Suzuki TSR125 very odd running problem

[MattWadz]

Posting for a friend :

Suzuki TSR125 L reg
2 stroke
Liquid Cooled
6 speed
E/powervalves

the bike is a tsr125, on an L plate, just had a new piston kit but was still running crap before this. the bike is quite hard to start, and usually needs to have the throttle kept open a bit to start, once it does start the revs dont seem very responsive, it seems to rev a bit to slow and isnt 'crisp' as it should be?

Carb has been cleaned and inspected meticulously twice, reeds and reed block is fine, all gaskets are good, oil pump is working fine.

the carb settings are :

Needle : Middle slot (c clip)
mixture screw : 2 1/2 turns out
idle : wound all the way in and it still barely idles
Main jet is standard along with all the other jets, exhaust is also standard.

the bike will start more easily if the throttle needle is on the bottom notch allowing more fuel in, but still runs badly. tried various plugs all new and still no fix.

the bike has been fiddled with by some sort of 'chav' before and ive noticed that the intake manifold rubber has two pipe nipples coming out next to each other facing upwards, they both lead directly into the intake rubber but someone has cut a pipe and joined them together using the same pipe, if this is unplugged when the engine is running it automatically revs its bollocks off due to the increase of air.

anyone have any ideas?

Could this be a timing issue?

Thanks for reading my essay!



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Pitbike x2, Mini Moto x4, China Quad, 02' Suzuki AP50 > 03' MBK Nitro > 86' Suzuki GP100 > 02' Yamaha Jog R > 57' Honda Lead 100 > 95' Piaggio ZIP Rst 50 > 51' Suzuki TS50x > 83' Honda CB125TDE Twin > 51' Yamaha Aerox > 98' Kawasaki KX60 > 89' Yamaha DT50MX > 80's Honda QR50 > 05' CG clone > 125cc China Pitbike > 91' Honda MTX125 RW-L > 09' Peugeot Speedfight 2 LC LR > Lucky MX 140cc > Apache Tomahawk 50 Quad (current = 2010 Yamaha WR125R

[P.addy]

New piston kit, but have you checked the compression? Did you do the new piston kit or did said chav do it, honest, bruv.

[MattWadz]

yep we did the piston kit, got the right compression, runs the same! the old one wasnt even that bad, just changed it as we had a new one here. il upload pictures about the intake manifold in a minute!
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Pitbike x2, Mini Moto x4, China Quad, 02' Suzuki AP50 > 03' MBK Nitro > 86' Suzuki GP100 > 02' Yamaha Jog R > 57' Honda Lead 100 > 95' Piaggio ZIP Rst 50 > 51' Suzuki TS50x > 83' Honda CB125TDE Twin > 51' Yamaha Aerox > 98' Kawasaki KX60 > 89' Yamaha DT50MX > 80's Honda QR50 > 05' CG clone > 125cc China Pitbike > 91' Honda MTX125 RW-L > 09' Peugeot Speedfight 2 LC LR > Lucky MX 140cc > Apache Tomahawk 50 Quad (current = 2010 Yamaha WR125R

[MattWadz]

https://s1176.photobucket.com/user/MattWadz/media/TSR125INTAKE.jpg%20

https://i1176.photobucket.com/albums/x322/MattWadz/TSR125INTAKE2.jpg?t=1388699920%20
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Pitbike x2, Mini Moto x4, China Quad, 02' Suzuki AP50 > 03' MBK Nitro > 86' Suzuki GP100 > 02' Yamaha Jog R > 57' Honda Lead 100 > 95' Piaggio ZIP Rst 50 > 51' Suzuki TS50x > 83' Honda CB125TDE Twin > 51' Yamaha Aerox > 98' Kawasaki KX60 > 89' Yamaha DT50MX > 80's Honda QR50 > 05' CG clone > 125cc China Pitbike > 91' Honda MTX125 RW-L > 09' Peugeot Speedfight 2 LC LR > Lucky MX 140cc > Apache Tomahawk 50 Quad (current = 2010 Yamaha WR125R

[misscrabstick]

Those stubby things on the manifold I would guess that they are supposed to connect to some sort of plenum chamber thingy, at least that is what I have seen in the past.

