expansion pipe rattle

[blasterfied]

I was going for a ride today to break in my new chain. While it was warming up, I could here a rattle sound. I shut it off, I then tapped on the exhaust, I could here the rattle. I removed the expansion pipe (stock) and then shook the hell out of it. Nothing came out, so my thoughts are it's a baffle of some sort broke loose right?

Im planning on getting a new full exhaust soon...I need rear tires first. Due to the holidays coming up my spending limit has decreased....a lot!

Is there anything wrong with continuing to ride like this? Besides the annoying rattling. I replaced the pipe, and It fired upup 2 kicks after sitting for a week. All stock

 

[Awk08]

there is a cast iron baffle inside, and yes they break loose.
it can 1/2 block the pipe, resulting in poor performance(happened to me)
or possibly overheating and a meltdown ?

time for a new pipe !
or cut about a 3"x3" hatch door, remove the piece and weld shut

 

[Blaaster]

If my memory serves me right there is a packing stuff under the baffle.

Removal of all the crap inside the pipe makes it perform a little better.

Be careful though it may need re jetting.

 

[Maniacmotomouth]

So I could cut my stock pipe and clear all the packing out and get better performance

 

[blasterfied]

I figured the baffle is no longer adding any restriction. And rejetting may be needed.

With a FMF or toomey or any high peformance exhaust, I know jetting is required regardless.
I heard that some guys completely remove the air filter box cover. I have worked on many quads and dirt bikes, and I would always do air box mods like a 12 hole or recomendations from the manufacture. Never seen any of them mention completely removing the cover. Must of the quads I work on are 4 stroke, is there a difference between 2 stroke and 4 stroke, when it comes to letting them breathe when upgrading exhaust and jetting?

 

[Blaaster]

I figured the baffle is no longer adding any restriction. And rejetting may be needed.

With a FMF or toomey or any high peformance exhaust, I know jetting is required regardless.
I heard that some guys completely remove the air filter box cover. I have worked on many quads and dirt bikes, and I would always do air box mods like a 12 hole or recomendations from the manufacture. Never seen any of them mention completely removing the cover. Must of the quads I work on are 4 stroke, is there a difference between 2 stroke and 4 stroke, when it comes to letting them breathe when upgrading exhaust and jetting?

Got it in one!

Take the lid off a Blaster air box increase the main jet by two sizes.

Any changes to inlet and exhaust breathing require a change in jetting.

 

[blasterfied]

I know about jetting and when it is needed. I opened a ATV/small engine service and repair shop 7 years ago, and still going strong today.

Rather than removing the air box lid because this guy did, mods to a air box cover has helped dial in instead of assuming the jetting since not all systems are the same. Not to mention, where you are on the globe.

 

[Blaaster]

I know about jetting and when it is needed. I opened a ATV/small engine service and repair shop 7 years ago, and still going strong today.

Rather than removing the air box lid because this guy did, mods to a air box cover has helped dial in instead of assuming the jetting since not all systems are the same. Not to mention, where you are on the globe.

If you have been in the business for 7 years or more you will realise the importance of perfect jetting, how to achieve it and how to test for it.

Any modifications to either inlet or exhaust (especially on a 2 stroke) should be confirmed by performing a plug chop to ensure the correct AFR.

I reside in Australia and jetting practices are identical, no matter the Global position.

It is temperature, humidity and elevation that affects the AFR not whereabouts in the World one lives.

In my 55 years of working with motors I have witnessed many RAG Engineering employees remove an air box lid to lean out the AFR, when a simple air filter clean would have been sufficient.

 

[schoeman]

good evening
i have just become a member of the blaster family by getting two blasters. i have one that had a bad piston slap i have fitted a new piston kit as well as resized the bore to fit the oversize piston... what i have noticed is that i have a knocking noise inside the exhaust expansion pipe. please could someone assit with the reason this can happen,,, i also need to know how to work out what jetting to do on the carb i have gone 1.5mm oversize on the piston.

thank you regards Richard

 

[Blaaster]

Knocking noises in the pipe can be caused by a couple of things, detonation is one, where the AFR is too lean causing the motor to pre ignite.

Be wary that if you have detonation it will quickly destroy the motor.

Other noises can be a loose object in the stock header caused by the internal packing releasing from its fastenings.

There is no need to adjust jetting for the over bore.

I strongly recommend that you leak test to see if the motor is airtight.

Air leaks can dangerously lean out the fuel mix, this may be the cause of your noise.

 

[schoeman]

good evening
thank you very much, i am still new at this sorry for the stupid question what does AFR stand for, and how can i determine if it is pre ignition? at this stage i thing the mix is a bit to rich as the bike is smoking quite a bit even when hot.
thanks again have a good evening

 

[Blaaster]

good evening
thank you very much, i am still new at this sorry for the stupid question what does AFR stand for, and how can i determine if it is pre ignition? at this stage i thing the mix is a bit to rich as the bike is smoking quite a bit even when hot.
thanks again have a good evening

Air/Fuel Ratio.

You should plug chop to see if the AFR is correct.

Is the smoke white and stinky?

The smoke could be caused by a leaky crankshaft seal allowing air and oil into the crankcase.

A leaky seal can upset the AFR.

Do these things...............................................................

Before you make the plug chop run it is important that the float level is correct, the idle is set correctly and there are no air leaks in the system, otherwise the smoke ring may lie about the AFR.

WHEN ALL OF THE ABOVE ARE CORRECT PROCEED WITH THE FOLLOWING.

Warm up motor to operating temp.

Fit new B8ES plug, ride WOT through the gears and hold WOT in 5th or 6th gear for 10 seconds, or as long as you can safely.

Switch off the motor and pull in the clutch, apply brakes to come to a stop quickly.

Take the plug out and replace the old one for the ride home.

Carefully cut the threaded end off the plug to expose the insulator.

There should be a smoke ring of a cardboard or biscuit colour around the insulator.

If it is non existant or a very light colour, you are lean and require a larger main jet.

If it is a lot darker you are rich and may go down a size in main.

I prefer to run a little on the darker side, I may loose a little power but it is worth it for the peace of mind that I won't need a rebuild so soon.

http://www.blasterforum.com/do-yourself-20/how-plug-chop-38674/

http://www.blasterforum.com/engine-13/plug-chop-how-vid-48226/

This is a good to go plug.

This one is a little rich, but I would run it, I like to be on the safe side.

You have to get up a reasonable speed so that you can get the motor to pull strongly.

Then hold it Wide Open Throttle (WOT) for 10 secs or as long as you can.

The idea is not to get speed but to make it pull strong at full throttle to get onto the main jet circuit.

I find I can safely do it on a short run by applying the brakes some.

If you have not enough room you can use 4th or 5th gear with good results.