Pinned So what have you done to your bike today?

The clutch rattle is sometimes the carbs not balanced evenly.

 

Yeah I balanced the carbs maybe 150km ago at the most unfortunately, I can live with a little rattle on idle, I'll refurb my spare clutch basket one day haha

 

I recently picked up an older ZXR250C engine (engine number is a low number) from one of the forum members who was going to rebuild it, but decided to let it go for a very fair trade. He had acquired it as part of a purchase, but had never run the engine or pulled it apart. There is no way of knowing how many miles are on this engine.

We did a quick compression check before I took it away, but as the engine had no oil in it and the combustion chambers were quite oily, I thought it best to do the final test when I’d given the engine a good look over back at my place. The initial compression test seemed to indicate no major issues (i.e. zero compression) so I set about discovering what I was dealing with.



My initial thought was that this engine had not been loved too much. I pulled the Water pump cover off and was met with brown goo which meant cleaning out the entire cooling system. Even some of the hoses were clogged full of muck. As part of checking the cooling system, I pulled the thermostat cover off and had a look in there. Again, muck, but at least the thermostat worked, so a win there. Replaced the thermostat O-ring with a new unit as the old one looked like it was squashed beyond being effective.

Pulling off the clutch cover showed me this engine was probably not run by the original owner as the clutch pack was not installed properly.



I then pulled the sump off to have a look at what was going on down there. It was, again, full of muck. The oil pickup was clogged up and the PRV needed to be cleaned out as well.



Once I realised that I was dealing with a neglected engine, I didn’t assume anything and started checking everything. First port of call was the valve clearances…wow! Some WAY out of spec numbers in there. Ordered some replacement shims and then bolted her back together. There is a witness mark on the cam cover were the cam chain has said hello to the metal, but the chain was tight when done up so maybe the cam chain had been replaced at some stage. I won’t know for sure until the engine is running. The cams looked in good condition, so that was a win.



I pulled the starter motor off and had a look inside as it seemed to be very tight. Surprise… it was also full of gunk and dry, so it was given a proper clean, lubricated and rebuilt to ensure that wouldn’t be an issue later on.



Okay, so all the engine ‘parts’ have been checked and addressed. I didn’t pull the head off as I am running out of time so firing it up will be the acid test for this motor. I did do a compression test after the engine was back together and found one cylinder (#3) was low even after a couple of tests. This might just be a tight ring from not being run for a long time. The other cylinders all had reasonable compression, so I am hopeful that it will fire.

I need to install some carbs and boots as well as a few other bits.

So, engine will be put into a frame soon and some fuel and spark will be provided to check if we have a workable motor. Unfortunately, my ZXR250C roller has a few electrical issues that I will need to attend to before final check. Thanks to @jmw76 recently helping me with another project, I no longer fear (not as much as before) pulling apart these old plugs and redoing them with new units. I will post more when I have put the motor into a frame and (try to) fire it up.