Hard Starting Engine

[bobber]

Its a good habit to shut the fuel off when parking the bike, but remember to turn back on, sounds silly, but I know one person (me!!!) who did forget, with interesting results in rush hour traffic!
Most shut fuel off when parked to remove possibility of hyraulic locking a piston if a carb float valve leaking, espicially when on side stand. I ended up changing fuel petcock's to aftermarket as the stock started to weep on both my X's.
When bike is parked for awhile carbs will dry out and need to be re-filled, which takes time, with 6 carbs. How good of flow do you have coming from the tank? My be something to check as your petcock screen could be dirty, restricting flow or air vent in tank cap partially plugged. Both I have experienced although the blocked tank vent only on a snowmobile allowing engine to run like a raped ape for couple of minutes until, god bless 2-strokes, it decided to remove couple pistons and nika-sil cylinders.

[Louis]

I know this sounds real stupid?? How old is the gas or maybe there water in it. Louis

[BASTOK]

I have some similar problem. I have an 80 X and when the days are really cold, near 0ºC, and if I let the bike 2 or more days without starting it, it takes like 10 cranking attemps for her to start (with full choke).

Last summer I put a K&N filter, and maybe I was thinking that the more Air flow the filter gives could afect the air/fuel mixture that fill the chamber, and difficulting the starting.

Could it be part of the problem?

I will check the choke operating springs also.

When hot it runs very good.

Thanks in advance.

George

[EMS]

1980 and later CBXes have a vacuum valve between the petcock and the float chambers. If the bike sits for a longer time, the fuel in the float chambers evaporates and the vacuum valve prevents filling them when you turn the petcock on. The engine needs to crank to do so. It usually takes a little longer until the chambers have enough fuel to get into the motor and enable starting.

[pgilliam1]

1980 and later CBXes have a vacuum valve between the petcock and the float chambers. If the bike sits for a longer time, the fuel in the float chambers evaporates and the vacuum valve prevents filling them when you turn the petcock on. The engine needs to crank to do so. It usually takes a little longer until the chambers have enough fuel to get into the motor and enable starting.

So this is "normal?"

My first winter with my new to me 1981. Just had the carbs, valves and head done about 2 months ago and she runs and starts fine when it's warm. The choke operates fine as well. But after it sits in a cold garage for a couple of weeks it takes several attempts to start up. It did not want to start with the choke on (maybe it would have eventually, but it didn't seem like it).

Will the float chambers eventually fill on their own if you turn on the petcock and wait a bit? Should you just hold the throttle wide open when you're hitting the starter until it tries to fire? There has to be a preferred method here - Right?

[herdygerdy]

May be heading down a dead end fox hole with this one, but suggest checking for voltage drop at the coils while the bike is stone cold.

Using a Digital Volt Meter (DVM) measure and record voltage across your battery.

Then, with key & kill switch to on position, put black wire of your DVM to a good earth (eg; the wiring harness earth connector at the rear of the coil mounting bracket, and the red DVM lead to the terminal to the LH coil for cylinders 1 & 6, on the terminal on to which the black/white wire is connected at the coil. Record the reading. If more than 10% less than battery voltage, that may be the culprit.

A better way is to put your DVM black lead to Battery Positive terminal, and red DVM lead to Black/white lead. This measure the difference or voltage drop between those two points. If measurement is next to nothing - 0.5 or less of a volt (meaning voltage difference is naff all), you are good to go. But if anything more than 1-1.5 volts difference, then that IMHO would be marginal and deserves further investigation and rectification.

(Mike Nixon, you may have some comments on this approach?)

I have seen down to 9 volts which will not help cold starts one bit. If so, its time to go hunting for precisely where the drop is occurring. Suggest then checking voltage from the black/white lead (and using the same earth as before, for consistency) that comes from the kill switch through the wiring harness and into the brown 2 wire connector, found about half way down on the RHS connector mounting strip under the RH side cover.

