1985 GPz750 Starter Issues/Questions

Hey Gang,

Been a while since I checked in and posted here due to work and family limitations with my son about to turn 3 and start school, setting up his IEP for his accommodations for school, getting into the Team Manager apprentice program at work, and simply not being able to ride since it is winter here in Colorado and past few months its been cold as all hell. But, weather is warming up and snow is melting and can finally get some time to wrench on the bike and get it reliable and solid for this coming riding season.

Which brings me to why I am posting today and asking for help. Last fall on my last rides on the bike I had a helluva time trying to start it. I could feel the starter engage but it wouldnt turn over, like it somehow doesn't have the strength to turn over when I have the clutch pulled in. A few times I had to get help from Pops to actually push me until I could pop the clutch and turn the engine to start it. I did notice that if I put the bike in neutral AND pulled the clutch then around 50% of the time I could start it without issue, the other half of the time it still acted like it simply didn't have the juice to turn over. To finish up I would also add, battery is new and full topped off and charged and has been maintained with a battery tender this entire time.

Based on what I know and have read it seems like it is probably the start clutch, but I cannot fully rule out the starter as a whole. Does anyone know if this is the starter or the starter clutch specifically? If it is the clutch then I actually have to pull the engine and its a bit of a whore to do from what I hear, but to replace the starter is pretty darned easy and can do with the engine still in the chassis, right?

Thanks,
- Irish

When the starter clutch fails you will hear the starter motor spin only the engine will not spin and turn over. This is quite different from having a starter motor issue, where the engine does spin and turn over only it does so very slowly.

If the starter clutch has failed it is possible to change it with the engine in the chassis but it won't be fun.

Hi Ed,

Thanks for the reply and appreciate that. So based on the symptoms I described, what do you believe the issue is? From what I gather from your reply, you don't believe it to be the starter clutch correct?

Thanks,
- Irish

Well Irish,
if the engine is turning over, only very slowly, I'd check your battery terminals to make sure they are clean. Another thing is to try jumping the starter solenoid with a screwdriver too to see how fast the engine spins. Make sure the engine is in neutral first of course.

Hey Ed,

Sorry so used to always using "Irish" online hahaha, name is Brett and appreciate your insight and experience. When I can get the starter to engage and work it acts like a spring chicken, no issues at all and starts right up, this is especially true when the engine is warmed up and at operating temp, no starter issues then seems to be the trend so far with the short time I have had the bike.

So it is starting to sound less and less like a potential starter motor or clutch issue and maybe something else. I will touch base with Pops and see if he/we can't check this soon, as soon as I do get an answer will let you know. Appreciate your time and thanks again

- Brett

In case I need to clarify a few things to make a bit easier to pick out. It seems to have an easier time engaging when the bike is in neutral AND clutch is engaged. Also when the bike is up to temp I haven't had any starting issues, seems to be an issue only when cold but again bear in mind I have little time with the bike so my sample set is small. Lastly I can feel the starter engage the crank, so it isn't like the starter is just spinning without turning over the motor. Coming from an automotive mechanic background that was one of the first things I checked to try to isolate the issue down.

Thanks,
Brett

Did you try to jump the solinoid? Generally it will be hard to start when it's hot.
Steve

swest wrote: Did you try to jump the solinoid? Generally it will be hard to start when it's hot.
Steve

Hey Steve, haven't tried that yet but after Ed and yourself suggested I do so then that will be my next step. I'd also agree entirely that hard to start issues whether they be bikes or cars or anything else, it's normally even worse when hot. The fact that this issue is the reverse and it's hard to start when cold, makes me really confused. Currently the carb bank is off the bike and everything blown apart. After a bath in the ultrasonic cleaner it's shiny and clean ready to go back together, just waiting on parts to arrive now. But thanks to the busted POS tank petcock the carbs and intake were flooded with fuel so now the crankcase is contaminated and I have to change filter and fluids before I'd feel ok trying to crank the bike over. Lucidly I have to have the bike running to check the carbs and do a dynamic sync on them to get them dialed in perfectly. As soon as I try the solenoid bridge and get the result however I will post up here.

Thanks again,
Brett

Thinking in the point specifically of this being a cold start problem that disappears when up to temp I had a thought. Since the carbs and intake which also then means the cylinders were flooded with fuel when it sits for a week or longer maybe that could be it? I mean it's a long shot but maybe the issue was similar to hydrolocking with all that fuel in there and not letting the starter crank the motor??? Or maybe I should stop thinking after 7pm at night hahahahahaha

- Brett

You know what can happen when a engine hydrolocks.
Steve

swest wrote: You know what can happen when a engine hydrolocks.
Steve

Absolutely, however I highly doubt that is the situation and really think thats an extremely unlikely cause for the hard to start issue. Certainly not impossible and something I will be looking at, but very doubtful I believe.

- Brett

Hi, hope it's ok to jump in here rather than start a new thread...

I've just picked up a non-running '82 750 LTD.

The battery is shot so for the moment I have a 12v charger hooked to terminals.

Bridging the solenoid posts, the starter is spinning, or at least making a sound like it is doing something. I've taken it apart and cleaned it, brushes are in spec. Bench tested it and it spins fine, it's comparable with a different motor that I know to be working.

However, the starter is not budging the engine at all, though the engine turns freely with a 17mm socket on the crank.

The idler pinion is as per the manual - no movement clockwise, and moving smoothly and freely anti-clockwise. It is also moving clockwise by turning the crank.

There is no feeling of roughness or grinding with the idler gear, though there is a couple of mm (?) of runout. Is this acceptable ?

Appreciate any suggestions, thanks in advance...