Perhaps Mr Chav has thrown the plenum away and put some old crap bit of pipe on it? I do wonder if your engines running lean due to a defective crank seal perhaps on the flywheel side? maybe it's sucking in air through that? I'd expect tons of smoke if the primary drive seal was defective.

If you do have a defective flywheel side crank seal I would expect some oiliness around the insides of the flywheel/coils and maybe feel some puffing if the engines running?

[misscrabstick]

Ohhh I also see orange gorilla snot gasket goo between the crankcase halves!!! uhoh!

[bladerunner]

The intake manifold pipe is suzuki's version of yamaha's boost bottle found on the lc's. Same as the RGV250.....they just use a length of tube to absorb the kinetic energy of the intake charge and in theory dump that same charge back into the intake when on the intake stroke. It does look odd if you've not seen it before but that's how it's supposed to be. It does sound like you've got a lean mixture on the idle circuit thus better if you lift the needle....so if you don't have air leaks or bad crank seals. Try turning in the air screw by a turn and see if that helps. Not unknown for it to be that simple sometimes!

Edit. On the track RGV's a std mod was to cut a pipe as short as possible to link the 2 intake holes together.....mostly because we set them up for WOT and little else so harmonics or road manners was not an issue.
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Current bikes...cbr929, KDX200's, Rd125lc mk2, RGV250's

[MattWadz]

So that pipe should be longer than t is ? It has been shortened because its kinked! Will make it leaner tomorrow and reply back


Thanks all!


____________________
Pitbike x2, Mini Moto x4, China Quad, 02' Suzuki AP50 > 03' MBK Nitro > 86' Suzuki GP100 > 02' Yamaha Jog R > 57' Honda Lead 100 > 95' Piaggio ZIP Rst 50 > 51' Suzuki TS50x > 83' Honda CB125TDE Twin > 51' Yamaha Aerox > 98' Kawasaki KX60 > 89' Yamaha DT50MX > 80's Honda QR50 > 05' CG clone > 125cc China Pitbike > 91' Honda MTX125 RW-L > 09' Peugeot Speedfight 2 LC LR > Lucky MX 140cc > Apache Tomahawk 50 Quad (current = 2010 Yamaha WR125R

[bladerunner]

Yup so Long as it does not leak tbh it makes stuff all difference Suzuki even made an intake manifold with no brass outlets available from the race kit catalogue for the RGV. I can't say for sure with the TS carb but it's richer you want to make it....the screw is an air bleed jet..ie more turns out allows more air in rather than fuel so screwing it in makes it richer not leaner....which sounds like what you need. Also hope you set up the power valves properly if you fitted the new piston as these fail easily if setup wrong....and they need setting up with the exhaust off the bike as due to play in the pulley due to wear makes the factory stamped marks pretty off the mark. .....single Grey wire on the TSR under the tank/ air box area is used to earth the power valve controller in the closed position ....unplug that also gives you a working power valve !!!
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Current bikes...cbr929, KDX200's, Rd125lc mk2, RGV250's

[misscrabstick]

Idle air screws only do anything up to about one eighth of the throttle, after this the needle position regulates the mixture, then the cutaway profile of the slide and then the main jet size at around three quarters to flat out.

Check the main jets very carefully, it is not unknown for the hole to be way smaller than it should be due to being partially full of old gungey poo from dried up fuel.

[evoboy]

Is the exhaust coked up? Is the float height correct?

Have you checked the crank seals? Its been apart before so they may not have been installed correctly?

It does sound lean. Does it run any different on choke?
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Suzuki GT250 x7------- Fazer 600------CB250RS------Aprilia Rally 70----- Bandit 600

APT Motorcycles

[bladerunner]