To make sure the coils are getting the full 12 volts all the time, I have installed an ignition coil relay kit on mine. Happy to fabricate up a plug 'n play ignition coil relay kit for sale to members if needed.

Link to vid below is a cold start of mine when it had not been started for two days, in Sydney winter, this with new Procom igniters and ignition coil relay fitted.

http://youtu.be/njL1UDDyqTQ

Let us know how you get on and watching this with interest.

Cheers..Tony

[daves79x]

Tony's improvement is very likely to help just about any CBX with the stock components, Pro-Link kit to follow.

The subject of had starting has been beaten to death and if you search it up here, you'll have a day's worth of reading about it.

I'll cover the main points. If all's well with the bike and carbs (accelerator pump particularly), this is what you do: First, the vacuum valve is just that - it requires engine vacuum to open. That is achieved by cranking the engine, OR, as I have described a thousand times, locating the vent line from the vacuum valve (should exit over the airbox and down inside of right frame rail to the common exit for all the other hoses). Pull it out at the bottom and keep it tucked right there where you can access it easily. Before trying to start after the bike sits a few days, turn the petcock on, then blow and hold pressure on the vent line. This will hold the diaphragm off it's seat to fill the carb bowls. A couple of 10-15 second 'blow and holds' will do it.

Next, with the key 'OFF', quickly twist or 'blip' the throttle 15-20 times. If working, the accelerator pump will shoot a good charge into the intakes. Then, with full choke and no throttle, turn the key 'ON' and hit the starter. The bike should attempt to fire quickly, and if it does, while still cranking, SLOWLY roll the throttle on just a bit and it will fire right up on all cylinders. If it does not fire right away, turn key 'OFF' and repeat blipping the throttle and so on.

Next I'd strongly advise against running the bike 'every couple of weeks' in the Winter unless you can get it out and ride it 20-30 miles. If that's not possible, fill the tank, drain the carbs and park it for the Winter. You'll do far more harm by just running it a bit in the garage.

All this has been chronicled a million times here and elsewhere, so do a search for more details.

Tony is certainly on to something with his updated electrical component kit. It will no doubt help many bikes tremendously, but the inherent starting difficulties with these things after sitting might not be entirely solved and the above procedure DOES work.

Dave

[pgilliam1]

I did do a search before my post, but after reading a few posts, the hard starting after temporary storage and when cold appeared normal.
I will check the voltages. This bike has the Euro stator upgrade and the amp and voltage gauges seem to show good output voltages. I have disassembled and cleaned all the contact points on the coil assembly and checked them for cracks. But I also understand that the coils can get weak over time.
I'm not sure if the shop did anything to the accelerator pump when they rebuilt the carbs - probably not. Not sure how to test the pump - I'll do a search here and check the manual.
Seems the problem is more about getting fuel to the cylinders than voltages. I say that because others have had good results with spraying fluids directly into the air box before starting. Dave, I will try your method too. Would leaving the petcock open when stored keep the carb bowls full or would it cause worse problems?
I don't understand why starting the bike in the garage and getting it up to running temp (say about 5 to 7 minutes) is a bad thing? I do use Star Tron in the gas tank and keep it topped off when I won't be riding for a while.

[EMS]

This bike has the Euro stator upgrade .

Forgive my ignorance, but what is this?

[NobleHops]

I did do a search before my post, but after reading a few posts, the hard starting after temporary storage and when cold appeared normal.
I will check the voltages. This bike has the Euro stator upgrade and the amp and voltage gauges seem to show good output voltages. I have disassembled and cleaned all the contact points on the coil assembly and checked them for cracks. But I also understand that the coils can get weak over time.
I'm not sure if the shop did anything to the accelerator pump when they rebuilt the carbs - probably not. Not sure how to test the pump - I'll do a search here and check the manual.
Seems the problem is more about getting fuel to the cylinders than voltages. I say that because others have had good results with spraying fluids directly into the air box before starting. Dave, I will try your method too. Would leaving the petcock open when stored keep the carb bowls full or would it cause worse problems?
I don't understand why starting the bike in the garage and getting it up to running temp (say about 5 to 7 minutes) is a bad thing? I do use Star Tron in the gas tank and keep it topped off when I won't be riding for a while.

