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JCL MP250A Lihai 257cc powered Just did an oil change on my JCL and made double sure not to over fill it to get that out of the way right off. Went for a quick 5 mile rounder on her and right before I got back to the house I hear a loud hissing sound over the motor sound for about 5 or six seconds then the scooter quit pulling. Oil all over the CVT .Someone please tell me there is a replaceable shaft seal from the outside of the engine under the variator. I have not done a full investigation but I think this is where it is comeing from. Has this ever happened to anyone else ?

What you said all makes for good logic to me jct .

I do know that I had a KZ 650 with stock bore "But" It had a 3/4 cam installed (what ever a 3/4 cam was), jetted, and a Kirker header. And if I remember right some head work done. All the work was done by a professional. I bought the bike that way in a distress sale for $600 back in about 84. It was a 79. Anyway, this bike was one of the baddest arse bikes in Fort Lauderdale at the time. It took a worked up Kawi 900 to take me "not stock, no way". Everyone that liked bikes wanted my bike. Finally someone stole it. Anyway, The moral of the story here is " Breathing, breathing, breathing. Thats what makes noticeable HP. Not fairly small displacement gains. Just like Cyborg has mentioned above. So I certainly agree with you Cyborg. Now ! Where can I find a cam for this thing that will make higher RPM power.

After all this time no one has ever bought and/or installed this rather expensive mod ? I want to buy and install the big bore kit on my JCL MP250A Linhia scooter engine. But I have absolutely no verification how it will effect my performance. It has been quite a while since I've been looking for the elusive person that may have bought one of these. Still no one has one huh ??

You got me wanting to get a KLX 250 instead of a scooter. I want to get one and lower it, Make the swingarm longer and put a CVT on it. So I can have my cake and eat it too. What is the HP on a Kaw 250 single like yours ?

JCL MP250A Lihai 257cc powered / This is how it all ended up here. This info is not for a 50cc-150cc scooter. They are a different animal in some ways to the Yamaha 250 / Linhia powered scoots. I have come to the conclusion that my 257cc Linhia will not go any faster on the top end without a meaningful power upgrade. Like a "real" 295 cc (300) cylinder / piston change plus maybe a little upjetting ? It just dosn't have the torque in its present form to go any faster than 68 mph with my 270 lbs , head right up in the wind resistance situation. I don't care what I do to my variator it just can not change this fact. But I have learned a lot about what works and what is a waste of time. #1 Forget about a bigger or a performance carburator if you don't improve your flow in some meaningful way ie: porting your head and exchange some torque for HP , And get an open / noisy exhaust and and lets not forget a performance pod style airfilter, also more noise. Yes , your intake makes noticable noise with no airbox. " It will sound faster " with just a pod airfilter and a more free flowing exhaust, But in reallity the numberes will change no more than slieghtly if at all. But if you are young and like to be noticed this may have some value. #2 Variator changes gave" ME " (big and heavy) no more top speed. But if a rider is much lighter than 270 lbs. this is what you want to do. #1 On the variator improvment, Shorten your variator boss by 1 1/2 mm do not exeed 2 1/2 mm shorter than stock or your belt will almost climb off your variator at top speed. This will allow your variator to reach its full out high gear. In stock form they stop short of this. #2 on the variator improvement, Exchange your 14 gram rollers for 11 gram "sliders" This will give you everything this motor can offer (with the boss mod too) IMO. I have four 12 gram sliders and four 11 gram sliders. This is what I personally want because I am going to get more power in this engine in the near future. But number 2 will keep you in the higher RPM for maximum excelleration and number 1 will give you full top end capibillities. You CAN have the best of both worlds this way.

Read more: itistheride.boards.net/thread/9619/mph-more-great-257cc-linhai?page=5#ixzz4PQde3hJC