ZXR250c hard starting etc

[fricks]

UPDATE BOTTOM OF POST:

Hey folks,

Forgive me for my 1st posting being a request for help! But im starting to run our of ideas...

A few weeks ago one night, the bike ran out of gas, threw some more in it and it ran fine all the way home. Next morning, start it to ride to work and I thought I noticed the exhaust note didnt sound right. Didnt think much of it as the difference was pretty borderline.

Started the trip to work, bike felt a fraction down on power and slowly got worse and worse during the trip. Eventually coming up a hill the bike 'snapped' back to normal and all the power was back.

During the trip I noticed the exhaust note was definately different - sounded to me like it was running on 3 cylinders which i thought would explain power loss etc.

After work - Bike starts fine and begin riding home. First couple of hundred metres the bike seemed a fraction down on power but then came fine again. Pulling into my street, stopped at the intersection and the bike was having a hard time idling and wanted to die. Died at the bottom of the driveway and wouldnt start again.

## What I've Done ##

* Pulled off carbs and cleaned out jets etc. Looked pretty clean to begin with. I thought when it ran out of gas it may have sucked some crap through into the carbs? Started the bike again and took 4 - 5 sec's to 'catch' but then would keep dieing whenever i tried to adjust the choke so it would idle below 4k. Started it and let it idle at 4k and after 10 sec's the rev's slowly dropped and died again. Today it wont even start.

* Tried a known good battery off another bike to try for arguments sake. No win.

* Pulled the spark plugs and checked those. Were a little wet but figured that would be from trying unsuccessfuly to start it earlier. Colour appears to be fine to me - can throw up some pics later if needed.

* New unifilter air filter fitted when carbs were off. Plus cleaned out and sealed the tank too.


Sorry this all long winded but figured the more info the better. Has anyone out there got any ideas/things to check? I hanging out for another ride!!

Cheers

UPDATE:

Since the bikes been running again, the problem has been coming up again and seems to be progressivly getting worse each day. Went fine for about a week, no issues at all - no gradually getting worse/occuring more often.

Appears to be happining once the bikes up to/near operating temp. But I will occasionally notice it in the morning when starting it first time. Almost sounds like its running on 3 cylinders; exhaust note different. But once i give it a chance to warm up a bit it usually comes right before i ride off.

When it starts playing up when its warm/near warm it turns to a gutless shit. No 'snap' in the throttle, sluggish etc. When its like this, if i come to a stop and let it idle it will want to die. Then when i try to restart it it normally wont start again. If i leave it to cool for a while it will normally start again.

Flatmates and I are starting to think it could be a spark/electrical issue. Reason being fuel system appears to be fine, tanks clean/sealed, fuel taps mint, no blockages in line between tap and carbs. New airfilter fitted a few weeks back which should be fine. Hasnt got excess filter oil on it.

Another reason why i think it could be electrical is a couple times when its been in 'shit mode' and i have been crusing along, you can feel the bike momentarily 'snapping' back to normal and then turning to shit again. But its intermitent, like a loose connection or something.

Plugs were out last time and they appeared to be fine.

Has anyone got any ideas? If i think of anything else which might help i will add it later, Cheers!

[The Pastor]

Whats the air filter like

chuck half a cup of meths in the tank and see if that helps (water in the petrol)

[fricks]

Sorry forgot to mention - will add to original post...

Air filters a brand new Unifilter. Was changed when the carbs were off. Plus the tank was also cleaned out and sealed too.

[The Pastor]

There is a vacume pipe on the zxr250 that is required for the bike to run, you havnt forgotten to put that back on? Skidmark will be here shortly he knows lot about zxr250s

[fricks]

Vacuum pipe? Where abouts is the pipe located? cheers mate

[The Pastor]

Im not familia with the zxr250, but it goes from the carbs to the airbox i think......

[fricks]

Hmmm oh ok. There is a spot on the top of the airbox for a hose which it never had from the get go. Plus one on the bottom of the tank which never had a hose either. Its my first bike and ive only had it for 3 months so im still a little 'green' on some things heh

Cheers RM, i'll wait see if Skidmark drops by

[The Pastor]

I'll tell you what mate your discription and methodolgy is 100 times better than some of the shit that gets posted on here from newbies!

[discotex]

Have you tried running it on PRI? That bypasses the vacuum feed from memory.

I had heaps of problems after running my old one dry. Wouldn't start on reserve until I let it sit on PRI for a couple of hours. I figured there was an air lock or something.

[fricks]

I'll tell you what mate your discription and methodolgy is 100 times better than some of the shit that gets posted on here from newbies!

Haha cheers


Have you tried running it on PRI? That bypasses the vacuum feed from memory.

I had heaps of problems after running my old one dry. Wouldn't start on reserve until I let it sit on PRI for a couple of hours. I figured there was an air lock or something.

Yeah when I first threw the tank back on I needed to put the tap on prime to get some fuel running down the line. I done this until I could see a decent amount in the inline fuel filter between the tank and carbs. It never had a fuel filter so I fitted one when the tank was off. From what I read, prime gravity feeds the fuel out of the tank and the ON position uses vacuum. May be wrong though...

