Works 30s and then dies

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TN-592
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Works 30s and then dies

#1 Post by TN-592 » Mon Nov 12, 2018 9:30 pm

After i start a bike it work for about 30-50s and then it stops even if i rev it high,after it is not possible to start it again
Have anyone had the same problem?
Have checked
Float level,spark,air screws,cleaned the carbs...using the correct sparks....no airbox...

brrrappp
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Re: Works 30s and then dies

#2 Post by brrrappp » Mon Nov 12, 2018 9:45 pm

Sounds like fueling. Have you tried with the petcock in the PRI position or while using a test tank?
Have you verified fuel flow from the tank to the carbs by pulling the drain screws at the bottom of the bowls?

justind97
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Re: Works 30s and then dies

#3 Post by justind97 » Mon Nov 12, 2018 10:44 pm

Definitely sounds like fueling. About the right amount of time at idle for the bowls to drain.

TN-592
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Re: Works 30s and then dies

#4 Post by TN-592 » Tue Nov 13, 2018 3:34 pm

That is what a thought,i was positive it was the fueling problem....but i have tried so many options of fuel delivery
Tried:test tank,different options of float level,choke on,choke out,did'n mix any of carb components like placing wrong slide or wrong float bowls or any of the components have checked them so many times......compresion is all good i have totaly new top end cub 465cc but the same ting happened with the old rd cylinders...........now i am suspecting the spark is not strong enought.......but there is one thing i did't have battery connected can that be a problem?

brrrappp
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Re: Works 30s and then dies

#5 Post by brrrappp » Wed Nov 14, 2018 3:03 am

I know mine will run with a dead battery. I don't think it will start with the battery disconnected. it's worth trying a known-good battery.
I would also remove the Coil from under the tank and clean the area of the frame and the part of the coil that attaches to the frame with sandpaper. Check the plug-in connections from the wire harness for good solid contact. If you haven't already, cut 1/4 to 1/2 inch off from the plug wires and thread your plug caps back in.

Earlier this year I had a similar issue where one carb had a stuck float and let a bunch of fuel pass into the engine. It would run briefly on one cyl and wet the other plug. After resolving the float issue it took 4 new spark plugs on the left side and running it a few miles to get the excess fuel blown out. Now it starts good.
Check carefully for any exposed wires that could be grounding out. This is a low likelihood issue:
I had an RZ that had fried ground wires in the middle of the harness. I ended up replacing the entire wire harness. The previous owner had done a poor job of splicing- for what I do not know. As the wires got hot from grounding out the bike would die. It would run great for about 30 seconds or so and die until cooled. It was hard to identify because the harness was all taped up like stock. The spliced wires were in the middle of the harness and grounding against each other.

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nokturnal
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Re: Works 30s and then dies

#6 Post by nokturnal » Wed Nov 14, 2018 9:40 am

fucked vacuum on the tap?
:smt017

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JonW
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Re: Works 30s and then dies

#7 Post by JonW » Wed Nov 14, 2018 7:13 pm

nokturnal wrote:fucked vacuum on the tap?
This made me smile and reminded me of an old letter in technical help section of a bike mag ages back, the story was something like this:

"I have an RZ350 and its not running right, i took it to the mechanic who revved it up and listened to it, turned to me and said 'shit in the airbox' then walked off. I wonder if you can advise me, how often do I need to do that?"
80 XT500 Supermoto!
81 RD350LC Resto
82 RD421LC Hybrid
82 RD350LC decapitation project
82 RD250LC JDM '251LC' YPVS
83 RZ350 Resto
84 RZ500 Resto
85 RZ350 F1 Resto
86 RZ350 F2 Resto
86 RZ350 F2 Hybrid

Like Watches? www.PloProf.com & www.DeskDivers.com

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nokturnal
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Re: Works 30s and then dies

#8 Post by nokturnal » Thu Nov 15, 2018 12:41 am

I’m here all night...
:smt017

TN-592
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Re: Works 30s and then dies

#9 Post by TN-592 » Thu Nov 15, 2018 6:31 pm

It's the spark problem,yesterday i have checked the spark of the working rd and it is like 10 time more powerful than mine,so i started to check for the spark problem and find out that i have a strong spark just when i ground one of spark cables and at the other one i have a good spark but if is not grounded than there is wery weak spark on the non grounded cable
Have checked the resistance of the primary coil got 6 ohms on primary and 5900 ohms on secundary which is i supose in a range of what the manual is saying

brrrappp
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Re: Works 30s and then dies

