Increase performance?

[30-Arider]

Im one of those guys always looking to go faster. So after reading about the mods on here with exhaust and intake, with people looking for that little bit extra..... I was inclined to put an email into a long time guy Ive delt with for over 20 years at LA Sleeve. Over the years on many bikes I have sent out a cylinder, piston and head and typically turn around time was 2-4 weeks. This has resulted in increasing a motors cc up 25-75 cc. I have made 125's up to 150cc, 250's to 300 etc.

So the email I sent was a descrition of the Lifan motor; its bore and stroke dimensions to see if it is possible to increase the cc's of the motor with maybe an aftermarket bit from Weisco for example to fit an XR250 etc.... by 25-50cc which would provide a whole lot more grunt...that is if the bottom end can handle it.

Once I get a responce I will let the board know. If this is do-able it would be very interesting to see how well one of these bikes would perfom...Talk about creating a dual sport China sleeper. Can I hear wheelies at will?

[red2003]

I think the lower end will take it easily as long as you didn't spin it any higher, and kept the piston weight the same. I would think a 250 cc bore job, head porting, larger valves, bigger cam, the lifan 30 mm carb, and a good aftermarket exhaust would net 22 - 25 HP. The trouble is you just doubled the cost of the bike whose primary benifit is affordability. But these exact thoughts have been coursing through my mind since I've owned the bike. I say, "GO FOR IT". Your bud should produce a bolt on big bore kit. I'm sure it would sell.

[30-Arider]

Originally Posted by red2003

I think the lower end will take it easily as long as you didn't spin it any higher, and kept the piston weight the same. I would think a 250 cc bore job, head porting, larger valves, bigger cam, the lifan 30 mm carb, and a good aftermarket exhaust would net 22 - 25 HP. The trouble is you just doubled the cost of the bike whose primary benifit is affordability. But these exact thoughts have been coursing through my mind since I've owned the bike. I say, "GO FOR IT". Your bud should produce a bolt on big bore kit. I'm sure it would sell.

All good points. To keep it all affordable only only go up 50cc, with exhaust mods (preferably a new slip on muffler or removal of baffles, Air Box and filter change and jetting up all keeps intak eand exhaust mods on the low side cost wise. Id wouldnt bother with any porting, increaed valve size without a cam change and like you said thta will cost too much. Im thinking basic resleeve for an additional 30-50cc. I think basic air filter change, exhaust mod of stock system and jet change in carb should be good enough to make it feel like adifferent motor. My worry is only bottom end cause Weisco is typicaly 90% of the time the #1 most common used piston. They are forged and weigh a lot more which equals more crank and rod bearing stress. When I emailed my buddy I told him Id rather go with something like a Pro-From similar to a stick drop cast slug or even if possible a stick Honda piston in the 230-250 cc range. Im guessing his first respnse is gonna be to take a micrometer to measure the distance between the wrist pin and the top and bottom of the stock piston. I'll keep you informed asI get info RED.

[red2003]

I would be more worried about a balance issue with a heavier piston. I bet you could get a custom piston made to whatever specs you need, and they could build it light to match the stock weight. Since you already have the bigger Lifan carb, you could go to 250 cc, port the head yourself, do a pod air filter and slip on muffler. I bet you'd be right around the 20 HP range, and that most certainly would be noticable. Go for it man!!!!

[deputygene]

I think it would work, I would like to see 50cc more oomph also. Over on the Hyosung site, (I know, different motor) the dealers in england will bore out their XRX 125 to a 150 with a Honda piston, or 175 with, I think, a Suzuki piston.

[blimpman]

Originally Posted by 30-Arider

Im one of those guys always looking to go faster. So after reading about the mods on here with exhaust and intake, with people looking for that little bit extra..... I was inclined to put an email into a long time guy Ive delt with for over 20 years at LA Sleeve. Over the years on many bikes I have sent out a cylinder, piston and head and typically turn around time was 2-4 weeks. This has resulted in increasing a motors cc up 25-75 cc. I have made 125's up to 150cc, 250's to 300 etc.
Can I hear wheelies at will?