[Harvd]

Not that i have any ideas, but you deserve to be going. As RM said, you're actually doing pretty well and have done everything i could of thought of.

Some people dont seem to have a brain, good to see you do.

Good luck

[skidMark]

Hmmm oh ok. There is a spot on the top of the airbox for a hose which it never had from the get go. Plus one on the bottom of the tank which never had a hose either. Its my first bike and ive only had it for 3 months so im still a little 'green' on some things heh

Cheers RM, i'll wait see if Skidmark drops by


Hey dude, you will need that hose, it shouldnt rev above about 9k without it...

it goes from the top of the airbox (near the battery and start relay)

on the c models you will have a little box with 3-4 hoses that sits on 2 prongs made into the frame a bit behind the steering stem, but more towards the front than the widthways frame brace that the coils mount into... you have to run a hose between the two... im suprised it ran properly to start with like that... any strange knocking etc?

get that sorted first and your symptoms may change somewhat...

sometimes zxr's just need a good thrash to blow the cobwebs out properly...

if you cant sort it i can come down one day and have a look... it would be a weekend when i was going to whangamata for a ride though, just flick me 20 for gas or something for the extra distance.

[fricks]

Hey dude, you will need that hose, it shouldnt rev above about 9k without it...

it goes from the top of the airbox (near the battery and start relay)

on the c models you will have a little box with 3-4 hoses that sits on 2 prongs made into the frame a bit behind the steering stem, but more towards the front than the widthways frame brace that the coils mount into... you have to run a hose between the two... im suprised it ran properly to start with like that... any strange knocking etc?

get that sorted first and your symptoms may change somewhat...

sometimes zxr's just need a good thrash to blow the cobwebs out properly...

if you cant sort it i can come down one day and have a look... it would be a weekend when i was going to whangamata for a ride though, just flick me 20 for gas or something for the extra distance.

When you say it shouldnt rev above 9k without that hose, do you mean it shouldnt be able to? Because its rev'd past 9k before.

I dont recall seeing a box by the steerer tube/coils etc. Any idea what its called/photos? I will have to have a look tonight when i get home and report back. Is it some sort of solenoid/vacuum box?

Its been running fine until all these recent problems. Almost daily use for 3 months id say. It does have a slight knocking at idle but I had heard this was sometimes a common thing on ZXR's. The knockings audible but I wouldnt say loud.

Cheers mate I really appreciate the offer. If I cant get it sorted sometime soon I may just take you up on that. Would be happy to fix you up with beers/cash for your troubles

[fricks]

Just checked for this box and cant see anything which could be remotely like it. On the inner left hand side frame rail (between steerer tube and horizontal bar by coils) there are 3 tabs welded on. Looks as though something is supposed to be sitting in there. Im geussing this is where it should be

[Paul in NZ]

This would be the 3rd or 4th Jap 250/4 that I have heard of that has had all sorts of odd problems after running out of gas? Very strange... Maybe the fuel tap has some crud in it?

[fricks]

I opened the fuel tap by pulling the plate off the back of it and look clean to me. Wasnt sure how much further i could pull it apart though...

[skidMark]

Just checked for this box and cant see anything which could be remotely like it. On the inner left hand side frame rail (between steerer tube and horizontal bar by coils) there are 3 tabs welded on. Looks as though something is supposed to be sitting in there. Im geussing this is where it should be


Yep you do need one...

strange that its run without it.... how high have you revved it, you want to be getting it upto 17-18k rpm a ouple of times a week at least or it'll run like a sak of shit, sometimes you just have to give them a good thrash to blow the cobwebs out if you ride them low in revs all the time they do run like crap.

[fricks]

Its been revved to 17-18k before. Do you know if it is possible to bypass this valve somehow which could explain why its been running fine without it?

Im on the hunt for one at the moment, but I dont really know what they look like and the places ive enquired about one dont seem too 100% sure what im talking about which is making it harder.

Any ZXR owners out there able to do me a favour and quickly whip their tank off and grab a photo for me please?

[Benk]

What was the problem again Shaun? :clap:

[skidMark]

Its been revved to 17-18k before. Do you know if it is possible to bypass this valve somehow which could explain why its been running fine without it?

Im on the hunt for one at the moment, but I dont really know what they look like and the places ive enquired about one dont seem too 100% sure what im talking about which is making it harder.

Any ZXR owners out there able to do me a favour and quickly whip their tank off and grab a photo for me please?


I would doubt it is your problem if it has run fine up until now without it, but you should have one, i have never found a way to bypass it, it balances between the carbs and the airbox.

i think you should take your bike for a decent fang and wind it right up 10 times at least...

will probably come right.

[fricks]

Well it seems to be running fine now. Goddam fuel filter seemed to be the culprit! The fuel wasnt flowing through it properly. Removed the filter and after a little cranking it fired up and was running fine. Benk took it for a ride around the block and ran mint.

