"Biturbos and "Silver Bullets"

Over the past few months i have seen many posts from guys who have installed Biturbo pipes on their Silver Bullets and Golden Bullets with the A3 engine. Almost all of them have stated that they were dissapointed with the performance increase (or lack of). I have had the same exact experince with a Silver Bullet after a Biturbo was intalled! Very little difference in performance!! At first i thought this was just the nature of the A3 engine?

But, then i noticed something that has never occured to me befor! The stock exaust pipe on the Silver Bullets and Golden Bullets with the A3 engine drops straight down out of the engine and runs straight back without all the "snakey" bends and turns that the A35 stock pipe has! Also the diameter of the stock A3 pipe is much larger than the A35 pipe!

All of this, leads me to the conclusion that the A3 stock pipe is much more efficient that the stock a35 pipe! So, that is why you don`t get much of a power increase when you install a Biturbo on a Silver Bullet with the A3 engine.

And just the opposite is true if you install a stock A3 pipe on a Targa with the A35 engine, you will get nearly as much of a performance increase as you would if you had installed a Biturbo on it!! Yes, i beleive the old A3 pipe is that much better!!!

Now, what do you think?? Am i wrong? I want to hear some other opinions on this!!


Re: "Biturbos and "Silver Bullets"

Kevin Harrell /

I got halfway through your post and came to the same conclusion. I have a Tomos TT with the A35 engine and the standard pipe. There is a bike with the A3 engine in a local motorcycle junk-yard. So, I think that I will try this out and report back.

Re: "Biturbos and "Silver Bullets"

chuck russo va /

i herd the same thing from the guy at my local moped shop

You are Correct, Ike.

Reeperette /

Those stupid twists and bends in the A35 Stock Exhaust pipe have no logical reason to be present, and serve only to reduce the efficiency of the exhaust system, it seems.

The tube from the exhaust manifold to the muffler is a significantly smaller bore on the A5(A35) than it is on the A3, as well.

The A3 is actually a pretty decent exhaust, stock...and if you pull the baffle you get a more agressive exhaust note with less hassle of unclogging them...unfortunately those baffles clog up real fast, especially on a rich mixture.

If you don't want the chunkier exhaust note, you can remove the baffle, clean it, and then drill four evenly-spaced rows of 3/8" holes in the rearmost part of it, but the effect is pretty miniscule compared to the amount of effort, there.

Also, the gears in the A3 engine are cut different, they are angled, which is more efficient, and the A3 does seem to have slightly "taller" gearing in it....the A5(A35) gears are straight cut, which severely increases chances of slippage and cracked teeth, and the gearbox seems a bit "shorter"... having ridden both for many a year, the A5(A35) seems to "top out" too early.

And one of my main rips between the engine types is the clutches, the A3 clutches are nice and meaty, with lots of solid material and it goes ALL THE WAY AROUND, providing more positive contact and a solid grip, increasing efficiency and reducing wear.

Now, look at the A5(A35) Clutches, and what do you have ? three TINY strips of shoddy material that doesn't even run the full clutchplate surface...no wonder the damn things slip so badly coming out of 1st gear, they do not have enough proper clutch material to sustain a good grip, and it wears out right quickly.

Not to mention, when it wears, it crumbles, leading to debris in the transmission which very quickly leads to other problems.

Give me the A3 any day of the week, the whole A5(A35) system, although billed as an "upgrade" is naught more than a cheap, shoddy knockoff of the original, and much more reliable, A3 system.


Re: You are Correct, Ike.

Hey, I save all the A3 pipes I can and install them on the A35 engines, they work aswell as the biturbo, and moify the end piece (baffle) to breath better... I think the not having a reed valve is the only negetive part of the whole A3. Doug D.

Re: "Biturbos and "Silver Bullets"

I hope this post doesn`t cause the Biturbo stock to "crash" !!



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