gs125 running problem

[headless]

i've got a gs125 fitted into a cagiva frame and up to now i can't get it to run any good it'll start and rev to about a quarter turn on the throttle (sorry dont have a rev counter fitted) it doesn't have its original air box cause theres no room for it so instead it has a ramair foam style one fitted
would it help if i adjusted the fuel/air mixture or re-jet it to suit the filter? not to try get any more power out it (as if) i just want it to run and drive smooth

can anyone help?

Dave

[John Hopkins]

are you sure it's a genuine GS125 and not one of those Chinese copies.. Not that I can help but if it is a chinky crap engine you might be wasting time and effort..timing is always out on them and the bearings are made from leftover takeaways..

John.

[headless]

its definitely a genuine suzuki :thumbu:

had the question posted on another forum and i've been told to up the jet size about 15%ish

Dave

[Grav]

Sounds about right.

[matthewmosse]

What age engine? the more modern ones seem to have narrower bore pipes and are apparently well down on power, I'd geuss the modern emisions regs led to strangled preformance compared to older models - Just a thought and depends on the engine age / pipes fitted?

[headless]

it came out a 2002 model and it has a cv carb and a home made front pipe from a cx500 and the original twin silencer

Dave

edited to say the twin pipe was off a cagiva roadster 125

[dodgyphil]

SO what happened to the rest of the cagiva roadster?
Phil

[headless]

the top end went and i didnt have the money to repair it sold it for 200 bought it back for 20 with a gs engine :thumbsu: and fitted it

http://i190.photobucket.com/albums/z5/gsfighter_2007/Photo0005.jpg

Dave

[matthewmosse]

Nice looking project. Fraid I've none expirience with those more modern carbs, mine was a 1981 model so had a different carb setup but had similar airbox issues once - was not getting enough air, when you thrashed it properly down a hill it would pick up and rum ok but flamed from the exhaust somit chronic, a freeer flowing air filter sorted that one.........

[kajir]

a foam filter may not give enough vacuum to open the carb cv slide properly, try covering the filter with a bag with a few holes in it and see if that helps. You may have to make a small airbox if this is the case
good luck mate

[PeteHaddock]

this reminds me of a field bike i had years ago with a honda 125 engine. It had the same problem in that the original airbox didnt fit in the frame so fitted a little k+n style filter. engine ran shit until we took a tupperware pack up box and drilled holes in it before mounting it over the filter so if the bag idea works that could be a more permanent solution.

[headless]

so i went from a 102.5 to a 122.5 jet these are keihin jets and to be honest i'm not sure if i've got the jump up in size right
this is the chart i found

Width------Keihin # -- DynoJet # -- Mikuni #
0,0350---- 92,5--------- 92----------- 86,3
0,0360---- 95----------- 94----------- 88,1
0,0370---- 97,5--------- 96----------- 90,0
0,0380---- 100---------- 98----------- 91,9
0,0390---- 102,5------- 100---------- 93,8
0,0400---- 105--------- 102---------- 95,6
0,0410---- 107,5------- 104---------- 97,5
0,0420---- 110--------- 106---------- 99,4
0,0430---- 112,5------- 108--------- 101,3
0,0440---- 115--------- 110--------- 103,1
0,0450---- 117,5------- 112--------- 105,0
0,0460---- 120--------- 114--------- 106,9
0,0470---- 122,5------- 116--------- 108,8
0,0480---- 125--------- 118--------- 110,6
0,0490---- 127,5------- 120--------- 112,5
0,0500---- 130--------- 122--------- 114,4
0,0510---- 132,5------- 124--------- 116,3
0,0520---- 135--------- 126--------- 118,1
0,0530---- 137,5------- 128--------- 120,0
0,0540---- 140--------- 130--------- 121,9
0,0550---- 142,5------- 132--------- 123,8
0,0560---- 145--------- 134--------- 125,6
0,0570---- 147,5------- 136--------- 127,5
0,0580---- 150--------- 138--------- 129,4
0,0590---- 152,5------- 140--------- 131,3
0,0600---- 155--------- 142--------- 133,1
0,0610---- 157,5------- 144--------- 135,0
0,0620---- 160--------- 146--------- 136,9
0,0630---- 162,5------- 148--------- 138,8
0,0640---- 165--------- 150--------- 140,6
0,0650---- 167,5------- 152--------- 142,5
0,0660---- 170--------- 154--------- 144,4
0,0670---- 172,5------- 156--------- 146,3
0,0680---- 175--------- 158--------- 148,1
0,0690---- 177,5------- 160--------- 150,0
0,0700---- 180--------- 162--------- 151,9
0,0710---- 182,5------- 164--------- 153,8
0,0720---- 185--------- 166--------- 155,6
0,0730---- 187,5------- 168--------- 157,5
0,0740---- 190--------- 170--------- 159,4
0,0750---- 192,5------- 172--------- 161,3
0,0760---- 195--------- 174--------- 163,1
0,0770---- 197,5------- 176--------- 165,0
0,0780---- 200--------- 178--------- 166,9
0,0790---- 202,5------- 180--------- 168,8
0,0800---- 205--------- 182--------- 170,6
0,0810---- 207,5------- 184--------- 172,5
0,0820---- 210--------- 186--------- 174,4
0,0830---- 212,5------- 188--------- 176,3
0,0840---- 215--------- 190--------- 178,1
0,0850---- 217,5------- 192--------- 180,0
0,0860---- 220--------- 194--------- 181,9
0,0870---- 222,5------- 196--------- 183,7
0,0880---- 225--------- 198--------- 185,6
0,0890---- 227,5------- 200--------- 187,5

the bike now runs but is hard to start,
when i put the choke on its fires only for a couple seconds,
i have to do that a few times then put the choke off and it starts after turning over a couple times and then it pulls ok on low revs then starts to die mid revs and only if you open the throttle full it will pull up the rev range
and i should also mention that i changed the filter to a k&n style one and i needed to tape about 95% of the filter up to get the bike to run at all

can anyone help me with this?

Dave

[bird]

have you considered changing the carb? as both air intke and the zorst have been buggered about with it might run better with an old style slide jobbie, and you could pick one up for the price of a handful of jets:

http://cgi.ebay.co.uk/Motorcycle-Carburettor-Suzuki-DR125-GS125-Slide-Type-/350428884898?pt=UK_Motorcycle_Parts&hash=item5197306fa2

[headless]

right got a big improvement i took the carb off and went to find the size of the pilot jet and how many turns out the mixture screw was out

started with the mixture screw and it wouldn't move :mad:
then turned my attention to the pilot jet to see what size it was and noticed it had a rubber plug over it as standard,
i thought i'd remove it and try that i took the bigger main jet out (122.5) and replaced the original one (102.5)
left the air filter taped up it ran about the same as i was getting before so i took the filter off and it started running great, then took it for a run to see what it was like under load and it was great apart from a little flat spot but i hardly notice it when i'm driving

so great result

Dave

[wurzel]

I am using one for commuting - it too had a huge flat spot from 5-7k that it would not pull through in 3rd - swapped up 1 jet size and it is cured.

I am also now getting stupid mileage from a tankful even lugging my 15+ stone (as in 206 miles from last tank) even though it tends to get ragged to hell as only way to make progress