PE400 Pipe

[Grunter215]

Does exhaust on PE400 have restrictors in them? Do RM pipes fit,if so how would they effect the power.

[maxvmx]

A PE 400 pipe does have internal baffling, and a RM 400 pipe will not fit.

[oldfart]

RM 400 also has internal baffle.

[frostype400]

you can get a jemco pipe I think alastair maxwell may be the importer for them??? alot of people would be after a 400 pipe though like me.

[Grunter215]

Thanks guys.. Its been used for VMX so is it worthwhile taking the restrictor out. If so where exactly is it located?

[oldfart]

best you visits  The   PE site has the low down on where it is on PE and how to remove it .........ring ring ring    calling   luke or Leith
Rm 400 are an easier fix all you need to do is cut pipe where it passes under rear of tank .

[LWC82PE]

Ok, whats inside these pipes is not what i call a baffle or restrictor as such. All it is is some mesh sheet spot welded to the inside 'bulbus' part of the pipe. Its not a series of restrictor plates. Its is primarily in there just to cut down on the 'tinny' sort of noise so the bikes coould get ADR approved. In my opinion its a waste of time to take this out. Just leave it in there. if you really want more performace get a decent modern pipe made by GMC, Lozza or someone thats built to your engine specs. I just dont think its worth it to cut up an original pipe to take that mesh sheet out as its not a huge restriction. So dont keep thinking there a 'restrictor' in there. Restrictors are usually in the form of a airbox lid or snorkel that blocks part of the opeing off, a disc inside the inlet manifold, a disc inside th exhaust manifold/start of the pipe or in the case of some pre 80 PE's a BIG steel washer/disc reducing the pipe ID a lot smaller.

The PE will benefit far more with a decent set of shocks and fork set up than taking the mesh out.

[lukeb1961]

what Leith said. 

cutting up an original PE400 pipe is sub-optimal. Sell it on eBay and buy a pipe from GMC instead.


Luke

[BAHNZY]

Not sure that not having a restrictor plate is correct. My 78 PE250 had a plate installed in the back end of the chamber, close to the start of the stinger.

[LWC82PE]

In my last post I have said PE400's dont have restrictor plates (in the guts of the pipe) and that some pre 80 PE's do have a restrictor plate in the middle of the pipe. I have said 'some' as i couldnt remember if it was 78's or 79's or both. Just take a look in the Clymer manual, it shows it in there.

The PE400/250 T/X/Z did have a washer just inside the exhaust pipe as it leaves the barrel but these are all long gone. Everyone took that out the day it was wheeled out the dealers door

As Luke said, the original PE400 pipe will be valuable to a restorer, so if you want to muck with it for more performance then look at geting a aftermarket one.

What will help the standard pipe though is to burn ALL of the oil and carbon out. You can often have a 6mm+ thick coating all inside your pipe. I light them up inisde with the oxy then use compressed air gun to blow the fire along the pipe. It leaves the inside so clean you could eat your luch off it.

[oldfart]

Leith ,  Good point      burning excess carbon build up from inside of chamber .            Just make sure you do it outside in a well vented area      no carbon tax  payable YET 

[GMC]

As Leith says, a  lot of ADR style pipes have that inner perf. sheet inside the chamber. They’re not a baffle as such but are designed to keep the noise down. Some models did come out with the “washer” in the header or stinger but most of them would have been removed very early on.
Some say taking out the perf sheet from inside the chamber makes them run better but I’m not convinced. It’s a lot of work to remove for no real gain.
It’s not like they designed the perfect pipe and then added the inner layer later.
You will often see these ADR style chambers will have a small step in them which is where the inner layer starts/ finish’s.
Burning them out may not be the best either, it’s fine on a normal pipe but these style chambers often have a fiberglass layer in between the 2 skins which would get damaged from the heat.

Isn’t the PE 400 motor a completely different spec to the RM 400 motor or is that only for certain years?

[LWC82PE]

yes thats right, the PE400 motor is totally different to RM400's. RM pipe wont fit PE400. The RM/PE250 pipe will go a lot closer to fitting the PE400. Its basically just the header length that is a bit different due to the 400's bigger bore spacing the exhaust mount out further, requiring a shorter pipe. I havent tried this my self but a few guys i know with PE250/400's have compared fits of pipes and told me.

Yeah i just burn all the thin packing out between the mesh and the pipe wall, although its mostly already blown/burnt out anyway.

[frostype400]

PE400 is an oversquare barrel same stroke as the 250 and that is why it fits in the 250 frame the barrel is wider than it is tall but I have read in magazines that it held with the rm400 easy when it was stock around the mx track so some good shocks and I reckon it would beat the rm such an easy bike to ride if you fall off the pipe you can get straight back on.

I have got a 400x in my shed that is running a full stock exhaust system and it flies because I believe it has had porting work.

[TT5 Matt]

Leith ,  Good point      burning excess carbon build up from inside of chamber .            Just make sure you do it outside in a well vented area      no carbon tax  payable YET 

didnt we pay that tax when we brought the oil