190cc same performance as original 150cc help...

[visthum]

Ok i know that 190cc aint that much but common, my original 150cc did 90km/h on good days and my 190cc do the exact same.... I even change the Secondary gears (final gears) from original 13/40 to 16/37 and i did not notice ANYTHING, maybe a slight increase in acceleration but that's it.

I have 30mm carb with 125main and 42 pilot, open exhaust, A9 cam and also different CDI. Oh and a larger variator... I have a gut feeling the original cam ran better, at least it had more power from start... should it try it again now with new gears?


It feels and sounds like it has a lot more power to give when i'm maxing it but i am not sure what to change. I remember with my 150cc, i could really rev it out, but on this one i can't. In my ears 125 main jet sounds Very small and also the variator weights are the same as original, 13g i believe. 

I'm very disappointed in the performance, i put a lot of time into this for what... 
The store i bought the new secondary gears "+25%" promised that it with go from 90kmh to 120kmh no doubt... 

Any recommendations what to try out and change before i give up? I am also waiting for a kehin 30mm carb to put on it instead to get rid of auto-choke and stuff.


I got 130 and 140 mainjets to try if you guys think that is a good idea, also i am using "sport filter". Gonna check sparkplug color tomorrow 


Thanks in advance for any tips, hope someone points something out.

Also reason why i want it to get to around 110km/h is because i have to drive on highway a small bit to work 

 

[90GTVert]

Have you gone through any tuning process rather than just putting in the 125 main jet? Sounds like you haven't. If not, that would be #1 on my to-do list. Roller/slider tuning would be #2 on there if not already done. Checking compression is not a bad idea either. If you find that it's low and can't see any other reason, maybe try the stock cam again. I measured out dynamic compression and the A9 really made it take a dive on my 155cc.

www.49ccscoot.com/faq/carbtune.html#mainsel


If you have to ride 110km/h (68MPH) regularly, you may want to look into a bigger scooter if the opportunity arises. That's asking a lot of a 150/190cc. That's generally around the top of the range for a 250cc liquid cooled scooter. Reaching that speed at some point is one thing... sustaining it is another. Something like a 400cc or above is better suited for those speeds. I'm not trying to discourage you, and we'll offer assistance if we can to see if you can get this 190 going better, but it's so much easier to get out on the highway on a big scoot with power to spare and they're more likely to be reliable for you.

[tiny]

I agree with 190. My 150cc will do 105-107KPH but will suck back the gas like no tomorrow. it prefers a good 75-80KPH cruse & that's where I get best fuel economy.
Constant expressway use I would go minimum 250-300cc engine.
Your 190cc engine may have better power and torque then the 150 but set up more for the lower-mid rpm range.

[visthum]

Thanks for the answers. I have not done any tuning to the new tuning variator, they sent with me 13g weights for it and it really feels like it don't rev out all the way. If it put it on stand and rev, it will rev Much higher. Also clutch is new. Basically everything is " Tuning " as i bought a complete set from Germany.
Compression is good and when it was new, i had trouble starting it because of the high pressure, the A9 cam solved it for me but maybe now i can put on original cam again that gives me higher pressure.

I can't understand why the different final gears didn't do Anything for my top speed, the power is there, i got more acceleration but a bit poorer takeoff, just like they stated i would get but they also stated higher top speed... Not getting it.


What variator weight should it try first, they are quite expensive.


I really hope the new type carb will put new life in it, right now i have a 30mm CVK carb and i really hate it lol.

Also i get flames coming from exhaust when i slow down, i know the gasket i have now is not perfect and is leaking a bit at the exhaustflange. But the flames what do they indicate?


I just have to ride 110km/h for like 6km so it's not far at all. The rest are 90 km/h roads.



Things i will try tomorrow is putting on original camshaft and try again, maybe they already put in the best one as original as they state in paper it should do 90km/h original.

[visthum]

Tried the old Cam but really not much difference, a bit loss in top... But sadly it is totally wreck again now... Piston got stuck in cylinder and also the starter clutch is about to give up AGAIN. This time i am ordering good quality 180cc cylinder and piston, what they sent me from Germany was a no name not even really 180cc, more like 175cc, i measured it.

Thankfully my crank is alright. I guess oil cooler is an absolute neccessity on 190cc... Even though i thought it was not that hot.

[90GTVert]

My 155cc ran hot as hell. I think an oil cooler is a good idea on any GY6, especially if they get ran hard. Some of the nicer brands even put them on stock GY6 scoots. It made a nice difference in temps for me.

49ccscoot.proboards.com/thread/16180/139qmb-cooler-information-installation-help

[jaga4life]

Run 15w50 Mobil 1. Iv always used it in my air cooled engines that I know are going to have the piss beat out of them. Never really had any major problems and iv held a lot of 4ts WoT on 95 degree days.

[visthum]

Thanks. Gonna see if i can find 15W50. 10W40 is what i've ran now. I checked the cylinder, it was all fine but what was not fine was the exhaust valve. It had bent and caused the piston to crack and broke, but the Cylinder is fine lol... Gonna have to run with original cylinder head this month and then order a Naraku head next month.

Anyway, the cylinder i got with the kit was only 175cc lol... So now on Monday i will get my 180cc Naraku cylinder and piston, guess, with the stroker it will be true 190cc.

I just don't get it how the exhaust valve could bend and get stuck and crashing the piston? The chain did not slip as timing was correct. Do you guys think that my leaking exhaust gasket is the cause of this? I ordered an exhaust gasket that will cover the whole flange, like on 2stroke engines i hope it will seal perfect.

I have to ask, the store i ordered the kit from said i would also receive 2mm Alu cylinder riser or spacer but this i never got, when installed, the cylinder and piston is same level when TDC = flat, should it be like this or should there be gap so the piston TDC is a bit below cylinder top?


Sorry for my bad explanation waiting for the coffee lol...

EDIT:

scootdawg.proboards.com/thread/55776/gy6-valve-lash-started-changing
Found that thread they show pictures, mine looks exactly the same. 
Also i forgot to mention that i was running quite lean as i had crack in manifold tube and was riding to a place to pick up a new, and on the way there the air filter popped out lol... Gonna read up more about this bent exhaust valve issue. 


EDIT2:
www.gy6-motor.de/GY6-Dragster-racing-performance-crankshaft-615-38mm-stroker-crank-
That is the crank i have. Doesn't say anything about needing spacer. 1mm spacing is almost what normal headgasket gives.. hm