Hi, I'm wanting to get chromoly push rods but I'm not sure what length I should be using since I have the champion rockers and 26lb springs with a hot265 cam. The bike is an rb200 and I've been told a clone made by taotao. Would I need a billet pushrod guide to go with the rocker? I'm new to all this so any help is greatly appreciated. thanks guys!
Chromoly push rods?
- Thread starter Vape N Snakes
- Start date
I use an adjustable pushrod to check pushrod length then buy the cut to length 1/4" pushrod sets from isky. Depending on what type of rocker arm you are going to use will determine how you set your rocker arm geometry. For a fixed fulcrum rocker arm with the adjuster on the pushrod side you first set the valve side geometry by the pedestal height. If the adjuster is on the valve side like the later model champion rockers (not sure which ones you are talking about) the pushrod length determines the correct geometry. If you are using fixed fulcrum rockers you do not use guide plate because the rockers can not rotate as the shaft keeps them parallel to the valve. I'm attaching a couple of pictures of fixed fulcrum rockers, one is the champion with the adjustment on the valve side, the other EC roller rockers.
last pic is setting valve side geometry (mid lift method). There is a good video on geometry/pushrod length on youtube by Gage Motorsports. it explains setting fix fulcrum geometry on valve and pushrod side. Beware this is a complex subject. Last pic is setting mid lift geometry.
last pic is setting valve side geometry (mid lift method). There is a good video on geometry/pushrod length on youtube by Gage Motorsports. it explains setting fix fulcrum geometry on valve and pushrod side. Beware this is a complex subject. Last pic is setting mid lift geometry.
Attachments
If you are not changing valves just cam, rockers and springs if you set it up using the lash cap(s) that came with the engine the stock length may be OK but you need to check. Do you have a way to measure the actual lift at the valve? Normally you would use a dial indicator, but if you are careful you could use a 6" machinist ruler to measure. then at half that lift you would check that the rocker arm is 90 degrees to the valve tip again using a ruler thru the center of the fulcrum to the tip of the valve. If close then set the valve lash and check pushrod cup setting. Watch the gage video about pushrod cup adjustment and make sure you understand the importance of the cup location and how it affects the rocker ratio.
GAGE Motorsports: Proper Rocker Arm Geometry - Bing video
GAGE Motorsports: Proper Rocker Arm Geometry - Bing video
Did you check valve length? It affects the valvespring installed height and seat pressure. Harbor freight has cheap dial indicators, magnetic base and digital calipers which you should have if you want to build these small engines. I made a base to mount on the head and engine for various checks. The SI valves I buy are all longer than stock even the ones that are not labeled and longer.
Attachments
No clue on those check the length if they are the same I would assemble it with the champion rockers use stock pushrods and see if you can set the lash correctly and if the adjusters wind up centered not too far to one end or the other. you have the older style champions, they are a quality piece and do not require guide plates.