Odd symptoms - no idle and mostly no start

[Itsme]

Hi All

I was out on my GN250 on Friday when it suddenly had symptoms like fuel starvation, the motor faded and after a few seconds died. It started with a lot of turning the motor over and would run at anything over tickover but would die if the revs dropped too low so I kept the throttle high. If it died it would take a bit of getting going again.

When I got home I had a look at it and when trying to start it the motor would turn over and sound like an old stationery motor trying to get going. The irregular firing would get faster until it started and then it would run until the revs were allowed to drop when it would cut out again.

I checked and charged the battery which is a bit old, but also used the new battery off my Inazuma to test it, cleaned the carb, changed the plug for a new one and checked all the wiring connections. Still no change and now it doesn't seem to start at all.

The plug is getting wet and is sparking well but the motor just won't run. I'm guessing that the chugging as it turns over is the best clue but I don't know what it is telling me.

Any help gratefully accepted gents.

Ian

[CrazyFrog]

Blocked pilot jet?

[Itsme]

I wondered about that but haven't had chance to check it yet.

Ian

[iansoady]

That woul be my first port of call as well.

[Itsme]

Thanks, I will report back when I have had chance to check the pilot jet.

Ian

[Itsme]

Hi All

Well I blew through and checked the pilot jet which wasn't blocked, checked again all carb settings, changed the plug again and charged the battery again and nothing.

This problem is a could be, might be, what about, try etc. and I don't have the time or money to keep replacing things in the hope that I can find the problem. So it is with a heavy heart that I am retiring the Mighty Midget with a laudable 51000 miles on the clock, hopefully temporarily. The Inazuma (AKA Newzuki) will pick up the mantle of my everything bike from now on. It may be bland but at 12000 miles and being 23 years newer than the MM it makes sense.

I will hold a short memorial service for the MM in the sure and certain hope of resurrection at some future date.

Ian

[Moto63]

So it is with a heavy heart that I am retiring the Mighty Midget

I will hold a short memorial service for the MM in the sure and certain hope of resurrection at some future date.

Ian

Ian. You have my deepest condolences, the MM is gone but definitely NOT forgotten. Hopefully some day it can be renamed the “Phoenix” and rise from the ashes 🔥
Best of luck with the Suzuki filling the gap and don’t give up hope of the “Phoenix” riding again 🤞👍
Cheers, Michael

[CrazyFrog]

Perhaps it's worth considering the old adage that 90% of fueling problems are electrical and 90% of electrical problems are fueling. Unusual symptoms, but it could be the coil ...

[Itsme]

Thanks Michael I really do appreciate the support and the encouragement to keep thinking about getting the MM back on the road one day. Despite its faults and failings the little sod is probably my favourite bike ever. Even this afternoon as I was tucking it away in the side of the garage I was mulling over what might be wrong. I just think a little rest and some tlc will do it good.

Cheers Pete I saw your comment and agree entirely and maybe a little thinking time is what is needed.

Cheers both.

Ian

[iansoady]

Perhaps it's worth considering the old adage that 90% of fueling problems are electrical and 90% of electrical problems are fueling. Unusual symptoms, but it could be the coil ...

Or even the CDI (if it has one) which led me a merry dance on the XBR for months. I was convinced it was the carb till the driver on my taxi of shame asked whether I'd considered the CDI.

[Itsme]

It could well be the cdi which of course is 30 years old, but I tried my cheap, Chinese replacement which did work before and there was no difference. The problem is I don't know if that's because it didn't cure the fault or it just packed in as it really was cheap and I only bought it because I was curious to see whether it would actually work.

Anyway I am giving it a break and taking some thinking time.

Thanks

Ian

[Itsme]

I'm beginning to think it might be an ignition fault, possibly a wire somewhere shorting out. I say this because every time I try the motor and then pull the spark plug it is wet. Surely if it were starved of fuel it wouldn't be wet. Unless it is flooding. See what I mean about it being a might be, could be kind of fault.

Ian

[Itsme]

Hi All

As I said to Bill in another post, a penny may have dropped with the MM's fault. I have cleaned out the carb several times since the fault began, but haven't been able to check the diaphragm as the cover screws are seized in. I thought no problem as I replaced the diaphragm not long too ago.

However as I walked past the bike I noticed the carb which I had left on my other bench and from the inlet side I noticed the slide was about a quarter of an inch up in the body of the carb. I worked it up and down but it was stuck at open and wouldn't return to the bottom of it's stroke. Bingo! The motor can't start if the slide is stuck open as it is flooding a dead motor. I know I could be mistaken but with nothing else being wrong this is surely a very likely candidate.

I have decided to spend some time putting some things right instead of rushing as I have Newzuki back on the road. I will of course report back when there is a development.

Ian

[iansoady]

Sounds like a plan!

[themoudie]

Aye Ian,

Giving it a flush!  Sounds like the route I would venture down. Maybe even a cheap Chinese replacement, even though it may not be a CV carbie. Alternative would be conversation with these boys:-

NRP-carbs

Out for two hours tonight viewing a wee aurora, with temp's -4°C, quite weak compared to other places, such as northern Canada. Homemade soup and pizza and trying to warm up now. Daft!

Good health, BillR