Thumper Club Forum
Technical => Bike Problems/Questions => Topic started by: Itsme on November 26, 2023, 03:46:08 PM
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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
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Blocked pilot jet?
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I wondered about that but haven't had chance to check it yet.
Ian
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That woul be my first port of call as well.
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Thanks, I will report back when I have had chance to check the pilot jet.
Ian
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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
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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
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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 ...
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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
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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.
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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
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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
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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
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Sounds like a plan!
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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 (http://www.nrp-carbs.co.uk/index.htm)
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. ;D Daft!
Good health, BillR
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. ;D Daft!
Good health, BillR
Aye... possibly, but still entertaining so please don’t stop 👍🥃😉
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Strange that the screws are seized given that you replaced the diaphragm recently....
I'm sure that this is grannies and eggs but I used to really struglle with the cross-head screws on Japanese bikes till I discovered that they were not Phillips but JIS which have a subtly different profile. Obce I got a set of the proper screwdrivers - which weren't cheap but a Xmas presnt from my dear wife - they very rarely defeat me unless throughly bodged by previous attempts.
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I don’t think you’ll be the only person on this site to have made that mistake Ian. Think most of us thought they were Phillips stew heads 🤦???🤦???
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Gentlemen you are both right; the screws weren't seized just wouldn't yield to my ill fitting Philips. A tap with a hammer on the screwdriver did the job and will have to suffice until my wife gets the hint and buys me a nice pressie,
Ian
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This looks like a decent set at a reasonable price. The ones I have are made by Vessel and although excellent were a bit expensive.
https://www.halfords.com/tools/hand-tools/screwdrivers-and-hex-keys/sealey-4pc-jis-screwdriver-set-453366.html
By the way apologies for my appalling typing recently - suffering from shingles which is quite unpleasant :(
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Thanks Ian for the suggestion and I hope the shingles clears up quickly as I believe it is very nasty.
Ian
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Aye Ian,
Thank you for the Hafrauds link.
Sorry to read that you are suffering from the shingles. Up here once you are 70+ the jag is free on the NHS. Ironically, I attended my surgery for a flu jag and noted the poster on the wall and asked if I might have the jag there and then at 67 years of age. "No", was the answer, so had the flu jag and banter, with the nurse. Next morning I had an itching welt, about 2" x 3" in the middle of my chest and after sending an image to the Doc, he confirmed that I had shingles! :o Calomine lotion and a silk handkerchief taped over it to prevent rubbing, helped, but the internal pain through my chest to my back was very unpleasant. All in it took about a month to calm down and clear up. I'll be getting the jag next year!
Hope you improve and can be chipper for Xmas/ New Year.
Good health, Bill
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Thanks both. The jab is available in England as well to over 70s - including me - but our local GP practice isn't very good about telling people about such things otherwise I'd have had it. Oh well. What can't be cured must be endured.
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Sorry to here this Ian. I can remember my Mom having shingles when she was in her 70's and it was pretty unpleasant. She ended up with neuralgia too as a result of the shingles.
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Hi All
If you've read my post about what I've done to try to get my GN250 running you will know that a) I have tried all of the usual suspects for a non-starting bike and b) I have nearly given up on the bike yet again. However I hate being beaten.
I thought as I have tried all the obvious ignition and fuel problem sources I would widen my explorations so I checked the valve clearances. As the GN is a fairly rattly motor I usually set the clearances at the bottom end of their range. I reset the clearances to the maximum specified and I now get a promise of starting! Unfortunately due to multiple attempts at starting yesterday the battery went flat very quickly so it is now on charge.
I'm not confident that I have solved the problem, but this is the nearest I've got to a start in months. If the bike starts I might give it a full strip anyway to make sure everything is as it should be as I would want to know if the valve clearances were the issue for a reason.
Keep your fingers crossed.
Ian
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I for one Ian will definitely be keeping my fingers crossed 🤞
I’d hate the MM to be shoved in the corner of your workshop under a dust sheet and forgotten about 🤦???.... here’s to a positive result, best of luck 👍
Cheers, Michael
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There's a saying in Guzzi (and no doubt other) circles that a rattly engine is a happy engine. Loose tappets don't usually cause much harm but tight ones can be the devil.
In other news I now have the neuralgia Pete mentioned so still suffering although better than before. The worst bit is that spending any time in the garage makes it worse......
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Hi Ian and Michael. Sorry to hear your health is still being a nuisance Ian and thanks Michael for the good wishes. Sadly I have to report no change whatsoever this morning with a fully charged battery. Whatever I thought I was hearing yesterday just didn't turn into any positive results.
I appreciate your sentiments Michael but I don't think I can pursue this problem any further, at least not for now. Apart from the fact that I am now totally baffled as to why the bike won't start, it has become what my wife terms a time burglar. In other words I have projects that I want to get on with but the MM is taking up all of my time. And of course it is in danger of becoming a money pit.
In a strange way I think it has committed suicide; think about it, it played up on a ride out with my mate, got me home and hasn't run since despite time and money being spent on it. Whatever, it is now covered up until I do or don't get a surge of enthusiasm in the future.
Ian
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Oh Ian,
Give the poor wee bugger a cuddle from me, cover it up and await some spring warmth, when like a pheonix, it may arise from it's slumbers. ;)
Yesterday the Boy Bros, which inspite of a carb refurbishment, has always been a reluctant starter after being left cold for a while ( no electric fuel pump, just a microlight diaphragm replacement!) due to fuel evaporation, took its time to fire up! Clean the plugs, re-gap, then afore trying again, heat up the last plug with the MAPX blowtorch to red heat and fire it in! :o Still a bit dottery, but a wee juggle of the choke and throttle got it fired up, it's a close thing between too much choke and flooding it. You'll crack the MM woes I'm sure. :)
Good health, Bill
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Thanks Bill. This is why I love Thumper Club; you give up on a seemingly pointless project and along comes someone with an encouraging word or two and suddenly things don't seem as bad. I know deep down that I love the MM and will never totally give up on it, but sometimes I need to pretend I've had enough to bring me to my senses.
Watch this space!
Ian