Stuck clutch and over revving engine ....not in that order.

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dissident75

New Member
Nov 23, 2010
15
0
0
Houston TX
Here's my story. IT might be a bit to read but I could really use some help. A few issues. I finally got around to ordering my kit and I ended up ordering a Black z2-80 slant head kit. I installed it on Saturday and didn't bother running it until yesterday since I didn't have a chance to get a gas can etc until then.

Well, I have to say it was a blast to ride. Electric just doesn't compare and I had a 1000watt 48v kit. Now here are my issues.

First the throttle response was fine but it wouldn't idle. When I let pull the clutch it just runs away like mad. Figured out that is because my carb slide won't go all the way down so I choke it out a bit to try and keep that from happening. Then I noticed it was bogging at wot and looked a bit closer and the nuts had backed off the intake a bit and by re-tightening then the issue went away.

So I spent the afternoon riding it around trying to shake out any potential issues but there seemed to be none after the initial throttle bogging issue and the crazy revving engine.

Cut to this morning and i decide to try to ride it to work. I get about 4 miles (a fraction of what I did yesterday) and notice the vibrations are really bad. I look down and see the engine is not at the same angle I had it mounted at. So I pull off the road and pull out my multi tool to start tightening nuts only to notice that not only have the nuts vibrated loose, one in the front is gone completely, and one in the back as well as the engine mounting stud was gone. I was shocked since I made a point of tightening these joints pretty tight. I neglected to use locktite on them since I only have the permanent red thread locker and thought it would be overkill.

So I decide to get everything as tight as I can with the hardware there and take it home and do some repairs and call out of work.

I start pedaling down the street with my clutch pulled in and locked and after a mile or two while riding I accidentally released the clutch engaging the engine.

The rear tire locked solid. Pulling the clutch in no longer disengages it even though the arm clearly moves and the stiffness of the pull is the same. I got down closer and noticed that apparently one of the screws that cover sprocket was now missing. It appears to flex out a bit when I pull the clutch in that corner with the missing screw. I moved the other identically sized cover screw and moved it into the missing ones place but it still wont disengage and the tire is still locked.

So my questions are these.

What is up with the clutch?
Does anyone know what size threaded rod I need to replace the engine studs?
Any ideas about the crazy revving engine? I have the throttle cable fully threaded in, so I don't know where the cable length is being eaten up. I'm going to go back out and mess with it again some more now but the clutch issue is kind of a biggie for me. Any help will be appreciated.
 

2door

Moderator
Staff member
Sep 15, 2008
16,302
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63
Littleton, Colorado
As far as your throttle problem, from what you said, "because my carb slide won't go all the way down"
You might have the slide in backwards. There are slots on the sides of the slide. The long one goes to the right (as you look down from the top) and the short one goes on the left.
Make sure you have no sharp bends or kinks in the throttle cable from the twist grip to the carburetor.
Tom
 

bairdco

a guy who makes cool bikes
Aug 18, 2009
6,537
264
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living the dream in southern california
the bolts and studs are usually M6 x 1.0 thread, except for the magneto cover, which are smaller, M8 x 1.0 i think.

the lengths vary, it's best to take them out and bring them with you to match them up.

see if you can find a good industrial fastener place in your area, it's way cheaper, and they'll have a better selection.

the clutch issue could be caused by the loose bolts, or a jammed chain like goatherder said, or maybe the actuator rod popped out of it's hole.

the over revving thing should be simple. since you know the slide's not going all the way down, and assuming it's not jammed in there, and that the cable's not hanging up on the edge of the adjuster barrel, do this:

back out the idle adjustment screw all the way.

screw the barrel adjuster on top of the carb and at the lever all the way in.

look into the carb and the slide should be all the way down. if not, check for kinks or tight bends in the cable. as a last resort, you'll have to cut the cable housing back. if it gets to that, post again and i'll help you through it if you need it.

look into the carb again as you screw in the idle screw. it should slowly start lifting the slide as it turns in.

the factory idle setting is 3.5-4 full turns out, meaning, if you screwd the idle screw in all the way, then back it out 3.5 to 4 turns. this isn't always correct, and usually needs some fine tuning.

now twist the throttle and make sure the slide moves all the way up until you can't see it anymore. if there's a lot of play in the throttle, back out the barrel adjuster on the carb while watching the slide. you want to get the slack out without raising the slide at all.

hopefully, it'll fire up now, and you can fine tune the idle with the screw.
 

dissident75

New Member
Nov 23, 2010
15
0
0
Houston TX
Since I posted I took the sprocket cover off and just as GoatHerder mentioned the chain was jammed. That was a good call. I also pulled the carb, throttle, and cable etc off thebike and redid the whole thing.

After fiddling with it all, reassembling it, and adjusting the idle screw, I now have the slide going through the full range of motion and the idle is down to a normal level. I'm unsure where I managed to get additional cable from since it looks the same as before but the slide moves properly now, but I'm not one to look a gift horse in the mouth. It must have been binding somewhere, my guess is in the throttle assembly.

Great advice from everyone here. And knowing those screw sizes is going to come in very handy. I don't know where a good industrial fastener place is nearby but McMastercarr ships and they have nearly everything.
 

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biknut

Well-Known Member
Sep 28, 2010
6,631
409
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Dallas
I just buy M6 bolts from the hardware store and hacksaw the heads off and use them for engine studs. It's a good idea to double nut the rear studs.