I want about 5 MPH more top speed on my JCL MP250A By 4950cycle (Read 3,385 times)

[4950cycle]

I was told the quickest and one of the easier ways to get quicker acceleration and / or a bit more top end is to modify the variator on a scooter CVT. I myself am plenty satisfied with my acceleration. Even with my 260 lbs. 6 '2 self. But I would like a wee bit more top end. The only aftermarket variator I could find for a 257cc (260) Linhia engine was a Doctor Pulley Linhia " ATV " variator on Ebay. Now I know the Starter clutch for a 260 Linhai "ATV" has more spline teeth than a the Scooter 260 . I wonder if the variator has differences also ? And could I eeeak 5 more MPH with a variator and slider modification even so ? Any feed back fellow Scoots ? btw I go 63-67 mph now per scooter speedo. PS I've decided to go for a 32mm Performance carburetor instead of my stock 30 mm. And some Dr. Pulley sliders instead. Waiting on the 32 carb now. Haven't ordered the sliders yet. One thing at a time I say.

Read more: itistheride.boards.net/thread/9619/mph-more-great-257cc-linhai#ixzz4Gra5mUt3

[jct842]

First thing I would look at is the rpm at the top speed you get now. Depending on if it is wound out or not to decide on what weights you have and what you need to go to. If you don't have a tach get one on there. If you are a whole lot under red line you need to go lighter in weights which is what I would suspect.

Doubt if you will be happy with a larger carb with out doing other mods to go with it. Jetting is usually all that is needed.

[4950cycle]

BTW, Thank you for responding. I believe you are right in saying basically "lets see what the motor is doing during top end first" Then change RPM per speed (sliders) once we know something. Is that what you are saying ?

[jct842]

First of all what is the rpm at top speed? Do you have any big hills or are you riding in pretty flat territory? Any Idea what the weights are in your variator? Is your belt fairly new and good condition?

If you go lighter with weights/sliders it is like going to a lower gear. Heavy weights similar to shifting from 4th to 5th gear. You only have so much power and if geared to high you can go slower. Geared to low and you run out of rpms before you get to the speed you want.

Open up the variator and find what their weights are. Clean it out and then take a ride and note the rpms at top speed and get back here with results. If it is gunked up you may be surprised.

[4950cycle]

The scoots onlys got 7,000 miles on her. I doubt she's got much wear or gunk built up. Got my Gel Batt finally. She ran pretty good yesterday after a fresh fill up of BP premium. The scoot tach said 6900 RPM at speedo indicated 68-69 mph. So I checked stock Linhia 257 cc specs and they said 16.7 hp at 6500 rpm. So, what this tells me is is I'm most likely already getting all she has to offer with me being so big and such. No ? Or should I hope I can over rev her a bit for lets say 74-75 mph ? I'd be plenty happy with almost 75 mph without being in a tuck. And small rolling hills with some flat sections BTW. Thanks so much for the coaching PS. the motor is not buzzing that bad at 6900 RPM 8,000 red line btw.

[4950cycle]

Aug 10, 2016 12:13:25 GMT -6 jct842 said:

First of all what is the rpm at top speed? Do you have any big hills or are you riding in pretty flat territory? Any Idea what the weights are in your variator? Is your belt fairly new and good condition?

If you go lighter with weights/sliders it is like going to a lower gear. Heavy weights similar to shifting from 4th to 5th gear. You only have so much power and if geared to high you can go slower. Geared to low and you run out of rpms before you get to the speed you want.

Open up the variator and find what their weights are. Clean it out and then take a ride and note the rpms at top speed and get back here with results. If it is gunked up you may be surprised.

The scoots onlys got 7,000 miles on her. I doubt she's got much wear or gunk built up. Got my Gel Batt finally. She ran pretty good yesterday after a fresh fill up of BP premium. The scoot tach said 6900 RPM at speedo indicated 68-69 mph. So I checked stock Linhia 257 cc specs and they said 16.7 hp at 6500 rpm. So, what this tells me is is I'm most likely already getting all she has to offer with me being so big and such. No ? Or should I hope I can over rev her a bit for lets say 74-75 mph ? I'd be plenty happy with almost 75 mph without being in a tuck. And small rolling hills with some flat sections BTW. Thanks so much for the coaching PS. the motor is not buzzing that bad at 6900 RPM 8,000 red line btw.

Read more: scooterdoc.proboards.com/thread/13008/mph-more-top-speed-mp250a#ixzz4H8IJdo8O

[jct842]

Yea your pretty much there as far as power. jetting and air cleaners and exhaust might give a bit more power.

There is one other suggestion, pull the cover over the variator and use a marking pen to put a bunch of lines from the center of the inside of pulley to the outside rim. The idea is to see if the belt is going all the way to the top of the pulley. (Then you take it out for a ride at top speed) When it is at the top that is the so called high gear and the marks you made will be erased. If it does not go to the top then replacing the weights with slightly heavier weights might help. I doubt if there is any single thing you can do for a big increase in speed.

