Help needed ! Intermittent engine problem on 125

Hi,

I was riding my Suzuki EN125 (grey import version of GS125)
yesterday and the engine started to splutter and surge. When the revs
dropped below about 2,500 rpm the engine just died. Faint white smoke
was coming out of the exhaust. The problem was getting worse so I
rode home keeping the revs high and using the back brake. I now know
how it feels when the back wheel locks and the bike slides from
underneath. Of course, the problem cleared when I was literally in
sight of home. I rode the bike to the dealer who checked it and
couldn't find a fault. They didn't charge me for the time they spent
checking the bike – top guys.

The bike has been completely reliable until now. I bought it with 900
miles on the clock and it is up to 1,800 miles. The bike has been
regularly serviced.

Today when I went out for a ride the same thing happened. Surging,
spluttering, cutting out, but a bit less severe than yesterday. Again,
the problem cleared after about 2 miles of riding but the engine feels
“lumpy”.

The first time the problem happened I was on my way to my practical
test. I was hoping the problem would clear on the way but it didn't, I
couldn't take the risk of the bike dying on the A41 or the A1, and I
just had to limp home. I forfeited the £60 test fee. The test was too
early in the morning to get to the training centre to see if I could
hire a replacement bike. The absolutely galling thing was the problem
disappearing within 200 meters of home. I'm gutted. 8-( Perhaps the
bike doesn't like North West London. 8-P

I know little about the mechanics of bikes, but I guess they are
relatively simple on a 125. The only places I can think the problem
could be:

Problem in the fuel?
Fuel supply to carb: Some blockage somewhere? Valve problem?
Faulty carb: So fuel does not mix well with air and ignite
Faulty HT electrical supply or spark plug: So fuel / air mixture not
igniting “regularly”
Exhaust problem: Again valve problem on exhaust side? Exhaust not
being cleared from cylinder therefore messing up replacement air /
fuel mix on next cycle?

Could there be some other cause?
Has anyone else experienced this problem and can stroke his / her
beard and say, “Aha! The problem is .... and the fix is .... ?” (bit
of a long shot I know)
Is there anything I can check or examine to try and identify the
cause?

Thanks for any ideas.

Welcome to the joys of motor cycle maintenance.

Test now due Wednesday and I can't have confidence the bike will be
OK. 8-((


Clive

 

You haven't put diesel in it have you?

 

Anything is possible I suppose and that's what one of the guys in the
shop asked.
However, the receipt I have from the petrol station states 7 litres of
unleaded. And I'm assuming the poor 125 engine wouldn't make any
progress, let alone faltering, intermittent stuttering if evil-
smelling derv was sloshing around in there.

Clive

 

Grit in the jet, I'd say. Wobbly grit that allows fuel through when
it wants to, then wobbles back and blocks it when it feels like it.

Always good advice.

 

Snip, you fucking twat.
--
Dave
GS850x2 XS650 SE6a

"A scone and tea at half past three
Makes the day a little brighter
Keep your cakes and fancy tarts
And stick them up your shiter."

 

Using the patented Mavis Beacon "Hunt&Peck" Technique, Grimly Curmudgeon

He's still trying to clear his name over the stiff.

"Can't have been me what cut his head off guv, I've never learned to
snip."

 

I'll quote you as a defence. I'm sure it'll do the trick !