reeds and carb swap

[John]

Have a blaster. Going to change the reeds to Byesen reeds. When searching for them, i noticed reed cage spacers. Should i get a spacer too? Also can get a Keinin 34mm carb cheap. Will that fit the boots? And wif I should do the spacer, and the Keinin fits the intake, what mods will i have to do to the boots to make everything fit? The guy i bought it from said it hsd a big bore kit. Havent opened it up to measure it but doubt it has it but it is piped.
New to Blasters and appreciate all the help.

John in Vegas

 

[Blaaster]

If you are going to upsize the carb to 34mm you will need the reed spacer to allow you enough room for the carb to fit.

You will need to buy a new boot.

Unless the engine has been ported and/or you are running specialised fuel, the stock carby is the best choice for your engine if you do not have a BBK.

It would be a great idea to check if the carb has been jetted to compliment the pipe.

Another tip, leak test it at least twice a season, good idea to do one while you have the carb off.

Post up your mods and someone will comment on your jetting requirements.

 

[tfaith08]

I'd say to go ahead with the reed upgrade, but not the spacer unless you have a pipe installed that takes advantage of a larger displacement in the cylinder AND crankcase. For example, if you have a pipe that's meant for a big bore kit and you don't have one installed, you might benefit from a spacer. Other times, a spacer might be needed to increase clearance for the carb on some applications.

However, it is generally a bad idea to move the fuel source away from the engine.

As for the 34mm Keihin, I'd go for it. A lot of people like the 39PWKs with big bore/stroker kits, and those provide about the same powerband that a 34mm would contribute to for a 200cc engine. If it has a big bore (which is likely a .5mm overbore from a worn piston), the 34mm will do some nice things for you over the stock carb or any Mikuni for that matter.

You're on the right track with a lot of this. The reed upgrade is a decent upgrade, but I'd go with the head mod for a similar dollar amount.

To compound your ideas, I'd look at it as a stage setup of sorts.

Stage 1: Pipe and filter w/o airbox
Stage 2: Reeds, timing advance, and head mod
Stage 3: Big bore kit or porting
Stage 4: Ported big bore kit and carb
Stage 5: Big bore/stroker build

Stages 6+: Cut a 40cc dome, get some custom 800-950 main jets, advance the ignition by about 30 more degrees, weld the crank, install a Hinson clutch, shot peen and micro polish the gears and rod, and run nitromethane



EDIT: When i say to go with the carb upgrade, I'd do it because I'd know that I'd be doing more mods to it down the road.

 

[Blaaster]

Reeds will not give any more power, just an increase in throttle response.

However as at faith has commented, for the same amount of cash a head re chamber will give a marked improvement in power.

If you are running an expansion chamber which favours the low/mid range, then a reed spacer will move the power to come on earlier.


You were concerned that it is not big bore, if it is in fact just an oversize stock cylinder, then in fitting a large carb you will not gain anything, you may even loose.

The 26mm stock carby is perfectly adequate for as stock engine unless you run sophisticated fuel.

Post up your mods so we know exactly what to advise on.

 

[tfaith08]

Reeds will not give any more power, just an increase in throttle response.

I have a very good friend who works at a shop with a dyno that says they're good for 1-2hp in some applications. He also said that newer reeds lend more to top end than worn ones of the same brand and model because they're stiffer for the first hour or so of use. It should be noted that though this is true, it is very incremental and will only give, as Blaaster stated, more throttle response as far as the ass-dyno is concerned.

Either this weekend or next, the Banshee will be going down for a few pulls