RD350 Exhausts First Baffle holes significance

[Pravin]

Hello Experts ,

I have come by to a set of exhausts which are locally made as copy of RD 350 Exhausts and are quite popular as I can say ...

The main difference we found is the USA/Indian Exhausts has holes in first baffel from engine -- USA ones has 4 each - left and right and Indian exhausts had 4left and 6 right

And the copy I have seen doesn't  have any holes but just 4 plain baffle plates spaced in the exhausts that too is not similar to Yamaha specs..

Now as per my understanding the holes are made to handle the back pressure and if there are no holes it may cause overheating of the engine-- STOCK ENGINE ..with Stock porting and ignition and fueling ...

Anybody can share any consequences involved in such design without any holes ?

Regards,
Pravin Dalvi

[m in sc]

the (original) plates and holes are to allow the exhaust to flow in and out ~ between the plates and the internal baffle holes and deflectors. ie: exhaust goes in the front, gets deflected  OUT the baffle holes, into a chamber between the muffler plates, then back INTO the silencer baffle to the next plated chamber in the muffler.

that being said.. you need a matching set of baffles & muffler plate spacing. or, go at the internal baffles with a drill bit.

     

[Pravin]

Thanks SC ,
Just want to understand if I run the bike like this ... Without matching baffels ..say stock baffels with muffelers with out any holes ...

What are the results we expect ? Performance issues ? Damage to engine ? Yamaha must have kept some logic behind those 4 holes in first baffel right ?

Cheers ,
Pravin

[m in sc]

would be very hard to determine without seeing it...  it might be fine?  but if the exhaust cant flow enough will absolutely fry a topend. I killed a motor on my 350 due to a collapsed baffle in an expansion chamber. RH cyl melted the piston.

[scully]

Ever look down a rd pipe with over 10k miles on it lol... What holes ?

[2t Fan]

I feel if the gasses can pass freely then it will improve performance and engine life. If lack of holes are preventing the gasses from passing freely it is not good for the engine. It may result in overheating etc... normally such situations are rare

[Pravin]

would be very hard to determine without seeing it...  it might be fine?  but if the exhaust cant flow enough will absolutely fry a topend. I killed a motor on my 350 due to a collapsed baffle in an expansion chamber. RH cyl melted the piston.

Makes sense , ideally should stay away from such designs

Regards,
Pravin

[Striker1423]

I feel if the gasses can pass freely then it will improve performance and engine life. If lack of holes are preventing the gasses from passing freely it is not good for the engine. It may result in overheating etc... normally such situations are rare

There's a video of a snowmobile with the exhaust can damn near on fire cause it was blocked up with mice nests I think. Was glowing cherry red at night. Guy was like, my sleds running like crap and its spitting flames. 

[m in sc]

[/quote]

Makes sense , ideally should stay away from such designs

Regards,
Pravin
[/quote]

it was a straight thru baffle core. lol. just old and the vibrations broke it internally on an FPP chamber. totally my own fault as i hadn't checked it in a while. Tim (kawasakitriple freak) was actually on that ride. I think he was more upset about it than i was. 

regarding the OP:

heres the way i look at it:

measure the baffle plates in the pipes. as long as the center core internal plates on the baffles are about 1/2 way between the muffler plates, you should be ok.

[Pravin]

Got that ....and with no holes I should be ok even ?

Regards,
Pravin

[m in sc]

you have pictures of this baffle?

is it straight through?

[Pravin]

Yes baffel  is straight flat vertically spot welded but only no holes :(

I'll check and share pic ..

Regards,
Pravin

[Quicklimegirl]

Ever look down a rd pipe with over 10k miles on it lol... What holes ?

Well that's why it's an imperative part of maintenance on these to remove and totally clean the baffles WITHOUT waiting 'til 10K miles, more like every 3K.  A welding glove and handheld propane torch are your friends..........

[Pravin]

OK my sincere apology to all !!

I think I am sensing there is mis understanding due to my lack of explaining the topic correctly .

I meant to say baffel plate and not the baffel or flute :((

So let me start over , all the rd350 250 400 exhausts have 4 bafel plates which are vertically spot welded at a distance say 120 90 90 90 from back of the exhausts and the baffel or flute slides through them via the center hole .

Now the first baffel plate from engine side has 4 holes in left and ryt exhausts .

Those holes I am talking about which are 10 or 12mm in diameter spaced evenly across the baffel plate  ..

Now if those holes are not there .. what's the impact ?

Sorry again if I have caused confusion but trying to get information here whether exhausts though dimension and look wise they are same but don't habe holes in first baffel PLATE ... Should thay be okay ? I suspect not ..

Attaching the pics

Regards,
Pravin

[m in sc]

you're talking about the plates IN the muffler body? no us model rd ive seen has the holes that ive noticed TBH.