combustion chamber

[aussiemonster]

I have bought a 146 cc kit from maylands performance,it should be here in perth early next week.I have ordered the lightweight oil slinger also
i have stripped the bike of its head and cylinder oil slinger etc.
I have got hold of a lifan bv head.The valves are bigger than my original head obviously,but the ports are smaller and not as 'finished' for want of a better term.I can sort that out,but one thing i noticed is that the combustion chamber is way bigger on the lifan.I dont own a burette,to measure the difference,but i do powerlifting for a sport,because of that i'm a steroid user at times so i used one of my syringes.i set the heads up level etc and the jialing head took 10.5 cc's to fill the combustion chamber,the lifan took 15 cc's.
That is a big difference.I'm hoping the bigbore kit has some sort of dome on it or i'm going to lose a lot of potential compression,if i use the lifan head.
My original piston is slightly dished (about 2 cc's worth).
Is it still worth using this lifan head,what i gain in valve size,i will lose in compression?.Does anyone else running this combination know the true compression ratio.I was hoping to have around 10:1 OR 10.5:1,pretty safe but still a boost in performance.what do you think my best options are.I'm not trying to build a big peak horsepower engine,i'm after all the midrange torque i can get,in the rev range that we use in everyday riding around,especially when i ride the bike on road,which will be most of the time.cheers

 

[Cactus Jack]

Dude , you could have said your gran is a diabetic and you used HER syringe or you used your horses worming syrup syringe or something like that .... LOL ..

You'll find the answers to all your Jialing 146 with Lifan BVH questions on Planet Minis ..... I've read everything you're talking about on there but can't find the threads they were on .... the info is pretty well jumbled all over the place on that site ....... most people use an Akunar piston with that combo ....

 

[tubes380]

the kit will come with a hc piston and in fact you should use a lifan head otherwise the compression numbers are too high, most people run the 146 kit with lifan head, ported and polished and a mid range cam, you should be very happy with the setup also there a couple of little install things that you need to be aware of, look on the planetminis forum and it should give you a run down of everything youll need to know, also did you think about hd clutch springs???

 

[crazzy #1]

i think that the thread in planetminis should be copied and past (i mean abriviated) into miniriders

 

[Le|Garage]

The compression numbers with the tb146 kit and lifan head should still be better then stock. It isn't reccomended that you run that kit with the standard jialing/loncin head unless you use high octane fuel. It'll be fine. If the compression is too low for your liking, you can get an akunar piston for about $40 which will fit the cylinder.

 

[Cactus Jack]

The Jialing 146 kit pistons have a Jialing chamber sized dome in the centre .... the Akunar piston has a full piston width dome which suits a BVH chamber better ....... deep valve reliefs also contribute to lower compression ....... of course you could assume that the larger domed piston could also be heavier unless the dome is hollow underneath ... then there's also the weak Jialing kick start mechanism and cases to consider .......

How to calculate TRUE compression ratio :

True Compression Ratios Article by Bill Cole

 

[aussiemonster]

Hey thanks guys ,this is great info,i really appreciate it.Yeah sorry about the steroid thing,its just i don't lie about anything,no offense intended,hey the 'roids paid off,2 state titles and 5 aussie records,and i haven't dropped dead yet,anyway back to subject.Again thanks i am one of those people that will keep on a subject until i'm the full bottle and put it into practice,so i know for sure,what is what.These engines are fun to play with because the costs are not over the top(unless you want them to be,i guess).I just bought a lightweight sprocket for the ducati from ducati performance $400.00 and that is for one rear sprocket,for crying out loud!!!
I reckon by the time the duke is finished it will owe me $35,000!
but hey if you are passionate about something you have to see it through,or what is the point.That is why i'm so keen on this pit bike,i want to know my subject matter,and put it into practice.if i may ask ,i paid $130.00 for the lifan head,and they want $100.00 to $130.00 to port it,is that ok or what.It all seems so cheap to me,but i have no prior experience to compare it to,so whats the go fella's.I am wanting to change carbs,and the pipe,what are your recommendations,i thought vm26 mikuni and with the pipe i don't want to over do it as i do ride on the road,so a bit of discretion is probably warranted.As usual any and all advice appreciated.As this pans out i will let you's know the results good or bad.Again thanks for all your help.cheers dave