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[aigram]

Yesterday I had the pleasure of stalling my '89 FJ while becoming accustomed to taking off with a passenger. Boy did it not want to do a hot restart, it seemed like the starter could hardly turn the motor over (had the throttle cracked, too).
Is it possible to use (3) RPM 5-pin relay and connector socket to supply voltage bypassed of the stock voltage regulator for the headlight, starter, and coil circuits?

[CutterBill]

Let's think about this for a minute...

When that bike was new, it did not have a hot crank problem. You haven't made any changes to the starter system that would require a redesign of the starter circuit. So clearly, something has changed. Your bike already has a relay, it's called the starter relay* (or sometimes a contactor.) A relay is nothing more than a switch; it's either ON or OFF. If it's ON, then it's ON. Adding another relay will not make it "more ON."

Is the battery tired? If the engine cranks over with a jump from your car battery, then the bike's battery is worn out. Or simply not fully charged. Check the charging system; connect a voltmeter to the battery and run the engine at about 3K RPM, should be around 13.5-14.0 volts. That all checks out? Ok...

Check for high resistance thru the starter relay. Disconnect the starter cables from the relay. Connect an ohmmeter across the relay terminals and energize the relay. There should be no resistance (0 ohms.) If there is resistance, replace. Check voltage at the battery while cranking the engine. Then check voltage at the starter while cranking; the two voltages should be the same. If not, you are losing voltage thru the relay. Replace.

And cranking voltage should be about 9 volts. Much lower than that points to either a bad/not charged battery or a bad starter (shorted windings.) More detailed troubleshooting can be found in the FSM.

The bike worked fine when it was new. Fix the problem; don't cover it with a Band-Aid.
Bill

* Pet Peeve: it's called a relay, not a "solenoid." A solenoid converts electrical energy into mechanical motion. Early cars used a solenoid to pull a gear into engagement with the flywheel. Not so much anymore.

[ribbert]

Let's think about this for a minute...

When that bike was new, it did not have a problem.......

 

[ribbert]

The bike worked fine when it was new. Fix the problem; don't cover it with a Band-Aid.
Bill

 

[chiz]

My bike did the same damn thing and I fussed with it for quite a while. Always had in the back of my mind that this sucker could use a new battery.
  So I gave the old bird a new one and now it starts anytime anywhere.
 Chiz

[Bill_Rockoff]

These are old bikes, and they run hot. The starter is mounted behind the cylinders, where it gets hot.

An original starter is an old electrical winding that has been in a hot place for a long time.

Similarly, our bikes are unkind to batteries, and a newer one is usually better than an older one.

However, a new starter may make a huge difference.  Sure helped me. I replaced my 2-pole 110,000 mile starter with a new 4-pole one from RPM and my bike starts much more easily, much more reliably, now. (Still needs a starter clutch, but that's a different problem....)

Good luck.

[aigram]

Let's think about this for a minute...

When that bike was new, it did not have a problem.......

 

Or, it absolutely did. Because design compromise decisions made in the 80's. As with any vehicle. It also seems like in general, a hot crank problem is a known issue with FJ's.
Regardless I've never measured the resistance across the starter relay, thank you for the tip The battery voltage is between 13.5-14v while running, and it's a newer closed cell style battery.

[racerrad8]

Alex,

Let me weigh in on this subject. Sorry to hear you had a hot start issue. The starter system was upgraded by Yamaha just a few years into the manufacturing due to hot start issues. The original starter system was "weak" when manufactured and somewhere in the late 80's-early 90's they changed from a two field coil starter motor to a four coil starter motor. This almost double the torque available when starting the engine. Yes, the system worked alright when brand new, but once wear in the electrical components and battery settled in, there was a problem that Yamaha had to correct.

When that bike was new, it did not have a hot crank problem...
Bill

Alex, technically your bike did have a starting issue when it was new.

Now, could your starter solenoid** be bad/worn and causing the issue? It very well could be, it might have started your FJ hundreds or thousands of times. Each time the contacts engage, there is wear that occurs. Bill is correct that the system can be diagnosed by checking resistance and voltage drop. But, unless you have a inductive ammeter, you are not able to measure the ampere draw of the starter motor.

Some people have had positive results by cleaning the starter brushes of their starters.

But, in order to truly fix the hot start issue you should change over to the current Yamaha four brush starter.

* Pet Peeve: it's called a relay, not a "solenoid." A solenoid converts electrical energy into mechanical motion. Early cars used a solenoid to pull a gear into engagement with the flywheel. Not so much anymore.