I think a little more performance could be had but why? We didn't pay alot of $$ for these bikes in the first place. If you wanted a 20-30 HP bike you could have bought a used XR or DR or KTM or KLR and had a real performance bike for not alot more $$. In my opinion, that is not what these bike stand for at this point. They are just a basic, decently performing street/trail bike. Not one to ride on the MX track or do wheelies and jumps on. I guarantee you they won't take those stresses very long. You would be better off $$ wise in putting in stronger fasteners all the way around, better chains and sprockets, better tires & tubes thereby making the bike last longer as it is.

5 years down the road from now the Japanese will have very stiff competition.....

[30-Arider]

[quote="blimpman"]

Originally Posted by 30-Arider

I think a little more performance could be had but why?

*****for the sake of doing it....that is how all performance upgrades begin. How many motorcycles produced in the last 30 years have not had some sort of performace uprgrade added..none that I cant think of. Even the Pitster Pro my wife rides on a Moto Cross track has upgrages to make the engine go from 125 cc all the way up to 185cc big bore kits.

We didn't pay alot of $$ for these bikes in the first place. If you wanted a 20-30 HP bike you could have bought a used XR or DR or KTM or KLR and had a real performance bike for not alot more $$.

***I disagree with the statment not for a lot more unless I was gonna buy a bike at least 10 years old and thrashed. And I do already have a permformace bike...and I personally dont think any amount of cc's is gonna make this a performance bike..... just due to the limited rigitity of the frame, poor welds, and limited rear suspennsion; but I understand and repscet what your saying


that is not what these bike stand for at this point. They are just a basic, decently performing street/trail bike. Not one to ride on the MX track or do wheelies and jumps on.

*****I agree its a basic trail bike....but regardles of the added power if you hit a triple on this bike with a 50cc motor or 250cc you and I both know its gonna hurt this bike bad. I dont think 50cc increase is gonna do anything but wear the heck out of some chanins and sprockets faster.


I guarantee you they won't take those stresses very long. You would be better off $$ wise in putting in stronger fasteners all the way around, better chains and sprockets, better tires & tubes thereby making the bike last longer as it is.

5 years down the road from now the Japanese will have very stiff competition.....

***Time will tell on that one.

Again I understand and respect your opinions and where your comming from...there is a lot of truth in what you say. I may very well learn the hard way...but I just cant leave well enogh alone. If I can make it produce more torque with more cc's and the bottom end can handle it Im gonna try it.

[frostbite]

Again I understand and respect your opinions and where your comming from...there is a lot of truth in what you say. I may very well learn the hard way...but I just cant leave well enogh alone. If I can make it produce more torque with more cc's and the bottom end can handle it Im gonna try it.

Not everyone who purchases these bikes is looking for cheap transport or a low budget DS ride (for me its both). Some purchase them because they're a cheap ride to experiment with. If you blow a piston through the tank you're 'only' losing about a grand USD, much less $$$ than doing it to a CRF230, and you learn something along the way.

I say go for it, but I'd have that flame retardant jock strap ready.

[30-Arider]

[quote="frostbite"]

Not everyone who purchases these bikes is looking for cheap transport or a low budget DS ride (for me its both). Some purchase them because they're a cheap ride to experiment with. If you blow a piston through the tank you're 'only' losing about a grand USD, much less $$$ than doing it to a CRF230, and you learn something along the way.

I say go for it, but I'd have that flame retardant jock strap ready.

Ok the flame retaradant jock strap is a good one...very funny. I dont even think Id be out a grand...how much is it you can purchase a replacement Lifan 200 cc motor for ? About 5-600 correct?

[blimpman]

I'd agree that people use these bike for many different reasons.... I'd get asbestos socks too....

Please post all the experiments! It will improve everyone's knowledge. Basically the true reason for this site, right? It's all good!!

