We've looked at the budget performance mods in a previous thread.
That's some really good punch for the money.
Many folks are happy right there.
That bumps the power from about 15 hp at the rear wheel, to about 19hp at the rear wheel. Maybe even closer to 20hp in some Bullets.
But, what if somebody wants a little more than that?
Where do they go from there?
And the budget is still somewhat of a concern?
One of the more popular choices is to get a larger and more capable carburetor.
This is quite popular.
There are a variety of choices you can make.
I'm particularly fond of the flat-slide types, because they are the most advanced form of carb for our bikes.
The type and size of the carb you choose is going to be somewhat related to your use of the bike, and the expected power improvements at various parts of the rpm range.
The smaller carb sizes tend to retain better fuel economy, and also retain the most low-speed torque.
The larger carb sizes tend to give more power at wide throttle openings, but may not give as good fuel economy, and could give away a little low-speed torque, because they favor the higher rpm power.
The choice depends on how you plan to use the bike, and what characteristics are most important to you.
2 of the very popular options are the 30mm flat-slide, and 32mm flatslide, and another one that's been popular is the 34mm roundslide. Also, there are Amal carbs for those of you who prefer the vintage appearance of an Amal carb.
Personally, I have to admit that I'm not a big fan of Amal carbs.
Basically, going to a larger carb than the 28mm Mikarb gives you more power in the upper midrange and higher rpms. It doesn't give you much more down low, if anything. A larger carb doesn't really give you anything additional, until you open it up bigger than your previous smaller carb could give. But, when you do go to the bigger throttle positions, you get more power out of it.
The flat-slides are better, in that they flow so much better, they even give increased torque in the lower midrange, and a real stable idle, plus giving you great results at the large throttle openings. So, flat-slides are real good.
And that's about as far as you can go, while still staying out of the innards of the engine. That's the end of the line for external "bolt-on" stuff.
The bigger carb will yield you about 1-2 hp more than you had with just the free-flow upgrades, so maybe 20-21hp at the rear wheel as a total, if you tune it right.
All right.. Now we've got a carb on there that can feed our powerplant better at the higher rpms.
The higher rpms are where the power is.
So, that's why we need to be able to feed the engine well at those rpms.
And what more can we do?
Doing more is going to require taking some of the engine apart.
With a simple top end removal, we can install a higher compression piston.
We'll want to use a new forged piston, instead of just shaving the deck of the barrel, because the OEM piston is a little weak, and we don't want to push that piston much harder. So, a better piston with some extra compression would be the order of the day.
Several hundred bucks, and an afternoon's work.
Going to a 535cc kit will give you extra displacement along with your extra compression, and will be worth another hp or two on top of whatever the compression increase is going to give you. Doesn't cost anymore to get the 535 piston, but it will cost you to get your cylinder bored out to fit it.
When choosing a new forged piston to put in your engine, and on your stock alloy rod, it's a good idea to get the lightest piston available, so that you don't put more stress on the rod than the OEM piston did. So, a light piston is best.
Installing this higher compression piston has some special requirements, so that you don't push the compression too high, and this is something you can ask me about when you need to. There is a certain way to set the compression on these engines, and it's not complicated, but it involves some spacers under the barrel when you install the piston. The amount of spacers will be determined by the piston you get, and the cams you are using.
Speaking of cams.
There is a new set of cams that CMW is carrying now, called the ACE Clubman Cams.
These are special sets of cams made in India, which I inspect, and measure, and re-time to meet high performance standards.
These are the most "bang for the buck" in cam sets for the Bullet.
They drop right into the timing chest with no mods, and don't require any special valve springs, or any special anything. Except they do need to have the high compression piston in the engine to make them work right.
They are the least expensive performance cams for the Bullet.
But, don't underestimate them!
These cams really deliver some power!
They will work just fine with a stock head. No porting required for good results with these cams.
They're just a few pennies under 200 bucks for the set, and they include a new timing pinion gear with them too.
You can't beat this for the money.
Ok, so I said this is Level 2 for "bang for the buck".
How much is it gonna set you back in the wallet?
You can get a basic carb kit for about $200 and up, depending on what you choose.
A high compression piston is going to be near $300 more.
If you do a bore to 535, it could cost anywhere from $50 for your local shop to bore your cylinder, to up to about $500 for a complete big-bore kit and alloy cylinder(but the high compression piston is included with that kit as a package).
Your choice.
And if you want the ACE Clubman Cams, add another $200.
So, you're talking about at least $750, and maybe more, depending on what you pick out for your selections of carb and barrel type.
So, what is this gonna give you for power?
Well, let's say you go the whole 9-yards, and do all I described.
If you have a stock head without porting, and you keep the revs under 5000 rpm for engine longevity, you're gonna be around 28hp at the rear wheel. Maybe as high as 30hp at the rear wheel with a 535.
Torque will be up there at around 28-30 foot pounds too, peaking at around 3500 rpm.
That's nearly double the stock rear-wheel hp of a factory "bone-stock" Bullet.
It's a real kick in the pants!
Now remember, this isn't involving anything in the bottom-end, like crank or rod or bearings. And they are not the most robust parts in the world, in stock form. So, you gotta be a little careful with how high you rev the motor. It ain't gonna want to stop at 5000 rpm all by itself. It will run right past 5000 rpm if you let it.
So, you have to pay attention to your throttle hand.
Having a tachometer would be a good thing.
You also might want to look into a better clutch, like the miracle clutch or something like that, because it's probably going to make your stock clutch slip with all this extra power on tap. More power than the stock clutch can really hold well.
This REALLY wakes up a Bullet. When you've doubled the stock hp at the rear wheel, that's a pretty big upgrade.
And doing it for this little money, is unheard of in the world of engine modifications.
This is a very inexpensive cost for doubling your rear-wheel horsepower.
But remember, the bottom-end of the motor is not indestructible. So you're on your own to ensure that you take care of it, and don't go revving to the moon with all this new-found power. It would probably be a good idea to plan a bottom-end overhaul with improved high-performance parts down there, over the winter in a year or two, just to be on the safe side.