Zephyr 750 sounds like nuts and bolts floating at idle

[Philliprowley84]

Good Evening,

I’ve had my zephyr just of 6weeks now, the one thing I’ve noticed is that the engine has a horrible rattle at idle.
I have changed the cam chain tensioner to a manual one, though I noticed the clutch basket has slop and others think it maybe the primary chain.

Any help is appreciated!

Cheers
Phil

[Richard]

You can try to pinpoint the location with a piece of pipe holding it against your ear and touching with the other end the suspected area.

In my case most of the rattle went away after replacing the complete clutch basket, but it could be other things causing idle noise.

[Philliprowley84]

Thanks,
I pulled the sump plate off and the primary chain is sloppy, also the clutch basket is sloppy,
Have two questions;
Can an auto tensioner off a ZR7 be fitted?
Can the clutch rubbers be replaced?

Cheers
Phil

[hugojose]

The inconvience about the tensioner is the ZR-7 pivoted chain guide on which the tensioner presses is very different from the Zephyr's. The ZR-7's has a flat contact area for the tensioner plunger, whereas the Zephyrs is extended toward the tensioner. You would have to change this guide, and that requires pulling the engine cylinder block.

The total extended length of the Zephyr's tensioner plunger is about 28 mm, with the stop side bolt on. You can check how long is extending by replacing the stop bolt with a 6 mm longer bolt and tightening against the plunger before removing the tensioner. If it is less than 28 mm, it is still pushing on the chain.

Also, indirectly, it is possible removing the cross wedge cap and spring with the tensioner still on, and measuring how long is the wedge sticking out. Is about 10 mm before tensioning, and about 6 mm after taking up the slack.

It is important to understand how the tensioner works. It only pushes forward as needed, the cross wedge prevents it from moving backwards.

The Zephyr 750 sounds agricultural when cold at idle, but should smooth out was it warms. The primary chain can take a lot of slack; new is about 5 mm. Service limit is 25 mm. It does slap a bit when cold at low RPMs, but should quiet down above 1200 rpms.

How many Kms on this bike? What do you mean by the clutch rubbers??

[Philliprowley84]

Thanks,

There’s appears to be no tensioner on the primary chain now, there is roughly 10-15mm slack in the chain now.

We don’t really know how many Klms are on the bike as the previous owner replaced the speedo.

With the clutch I noticed there is slop in the basket with 3 elongated holes in the back.

[Freddy]

I have changed the cam chain tensioner to a manual one,

Hi Phil,
Starting with the easiest first....... Mind if I ask, what was your process for setting the manual tensioner?

[Philliprowley84]

Hi there Freddy,

Luckily I had the rocker cover off when I installed the manual tensioner, I tightened till no play then back off a turn.

[hugojose]

Sorry, Phillip, I thought you were asking about the cam chain auto tensioner from the ZR-7, not the primary chain tensioner.

No, the Zephyr 750 does not have a primary chain tensioner, and even though one was fitted on the ZR-7 (pressed into service as stop-gap to compete with the liquid cooled SV-650), the tensioner is actually built onto the crankcase. Not a separate piece. Basically you would need the bottom end of those engine, and it would be more practical getting the entire engine. Many years ago, in the old forum, a good daring fellow from Australia went into this, finding out the hard way it was not practical, but was good info for the rest of us.

The clutch basket actually does move back and forth, however not side by side. Only rubber I know near is a cushy drive on the secondary shaft, driven by primary chain, where the starter clutch rides. It is supposed to smooth out power flow between crankshaft and the clutch. There is another cushy drive in the rear wheel hub also.

[David Richard]

hi I'm sure someone with more knowledge than me will answer this ,but if you look on on going projects with stu s zephyr page 2 and that will show you the rubbers in the clutch ,david

[Freddy]

Hi there Freddy,

Luckily I had the rocker cover off when I installed the manual tensioner, I tightened till no play then back off a turn.

Couple problems. The valve cover affects chain tension. There is a guide inside the cover which the chain deflects around. So the chain would be over tight if tensioned correctly prior to fitting the cover. However, the tensioner backed out one full turn is way too much. So at the moment its somewhere in between those two issues.
Try this .......

Put the bike on the center stand and put into 5th gear. You probably already know you need to rotate the rear wheel a bit with one hand as you work the gear lever with the other to change up through the gears.

Loosen the lock nut on the manual chain tension a couple turns, and then undo the tensioner till its got no load. Now, screw the tensioner in with your fingers till its firm. Now bump the back wheel around in the forward direction with one hand to make the engine rotate, continuing to turn the adjuster in. You'll find as you bump the wheel around the tensioner will sneek up small amounts. You're not trying to tighten it with your fingers to be a 'tight as a drum'. Just nicely firm by finger pressure is about the best way I can describe it.

Now back it out 1/4 (a quarter) of a turn. Hold it in that position (I slip a ring spanner onto it which sits against the crank case), and then tighten up the lock nut with an open-ended spanner. Job done.

P.S. All done with the valve cover fitted.

See what difference that makes.