Ok, here's the situation.
HFG's bike is bu**ered!
I've had a look at it (reasonable mechanically minded) and can't figure it out. Nitro (trained mechanic, very mechanically minded) has had a look at it and can't figure it out.
HFG has changed (let me know Stella if I miss owt out) the coil and the spark plug. She's cleaned and eventually removed completely the fuel filter and has even replaced the carb in its entirety!!
Still no avail. Little Suzook don't wanna know.
Anyone with specialist knowledge of GN125s out there?
If not, HFG has stated that she's willing to take it to a dealer but she can't get it there. Anyone got a van?
Come on peeps, the lass needs our help.
The pretty lady in the tight low cut top (not that I noticed Mark, honest mate!!) is indeed correct.
(I was going to say "has a good point" but after the "tight low cut top" comment thought it would be just tempting for certain people and XK)
mechanic trained and tried on everything that goes suck squease bang blow in 2 or 4 stroke terms and have a van and bike trailer whichever is easier. willing to offer assistance either way.
awwww guys - you're great was chatting with Ghosty the other day & he's said to check the pickups - however, I'm sure that Dave had a look at them ...but can't quite remember now - we've checked that much on the bl**dy thing!! lol
I'm still of the opinion that its mechanical
I know you said Dave has checked the tappets, but if one or both of the valves are not seating then your symptoms would make sense.
Its not a long job to take the head off and check them for leaking.
Just turn it upside down (the head) and fill the combustion space with petrol, if it stays there they could be ok.
If it dissapears into the ports then regrinding is the cure.
Personnally I would regrind while the head is off anyway just to be sure.
Of course I could be wrong (perish the thought) but its not "major surgery" and something which requires only basic tools and knowledge.
Taking it to a dealer is a "last resort" remedy, as workshop time is very expensive.
I think you've spent enough on it already Stella, time for some good old fashioned Yorkshire common sense.
These bikes are sold worldwide and kept running on a shoestring by people far less educated than us. Basic principals are very simple and apply to all engines no matter what configuration from singles to multi's they all require "compression" to work effeciently.
I'm off the road till probably Wednesday but I will be at Squires by hook or by XK, so if someone could get it there I could have a look at it and it could possibly be ridden home.
Let me know if this option is required as I dont want to bring all the grinding stuff if I wont need it.
On the plus side, it might be quite instructional, for some, to see this once common practice actually carried out.
The pioneers were regularly seen at the side of the road "de - coking" and regrinding valves. The materials were inferior in those days and didn't last very long, and the oils and fuels left a lot of heavy deposits in and around the combustion space,ports,valve heads and stems and exhausts.
The bikes would become ever more sluggish until they would ultimately refuse to start even with a *bump*
Then it was out with the spanners and fix it cos there were precious few "dealers" to turn to.
Hey Ian - errr - nope I don't think he did
Em - I wish I could get the bike there ...maybe if I set of now I'd get there for next week
Also, am a bit nervous of riding her anyway cos of me knee!..mind you should hopefully find out more about that tomorrow!
Lezg - thanks for the offer- I may be taking you up on that one!
Gee Stella hunny hope some nice person comes rushing to your aid!
Preying for a solution to get you back on the road....and heres hoping that your knee heals much sooner than anticipated so you can enjoy riding again!
No Stella, he didn't do a full compression test cos if you recall I asked him.
However, he had done the normal "guess-timate" test if you remember (thumb tight over the hole oo-er) and said it felt ok cos he was unable to keep his thumb there.
Fair enough, the resultant pressure wouldn't have meant much to me, but to a mechanic who probably does this regularly I am sure it was a pretty good indication.
Of course, without a proper reading it can't be guaranteed.
No Stella .. I didn`t do a compression test .. But like Geoff says i did put my finger over the plug hole and there was sufficient pressure .. I think the problem is fuel related even though the carb is a brand new one .. it could be the main jet is the wrong size .. we just put the carb on .. it ran spot on the first time .. but for some silly reason it won`t now .. it does seem like fuel starvation .. ie if you let of the throttle it picks up .. it has a brand new plug .. we`ve changed the coil to no avail .. but not the coil and carb together .. but i think it might be the main jet .. Anyone have any other ideas .. Did you say you have changed the CDi stella ?
hey Dave - yeah I got one off E-bay from a breakers - they 'said' it was in perfect working order!
But Ghosty reckons it could be the pickups? & Sumo said to check all the connections that we can see to see for a dodgy connection?
Now when I start her - on full choke, she goes to about 3000 rpm & then as she gets warm she dies!. If I hold her on the throttle for a while, she seems to pick up a bit & tickover - but not smoothly!
If you replace the pickups , then you have replaced everything .. I still think it`s fuel related .. looks like the carb off again .. check main jet size .. It should have a 102.5 main jet .. There is one in old carb if that is wrong .. How can a 125 4 stroke bike cause so much heartache ffs .. lol
tell me about it!! But you've been a star with persevering with it for so long!! xx
Just had this Pm :
pick-ups are they fixed securly, Carbs check blow through/clean the idle jet. there might be a blocked filter where the fuel line goes into the carb-many people miss them, your bike might have one, they look like fine gauze and are hidden in the fuel inlet where the fuel pipe meets the carb. Air lock try running the bike with the tank filter open, your tank breather pipe might be blocked or kinked when the tank went back on.
By the way Em .. I`ve done the tappets .. and checked valve timing in fact checked evrything i can think of .. It`s a 4 stroke .. single .. hardly anything can go wrong
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