[4950cycle]

Thanks for the verification on my thinking. I will get to the variater marker test soon. Then on to something else here, I've heard mixed opinions on this 32mm carb with 125 main jets I ordered. ( Lihia 260s come with 30 mm carb, 110 I believe main jets ). Some say it will actually hurt my performance, Others say it should get me some small gains. And no, I'm not putting expensive , noisy exhaust and a pod air filter. The only time I have ever got any gains from these mods is when my motor had a lot of head work an Carb work done on a Kawi I had IMO . My exhaust breaths plenty for my new carb. , And I would rather be taking in cooler air from outside the scooter (like my stock big air cleaner)than sucking in hot air from my engine bay with a so called high performance pod filter. Any thoughts on this 32 mm carb I speak of ?

[4950cycle]

I just read my last post. Didn't mean to sound insulting jct842. I just never niticed any particular gains from a pod filter and opened up exhaust besides my cycle sounding faster with all the extra noise. But I was also looking for acceleration then. Now I'm looking for top speed. I'm looking for a different benefit now. Seems like the little 257cc one cylinder is already getting plenty of breathing now with stock setup. But I don't want to be to closed minded and shoot myself in the foot. Thanks again jct842 for the sound advice.

[4950cycle]

So far it looks like it fixed the problem (Fuel pump). Then put my scooter up on the center stand and took it up to the rev limiter a couple times to find out where it topped out. The RPM went up to about 8400 without breaking up at all. Any higher and the RPM was unstable. But it would go up to about 8700 as indicated on the not so precise scooter tach. What that means is I might get my 5 mph on top if my variator isn't maxing out already. And 16.7 HP will haul my 260 lbs any faster than it already will go. While I've got the belly and side exposed I am gonna do a much needed valve adjustment. " Again " About the 4 th one I've done. "THEN" next on the agenda will be that Marking the inside of the variator test we talked about

[4950cycle]

Aug 10, 2016 12:13:25 GMT -6 jct842 said:

First of all what is the rpm at top speed? Do you have any big hills or are you riding in pretty flat territory? Any Idea what the weights are in your variator? Is your belt fairly new and good condition?

If you go lighter with weights/sliders it is like going to a lower gear. Heavy weights similar to shifting from 4th to 5th gear. You only have so much power and if geared to high you can go slower. Geared to low and you run out of rpms before you get to the speed you want.

Open up the variator and find what their weights are. Clean it out and then take a ride and note the rpms at top speed and get back here with results. If it is gunked up you may be surprised.

Put my scooter up on the center stand and took it up to the rev limiter a couple times to find out where it topped out. The RPM went up to about 8400 without breaking up at all. Any higher and the RPM was unstable. But it would go up to about 8700 as indicated on the not so precise scooter tach. What that means is I might get my 5 mph on top if my variator isn't maxing out already. And 16.7 HP will haul my 260 lbs any faster than it already will go. While I've got the belly and side exposed I am gonna do a much needed valve adjustment. " Again " About the 4 th one I've done. "THEN" next on the agenda will be that Marking the inside of the variator test we talked about

Read more: scooterdoc.proboards.com/post/118208/quote/13008#ixzz4Hk2ULsNU

[4950cycle]

Got detoured on this project. The fuel pump quit so i ordered and installed another one. New fuel pump would starve out the motor at about sustained 60 mph running. I can't understand why because when I pulled the hose off the carb so I could turn the motor over and see how much fuel it pumps with each engine vacuum pulse it pumped plenty to run a 250. Hell, It looked like enough to run a car ! So anyway I put another new fuel pump I have on the scooter, Adjusted the exhaust valve while I was right in the area of the belly. Started her up with no issues. In a tuck it will get my 260 lbs butt up to about 71. But still couldn't go any faster than 64-68 while sitting natural top speed. I may put that 32mm carb I got in the mail today on tomorrow. I hope it won't become a nightmare to make run right.




Read more: scooterrebels.proboards.com/thread/2676/miles-hour-257-linhai-jcl#ixzz4Hw8ffDzv

[4950cycle]

Well, I put in the 32 mm carb today. Lost some acceleration and gained ZIP / nodda on the top end. It has a main jet the size between a #56 and 57 drill bit. I know because I checked. The seller said it is a 125 main jet (no markings) I think I will at least have to back off to a 115 Main jet. I would bet money I'm running rich. Havn't checked the plug yet. Got dark on me. BTW I bet this 32mm carb is no more than a mm bigger than the Japanese made stock carb measured it. Definitely do not buy one of these. Just mod your stock unit like Jct842 said . Save $100

[4950cycle]

Aug 9, 2016 16:10:50 GMT -6 jct842 said:

First thing I would look at is the rpm at the top speed you get now. Depending on if it is wound out or not to decide on what weights you have and what you need to go to. If you don't have a tach get one on there. If you are a whole lot under red line you need to go lighter in weights which is what I would suspect.

Doubt if you will be happy with a larger carb with out doing other mods to go with it. Jetting is usually all that is needed.

Folks, Take jct842's post to heart ! And do not buy a 32mm (BS) more like 31mm racing carb they call it. The one I got has at least a 125 main jet which is way to big unless you are gonna mod the rest of the breathing system and maybe even port and cam it. Just do what he says. Don't be a Hard head like me.

[4950cycle]

Get this, After all this I put my 115 main out of my old Jap 30 mm carb in the new 32 mm , New carb ran great then ! But no better readings from the tach and speedo than my old carb. I think it had a sleight edge on my old carb in the mid range. But not enough difference to change much. So what that means is if they will take this 32 mm back I want a refund.