Blueflame fitted exhausts pop on decel

[mjvw]

Ok so Blueflames fitted, but lots of popping on decel, so looking to do the following:

Rear header pipe to link pipe back of swing arm gasket blowing big time, after reading some posts onsite I have in preparation purchased.

4 x stainless studs and nuts plus header exhausts gaskets
graphite gasket for link pipe
s/s exhaust clamps



To fit rear link pipe gasket.... headers removed loosed off with a view to replace header studs with s/s plus nuts

Best practice if studs nuts seize (They will be) ????

1. socket long extension tap with hammer
2. Quality Nut splitter first or a bolt nut remover https://www.screwfix.com/p/erbauer-bolt ... lsrc=aw.ds
3. nut removed with splitter attempt to remove studs
4. nut removed refit just using S/S nuts do studs later.

Pairs blanking kit purchased to remove some pluming
choke cable that's as snapped at collar replaced at same time ( keeping an eye on the plastic snappy bits)

These will be fitted when exhaust sealed

Any advice would be appreciated

[MacV2]

Cut the nuts off with the nut splitter but you may need to dremmel the last little bit or use a small cold chisel.

Then plenty of Plus Gas on the studs over as many days as poss & use a stud extractor, you will need a 7mm one.

Rears tend to come out fairly easy it's the fronts that normaly cause issues...

Top Tips... Loads of Plus Gas, bit of heat & use the stud extractor give it a little nip up to brake the bond...

[AMCQ46]

I agree with Mac, if they look rusty, it is better to use a nut splitter.

If the bike has had an easy life and the front studs are pretty clean, and you want to take the risk (I did on mine), then lots of plus gas for a couple of days before and some heat

[mjvw]

Thanks MacV2 & AMCQ46 Starting plus gas routine then nut splitter and Dremel 7mm stud extractor, Front studs look to be in a fair condition but rusty, rear clean will keep you posted.
Thanks
mjvw

[mjvw]

Good day started penetrating fluid on header studs/nuts, wire brushed and cleaned front pretty solid, rear now out... penetrating fluid and a little opposite pressure plus a little back and forth with plenty of penetrating fluid and the nuts came off.

Released lower exhausts clamp and managed to remove rear header pipe from front assembly pipe without removing/slackening off front, have access to main exhaust from above may block off with cloth and clean off the stuck blown graphite gasket fit new one and see if I can then fit rear header back with new gasket at both joins.
Then would leave fitting of s/s studs to front and rear for when engine is out.

[AMCQ46]

Well done getting the exhaust off, but sounds like your bike was well looked after, so that helps a lot. keep the nuts clean and greased up with some copaslip, and you won't need the stainless studs.

[tony.mon]

Bear in mind that the standard studs are M8 where they screw into the head, but M7 for the nuts to screw onto. Not all aftermarket sets have both threads. A section of M8 stainless studding works fine, the clamp holes are big enough.

I have wondered why Honda used long nuts. There is enough space to get a spanner on standard length nuts, and if they rust in place the extra length allows the nut to exert enough torque to shear the stud on the M7 side.
A shorter nut is more likely to break the rust "weld" before the stud snaps.

By the way, if you strip the M8 thread in the head, the stripped hole is just the right diameter for you to tap it out to a BSF or BSW oversize.
I can't remember which size, but it's easy enough to look up.
It's easier than a helicoil, unless you already have a set to hand.

[mjvw]

Thanks for all the great advice going to see if rear header can be refitted in the next couple of days, don't think the front will loosen off so hope the rear refit works, interesting point regarding the OEM stud nuts they are long with that last thick flange at rear , going to run the S/S nuts and spring washer provide with the S/S stud kit onto the OEM studs.

The rear exhaust header to main exhaust gasket was well blown sprayed with heaps of leak detector, on start up i was covered in leak detector so once this is fixed I think the blueflames will not pop and fart on decel.

[sirch345]

Thanks for all the great advice going to see if rear header can be refitted in the next couple of days, don't think the front will loosen off so hope the rear refit works, interesting point regarding the OEM stud nuts they are long with that last thick flange at rear , going to run the S/S nuts and spring washer provide with the S/S stud kit onto the OEM studs.

