Cheap power when you need to do an engine job?
Let me suggest something:
$200 +3mm stroked and stuffed crank (since you are spending $180 for this anyway)
This is not a "drop in" in spite all the claims, but close and easy. Test it and trim as needed.
Besides the 5% displacement and HP increase, it increases open port window time about 12%, and creates an effective productive change to the exhaust timing so the power increase is better than the actual displacement increase.
1mm exhaust port raise. Raises the powerband without destroying bottom end torque. 2mm will start to make the engine a bit boggy on the bottom end and midrange and a bit too much of a screamer.
$60 modified cylinder head. Here is the stock head on the right, modified to the rear:
Another modified Blaster cylinder head below:
And here is a comparison of a hemi vs a torroidal modified head, either make more hp than stock:
Close up of another set of hemi vs a torroidal modified heads:
This cylinder head investment is key to building HP with a Blaster.
It speeds up the burn, reduces the deadspace, and allows higher compression without detonation.
Speeding up the burn will preclude the need for advancing the timing. The shape encourages turbulence to keep fuel in suspension and resist detonation.
Once bought, the head has to be installed properly with the right gap between the piston and head.
This is about 1mm (or 0.040") and is done by adjusting basegasket heights or filing the head.
These mods will bring you up to around 30hp. This will make a Blaster scream along pretty good.
An aftermarket pipe and opening up the airbox a bit will help make a bit more.
A surprising mod is to lightly port the intake windows and FILL in the intake side with epoxy.
This really improves the midrange power and make jetting much easier.
The cost is about $20 of epoxy and your time. More info here:
http://www.blasterforum.com/threads/improving-velocity.48827/
or here:
http://www.blasterforum.com/threads/more-low-mid-power.59613/page-2
I had a DT200 which supposedly makes 32hp stock.
I also have a
KTM 125, 250 and 300 which supposedly make about 40, 48 and 50 hp.
I also owned a 35 hp Raptor and my son has a Banshee which is what, 37hp?
We put a DT200 engine in a Blaster and
KTM 250 engine in a Blaster so we can do some interpolation of hp values based on the DT200 and KTM as bench marks:
17 hp stock
21 hp Air lid off, head planed slightly, timing advanced, FMF pipe and timing advance.
27 hp All the above plus a rechambered head with the timing back to stock.
- also 1mm squish, leak tested and careful attention to jetting
32 hp All the above plus exhaust raised 2mm (1mm recommended) like the DT200
35 hp All above, 1mm exhaust port raise and squared, intake opened and smoothed
37?hp All above plus epoxy filled intake and careful porting on intake side. Strong midrange.
All this on a stock carb. Aftermarket pipes are a help.
Each changes the character of the engine.
Things you don't need on a trail ridden Blaster are:
Larger carb - you need a lot more RPM and airflow before needed. Bigger is boggy.
Wiseco or forged pistons - read up on 4-square seizures. Clearance and scuffing issues.
Not needed unless you are doing crazy stuff in the rpm stratosphere near detonation.
In fact they bring some risks.
So:
1) +3mm crank
2) Modified cylinder head
3) 1mm raised exhaust port
4) Epoxy filled intake reedbox
5) Set the piston to head squish gap to 1mm
6) Open the airbox lid up
7) Aftermarket exhaust pipe
8) Leak test and do a plug chop jet set up.
9) HANG ON!
Steve