Patrick,

There is commonly a lot of condensation in a cold engine, which you see as white 'smoke' on startup. It takes a bit of running to heat it all up and evaporate it out the tailpipe or breather. When you start a stored bike with a lot of water in it, you'll see the motor oil turn a scary foamy light brown, that's mostly water in the oil. You obviously want that out of there, and it just takes time.

N.

[EMS]

Would leaving the petcock open when stored keep the carb bowls full or would it cause worse problems?
I don't understand why starting the bike in the garage and getting it up to running temp (say about 5 to 7 minutes) is a bad thing? I do use Star Tron in the gas tank and keep it topped off when I won't be riding for a while.

Patrick, there is no flow through the petcock when the engine is not running, so it will not help your hard starting issue. Nils has made the point about why you should not start the bike during storage. It really takes much longer than 5-7 minutes to cook all the moisture out of the oil. And the worst part is the condensation in the exhaust. It also takes around 20-30 minutes to replenish the charge in the battery used for starting.

[daves79x]

Patrick:

Nils and Mike covered it about all, but to emphasize, the exhaust will rot out in a few short years doing what you are doing. I seem to recall that you have years of experience with bikes and own several. This is the way you should be treating all of them in the Winter - fill the tanks, drain carbs on any that have them, cover them and forget about them.

Your starting problems are extremely typical and if everything is working reasonably well, doing what I suggest will be the easiest way. You can't skip any steps and there's a reason for every one of them. Now, in the Spring, just turn the petcock on, blow into the vent tube as described before, and with all fresh gas in the bowls, the bike will fire instantly - no blipping the throttle ritual needed. But you do need full choke and no throttle.

If letting the petcock open would keep gas in the bowls, what good is a vacuum valve? Not sure you quite understand what it actually does, but surely you've heard the horror stories of the dreaded hydrolock on the '79s without the vacuum valve? That's why you don't want the bowls being filled from an straight-through petcock while the bike is just sitting.

Do yourself a favor and cover the bike up until Spring!

Dave

[Jeff Bennetts]

Tony's improvement is very likely to help just about any CBX with the stock components, Pro-Link kit to follow.

The subject of had starting has been beaten to death and if you search it up here, you'll have a day's worth of reading about it.

Next, with the key 'OFF', quickly twist or 'blip' the throttle 15-20 times. If working, the accelerator pump will shoot a good charge into the intakes. Then, with full choke and no throttle, turn the key 'ON' and hit the starter. The bike should attempt to fire quickly, and if it does, while still cranking, SLOWLY roll the throttle on just a bit and it will fire right up on all cylinders. If it does not fire right away, turn key 'OFF' and repeat blipping the throttle and so on.

Dave

Dave has it pretty we'll covered! One thing I'd like to add is on most of these CBXes you need to keep pressure on the CHOKE lever while you crank the bike over, because the choke plates in the carb will not stay 100% closed, they return a bit if you just slide the choke lever to the on position and don't keep pressure on it.

[pgilliam1]

This bike has the Euro stator upgrade .

Forgive my ignorance, but what is this?

Ok, so maybe I'm not stating this mod correctly. Where my stator used to be there is a bolt-on unit that also bypasses the OEM voltage regulator (somewhere I read this mod is more common in Europe - hence the Euro upgrade description). My assumption is that the voltage regulator is built into the replacement unit???

I have never found any discoloration or indication of water contamination in my oil. It's always clear and clean and I check it before every cold start.

The more I post the more you all realize how little my mechanical breadth really is .

The cover is going on the bike - but it's coming off the next 50 degree day!

Thanks again for your support!