Topic: Pipes - No Back Pressure

[JerryRice]

I have a cb350f with low power.

I was told its got to do with my 2into 1 pipes that have no baffles. No back pressure.
Posted is a pic of my pipes. Does anyone know how I can find proper baffles for them?

I got the bike like this and have no idea what brand the pipes are. Hoping someone knows.

Thanks!

[JerryRice]

Anyone?

[speedy gonzalais]

My 650 had sito pipes i think they where after market but done the job now i have strait thru pipes but i find my bike to perform better.

[NickC]

The less backpressure the better. Why does everyone think you need backpressure?

[speedy gonzalais]

it depends on the engine 2 strokes struggle with no back pressure 4 strokes ive never had had a problem with.

[JerryRice]

u serious?

Do race bike have straight pipes?

[JerryRice]

I am comparing it to the 7 year old girl next door on her tricycle.

[BobbyR]

With no back pressure you probably run lean. You can check the plugs and rejet.

[ColinMc]

I am comparing it to the 7 year old girl next door on her tricycle.

LOL!!!! But seriously...you might lose a little bottom end, but that thing should rip on the mid to top end IF it's jetted properly for open pipes. What do you have for an air filter setup?

[MCRider]

u serious?

Do race bike have straight pipes?

Some do some don't. "Drag Pipes" are straight out no baffles. And the Harley crowd loves no baffles. The engine should be tuned for it though, richer jets likely.

Depends on the kind of racing. Many tracks/racing formulas have decibel limits and so baffles are required for that reason.

Likely your lack of power is not the pipes. You should have baffles as a good citizen IMO. Like these: http://denniskirk.com/jsp/product_catalog/Product.jsp?skuId=4403538&store=Main&catId=&productId=p4403531&leafCatId=&mmyId= but if you shop around you can find baffle inserts without the fancy name for $25 or less. I've even taken a baffle from an old CB750 pipe, which was about 12 inches long, had 2 ciircles welded on it and slid it into an open exhaust, fixed with a bolt, for a great effect.

Your power loss if its truly that bad is likely a worn out engine, low compression, but could be something less sinister like a locked up spark advance.

PS: Here's some baffles for $5 or so, quick and dirty. Weld two together for length and more back pressure. Fold the little tabs into the exhaust stream more for less noise and more backpressure.  http://www.jcwhitney.com/autoparts/Search?catalogId=10111&storeId=10101&sku=baffle

[JerryRice]

What do you have for an air filter setup?
- I run 4 mini K&N directly to each carb.

I am going to pll out the carbs soon and see what size jets that are there.
If running lean - I go larger correct?

[Sporkfly]

Correct.

[speedy gonzalais]

u serious?

Do race bike have straight pipes?

depends what bikes or sort of racing your refering to! if your using K&N filters then thats either to make it look better or go faster, if faster then back pressure will defeat that, after market filters are mostly designed to let more air thru than the standard filters this can improve performace if the extra air can get out as fast as it comes in thats why a lot of people like strait thru pipes plus the great sound they make thats on a 4 stroke, 2 stroke engines dont have mechanical valves they have reed valves but only on the inlet side, gasses can still escape down the side of the piston and out the exsuast on the firing stroke, back pressure prevents that from happening. but thats only my opinion from findings in life I may be wrong so correct me if i am any one.

[Honda_Nut]

Partially close the choke and if the performance improves, your jets are too small.

[JerryRice]

LOL, she is pretty fast. Ya I will forget the pipe issue and concentrate on the others. Thanks for all of the help!

[jonbuoy]

u serious?

Do race bike have straight pipes?

depends what bikes or sort of racing your refering to! if your using K&N filters then thats either to make it look better or go faster, if faster then back pressure will defeat that, after market filters are mostly designed to let more air thru than the standard filters this can improve performace if the extra air can get out as fast as it comes in thats why a lot of people like strait thru pipes plus the great sound they make thats on a 4 stroke, 2 stroke engines dont have mechanical valves they have reed valves but only on the inlet side, gasses can still escape down the side of the piston and out the exsuast on the firing stroke, back pressure prevents that from happening. but thats only my opinion from findings in life I may be wrong so correct me if i am any one.

http://www.southernskies.net/page_info/runningtwostrokeengine.html

Your not wrong.