**Now onto the debate of Solenoid Vs. Relay; here are the definitions.

so·le·noid: a cylindrical coil of wire acting as a magnet when carrying electric current. (NO CORE)

re·lay: an electrical device, typically incorporating an electromagnet, that is activated by a current or signal in one circuit to open or close another circuit. (FIXED CORE)

So, the short definition is...

A solenoid is a coil of wire when energized moves a "movable" magnetic core. The movable core can either be pulled in or pushed out to engage a set of contact points or create mechanical motion like engaging the starter drive on a starter motor.

A relay has a "fixed" core when energized draws down a lever and close the points.

The Yamaha FJ starter solenoid has a plunger that is pushed out when voltage is applied to the coil.
The RPM 5 Pin relay has a internal electromagnet that draws down the ever when voltage is applied.

I went ahead and cut apart a FJ solenoid to illustrate the movable plunger contained within. The plunger is drawn in and the spring loaded points close and send the battery voltage to the starter motor. You can see the wear/arcing on the copper contacts.

Randy - RPM

[FJ_Hooligan]

I'm just going to go back to calling it a "Bendix."  :-)

Surprisingly, I've had just the opposite experience.  My '85 with slightly higher compression pistons and a 2-pole starter always started much better than the 4-pole starter on my '93.

On the '93, I always had to crack the throttle for a successful hot start.

Also, the '93 had stock ignition and coils, the '85 has Dyna equipment.

[racerrad8]

I'm just going to go back to calling it a "Bendix."  :-)

That is the Ford specific "Bendix starter drive" which was actually inertia/spring loaded... no electrical requirement for engagement...

Randy - RPM

[ribbert]

I'm just going to go back to calling it a "Bendix."  :-)

That is the Ford specific "Bendix starter drive" which was actually inertia/spring loaded... no electrical requirement for engagement...

Randy - RPM

What is "Ford specific" about a Bendix drive? Bendix was a stand alone company that manufactured all sorts of things. If anything, I think they had closer ties to GM. The drive is named after him because he invented and patented it and it does need electrical power for engagement, albeit indirectly.

Noel

[ZOA NOM]

 

[ryanschoebel]

I have always had hot start issues on my bike, and just assumed it way the way of a 33 year old machine. But i noticed, after going to the rally, and getting a new battery and alternator, the whole way home, I never had any issues restarting. Usually, I would have expected it to start harder, but it seemed like there was no issues. Just a thought

[racerrad8]

I'm just going to go back to calling it a "Bendix."  :-)

That is the Ford specific "Bendix starter drive" which was actually inertia/spring loaded... no electrical requirement for engagement...

Randy - RPM

What is "Ford specific" about a Bendix drive? Bendix was a stand alone company that manufactured all sorts of things. If anything, I think they had closer ties to GM. The drive is named after him because he invented and patented it and it does need electrical power for engagement, albeit indirectly.

Noel

Noel, we are getting off topic.

The Bendix pre-dates me and my experiences are with my dad's 40 Ford coupe, 50's Ford pickup and Fordson tractor which all use the Bendix starter drive. At least here in the US, the Bendix was standard on all fords of the era, but not the GM or Chrysler manufacture lines. Bendix was also choice for Ford Motor Company when they went from mechanical to hydraulic brakes. Ford & Bendix as synonymous together here in the US.

That may have been different in Australia

Randy - RPM

[Pat Conlon]

Relay vs Solenoid: That's interesting, not important, but interesting.
If you go to the Yamaha parts diagram and look for starter solenoid, you wont find it listed under that name. Kinda like going to the Yamaha parts listing for your carb and look for an emulsion tube, you won't find that listed either.

Re: Algram's question on hot starts, here's my experience:
 
I bought my '84 new and I live in the desert. I can tell you that on a hot summer day with a heat soaked engine, my bike has struggled with hot starts. (along with the system over charging the battery, a separate subject**)
Yes, my wiring connections were clean, solenoid was fine, battery good, still the bike just struggled, and I lived with it for 22 years.

What helped me was the coil relay mod and a new 4 pole starter. New brushes in my old oem starter did not help.
Today even with the big 1380cc engine, thoroughly heat soaked, I have no problem with hot starts.  

Here's my take: Over the years Yamaha has made improvements to their products, like a good company should.
They did it with a new design on the shift forks and they did it with their starter motor.
The good news is that these improved products are backwards compatible with our FJ's.

** A battery can get weak from over charging, especially a sealed AGM.  

Hope this helps.....Cheers   Pat