first fire up and strange noise developed

[cruzin]

Just fired it up today for the first time. was sweet to hear it run. Sounds good. After a few starts I noticed an extended new noise after it starts for a few seconds kind of like the starter is slow letting go or something. No grinding or clunking more of a whirring. Can any one give me some opinions what could make noise for a couple seconds right after it starts. The noise goes away in about 2 seconds.
During rebuild I put a new compression spring in the starter line up of gears and moved its location like the service update said to do. I dont have the left cover on the engine but I dont think that would casue the noise.

 

[angus67]

does it do it every time you restart? It might just be no oil in the clutch assembly before a rebuilt motor. Once oil goes were it should, should be fine. A miss adjusted clutch can whirr too, but you have the left cover off, so that cant be it.

 

[cruzin]

Yes its doing it every time now. Did not do it at all for the first few starts. I soaked the disks

 

[cruzin]

Ill probably drain the oil and have a look in a couple days. weekend is over now and back to the grind. I really like the electric leg and want to keep it!

 

[vsop-dk]

Could you post a video clip of it or a sound clip?

 

[fredintoon]

Hi cruzin,
I'm not saying that your bike don't have a problem but you did say this is the first time you've had it running?
There's a famous quote:-
Letter from customer:-
My engine sounds like a bucketful of ball bearings being poured onto an iron plate.
Reply from Ettoire Bugatti:-
From the description your engine is running perfectly.

 

[cruzin]

Im including a vid with audio. I hope. Nope would not upload too large. I drained the oil and pulled the cover off. I ran the starter and nothing sounds wrong The kill switch was off so it woulldnt start. But there were no strange noises. I Pulled the start gear pack off and looked at everything seems fine. Tested the compression spring and it took near 5 pounds to get it to move.
In the video after the motor starts you can here it for about a second. Let me know what you think. Maybe its normal.
I will look for some videos of other folks starting their bikes and see if it sounds like theirs.

 

[vsop-dk]

Hi cruzin, would have been great hearing the sound... But... I can chip in, when im using the elec starter my engine also has a strange noise, thats not present when using the kicker.. its related to the starter im sure... if you look at some of my recent posts believe its in the "what have u done..." thread you can hear it when I start my engine.

 

[cruzin]

Nice bike, mine sounds something like that. must be that they make some kind of noise when pulling those gears out of mesh.I guess Im not going to get all worried about it.
Next problem to solve. I bought 2 , 3 phase rectifiers a year or longer ago, just after I fired the bike up for the first time Im smiling while its purring and I notice in my elec box smoke coming from my new rectifier. This is maybe 30 seconds of running. I hit the kill switch and shut it down. I reach down to check the wire and it pulls out of the spade connector. I had not crimped it proper. So I re crimp it. But it smokes after about 15 seconds of running every time I start it. I ohm it out and it was toast. The case of the rectifier is not hot at all just the epoxy area around my positive wire. I changed it out cause they are cheap china rectifiers and come in a 2 pack the next one does not smoke but gets hot around the same place in the epoxy. These are 30amp rectifiers. I wonder if I should have gotten 40 or 50 amp ones. I have this rectifier bolted to a 2.5" x 5" x .25 copper heat sink. Any thoughts on this? I may start a thread on this issue but will include the question here.

 

[vsop-dk]

Im not worried about mine... dont think you should worry either about yours.. But.. do worry about the rectifier/reglator.. I cant assist there with the amps but I know it shouldnt behave like that. Perhaps they Arent that good of a quality..!

 

[TwoManyXS1Bs]

... the next one does not smoke but gets hot around the same place in the epoxy. These are 30amp rectifiers. I wonder if I should have gotten 40 or 50 amp ones. I have this rectifier bolted to a 2.5" x 5" x .25 copper heat sink. Any thoughts on this? I may start a thread on this issue but will include the question here.

That's a good heads up.

Suppose we do a quick rough-out of a worst case scenario. Imagine the charging system putting out a heavy 15 amp current to replenish the battery, run the lighting, ...etc. Then consider that the diodes used in the rectifier might be the lower efficient variety, with a forward voltage (Vf) drop of 1 volt (or greater).

Power is current times voltage, so the three positive side diodes will be passing a total of 15 amps, at a 1 volt drop, making 15 Watts of heat. Add in the three negative side diodes and you get a total of 30 watts of heat.

I have an old Ungar soldering iron rated at 27 watts, and it gets hot.

Of course, the problem is worse if one or more of the diodes is internally shorted.

The real problem would be if the rectifier pack was improperly constructed or assembled, preventing good heat conduction to the case, which would allow hot spots to occur.

