Before I put the bike in the skip ........ (ZXR 250)

Hi all,

OK, Please can anyone help before I chuck my bike off a cliff (ZXR250)

Just had the bike back from the garage, to get the following done :

Carby synch / float level adjustment
Valves checked / adjusted
Timing chain tightened
New Spark Plug (#4 cylinder)
New rear tyre

Before this, I was breaking down with no power under load (Bad plugs) and rough running (Carb synch problem)

I swapped out the coils and leads myself, as the old leads were shorting to the engine block, and were cutting out in the wet ...

Then I took the bike to the garage for the rest of the work ....

Got bike back, running sweet, much smoother, power delivery good etc ...

Bloke at garage found one of the carbs had been replaced at some point, and the brass fuel inlet nozzle (in the carb throat) was different to the other 3, made it a bastard to get them sorted ... I am looking for a single carb now, waiting for pics from a seller.

He managed to get the carbs synched, set the float levels OK, but he said when it's hot the bike is hard to start, but can idle for ever without overheating ....

The main problem now though, is the bike NEVER overheated before, the plug for the fan was not even connected (I forgot to connect it when I serviced the bike when I first bought it), ran fine for weeks, never above 3/4 on the gauge on a warm day in the city....

Yesterday going into the city, temp goes off the scale at the lights, then just boils over, spewing coolant all over the road (From the discharge pipe under the bike) ... Bike will not start when hot if I kill the ignition and try firing up again .....

When cold / low level temp runs a treat - I also think the fan was not coming on (Plug is connected now)

I am going to check the thermo switch, and radiator fan motor, but my question is, why the hell would the bike overheat so quickly now when it was fine before the service ?? (The garage did a great job on the other work, not sure if he dropped the radiator for the plugs (He only swapped #4 plug, as the rest were fine)

I refilled the radiator before coming back home from the city, did not seem to get so hot as quickly in the morning, but as soon as I pulled up to my garage, and put the bike on the stand, I could see the gauge rising slowly in front of my eyes ...... Killed the ignition and tried restarting (Just above 3/4 temp) No luck .....

Any ideas would be greatly appreciated - Cant go for my first run up the Nasho without the bugger being reliable ....

Thanks.

Kwakka

Just went out this morning to get the Pink Slip renewal, ran perfectly all the way to redline, fuelling good etc ....

Temp OK to the garage, started fine after inspection, fanged it home, in the garage temp at 1/2.

Left it idling for 5 mins, guage almost up to red line.

Killed ignition, cooling system bubbling / boiling away.

Started again this time on full choke after 5 secs of hitting the starter.......

Is the fan working or not ??

uhm, my first idea is that the radiator cap might be shot.
Secondly the Impellers on the water pump could be shot.
Thirdly run radiator cleaner through your bike, have you ever done this? i always assume a bikes radiator (if its got one) is caked with shit when i get it and clean it the hell up both through the block and the radiator.

i'd be looking at the cooling system, just a fan or a lean mix wouldn't allow the system to overheat that much that quickly i'd think.

possibly a blockage, but unlikely. if it was my car i'd be looking at the thermostat and failing that, water pump but i dont even know if bikes generally have a thermostat. in any case, it sounds like the water aint moving the way it should so i'd start from there....

OK Guys thanks for the advice :

If I disconnect the water pump from the motor, and turn the motor over,should it spew out coolant quicker than gravity fed from the radiator, am I right ??

Or should I remove the pump all together and turn it using a drill somehow with one container full of coolant, and another dump container for the coolant to pass into ??

The thermo switch will be dropped into boiling water, with a test meter attached to both leads for a resistance /continuity check, should it go to or from infinite resistance depending which way the switch is under cold conditions, (Normally open / normally closed) - Does this sound right, or is there some form of resistance built into the thermo switch, or should I test this using another method ??

I will remove the fan and connect the bike battery directly to the terminals to see if it fires up.

The guy in the garage did mention the float levels were adjusted to 13mm instead of 15mm (I think that's right), does that mean a leaner mixture, or just a lower level of fuel in the float bowls of the carbies ??

I rechecked the pics of my carbs when I cleaned then out, and the inlet is shorter (Not longer, as I said earlier, sorry) :

See the LHS carby, shorter inlet Nozzle into cylinder #1 throat ....

Carb top 1.JPG (73.19 KiB) Viewed 3044 times

Could'nt check the bike today, had to look after my daughter, so tomorrow is the go ..... Thanks again ....

Pull the lead off of the fan switch and using a paperclip join the two wires in the lead together,
the fan should start immediately the connection is made. Oh these wires are "live" all the time i.e. they bypass the ignition switch so the fan can run on after you have stopped

Runa colling system cleaner through it as directed then Knock the guts out of the thermostat as well.
I think this is a seperate issue to what you've already had done.

The joys of new ownership of soemones else's drama's. I've Been going through most of the same type of crap on the "Hiace Kwak Tax pak"

r.e. the pump, if you take the pump off you should be able to see the impeller blades, if they look pitted worn / broken then just swallow your pride and cash and get a new one. if they look shiny and still reasonably tidy then it isn't likely that they're the problem. But first things first flush that radiator out (take ALL hoses off and force water through all radiator ducting and the block both in the normal direction of flow, and in reverse (some stuff could be stuck there going one way and be dislodged with a reverse waterflow). When i did this to my gpx when i first got it it took about ten goes back and forth until i was satisfied i had gotten rid of most of the crap.

Even then i ran plain tapwater for a few hours of running to flush it out and got more crap out, then i ran the tectalloy (good stuff) mixed with water for about 4 hours of running instead of the recommended 20 minutes and left it in over two days. Even MORE crap came out when i re flushed the bastard out. Only then did i bother putting the correct coolant in.

Too much time and effort wasted when it could have been kept at bay by preventative maintenance.

Thanks for all the helpful info guys, will defo be flushing the rad, and checking the pump

Tried the wire in the fan switch plug, fan works a treat - Nice one - Thx for that.

Tested the fan switch in some coolant on the gas stove (Missus was looking at me funny when I asked if she had a pan she did'nt want to use anymore !!

Switch is gooone, so will get another one asap ....

Now for the really bad new, seeing as I can do the world's stupidest things sometimes, thought it would be OK to have a look at the chain tensioner, if the battery was disconnected and did not move the bike whilst checking the tensioner out of the bike .....

Checked out the tensioner, put it back in , reconnected battery after doing this, and CLUNK CLUNK CLUNK on turnover, friggin chain must have slipped somehow

Now the alternator cover and rocker cover have to come off, reset the timing chain, and pray I did not bend anything - What a tool .....

Ah well, live and learn ......

It's all learning Kiltie, Knowledge wont knock you up carrying a little extra around with ya

Woo Hooo !!

Turns out when I removed the engine cover, and checked, the timing chain tensioner is a cam type adjuster - When I looked it had rotated to the point of rubbing against the clutch basket when cranking over .....

Redid the timing adjuster, refitted it to the bike, checked it was not touching the clutch basket, and put it back together .....

Fingers crossed, turned the motor over, and .... Vrooom !! Perfect !!

NEVER again will I remove something that looks like something, but is something COMPLETELY different ..... Oh, and I have a manual for the bike now

Hee Hee, the joys of messing with bikes at home ....