Recently one of my header studs broke off inside the head, so I figure while I have the head off I may as well do some internal work. I am going to replace the cam for sure, because it is the cheapest and easiest. So I have 2 questions.

Which cam should I use, stage 1 or stage 2 Hotcams, or something else? I want a good top-end gain, but it needs to still be rideable in tight woods.

What else should I do? Mild porting OR high-compression (11:1) piston? But not both (not enough $$). Will an 11:1 piston still run on 92 octane?

I am looking for the easiest and cheapest power I can get. Which combo will give me that? Cam and porting or cam and piston?

Thanks for your help!

RR1

p.s. GregV - better be on top of your game next time we hit Silver Lake! ;-)

 

IMO from what you said I think a stage 1 cam and an 11/1 piston would be the best bet. It saves you the money for the dual rate spring kit, and the stage 2 really needs to be ported. And yes this set-up should run on pump gas, I think.

 

Would I be able to run alcohol occasionally with an 11:1, or does alky need more compression than that to work best?

My engine is a year and a half old. When I change the piston, can I just drop it in, or will the cylinder have to be re-bored?

Thanks for the help ward!

Any other opinions/suggestions?

RR1

 

I know most will not agree but...... I would go with a stage 1 and have the head ported. High comp. will not add as much as good flow and high comp. makes power down low more so than up top.
And I would strongly suggest replacing the rod with a new shot peened one and having the crank balanced if you replace the piston, allthough many people do not I would and will be when I do mine.

 

I pretty much had the same question. I can tell that my tranny is on its way, so when it goes I was thinking of doing motor mods also, similiar to what RaptorRacer1 is thinking of. What is a good brand of piston and cam in the 11:1 category? It should run on premiun shouldn't it? Would I need valve springs too?

 

I do agree sixsixT, except he said easiest and cheapest. Unless he does the port work himself that would be a good bit more expensive. The better rod and balancing is a good idea too, but then again more money. But if the rod lets go then.....well talk about some bucks.

RR1, I personaly don't think it would be worth it to switch back and forth from alky to gas. You can run it on 11/1, but the more compression the better.

I take it your going to a stock bore set-up??? You need to have it at the VERY least checked and honed. I would be willing to bet that it will have to be bored out.


Farm Stud, JE is almost the only piston to use. There are others, but they are more money or less quality. IMO
Springs will depend on the cam you get. If you don't want to buy springs get a stage1 Hot Cam. Everybody is fairly satisfied with the Hot Cams, I know I really like mine (stage 2).

 

going by mods on my old banchee, porting makes a lot more power then higher compression.
that is what I would go with.

I know that it is two diferent quads, but that is what I had experience with.

 

Thanks guys, I tore my engine down today and have ordered a Stage 1 Hotcam. I am still trying to decide on the porting vs. piston issue. Am I correct in thinking that the 11:1 piston will boost torque while the porting will boost top end HP?

Thanks for all the help!

RR1

 

You have to remember that you're trying to get more air/fuel into the cylinder when you get a bigger cam. The reason you have the potential to lose low end power with a bigger cam is because the valves stay open longer. The longer the valves stay open, the more potential there is to have pressure bleed off.

The reason this works better at high RPM is because of the tendancy for the air moving at a high velocity to keep forcing it's way into the cylinder even though the cylinder is at or past bottom dead center on the intake stroke.

In order to bring back some of the low end power that is bled off, most people use a higher compression piston. This gains the pressure that was bled off back by compressing the fuel/air mixture more.

As far as the porting gaining high end power, it just depends on how you have it ported. If you have the ports hogged out then yeah, it will potentially have high end power. The reason I say potentially is because you need the intake and exhaust airflow to match the ports that you have. If you have the biggest, baddest port job on the market but have a stock airbox, carb and exhaust then it will not do you any good.

A good mild "cleanup" port job would probably be of the most benefeit. Maybe a little opening up of the ports would be in order but I'm not an expert on bike porting.

Hopefully this helps and is understandable!!!!!!!!

 

Thanks for the info BW. I got a quote from a local company for $325 for porting and a valve job. It is called 4wheel Thunder. I asked the owner how his porting compares to that of Trinity or Sparks, and he said that he has never seen a Raptor head with that type of porting so he can not make a comparison.

He said that his kit with a high compression 102mm Wiseco piston, porting, Web cam and springs, makes about 6-8 more HP than a stock piped and jetted engine. That seems pretty low to me for all those additions. Any thoughts?

Does anyone know how much Sparks, Trinity, Craycraft or Robertson would charge for a mild port and polish and valve job? I want to run stock valves and springs for now.

Thanks,

RR1