[quote="30-Arider"]

Originally Posted by frostbite

Ok the flame retaradant jock strap is a good one...very funny. I dont even think Id be out a grand...how much is it you can purchase a replacement Lifan 200 cc motor for ? About 5-600 correct?

[30-Arider]

[quote="blimpman"]I'd agree that people use these bike for many different reasons.... I'd get asbestos socks too....

Please post all the experiments! It will improve everyone's knowledge. Basically the true reason for this site, right? It's all good!!

[quote="30-Arider"][quote="frostbite"][quote]


*****Hey I may not have to experiment much cause it seems we have quite the mechanical technician on here already...on another thread someone claims to have ported and polished thier head, removed the Choke (Ive never owned a 4 stroke that starts well without a choke but what do I know), advanced the timing etc.

[red2003]

On a serious note, I have given this some extra thought. Using low cost vs performance as my premise, I put this thought out there. How about leaving the cc's at 197? No matter how you ramp up the displacement to 250 +, it's gonna be pricey. And, increasing the displacement without increasing the surface area of the engine for cooling purposes is asking for trouble. How about some head work? I did up the numbers quick and .033 shaved off the head will take the 9.2:1 CR to 10.5:1. That's about the safe limit of an air cooled engine on pump gas (super). While the head is off, hog out the ports and valve pockets as much as you feel safe doing, then a little bit more . Don't have to worry about coolant leaks so go crazy with the die grinder, but the material around the valves IS important to avoid heat cracking. Add an aftermarket CDI box (an XR200 box will work, I believe). This alone should give quite a bit more top end and let the motor spin up to 9500 rpm or so. I think it'll take those revs and not break. For sure this would be complimented with air intake and exhaust mods, but those are cheap enough. I bet you could get some pretty decent umph for a few hundred bucks. Thoughts???

[jkomp316]

If I end up breaking my motor after a year. I will buy another off ebay and rebuild the broken one like that. Port/polish, shave, ect. Its too cheap to not experiment with.

[TeamCheap]

Ok well first off I'm not big into engine rebuilding so school me please on these thoughts.

First thought/question:

how hard is it to rebalance an engine?
If a larger/heavier piston is used can the engine be brought into balance or is it just a pure match up game?

second (silly, simple) thought/question:

Does anyone have one of the 250cc engines out there to compare to the 200cc, how much of a difference is there between the cylinder/heads.
I know a lot of things would have to come together but I wonder just how much they changed the 200cc and 250cc engines.

Thoughts anyone?

[30-Arider]

Originally Posted by red2003

On a serious note, I have given this some extra thought. Using low cost vs performance as my premise, I put this thought out there. How about leaving the cc's at 197? No matter how you ramp up the displacement to 250 +, it's gonna be pricey. And, increasing the displacement without increasing the surface area of the engine for cooling purposes is asking for trouble. How about some head work? I did up the numbers quick and .033 shaved off the head will take the 9.2:1 CR to 10.5:1. That's about the safe limit of an air cooled engine on pump gas (super). While the head is off, hog out the ports and valve pockets as much as you feel safe doing, then a little bit more . Don't have to worry about coolant leaks so go crazy with the die grinder, but the material around the valves IS important to avoid heat cracking. Add an aftermarket CDI box (an XR200 box will work, I believe). This alone should give quite a bit more top end and let the motor spin up to 9500 rpm or so. I think it'll take those revs and not break. For sure this would be complimented with air intake and exhaust mods, but those are cheap enough. I bet you could get some pretty decent umph for a few hundred bucks. Thoughts???

Great idea's. I do beleive the increased compression will be somewhat more abuse on the bottom end, but minimally...I think its all good idea.
For me though, Im a no replacement for discplacement kind of guy. I think a piston even if an expensive Weisco, with being resleeved wont be much more than max a $300 investment as well. Im not one who is big on high RPM power unless its s motocross bike....but for a dual sport or enduro kind of bike Id much rather have the increased power down lower in the RPM range from CC's instead of increased RPM ability. Just my taste is all. Like I said Im waiting to hear back from my LA sleeve connection on this.