they fit into that go inside the carb body ? Or just the jets ?

Which other bike are you referring to? This is my only bike.. Yes I got carb spray up in through the. holes in the throat. Once started runs great. After a year sitting I only found drunk in the bowl and one float needle got stuck which I replaced and the bowl gaskets . So they stayed pretty clean.

[754]

I am referring only to CB 750 s I have had , some with carbs same as yours,  since 1975, none ever needed tape over the carbs to start or run better...
 And I know for a fact , I have had ones that were extremely ignorant to start until plugs were changed.

As far as your idle circuits, I will make this real simple.. very simple..
Let's say your carb jets and passages were like a garden hose and a nozzle on one end. Clean the nozzle , but hose is still blocked.. still wont work..  you have to clean the hose as well....... your hose is your carb body.
 Maybe something was getting through , but how much is the question.....

 There has to be a ready supply of fuel for starting, and it has to continue flowing through the ENTIRE IDLE CIRCUIT to stay Running...  and yours appears not to do that .... but once it is clean it will probably start up and idle easily.
 If anyone touched the linkages and fast idle parts, that may affect things too. .

 But as said before , if you give it a shotof gas or starting fluid from external source and it fires instantly,  that would show your idle circuits are not working.

[juntjoo]

I am referring only to CB 750 s I have had , some with carbs same as yours,  since 1975, none ever needed tape over the carbs to start or run better...
 And I know for a fact , I have had ones that were extremely ignorant to start until plugs were changed.

As far as your idle circuits, I will make this real simple.. very simple..
Let's say your carb jets and passages were like a garden hose and a nozzle on one end. Clean the nozzle , but hose is still blocked.. still wont work..  you have to clean the hose as well....... your hose is your carb body.
 Maybe something was getting through , but how much is the question.....

 There has to be a ready supply of fuel for starting, and it has to continue flowing through the ENTIRE IDLE CIRCUIT to stay Running...  and yours appears not to do that .... but once it is clean it will probably start up and idle easily.
 If anyone touched the linkages and fast idle parts, that may affect things too. .

 But as said before , if you give it a shotof gas or starting fluid from external source and it fires instantly,  that would show your idle circuits are not working.

I wish there was a cut out diagram for these carbs. I did squirt fluid through from the bowl side through into the throat through the three little holes. That's the secondary jet, the "idle" one right? I thought mine were different from the 750 in that mine only have two jets, main and idle. Yours have that other one whereas mine is plugged there. Then I have the air screw in the back, front really, with the spring and gasket. Again though, once started runs strong and idles fine. As far as starting, I thought the accel pump is what matters for mine whereas carbs without accel pump rely on main and idle circuits. I Def have fuel as my plugs are wet. And no, carb spray didn't help this time really, as it used to a year ago when I'd always have a little can on the bike. Gonna fill up this new batteryz stick the charger on it and get back to it in the morning....

[Alan F.]

Has anyone asked how old the fuel in the tank is? Is it E10?  Drain the tank and float bowls and add new fuel?

[juntjoo]

Has anyone asked how old the fuel in the tank is? Is it E10?  Drain the tank and float bowls and add new fuel?

Fuel is good. Using the stuff I get for my mower. Otherwise I use the 90 stuff

[MRieck]

I didn't see anybody mention this but if your valves are tight (no clearance) the engine will be very hard to start as it doesn't create enough compression (which is very important for cold starting). The bike will run OK once warmed up.

[juntjoo]

I didn't see anybody mention this but if your valves are tight (no clearance) the engine will be very hard to start as it doesn't create enough compression (which is very important for cold starting). The bike will run OK once warmed up.

Thanks. Unless they can get tight on their own I've adjusted them many times, just to be sure, in the past, before I let it sit till now, so I'd doubt that would be a factor

New battery charging now. Will pop in new plugs later and give it a shot

[PeWe]

Valves can tighten by their own when valves wear, stem going upwards.
That's why the lash should be checked.
Also a risk that a previous service caused no lash when setting lash with crank in wrong position.

[juntjoo]

Valves can tighten by their own when valves wear, stem going upwards.
That's why the lash should be checked.
Also a risk that a previous service caused no lash when setting lash with crank in wrong position.

8 think you're saying make sure you adjust em correctly with valves/crank in correct position with cams down right? 8 did em a bunch of times back then cuz I think I did it wrong a t first a couple times possibly ruining one of my valves I had to replace actually.

[drumstyx]

Yeah sounds more like a fuel issue -- I had a hard start with my '78 when the fast idle cam was adjusted way too high, meaning the throttle was open too much at full choke, and it'd always take TONS of effort to get going.

Not sure what carbs you've got, but point is, it ran well after warming up, so it was a carb issue.

[evinrude7]

Yeah sounds more like a fuel issue -- I had a hard start with my '78 when the fast idle cam was adjusted way too high, meaning the throttle was open too much at full choke, and it'd always take TONS of effort to get going.

Not sure what carbs you've got, but point is, it ran well after warming up, so it was a carb issue.

I'm thinking VBs


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[juntjoo]

Not with them at the moment but they are the ones with no overflow tube and they have two of the three tubes for jets used, main and slow /idle(?) with the lowest protruding one plugged.