May have been an airlock or something inside the filter and wasnt letting the fuel flow into it. It probably would have been a long time before i would have thought to check the filter if it hadnt have been for the flatmates giving me a hand and going back to check the basics! :rolleyes:

Thanks to Skidmark and co. for the help and suggestions :drinkup:

[skidMark]

Well it seems to be running fine now. Goddam fuel filter seemed to be the culprit! The fuel wasnt flowing through it properly. Removed the filter and after a little cranking it fired up and was running fine. Benk took it for a ride around the block and ran mint.

May have been an airlock or something inside the filter and wasnt letting the fuel flow into it. It probably would have been a long time before i would have thought to check the filter if it hadnt have been for the flatmates giving me a hand and going back to check the basics! :rolleyes:

Thanks to Skidmark and co. for the help and suggestions :drinkup:


sweet.... but one day i'm taking ya tank off!!! i wanan see how somebody bypassed the airbox to carb thingymadoodle........ means i can run pod filters.... hi five!

[fricks]

No worries mate, more than welcome to come by and check it out next time your in Tauranga

[skidMark]

No worries mate, more than welcome to come by and check it out next time your in Tauranga


it smells funny there :banana:

lol sweet as man will pm ya when im heading that way.

[Benk]

it smells funny there :banana:

lol sweet as man will pm ya when im heading that way.

Whats the point of a pod filter?

[Dealer]

Whats the point of a pod filter?

To look pretty. oh and increase the airflow by 0.2%

[Benk]

Itd decrease cold air airflow if you removed the airbox though?

[tychver]

Itd decrease cold air airflow if you removed the airbox though?

On a fully faired bike this is normally true.

On an unfaired bike it'll make more power with a pod filter or open carbs until about 150kph. Much above that and you need to find some stiller air.

It's common practice on certain bikes to drill holes the the airbox lid to get some extra flow and run a pod filter mounted inside them.

I run a pod an no airbox on my cb250rs. Only now I have to find a bigger jet or I'm going to melt the piston. It was already running lean up top.

[Sparrowhawk]

Well it seems to be running fine now. Goddam fuel filter seemed to be the culprit! The fuel wasnt flowing through it properly. Removed the filter and after a little cranking it fired up and was running fine. Benk took it for a ride around the block and ran mint.

May have been an airlock or something inside the filter and wasnt letting the fuel flow into it. It probably would have been a long time before i would have thought to check the filter if it hadnt have been for the flatmates giving me a hand and going back to check the basics! :rolleyes:

Thanks to Skidmark and co. for the help and suggestions :drinkup:

Those fuel filters have a lot to answer for. I had some similar probs a coupla months ago. Previous owner had fitted an inline filter, using radiator hose. Of course the rubber perished and clogged the filter. Got rid of it, put fuel hose in instead, no probs since.

Might be worth checking what sort of rubber hose you've used, coz the fuel will degrade radiator or air hose.

[Benk]

On a fully faired bike this is normally true.

On an unfaired bike it'll make more power with a pod filter or open carbs until about 150kph. Much above that and you need to find some stiller air.

It's common practice on certain bikes to drill holes the the airbox lid to get some extra flow and run a pod filter mounted inside them.

I run a pod an no airbox on my cb250rs. Only now I have to find a bigger jet or I'm going to melt the piston. It was already running lean up top.

Cheers. This makes good sense.

[skidMark]

i would still run an airbox of a sort but not the factory ones....pod filters with a shround to protet from engine heat then ducted to the piping/ ram air of the left fairing.... or i would use the pipes on top of the tank and set them up for actual ram air, and relocate the reg/rec so it still gets cooled.

[imdying]

On an unfaired bike it'll make more power with a pod filter or open carbs until about 150kph.Gross generalisation that basically is incorrect.

It's common practice on certain bikes to drill holes the the airbox lid to get some extra flow and run a pod filter mounted inside them.What is this 1985?

I run a pod an no airbox on my cb250rs.Oh, it is... as you were :rolleyes:

[fricks]

Problem is back.:angry2: First post updated with new info

[FruitLooPs]

If you can get it running on three for a period of time you can try splash some water on the headers which will narrow down to the bad cylinder for you.

My friends zxr250a is a pig in winter, takes quite a lot to start it and has changed the battery at least once and left the bike at home each winter for a day here and there when he cant get it started. A few times it wouldn't start without a push start on gas that was in the tank for a few weeks. New plugs normally set him right for a while, but the bikes seem very sensitive to cold and a less than perfect battery.

Good spot on the fuel filter, there are a few out there that are too restrictive.

I guess its possible they run quite a rich mixture from factory, and combined with extra choke on cold mornings and carbon coated plugs you might get inconsistent running and jerking if it fires on it some of the time.

I know i've had my 2-stroke single run with a pretty fouled plug for a few 100m with almost zero response before it finally coughed and died. In the weeks prior to that it had lagged off the line quite a lot, and needed quite a bit of nursing. New plug and it was great again, but then again its 2T so has oil to foul with too :)