A-11 cam vs. A-12
 

I have been researching the best camshaft for my modified GY6 150cc Crossfire 150R. Since it is modified with a 62mm cylinder, large valve head and a 8mm stroker crank with a 30mm carb and it is mainly ridden in flat sandy locations, I am trying to decide between a A-11 and A-12 cam. Some forums state the A-11 cam creates clearance issues on some engines. It appears that it has decent low end and plenty of midrange. The large displacement should offset some low end losses. The A-12 is a low end with some mid range (some say it is a rockcrawler cam). I saw that on some forums that a 8mm stroker should not rev to high, so that is also a concern. Any input would be greatly appreciated.:eeek:

The way I look at it, if you have a big bore, that will accomodate the bottom end for you and I'd go with a lower numbered cam. The lower the number the higher the RPM power range but you lose it on the bottom end....unless you accomodate the bottom end with something like a bigger bore. I'd look at an A9. Maybe Tom can chime in since he has likely tested these setups out in detail.

It would be great for more info.
 

Since I have the 62mm bore and a massive 8mm stroker, I also thought a lower number cam would be better. I already have a A-9 cam, but some forums state that the long stroke and big bore should not be used in the higher RPM band. Some sites state that the A-9 should only be used in smaller stoick displacements. It does not make sense to me. A few people say the A-10 or A-11 is a better choice for the larger displacement. It is ridden in flat sandy trails. I am hoping that someone has tried large bores with multiple camshafts. Thanks.:biglaugh:

My experience with full sized car engines would say not to use the high rpm cam. If you take a motor making low rpm power you would be better off to add to that power and set the buggy up to use it wisely. Tall tires would help in sand and help top speed. With a powerful low rpm motor, you would be able to turn them even in sand. If you use a high rpm cam on a motor making low rpm power, you lose some of what you have but don't have anything else on the top end to gain anything....end result a motor that does neither. With full sized cars, wanna be hot-rodders always slap a big cam in an average motor and it drives me nuts!!! Just my opinion, and I am new to small engine performance, so I could be wrong.

My set up for Fl was 180bb, port and polish head, a-12 cam, stroker crank, 30mm slide carb, 12g sliders, yellow main, stock sproket, 24in rear tires. With this set up the fastest 250 at the buggy bash was less than a sec faster than me in the drags. Could climb anyhing you wanted and most of it under half throtle. Would dig the tires to china if you wanted

Since I have the big bore and the 8mm massive stroker, I will try the A-11 cam. The A-12 seems like a good choicefor a slightly smaller displacement, but the A-11 seems like it will provide a little better midrange. The slight loss in low end should be offset by the increased stroke. I will let you know how it does. Thanks.

It comes down to sproket and tire. I used top end sproket and very large tire to get back what the cam took. I wanted more clerance so the a12 was the way to go