Quadrider10,...The carb size on any engine is very important! A larger carb will help pull a little bit and I do mean a "little bit" harder in the top end (higher rpm's of the powerband) than the smaller carb,but........at the sacrifice of torque in the low end (lower rpm's of the power band) when your riding.
Example... My riding is all over the place,and I have to sometimes crawl over obsticles,and haul ass up steep hills with points of "No Return". I need my torque where I can use it and this is what a properly sized carb does. there is nothing worse than your blaster,or any other atv falling on its face (loosing power and getting soggy) when you need the power the most (up steep scary hills,deep sand,etc). Too large a carb will turn a crisp running engine into a very lethargic wet rag in a hurry.
Years ago when I found out that the stock blaster carbs were 26mm,I said "thats too small .... it needs abigger one" I was wrong! Think of it this way...take a two stroke 125cc MX bike for example: YZ,RM,KX,or CR 125....These don't have a throttle,they have a "switch"! They are all top end! They are designed for screaming top end rpm's,because thats where they are used... on a "track". Short bursts of high rpm,high output power. The carbs are huge because they support the high rpm's. Try riding that 125 on the trail with all sorts of obsticles that require torque,and you better plan ahead.
When I hear people putting on 35mm carbs on a blaster engine,I think they're cheating themselves out of torque. On a drag blaster I totally get it. Once you port your cylinder,the "cork" in the system changes to a different spot...carb,pipe,silencer,air filter,etc. There's nothing wrong with un-corking the bottle,just don't cut the top of the bottle off.
When it comes to feeding an engine... VELOCITY IS EVERYTHING! On a two stroke engine you have lots of factors that come into play. The piston coming up is creating a vacuum in the crank case creating a void that needs to be filled. Thats where the air fuel mixture does a better job of filling that void when its at high velocity. Don't forget that atmospheric air pressure (about 14.7 psi) is also ramming the air/fuel mix in.
The other problem with bigger carbs is that they are NEVER a bolt on. The spigot is always bigger,but is still usable with stock intake boots,and the air box/air boot side is always 15mm or more FREAKIN bigger. What a pain! This causes all sorts of extra things to take care of after you install the carb.
A slightly bigger carb can help. Me personally...I wouldn't go past a 30mm,because I don't want to kill velocity. All the newer carbs are flat slides and "D" slides,etc. They help increase throttle response on the larger carbs because on the larger carbs the velocity is lower because of the larger carburetor bore. A neat set up...but if you have high velocity,you don't have an issue with throttle respose in the first place.
Everybody seems to make fun of the "old round slide" carbs calling them vintage and what not,but for me personally,I'd take a properly sized,properly jetted smaller carb (vintage or new) any day of the week over a "big carb" on the same engine. Bigger is without question,not better.
Example... My riding is all over the place,and I have to sometimes crawl over obsticles,and haul ass up steep hills with points of "No Return". I need my torque where I can use it and this is what a properly sized carb does. there is nothing worse than your blaster,or any other atv falling on its face (loosing power and getting soggy) when you need the power the most (up steep scary hills,deep sand,etc). Too large a carb will turn a crisp running engine into a very lethargic wet rag in a hurry.
Years ago when I found out that the stock blaster carbs were 26mm,I said "thats too small .... it needs abigger one" I was wrong! Think of it this way...take a two stroke 125cc MX bike for example: YZ,RM,KX,or CR 125....These don't have a throttle,they have a "switch"! They are all top end! They are designed for screaming top end rpm's,because thats where they are used... on a "track". Short bursts of high rpm,high output power. The carbs are huge because they support the high rpm's. Try riding that 125 on the trail with all sorts of obsticles that require torque,and you better plan ahead.
When I hear people putting on 35mm carbs on a blaster engine,I think they're cheating themselves out of torque. On a drag blaster I totally get it. Once you port your cylinder,the "cork" in the system changes to a different spot...carb,pipe,silencer,air filter,etc. There's nothing wrong with un-corking the bottle,just don't cut the top of the bottle off.
When it comes to feeding an engine... VELOCITY IS EVERYTHING! On a two stroke engine you have lots of factors that come into play. The piston coming up is creating a vacuum in the crank case creating a void that needs to be filled. Thats where the air fuel mixture does a better job of filling that void when its at high velocity. Don't forget that atmospheric air pressure (about 14.7 psi) is also ramming the air/fuel mix in.
The other problem with bigger carbs is that they are NEVER a bolt on. The spigot is always bigger,but is still usable with stock intake boots,and the air box/air boot side is always 15mm or more FREAKIN bigger. What a pain! This causes all sorts of extra things to take care of after you install the carb.
A slightly bigger carb can help. Me personally...I wouldn't go past a 30mm,because I don't want to kill velocity. All the newer carbs are flat slides and "D" slides,etc. They help increase throttle response on the larger carbs because on the larger carbs the velocity is lower because of the larger carburetor bore. A neat set up...but if you have high velocity,you don't have an issue with throttle respose in the first place.
Everybody seems to make fun of the "old round slide" carbs calling them vintage and what not,but for me personally,I'd take a properly sized,properly jetted smaller carb (vintage or new) any day of the week over a "big carb" on the same engine. Bigger is without question,not better.
