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.

 

1985 Honda VT250FII...

I've been chasing an issue with this bike for ages and I finally had some time (raining) to have a harder look. The engine starts okay, but drops onto 1 cylinder after a few minutes of running. I had changed the plugs and checked the coils and leads to ensure they were okay. I had done a compression test; which was at the low end of acceptable, but the engine doesn't blow any smoke and starts pretty much first time. So, I decide to check the valve clearances. Checking the valve clearances isn't an overly simple affair, but it is certainly much easier than doing in on an NT400 or NT650 BROS!

Step 1: tear down.

You do need to remove a few bits to get access to the cams and timing areas. The VT250F runs water through the left hand side frame rail and the water drain is actually at the bottom of the frame; you can see it just near the side stand spring. The VT250F was also the first 250 to utilise a hydraulic clutch. All the more junk to watch out for during the disassembly stage. You don't have to remove the carbs, but the airbox and a few extra bits have to come off. The coils have to come off as they sit on top of the rear cylinder; the VT250F has a coil for each cylinder and a TCI unit for each coil! The radiator and a bunch of plumbing also has to be removed. Having to turn the engine from the alternator side means draining the oil (you have to remove the cover to access the flywheel), so I might as well do an oil/filter change while I'm at it.


Due to the narrow engine and the old-fashion tubular frame, getting to the front cams is actually pretty easy.


The timing wheel and marks are on the clutch side of the bike, so you have to rotate the engine from the other side which is a bit of a nuisance when you're on your own. Everything looks pretty 'tinny' in these engines, but they spin up to 14,000rpm without too much bother. The cam chain tensioners look like they are made from thin alloy that someone put a few bends in and said 'that'll do'. I've had one break and I couldn't believe how fragile they look/are.


Anyhow, the valve clearances were all out, so they're now back to standard, but I doubt that this will fix the cylinder dropping issue. I will see how the bike runs when I have her all back together again. Rain forecast again for tomorrow, so I might get a chance to finish then. If it's still not running right, then I will try some different TCI units next as these are an easy swap. I won't put all the fairings back on until I get the cylinder dropping sorted. It's a nice bike to ride (when it's running properly).

 

1985 Honda VT250FII (the ongoing saga)

I’m still fighting the VT250F. She just does not want to run on both cylinders. Having checked the electrics and set the valve clearances, I thought I might as well pull these carbs off and give them a once over. My records show it has been 8 years since their last clean up. Removing and refitting carbs on a VT250F is a task I really try and avoid at all costs. The later model carbs have a connecting ‘bolt’ that holds them to each other; original VT250F carbs do not & that's what I am running on this engine. So, they are held in place by the carb boots, the throttle connector and the airbox base.



When I did get the carbs off and apart, I did notice there was muck in the carb bowl that feeds the cylinder that doesn’t want to play ball. Not too much, but probably enough to stop the emulsion tube from working properly. Normally, I would be excited to find this as it may be the cause of my issues. Unfortunately, my experience with these bikes has taught me never to get excited as they tend to find lots of ways to play up.

During the carb rebuild exercise, I noticed a small part had perished.



The VT250F carbs have two of these little spacers/bushes that are used in the connection of the throttle between the front and rear carb.



I didn’t want to steal one from another carb set, so I did my best ‘MacGyver’ impersonation and found a nylon plug that had the same internal diameter. It was easy to cut down and it worked a treat.



After putting the carbs back on; the bike still doesn’t want to run on 2 cylinders, but I did notice it ‘runs’ on both when the choke is fully on. I will swap these carbs out for another set when I get a chance as I am starting to think there is something wrong with this set and it might be easier (& quicker) to see if I get the same issues with a different set

On a positive note, the bike now runs great on one cylinder with the correct valve clearances and a carby clean! The rear cylinder has better compression than the front (running) so the bike should run fine once I sort this issue out.

 

Prepped up the coil on plug conversion for the ZXR250

I have brand new ignition coils, leads and plug caps on already though so not in a major rush to fit these, unless there's an actual performance benefit?

(This is a donor engine on the bench)

 

I use the sealer drainings to fill the cracks in the concrete floor, sets nearly as hard as the concrete.

 

My question would be why was it burning oil?

 

It takes a lot of heat to burn that much synthetic oil. Does that model bike have an engine issue? I'm guessing it was a high mileage unit?