General engine Mods/ upgrades

[tmcpherson]

This summer I got a SSR 125. With a simple engine, it is easy to mod/upgrade and see improvements. This post is to show what I'v done to the engine, and to maybe help people see ways they can do the same.


1. First step was air. I put on a two stage air filter. This was simple and easy, add oil to the filter and your done aside from small jetting.

2. Next step was the carb. The stock carb is very odd and hard to find jets for. I bought a mikuni vm22. This new carb has good quality and easy to find parts for. IT DOES HAVE A DOWN SIDE. The air crew is on the bottom of the carb. This makes it very hard to adjust. There are other brands that are easyer to use. The mikuni does work though.

3. Porting the intake. I started with the stock intake and a half-moon shaped file. Then held it up to the engine intake port and determined how much to shave off. I continued to shave off the intake till it reached the same size as the engine port. Then I flip it around and started again on the other side. This took an hour or more with some patience. Jetting is needed and you can feel the engine rev faster and the RPMs climb better.

4. Porting the exhaust. This is similar to the last step, but not as hard I think. In the stock exhaust, there is a weld made that is large and all the way around the circumference of the exhaust tubing. It can give you a little better flow and some similarly faster reving.

5. my last step is a racing CDI. I know many people feel they aren't worth doing, But I tried it anyway. I took the old cdi off, fitting the new "racing" one on and started the bike.(the bike was warmed prior.) I noticed the bike ran a bit smoother and the bike also revved a bit faster too. I think for the price these cdi's are on ebay, they actually can work. I didn't think it would at first, but I cant change what I saw.


I hope people like what I'v done and have questions or more ideas. These were the engine mods/upgrades that I think are best "bang for your buck", I totaled less then $100 and saw a big different in the bike.

Thanks - Tom

 

[tmcpherson]

 

[mikkh]

These mods will kill longevity on these 125cc primary clutched engines. My record was 2 hours of riding time before the clutch basket exploded and took the side cover with it. My advice is to buy a secondary clutched engine (I am currently thinking about how to convert primary clutched engine to secondary clutched for cheap).

These racing cdi´s are bling parts. You would get real difference using the 8pin CDI style ignitons which indeed advance ignition curve.

 

[gottagetacheaperhobby]

The mods the op has done shouldnt hurt engine longevity, from the research I have done you can get to around 12 to 13hp out of the crank mounted clutch engines before they pop, and he would of only gained 1 (at the most 2) hp from his mods.

 

[tmcpherson]

I know for a fact that the mods I'v done haven't hurt my engine. I'v been riding hard on this engine for about 3 months and it hasn't shown any kind of damage. The oil doesn't have any metal flake in it either so thats a good sign too!

I wish I had a dyno, not that I would matter really, but its always cool to see your improvements.

 

[tmcpherson]

I'm not sure how to set up an 8-pin cdi on a lifan style engine. My ssr has a 6-pin cdi. I don't know where the other 2pins would come from

 

[my67xr]

Welcome to Minirider's.

Make sure you drop by in to our Introduction's thread and say hello there.
Introduction's thread




Horsepower at the rear wheel on a Lifan 125 is around 8hp - 9 hp, iirc they were rated at 10hp or 11hp at the engine.

If you are going to use the 'performance cdi' take your old one with you too when you go out ring, they usually don't last.
A lot of them are set up for 2 stroke scooter's so the timing is wrong in them too

Tuning the chinese Mikuni is easy enough, you just need to make a simple tool to do it.
Grab a 6" long piece of pvc tubing and a small flat head screwdriver bit.
Heat up the end of the tubing with a lighter etc and push the driver bit into the end, and that's it.
It make's tuning these Mikuni's a simple job.




The other thing i've found with the Mikuni 22/26 is the Pilot jet is too small (#15), it make's starting them hard then you need them to warm up for a while before you can use the throttle/
And most bike's using them seem to have a decent flat spot when cold as well.

If you replace the #15 pilot jet with a #20 it totally change's the way the bike start's and run's, it will be a lot smoother and easier to start, it'll have no flat spot's and ride a hell of a lot smoother.
A new pilot jet is about $5 - $10 from most bike shops, the part number you need is VM28/486 - 20
While you have the carby apart fitting the new jet, take the top off the carby and remove the slide, pull the needle and retainer out.
Then pop the clip off the middle notch, and refit the clip on the needle on the next one up, so it's on the second notch down.
It will need a quick adjustment of the mixture screw and then you're ready to try it out.

Fitting a new high comp piston will do wonder's for your bike as well,
and replacing the cam with something like the Z40 along with some better valve spring's will help make a bit more power


You need to use a Lifan 150 stator or a Z160HO stator to use the 8 pin digital cdi on your 125.
They will make the bike rev a little quicker, so it'll be a bit more responsive and make your kick start gear's last longer

The other upgrade i'd do is to fit a better/forged kick starter, you can get them pretty cheap now day's
Being in the US i'd look at the TBoltus website or ebay

When you get a chance check the valve/rocker clearance's and adjust them if neccessary, .003" on the inlet and .004" on the exhaust, do this at tdc on the compression stroke.
The carby might need a tweak after adjusting them to get the best out of it.

Other thing is the give it an oil change,
take the clutch cover off and clean out the oil strainer screen at the front bottom of the engine (above the sump plug)
While it's apart take the clutch outer plate off (4x screw's) and clean out the sludge in the centrifugal spinner filter too.


Cheer's, Craig

 

[motodevo]

These mods will kill longevity on these 125cc primary clutched engines. My record was 2 hours of riding time before the clutch basket exploded and took the side cover with it. My advice is to buy a secondary clutched engine

Any primary clutch engine will grenade the clutch quickly if held at high revs for prolonged periods. Altering gearing to suit your riding style can help keep you from revving the ring out of your bike regularly
The mods listed a good value ways of gaining a bit extra for minimal cash. I don't trust cheap cdi's as from past experience i have found they seem to sh!t the bed in no time flat. As for porting the intake, you want to make sure the heads intake hole is a little bigger than the manifold there is a little bit of play in the mount holes on the manifold, if it twists slightly when you torque it down you don't want a step between the manifold and head, this step will hurt airflow and have made all the porting a waste of time.

 

[velociraptor]

Do what you want with your own motor...support your local parts store.[emoji85]