Scooter won't go past 6000 RPM when riding By t84a (Read 13,913 times)

[t84a]

I guess unrealistically I was expecting 60-65. I probably would have bought a smaller and cheaper scooter had I done more research. 13" wheels.

I have a feeling the new carb may have a smaller main jet than stock. Thanks Alley. I appreciate everyone's replies and patience.

[t84a]

My scooter is marketed as a 200. I think actual cc is 170.

[Alleyoop]

Well if it is near 170ccs then I would upjet the carb and put on a free flow filter. I would start with a 120 main and work my way down, 117, 115 should be the smallest main jet for that displacement.
Alleyoop

[t84a]

Thanks. I just ordered a jet kit assortment and 11gm rollers.

[tvnacman]

Jan 17, 2015 13:48:26 GMT -6 t84a said:

Why would you knowingly sell me an incompatible carb? We spoke on the phone before I ordered it. So I need to re-jet? To what size? The valves were and are fine. How will lighter rollers translate to a higher top speed? The local scooter shop told me to not expect more than 55 and said the whole roller weight thing was more for the 50cc bikes because they lacked torque. I weigh 170.

Thanks for the replies.  I think we're chasing two different objectives though. 

Ken , you were looking for an adjustable a/f , I told you that the Keihin was good for stock 150cc with stock air box and muffler . I have checked the main jets they were 110 on the dozen or so I have checked . In the event that has changed let me know . Your setup is a little out of the norm from what we see here . It will be some trial and error to get it dialed in . Alley is a great carb guy . You have about the best starting point with the keihin you got from me .

John

[tvnacman]

Heaver roller weights keep your rpm down ,if you want higher rpm's drop the roller weight some . It will take more rpm to open the variator and will keep you in a lower gear longer . This we I'll increase your top end rim .

Now have you seen any improvements with the carb you got from me ?

These little engines need some extra attention in the beginning. Once you get the quirks worked out and adjusted you should be content .

When you had it apart you should have measured the inner variator pulley's diameter .

John

[t84a]

It's all good. I'll measure the pulley when I take it apart again.

[tvnacman]

Ken do you still have the pics of you cam gear ? (let Alley see it)
Al his engine is a stock 170cc could they designed it to only max out at lower rpm ? Could it already have taller rear end gears . Could it be a +2 crank and a 58.5 vs like a 61mm I'm not good with the numbers. There are a lot of items we need to know here . What size jets did you order ?

John

[t84a]

This one?

[t84a]

Jets:100, 105, 108, 110, 114, 115, 120, 125, 130 & 140

[Alleyoop]

Jan 17, 2015 19:47:16 GMT -6 t84a said:

This one?

Measure the studs center to center criss cross that looks like a B case to me and not your A case motors like your 157s
Alleyoop

[t84a]

Pretty sure it's an A

Engine: 161QMK-A

Although it has some differences like a 2 bolt valve cover. 

[Alleyoop]

Don't be to sure on that since yours has only TWO BOLTS holding the valve cover.
Measure the cylinder bolts diagonally center to center, if they are 3" then the stock 157 sizes apply, if it is 3.25, then that is a different cylinder and harder to find parts for it.

[t84a]

I'll have to remember to do that next time I have the cover off.

[dmartin95]

Jan 17, 2015 19:37:36 GMT -6 tvnacman said:

Could it be a +2 crank and a 58.5 vs like a 61mm I'm not good with the numbers. 
John

Based on his engine stamp, he has a 61mm piston.