jetting, compression 101?

[taped throttle]

am i over thinking this?

on a stock viper -- the comp is staggered so that the jetting can be the same straight across. my understanding is that this is due the single pipe design and heat. ???

on a piped viper -- the same holds true (staggered comp & straight jetting). except that kind of blows the single pipe theory out of the water! but there is still a heat issue. (SLP specs have straight jetting with the stock head.)

but on a piped viper with aftermarket head; peak, megapower, simons head mod (i think this holds true with simons mod), you can run straight compression and straight jetting, this is according to the techs at MPI and a lot of reading on TY.

so my question is why/how can you run straight comp and jetting with the aftermarket head? which sounds like this should always be true; what am i missing?

is it that you really shouldnt run the staggered comp with pipes?

Thanks

 

[redsnake3]

the reason that there is straigt jetting on the viper stock is that the compression is staggered to compensate for the 3-1 exhaust. the reason that it is still staggered compression in the heads if you add pipes is because the pipes do not affect compression, the aftermarket heads have straight compression put in the domes of the heads so that there can be straight jetting/compression on the sled, the pipes in no way affect the compression being staggered this is only due to the head.

 

[mrviper700]

A viper also has cooling issues with the mono head design, and the base gasket holes. Alot of times youll see youll need a tad more jetting in the mag cylinder because it runs the hottest in a viper. On a srx, its the pto that runs the hottest, in yamahas eyes, but its a small amount compared to the viper.

Much to manys beliefs you dont burn a sled down on the wrong main jet, its usually the needles that do the damage, over 80 percent of the time trail riding your never on the main circuit alone long enuff to even clean out the pipes, constant on and off the throttle for tight twisty trails and lots of corners is the pilot jet and needle circuits overlaping. What usually does the damage is having the needles stock, or too lean and then after a long wide open pass for say a 1000ft-1/4 mile on your large main jets, you let off the gas and the needle drops into the nozzle and shuts down the main jet and basicly shuts off the majority of the fuel while the engine is still at peak rpm.......................poof......mr.squeeky visits you.