Motorcycle Repair/1982 yamaha xj750 starting issue
QUESTION: I bought this bike as a winter project. The previous owner said it had a starter issue but do to melted wiring we had to push start the bike. The bike now has all new wiring, switches, and battery. All safetey switches (kickstand, oil level, neutral, etc) have been removed. After initial rewiring the starter would make a "whirring" sound like it was spinning but not engaging for 10-20 seconds then it would finally catch and the engine would fire right up. I had the carbs rebuilt and jetted (took about 6 weeks because the shop was busy). When I finally went to start the bike again the starter now makes the whirring noise for 30-40 seconds and when in engages the motor turns over very slowly then the solenoid just clicks rapidly. I have tried starting it with the battery charger hooked up to ensure I wasn't loosing voltage. Could this be a starter issue, a bad solenoid, or does it sound more like a starter clutch issue?
Note: I went ahead and ordered the "Arrowhead starter rebuild kit with brush holder (SMU9145)" and Yamaha solenoid already, just waiting on delivery
ANSWER: Hello Anthony,
Your problem is definitely starter clutch malfunction.
Additionally, your battery is discharged or generally weak.
The solenoid clicks when battery can't provide adequate power.
As for the charger been connected while cranking, no charger can provide the amperes needed,
except if, booster/starter function is available.
So, first make sure your battery is fully charged and try again. You'll see you're back to first
symptom. When the starter clutch engages, the engine fires-up.
You can also try with a car's battery jump-connected.
Closing, bear in mind that replacing the starter clutch, is no amateur's job and requires a lot of special tools.
P.S. Some times, starter clutch gets "rusty" if the bike hasn't been ridden for a long time,
and gets better with operation.
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QUESTION: I do have significant experience in car/truck repair, as in depth as engine building, but my motorcycle experience is limited. I was under the impression that to do the starter clutch it involved removing the side cover, removing the clutch basket, and the the starter clutch shaft would be accessible. I found a couple online salvage yards with the entire shaft assembly in "guaranteed working condition", do you think it would just be easier to replace the entire shaft as opposed to trying to disassemble and reassemble mine?
ANSWER: Hi Anthony,
Yes, the starter clutch shaft is placed behind the clutch basket, but my previous answer was based to the fact that average questioners are missing basic "special" tools, like torque wrenches, clutch hub holders and/or extractors, circlip pliers etc. Not to mention service/workshop manual.
As for what to choose about spares, I would first remove the shaft, disassemble the starter clutch, check each part, and then order.
It could be as simple and cheap as compression-springs (#7 in attached picture).
If the engaging surface of the main idler gear (#10) is smooth, without dents and/or signs of seizure, just replacing the springs will do the job.
Remove the shaft, disassemble it, and if you wish, take close-up pictures of idler gear, outer assembly and springs, send them to me and we'll decide what's next.
Feel free to get back to me any time.
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QUESTION: I installed a new Yamaha solenoid and daisy chained an extra car battery I had, 1000 cranking amps, to the motorcycle battery and hooked up the battery charger on "quick charge". I had to crank it a few times before the starter clutch finally started grabbing but I finally got the bike running. After that I've been able to start it with just the motorcycle battery, a shot of starting fluid in any carb, and 20-30 seconds of cranking while waiting on the starter clutch to engage. There is a dead spot on the starter, a few taps with a wrench was enough to get it cranking, my rebuild kit is in I just need the time for it now. The clutch is pretty weak so I think I'm going to hold off on fixing the starter clutch until I get a clutch kit ordered. I shopped around for starter clutch parts but the only place I've been able to find any is bikebandit.com and the word "affordable" isn't in their vocabulary. Do you have any suggestions as to where I could find parts for less than dealership prices?
I also downloaded the complete maintenance and repair manual so i'd have step by step pictures and torque specs for everything.
It seems there was a bug in the system, I've answered this next day, but I was just informed it wasn't received and published. Sorry about that.
Anyway, my weakest point in my profession, is searching for low prices...!
The starter clutch parts though, are pretty expensive, at all motorcycle brands.
Reason for that is, the precision and durability required, which are equal to those of a quality ball-bearing.
Let me remind you, not to order anything before disassembling the starter clutch.
As I stated before, it could only need the three springs.
Best Regards, and sorry for the delay,