RS 125 Spark Plugs!

[18_stuart_88]

Hello all,

Im having considerably high amounts of problems with my bike at the moment which is leading me on to selling it.

I have went through 6 ( going on 7 ) spark plugs within riding my bike 500 kilometres to and from work.

I realise the problem before the plug completly give way on me so i stop and take it out and give it a little clean up and shot off again, this solves the problem for about 5 mins and then it starts to happen again.
When im riding it becomes very very rough and cuts out on me when i come to a stop or pull in my clutch in any gear. It seems a bit like the bike is missfiring when riding as when i pull the throttle it isnt as responsive as normal. It feels a little like when your about to run out of petrol with the throttle.

y bike runs on a BR10 EG spark plug. Tried the BR10 EIX but it gave me the same problems. I have also got a 34mm Carb apposed to the standard 28mm.
Does anybody know what can be causing me to go through a spark plug ever 4 days or soo?

Any help would be greatly appreciated.

Stu
____________________
Make: Honda NSR 125 R Year: 2004 Colour: Black And Silver - Died on December 18th 2005, Layed to rest December 30th 2005 :(Make: Aprilia RS 125 Year: 2000 Colour: Black And Red - Derestricted Sold!
Make: Suzuki GSXR 600 SRAD Year: 1998 Colour: Red - White - Blue
Pic of My New Bike!!

[Kickstart]

Hi

Personally I would suspect the jetting is miles out (or the choke sticking), given it is eating plugs that quickly and you have a non standard carb.

However what exactly does the bike do to let you know the plug is on the way out?

2 strokes do tend to eat plugs but they should last a couple of thousand km.

All the best

Keith
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[18_stuart_88]

Hi,

Its realy hard to describe how the bike runs when the spark plug is about to give up the game on me.

The only way i can describe it is, it does not run as smooth as it should and it is very rough and bumpy when i use the throttle, if i try to go above the power band it throughs the about the place backfiring and miss firing and puffing smoke everywhere.
Just the way it feels when your about to run out of petrolium.

Stu
____________________
Make: Honda NSR 125 R Year: 2004 Colour: Black And Silver - Died on December 18th 2005, Layed to rest December 30th 2005 :(Make: Aprilia RS 125 Year: 2000 Colour: Black And Red - Derestricted Sold!
Make: Suzuki GSXR 600 SRAD Year: 1998 Colour: Red - White - Blue
Pic of My New Bike!!

[Skunkcap Freddie]

Sounds like the jetting is way off mate.

what else is done to the bike . Exhaust,powervalve connected ?


have you checked what size jets are in the carb

[Rob W]

As the others have said, seems like your jetting is way off. When I got knocked off in July /something/ happened to my carbs, and the bike would never run smoothly. Used to bog down between 4-8Krpm, but above and below that it was fine. When the gasket blew and I had a good look at the pistons, number 1 was covered in carbon so it had obviously been running rich even though the jetting was standard and the carbs were balanced and had been cleaned/inspected literally about 10 times and I could see NOTHING wrong with them.

In the end I had to get a new set of carbs and that sorted the problem. Try finding some settings for your carb and try them, if not revert back to the original one, that may solve your problem.


____________________
'16 GSX-S1000F

[Kickstart]

Hi

From the description it sounds like the way a bike behaves when you leave the choke on too long.

For a 34mm carb on the RS it should be around a 1650~160 main jet. However that is only really going to be important on full throttle, and on a short commute to work you are probably nowhere near that. As such probably check the needle jet position.

Also check that the choke is not sticking on (possibly from an incorrectly routed cable, pulling it on when the bars are turned one way). The needle valve in the carb could also cause problems, but it this way the problem then parking up without swiching the petrol off would result in a flooded engine.

All the best

Keith
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[theshmoo]

Kickstart.

This is the same bike I was talking to you about before. The last owner changed the carb so it took a bit of time to work what was going wrong with it. The mixture screw was turning with the vibration from the engine now fixed. The bike choke works fine except the bike starts without it all the time due to having the wrong carb.

stu ask the old owner for the right carb but he was not forth coming with it.
____________________
CBR 1100 blackbird.

[Skunkcap Freddie]

you don't need the choke when you've a 34mm carb. The bikes run better with them on. better mid range, not as jerky. If set up correctly it'll run fine

[Kickstart]

Hi

In theory it should be worse at the bottom end and in the mid range with the 34mm carb.

All the best

Keith
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[tommyboi]

if you do end up selling give me a shout

[18_stuart_88]

There is no way the guy will give me the 28mm Carb Shmoo!

Kickstart + Skunkcap Freddie should the 34mm carb only be good for high speed riding? Or should it be ok with both High speed riding and town commutting?

I mostly do town commuting to and from work 5 days a week. Could this still be down to the Jets being set up wrong that this problem is still excisting?

I have emailed Matt Cooper i think it is at Dellorto to see if he suggests the problem could be down to my Jets and have asked him to give me a price and match of jets which would be suitable for my carb to make it run smoother and stop all my spark plugs fouling.