#10 Post by brrrappp » Thu Nov 15, 2018 8:27 pm

TN-592 wrote:It's the spark problem,yesterday i have checked the spark of the working rd and it is like 10 time more powerful than mine,so i started to check for the spark problem and find out that i have a strong spark just when i ground one of spark cables and at the other one i have a good spark but if is not grounded than there is wery weak spark on the non grounded cable
Have checked the resistance of the primary coil got 6 ohms on primary and 5900 ohms on secundary which is i supose in a range of what the manual is saying
First: What bike/ignition system are we dealing with?
Some easy things to try.
Start with the simplest first:
Use a jumper wire to eliminate the Kick-Stand kill switch.
The kick-stand switch is the easiest thing to eliminate and is the most common spark killer on street bikes. It would not cause weak spark but it could be a cause of no spark.
Next: It sounds like you have a "known good" system at your disposal. Why don't you swap coils between bikes and re-test. I'm talking about the coil under the fuel tank that has the spark plug wires attached. If you take your coil from the problem bike and use it on the good bike successfully you know the coil is OK. If in doubt, do the opposite- put the known good on your dead bike and verify the weak spark.

When you put the coil back on the problem bike, make certain you have good metal to metal contact with the frame where the coil is mounted.

You didn't say if you tried replacing the battery. If you have a good, working similar bike you can easily swap batteries and retest.

If the bikes are the same system you can directly compare resistance of the coils under the stator.

These systems are simple.
There is a coil under the flywheel that creates the initial power for the spark. Some have two coils. One for Hi-Speed and one for Low-speed.
If the Low-speed coil is bad you get no spark at "kick-start" speed but you might be able to start the bike by bump starting in low gear. The bike will usually run fine at 3000+ RPM and it will usually stall at idle.

There is another small coil that acts as a crank position trigger or sensor. If bad = no spark. Yours is good.

The coil under the tank amplifies the voltage to make the spark. Some bikes have a coil for each spark-plug. The RZ uses 1 coil and the spark plugs both spark at the same time. This coil can ground out internally. The insulation on the internal coil winding will expand and contract with heat and vibration and ground out causing intermittent spark or no spark at all. Sometimes this appears as a bike that runs great cold and then loses power at operating temps or dies at operating temp.

The CDI makes adjustments to the timing. If you have spark, it is likely that the CDI is fine. 90% of the time CDI is a Pass/Fail component meaning Spark or No-spark.
If you really have weak or intermittent spark it's a bad coil, or bad ground.

TN-592
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Re: Works 30s and then dies

#11 Post by TN-592 » Fri Nov 16, 2018 2:02 pm

First of all thank you all for your help?
The problem was the recitifier(voltage regulator) the + wire was short cutting to the mass trought the faulty recitifer
I discovered that by measuring the amperage consumption between the battery and the bike while the key was off,there was 0.05 amps of consuption,have disconected all the instruments,cdi,ypvs....and still the there was the consuption of electric...after that i find it out the recitifer was short cutting the + wire to the frame,and that is why the spark was weak

After i disconected the recitifer the spark went normal and the bike started from the first kick!

And hear is the conclusion if you can handle the spark by your hand the spark is weak,when is normal there is no chance you will not jump when the spark kick you?

MK
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Re: Works 30s and then dies

#12 Post by MK » Fri Nov 16, 2018 3:01 pm

Now you got me curious.

What RD do you have exactly and if it's an LC or YPVS do you use an aftermarket DC CDI.
Why I'm asking? Well for those bikes the stock CDI is by no means connected to the 12V system and thus cannot be affected.
An aircooled RD with points ignition could show this effect.
Bye
Martin

TN-592
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Re: Works 30s and then dies

#13 Post by TN-592 » Fri Nov 16, 2018 4:10 pm

It is good question... that is what i thought to...and because of that I was not checking the regulator at first
My bike is ypvs 1ua

brrrappp
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Re: Works 30s and then dies

#14 Post by brrrappp » Fri Nov 16, 2018 5:42 pm

Someone will have a real answer. I'm sure. The RZ seems to need the battery attached to run. With that direct to ground short it has to have grounded some part of the ignition side as well?

TN-592
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Re: Works 30s and then dies

#15 Post by TN-592 » Sat Nov 17, 2018 8:00 am

Ignition coil dosen't need to be grounded to work,but there is one black wire straching trought the all components which needs to be grounded on two points near the voltage regulator and near ignition coil

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