en125 jet sizes

[ianrr18]

hey all, new to forum... I ride an en125, really only use it to and from work (8mile). looking to do the full license but need to save up. anyway hoping for a bit of advice.... my en125 is running really rough and slow. I have done all the usual checks, replaced the air filter, cleaned the carb. my next guess is either the jets or the valves. Anyone any idea what size jets ens have as standard? thanks in advance

[TUG]

Why would you need to change the jet size?
If its running rough then surely its something much more simple?
What exactly have you checked?
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Haz ER-5, innit!

[cb1rocket]

If it was running ok beforehand then its quite possibly the valves need doing. my friend's old GS125 (same engine) was down on power due to valve not being re-adjusted to suit.

Ignore the carbs and its jets. Unlikely to be the problem if it was running ok on a daily basis

[TUG]

Heres how you do your valves,
1) Rocker cover off,
2) Spark plug out,
3) Bike in gear (with wheel in air)
4) Have your tools ready, feeler gauges, spanner with pliers
5) Now rotate the wheel, stick a screw driver in the plug hole and feel the piston push it up, you are looking for the compression stroke, both valves will be closed (assuming this is a single cylinder bike)
6) Check this, if unsure the tappets will be loose on both sides, this will be your compression stroke.
7) Adjust your tappets according to the tolerances given for your engine.
8) Re-assemble. If you've not over tightened or made them too loose your good to go, just make sure the locknuts on the tappets is tight.
____________________
Haz ER-5, innit!

[ianrr18]

Thanks for the quick replies. Should have elaborated on what has led me to the jets...

When I had the carb off and stripped I noticed the main jet (i think) had been chewed up by a screw driver. The previous owner had put a mtc performance can on the bike so i'm presuming they oversized the jets as well... might be wrong though.

I have change the exhaust and can back to stock, I have checked the coil and plug, changed the fuel pipes and in line filter, change the oil and the filter, cleaned the carb, cleaned the chain etc. The only thing left I can think of is either the jets or the engine.

Thanks for instruction on valve adjustment, I am a bit nervous about doing this, so far avoided it... I have read some posts (on other forums) where people have had engines overheat and blow as a result of valve adjustment.

[TUG]

[ianrr18]

Thanks. I think I will give tis a look over at the weekend.

Managed to find a service manual in Portuguese! using Google translate discovered the valve clearances are

ADM (IN) 0.04 0.07 mm
ESC (EX) 0.13 0.18 mm

Might be useful for other members.

[TUG]

Try to find a uk spec one just to cover your arse. that is if your in the uk.
____________________
Haz ER-5, innit!

[ianrr18]

Evening all, here's any update...

Managed to get the uk gaps for the bike. turns out they are the same but good advice to verify.

Discovered the in valve not to bad, the out valve was really tight so loosened off to the correct space.

Took it out to test but still no increase in performance. It feel like it is holding back if that makes sense. I know it will never be the quickest bike in the world but I would like to keep up with traffic sometimes it never reaches 40mph

Any other comments really appreciated.

[N cee thirty]

you said about the previous owner puttin a diff exhaust on and jetting to suite that,and you changed the exhaust back

did you change the jetting to normal aswell? plug chop and all that
____________________
'00 Aprilia RS50 > '92 Honda CG > '99 Yamaha Fazer > '91 Yamaha RXS > '79 Suzuki X5 > 01' Honda Cg > 07' Honda Cg > 82' Kawasaki Z200 > suzuki gsxr 400 gk73a > honda vfr 400 NC30 Mod 2 Passed 09/06/2011

Jewlio Iglesias wrote: I actually did vote BNP once

[cb1rocket]

sell it, but it can fixed - the gs, en engines and even the gz crusier they are poor engines.

It probably worth checking the timing, checking the gasket hasn't blown and whether its been service well. It could even be ignition related but i doubt that and unless it was running erreactically

[TUG]

[ianrr18]

No, jet sizes are where I am struggling. Planning to dismantle the carb at the weekend to see if I can suss out the size.

Do you think they will be the same size as GS, GZ?

[cb1rocket]

Should be as they are identical engines

[ianrr18]

Bit more info. I have been told that the main jet size for the bike is 110.

Does that sound right, I thought it sounded quite big?

[cb1rocket]

someone with workshop manual or haynes for the gs125 engines can tell

Sounds about right but have you actually opened up the carb to see what jet size you have in there now?

[ianrr18]

Opening the carb tonight. I have had it open previous but didn't take much notice of the jet sizes as only opened to clean it.

Will let you know.