That would be a quality issue. Sounds prudent to have more than one, as in your scenario.

And, to check to see if your battery draws a lot of current during recharge...

 

[cruzin]

Do you think I should put a higher amperage one in it?

 

[TwoManyXS1Bs]

I guess you could. The higher amperage rating applies to the diodes. It'll still have to dissipate the same amount of heat. Maybe the heat sinking of the 40-50 amp versions is better, dunno. I'll stand in the corner and watch.

Edit: I've read that those compact 3-phase rectifier units were produced in response to the explosion in off-grid wind power generation. The eBay offerings may be just overstock/overproduction. Or rejects. Or floor sweepings...

 

[cruzin]

you wont see the smoke standing in the corner! thanks 2M

 

[retiredgentleman]

cruzin;

A 25 amp rectifier is more than enough for these bikes, if they are mounted properly on a heat sink. So, you do not need any larger than 25 amps.

I suspect you bought defective rectifiers. Another possibility is you have a short circuit in the bike's wiring drawing a lot of current.

Edit:
If you know how to measure current, connect your VOM into the + output lead that is leaving the rectifier. Set the meter to read on 20 amp scale. You normally have to move one of the meter leads (+ lead) to a different socket on the VOM.

 

[cruzin]

I put the spare one in before I took off the right side cover and ran it for a bit. Around the batt+ it got hot but no smoke yet. Ill have to look up the manual for my meter and see if it will do dc amps. thanks for the help guys.

 

[XSLeo]

Using that thick a piece of copper as a heat sink is questionable. That thick absorbs heat but won't dissipate it very well. The mass to surface area ratio is to great. Try a thinner piece of copper or drill it full of 1/4 inch holes.
Also, did you use a heat sink grease between the rectifier and heat sink? This help transfer the heat from the rectifier to the heat sink.
Another thing, is the rectifier and heat sink inside a box or out in the open. It needs plenty of air flow.
Leo

 

[cruzin]

Leo I broke all rules, I mounted it in my electronics box. Its open to the bottom. If I have trouble I will drill some holes in the front of the bot so air will flow on the back of the copper. The case of the rectifier never got above warm just where the pos batt plugged in and neither did the copper. Im hoping it was a faulty one. It only ran for maybe 30 sec at a time. Will know more after I get clutch side on again. I have to sort out if I got the clutch pack proper. All six fiber disks are 26.64 mm thick. That does not include the spring disk that is in the hub first held in by that round wire. Then I will button it up and post results.

 

[cruzin]

I was reading a post by Leo (what happens when you turn the key on) good post. They discussed the relay that is in the bikes (not sure which years) that after the bike starts you cant engage the starter again when voltage is on the relay. They talked of starter overrun. I wonder if that is what I am hearing. I do not have a relay in my wiring for that purpose.

 

[XSLeo]

It's a possibility, another might be the return spring on the gears. The wishbone shaped spring works to engage the gears, The coil spring helps disengage the gears. With the spring out, stretch it a bit. This will not so much make it stronger but push the gear farther. As springs age they get weaker, this is evidenced by measuring the over all height of the spring. If they measure up a bit short you can shim them, like done with valve springs or on a lot of less critical springs, stretch them.
On my 75 that had starter issues I not only tightened the wish bone spring, I tightened the return spring.
The safety relay is the relay you are talking about. It was first used in 72 to protect the starter system by turning off the power to the starter relay when the alternator created about 4.5 volts on the yellow wire, this tripped and held the relay. This stops the starter as the engine starts, it also prevents the starter from working while the engine is running. In 78 they added a second half to the relay that would turn on the headlight. Up to 77 the safety relay had 4 wires and just controlled the starter. 78-79 had 5 wires, 80 up had six wires, these controlled the lights also.
As I've said before the safety relay is much faster than your thumb. By the time you realize the engine ha started and you release the button, the has already been over run for a bit. The safety relay prevents this.
I doubt it will ever hurt the starter itself, but it can damage the gears and the cross shaft the starter uses to engage the engine.
It's not hard to wire in a safety relay. You can even use a lighting relay. I have picked up such relays at the auto salvage yard. They don't charge much. Get the 5 terminal ones. The 4 terminal ones just turn on a circuit, the 5 terminals ones turn a circuit off.
The terminals are numbers. most show the internal wiring on the side. The power wire too the starter relay cut it and hook one side to terminal 30, the other to 87A. These terminals are on when no power is applied to the relay.
No hook the yellow wire from the alternator to terminal 85, hook terminal 86 to ground. Now as the alternator starts to produce power , it sends power to the relay, relay trips and cuts power to the start relay.
Is using a stock relay, most any stock wiring diagram shows how.
Leo