Noisy CB125RS

Hi everyone, a post for all of you handy with spanners! This post is also
in the Classic Bikes newsgroup, so if anyone thinks it looks familiar, it's
because I'm getting desperate!!

Completely rebuilt motor on the RS, yet it still sounds like the big-end has
gone, despite having a rebuilt crank. Starts and runs ok, makes no
difference if you pull the clutch in.

Did notice when I took it for a run that it seemed reluctant to rev
properly, I put this down to the fact that it hasn't been used in ages, so
maybe a blocked jet etc....question is, does anyone think the two are
related???

Any ideas?

Rick.

 

Blocked jet and a fucked crank? No.

 

In uk.rec.motorcycles, richard.ingall amazed us all with this pearl of
wisdom:

Yer bearing shells.

 

Unless this is some clever play on words I don't know about... It's a
roller bearing engine isn't it? What other bearings did you replace? Did
you fit them properly, as in not tap the bearing in with the inner bit?
Are you sure you got the cam timing correct? Did you check the valves
for straightness? Did you rebore / fit a new piston?

Completely rebuilt? What does that mean anyway?

 

Roller bearing crank, YTC. It's just possible the alternator isn't on
the shaft properly - that can make an unholy din if it's a bit loose and
or wobbly. Sounds just like a fucked crank as well - ask a Ducati owner.

 

had the same thought myself last night, will give it a shot to see if
there's any wobble on the alternator later today

Rick

 

Also check for a loose clutch center nut and make sure the carbs are
balanced.

 

It's a single.

 

Cheapskate.

 

Some singles need their carbs ballancing though. Didn't some versions
of the XBR500 have a twin carb type setup?

 

You still don't "balance" carbs on a fucking single, YTC. The idea of
balancing is to get all the carbs on individual cylinders on the same
setting.

 

Ok grandad.

 

Cheeky young whippersnapper.

 

XT600/SRX600 were dual-carb singles - IIRC one was a slide and the other a
CV type.

 

The Older Gentleman says...

I bought a GPZ1100 with something similar wrong for **** all money
once. It cost me a temnner to fix.

 

Muck says...

Did they do a 10" dub mix?

 

I was more concerned about him impugning the holy simplicity of the XBR500.

 

Drum and bass, no, that's Ducati isn't it?

 

I thought some versions of the XBR had a different carb setup? Mine was
simpler than most XBRs, only having 3 of the 4 valves working.