Stu
____________________
Make: Honda NSR 125 R Year: 2004 Colour: Black And Silver - Died on December 18th 2005, Layed to rest December 30th 2005 :(Make: Aprilia RS 125 Year: 2000 Colour: Black And Red - Derestricted Sold!
Make: Suzuki GSXR 600 SRAD Year: 1998 Colour: Red - White - Blue
Pic of My New Bike!!

[Kickstart]

Hi

Should be fine around town, just that the 28mm should (in theory) be better at low revs.

Jet wise my early RS has the 34mm carb as standard. Has a 155 main jet, K57 needle on the first notchand air screw 1.5 turns out.

Oh, and 2nd hand 28mm carbs are pretty cheap.

All the best

Keith
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[colin1]

my rs125 fouls my plugs quickly too
its got a 160 jet and so i dont think its running petrol rich
it could be im getting too much 2 stroke oil but i dont wanna reduce it much just in case i cause problems

so my solution is just get good at cleaning plugs

a brass wire brush loosens it, and then wipe it off with the scourer on a kitchen sponge

spend a bit of time regularly and itr wont get too bad

ideally u shdnt have to do this, but if you cant solve the problem (like me) just get good at cleaning the plug
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colin1 is officially faster than god

[Kickstart]

[18_stuart_88]

Hi Keith,

The problem tends to arrise when im riding normal likes commuting to work speeds of 30mph - 40mph.

So do you reckon this could be a Jetting problem. If i was to buy new jets from Dellorto and try that would it do any harm to the bike?

Do you know which jets i may need? The only engine modification i have to the bike is the 34mm carb.

Stu
____________________
Make: Honda NSR 125 R Year: 2004 Colour: Black And Silver - Died on December 18th 2005, Layed to rest December 30th 2005 :(Make: Aprilia RS 125 Year: 2000 Colour: Black And Red - Derestricted Sold!
Make: Suzuki GSXR 600 SRAD Year: 1998 Colour: Red - White - Blue
Pic of My New Bike!!

[colin1]

i had it worse when commuting too

One solution is to run with the plug type that is recommended for a restricted rs125, and never rev the engine very high. This is a hotter plug and so will burn off the carbon stuff but if you rev high, you will increase wear.

I didnt have to clean my plug so often when i was using the hotter plug.

I would always change to the normal plug before a ride in the countryside in which i wd be revving high.

standard plug is a 10 and recommended plug for a restricted bike is either an 8 or a 9 i forget which.
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colin1 is officially faster than god

[Kickstart]

Hi

Would guess that jetting is the main issue. Any idea what jetting you are currently running? What position is the clip on the needle jet?

Running a hotter plug round town will probably solve the problem. Trouble is that doing this at speed will not increase wear to the engine but instead result in the plug getting far hotter with the possiblity of it failing dramatically and expensively (more likely to just have the plug die).

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[18_stuart_88]

Hi,

It seems that the Carb has a 158 Main Jet in it.

any ideas?

Stu
____________________
Make: Honda NSR 125 R Year: 2004 Colour: Black And Silver - Died on December 18th 2005, Layed to rest December 30th 2005 :(Make: Aprilia RS 125 Year: 2000 Colour: Black And Red - Derestricted Sold!
Make: Suzuki GSXR 600 SRAD Year: 1998 Colour: Red - White - Blue
Pic of My New Bike!!

[Kickstart]

Hi

Possibly slightly large, but also pretty irrelevant on small throttle openings. The main jet is only really important above about 3/4 throttle. Needle jet is the important one probably for this problem.

All the best

Keith
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[NC30UK]

Surely a larger carb has a larger pilot jet, so the bike will be running constantly rich throughout the rev range?

[Kickstart]

Hi

Will only have an effect at low throttle openings. The amount of fuel that circuit supplies is so small as to be irrelevant at high throttle openings.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[18_stuart_88]

Hi,

So do you reckon i could try and fit a 148 Main Jet and see what diffrence that does to the bike?

Thats what the previous owner had with the Carb but then decided to change it to the large Main Jet.

Stu
____________________
Make: Honda NSR 125 R Year: 2004 Colour: Black And Silver - Died on December 18th 2005, Layed to rest December 30th 2005 :(Make: Aprilia RS 125 Year: 2000 Colour: Black And Red - Derestricted Sold!
Make: Suzuki GSXR 600 SRAD Year: 1998 Colour: Red - White - Blue
Pic of My New Bike!!

[Kickstart]

Hi

148 might help IF this problem is occuring when you are using large throttle openings. If it is happening when bimbling round (which is what you seem to suggest is happening) then it will have no effect.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[18_stuart_88]

Nice One! Youve been a Superb help Keith.

I'll let you know how i get on when i try new Jets.

Thanks

Stu
____________________
Make: Honda NSR 125 R Year: 2004 Colour: Black And Silver - Died on December 18th 2005, Layed to rest December 30th 2005 :(Make: Aprilia RS 125 Year: 2000 Colour: Black And Red - Derestricted Sold!
Make: Suzuki GSXR 600 SRAD Year: 1998 Colour: Red - White - Blue
Pic of My New Bike!!

[Kickstart]

Hi

Check the needle jet first. Easier to check and change than the main jet, and free to adjust. And far more likely to be the problem.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing