Can having bigger valves create any running issues?

[Mattrix]

Please keep in mind this the first time I have ever opened a motor and tried this sort of thing,,, I did do my home work before starting.,.,.,Ok,,, I have an old Pitster Pro 125cc GPX motor,,, Its been smoking real bad due to needing oil rings replaced,,, Now instead of getting a new piston kit for it I decided to take the head off my other pit bike... Realizing the cylinder and piston are smaller on the replacement head I ended out having to swap pistons as well now when doing this I noticed the replacement head has much smaller valves on it so I decided to leave the original top part of the head (with bigger valves) on there only replacing the cylinder and piston.... Set timing up all is well bike fired on first kick was awesome but runs hairy like its being held back or something....

I just want to know if having the bigger valves on there is causing this and what I have changed has created this problem or is it simply a matter of setting the timing up correctly???? Please any help on this would be awesome....

[Mattrix]

&%$#@! these people are no help what so ever!!! time head to a better site were people actually help you!!!!!!!!

[Mattrix]

Please keep in mind this the first time I have ever opened a motor and tried this sort of thing,,, I did do my home work before starting.,.,.,Ok,,, I have an old Pitster Pro 125cc GPX motor,,, Its been smoking real bad due to needing oil rings replaced,,, Now instead of getting a new piston kit for it I decided to take the head off my other pit bike... Realizing the cylinder and piston are smaller on the replacement head I ended out having to swap pistons as well now when doing this I noticed the replacement head has much smaller valves on it so I decided to leave the original top part of the head (with bigger valves) on there only replacing the cylinder and piston.... Set timing up all is well bike fired on first kick was awesome but runs hairy like its being held back or something....

I just want to know if having the bigger valves on there is causing this and what I have changed has created this problem or is it simply a matter of setting the timing up correctly???? Please any help on this would be awesome....

your better off going to another site this site is shit az........................

[Mattrix]

your better off going to another site this site is shit az........................

Its ok got help from other site,,,, answer is the jets are to big and also need to adjust the fuel mix screw .......... wasent hard &%$#@! you 80 odd wankers that looked at this and didnt bother to help!!!!!!!!!!!!!

[dirtbkr188]

I'm sorry, I missed the question, could you repeat it please?

[563ripper]

Its ok got help from other site,,,, answer is the jets are to big and also need to adjust the fuel mix screw .......... wasent hard &%$#@! you 80 odd wankers that looked at this and didnt bother to help!!!!!!!!!!!!!

u mad?

[T Bolt USA]

IF your engine job was done correctly this will help tune you in

Engine and Carb quick check list - TBolt USA Tech Database!

1)Install Intake manifold to head and carb, oil gaskets and tighten bolts lightly at first then torque then down gradually in a cross pattern to provide a good seal and avoid air leaks

2)Make sure the carb is 100% clean, free of debris and you can see light thru both main and pilot jets

3)Double check you valve tappet adjustment .003intake and .004exh.

4)Make sure your exhaust gasket is installed properly.

5)Make sure all electrical connections are tight and you have a solid ground from the engine to the frame.

6)Check for good fuel flow and fresh fuel.

7)See our jetting guide and do a plug read.

http://www.tboltusa.com/store/tech.php?pid=61