K75 at 2800-3000 rpm - an issue or not?

[Oma Aika]

I'm still newbie with myt K75. I may once again use wrong words, hope someone understands my problem.

My K75 works very nicely and smooth but with constant speed at 2800-3000 rpms the engine sometimes jerks - not much and not all the time, maybe once per minute a jerk but it's annoying me a bit. With cold engine more. No jerking at <2700 rpm or >3100 rpms. And if even slightly accelerating, no problems at any rpms, including that 2800-3000 rpms.

Carburetorsystem has been synchronized recently and sparks look good. (But there is sometimes a backfire (1) when releasing throttle from high rpms)

[wmax351]

Both sound pretty normal.


If it only jerks when lightly accelerating or constant speed, it could be your idle bypass screw is misadjusted. You adjust the Idle CO, there are details on the site.

[Grim]

Somebody recent posted that they made an adjustment on the throttle position sensor and made that better. I think the tittle of the post said something about back fires.

Edit:
This is the thread. http://www.motobrick.com/index.php?topic=4583.msg28826#msg28826

It's on a 1100 so your mileage may vary but testing the TPS wouldn't be a bad or hard thing to check. A bad or misadjusted TPS could cause thos symptoms.

[Oma Aika]

Another very very very stupid question: how to change the H4 head lamp? Owners manual says open the phillips screw below the lamp but there is none visible...? The black plastic cover around the head light should be removed first? Again no screws visible...?

[Grim]

I believe you will find this helpful.
http://www.motobrick.com/index.php?topic=2252.0

[Oma Aika]

Thanks! Actually I have that manual, it says how to fix the engine but my problems are too simple, like how to open that head light to change the H4. Not even the simple Owner manual (page 59) says that... as far as I can see the black cover should be removed first but I can't see any screws.  :dunno2:

Edit: I needed to remove the fairing, then the lamp and then change the H4... should be easier, if needed to do on the road.

[Oma Aika]

Still about the jerking on low rpms - some told me that the Z-hose should be replaced regularly, that has something to do with jerking, too? Or just the TPS ans the idle pass screw? And are the "factory settings" good for these old bikes or some other adjustment values?

[wmax351]

Still about the jerkin on low rpm - some told me that the Z-hose should be replaced regularly, that has something to do with jerking, too? Or just the TPS ans the idle pass screw? And are the "factory settings" good for these old bikes or some other adjustement values?

The Z hose should be checked or replaced. Would make sense.


Check IBMWR.org. They have a guide to setting the screw.

[Oma Aika]

My bike was at the bike service and they adjusted the TPS. It's a rainy day today and didn't want to go for a decent test ride but it seems that it helped. The engine felt a lot better as I rode two miles home. They noticed that the Z-Hose is broken, too, but it'll take a couple of days before I get one.

But they noticed the same as I that the bikes power reaches about its maximum as soon as 6500 rpm and after that it doesn't grow much anymore. At the users manual it's maximum was at the 8500 rpm. They said that my engine may be a bit dirty as I mostly use rather low rpms.