The rear exhaust header to main exhaust gasket was well blown sprayed with heaps of leak detector, on start up i was covered in leak detector so once this is fixed I think the blueflames will not pop and fart on decel.

You're doing well

Out of interest which leak detector did you use

Chris.

[mjvw]

Thanks for all the great advice going to see if rear header can be refitted in the next couple of days, don't think the front will loosen off so hope the rear refit works, interesting point regarding the OEM stud nuts they are long with that last thick flange at rear , going to run the S/S nuts and spring washer provide with the S/S stud kit onto the OEM studs.

The rear exhaust header to main exhaust gasket was well blown sprayed with heaps of leak detector, on start up i was covered in leak detector so once this is fixed I think the blueflames will not pop and fart on decel.

You're doing well

Out of interest which leak detector did you use

Chris.

Sprayed on cold exhaust then start bike up better than burnt hands.
https://www.amazon.co.uk/Arctic-Hayes-P ... 87&sr=8-16

[sirch345]

Thanks for all the great advice going to see if rear header can be refitted in the next couple of days, don't think the front will loosen off so hope the rear refit works, interesting point regarding the OEM stud nuts they are long with that last thick flange at rear , going to run the S/S nuts and spring washer provide with the S/S stud kit onto the OEM studs.

The rear exhaust header to main exhaust gasket was well blown sprayed with heaps of leak detector, on start up i was covered in leak detector so once this is fixed I think the blueflames will not pop and fart on decel.

You're doing well

Out of interest which leak detector did you use

Chris.

Sprayed on cold exhaust then start bike up better than burnt hands.
https://www.amazon.co.uk/Arctic-Hayes-P ... 87&sr=8-16

It hadn't occourred to me to use something like that to detect for a leak in the exhaust system. I usually burn my hands
I normally use one of those 3 or 4 legged part pickers (that is used for retrieving a dropped nut or washer etc from the engine area) with a very thin piece of paper held in the prongs.

Thanks for the link

Chris.

[mjvw]

Up date... managed to refit rear exhausts pipe and lower exhausts gasket without removing front pipe.
have not checked for leaks as it was far to late to start the storm up, had to put a small chamfer on the graphite gasket so it lead into the main system without creasing (hope it mates ok) smeared it with silicon high temp gasket paste fitted and clamped up.

Biggest issue was getting the lower bolt onto the stud VERY limited access once pipe is position CCT/Shock big hands, chopped up a few tools that worked in the limited space before getting it right, so I could ensure the nut ran square onto the stud (don't known about you guys but hate not having feeling when running a nut or bolt in or on) If this does not seal I will have another go but this time I will remove the rear subframe for better access.

Still applying penetrating fluid to the front studs and nuts no movement.

[tony.mon]

Good progress. I still feel that using a nut splitter on the fronts from the start would have been easier. Removing the rear subframe sounds like overkill. Removing the whole system, two new port gaskets and the graphite seal will sort it.

Fitting the rear downpipe to the collector means that you have to pull the collector downwards in order to fit the downpipe into it. That movement will have disturbed the front gasket seal.


You might have fixed the rear but made the front worse. But I'm keeping my fingers crossed for you.

[mjvw]

Good progress. I still feel that using a nut splitter on the fronts from the start would have been easier. Removing the rear subframe sounds like overkill. Removing the whole system, two new port gaskets and the graphite seal will sort it.

Fitting the rear downpipe to the collector means that you have to pull the collector downwards in order to fit the downpipe into it. That movement will have disturbed the front gasket seal.


You might have fixed the rear but made the front worse. But I'm keeping my fingers crossed for you.

Good point about front gasket being disturbed going due to messing around to check it out when it stops raining, I have ordered a nut splitter just in case.

[mjvw]

Thanks for the no leaks at all checked still popping on decel but not half as bad, little bit of carb farting/hickups at 3000rpm this used to happen on the std pipes.
Looks like its time to remove pairs and see how it goes.