Mounting Triumph pea shooter exausts

[Buccaneer]

Hi all,

I'm fitting some peashooter silencers / mufflers, they are the Triumph type with a rectangular channel welded to the silencer, not the Norton type which has two pommels for mounting the silencer. The mounting method is very similar to the stock Yam method on my bike. I have to admit here that this is for an XS400SE, posting here as I guess this type of mod would more often be tried on a bike like the XS650 specials, or maybe some of you guys have sixties / seventies Triumphs as well?!

Will try to add a photo to show these mounts...

I'm looking for some advice on how the channel should be mounted to the hanger bracket. I have the stock hanger brackets and these look remarkably correct already!

OK to finally cut to the chase my problem is the bolt holes (slots actually) on the channels on the silencers seem to have almost no metal left in the key area where the bolt head or nut will be holding it to the hanger bracket. I was wondering if they are intended to be used with bolts directly (maybe a special square head bolt or nut is used?) or whether there should be a bar slid down inside the channel to take the stress? Any advice from those who have been here before would be gratefully received!


Thanks, Buccaneer.

 

[azman857]

I had some Dunstall replicas on my Norton and they had a similar system for mounting. I used a bar with threaded holes and the the plate was bolted on. Just be sure to use short bolts so you don't go through the bar and into the peashooters. Some locktite is a good Idea too.

 

[TwoManyXS1Bs]

We worked with this style back in the day. Seems there was more metal, closer-fitting slots, the bolthead could do it's job. Ditto azman857 for this newer installation...

 

[arcticXS]

I am sure azman's mounting tip works great, no problem there!
But you may be disappointed by the sound, if these mufflers have the standard, louvred baffle with no packing around it, like Norton Commando mufflers.
I got a pair of 1 1/2" Norton mufflers for my XS650, and a set of 1 1/2" single wall headers from Jerry Heiden (same as MikesXS, I believe). The sound was not even close to the deep rumble from a Commando 850, more a "buzzing" sound as revs increased. This must be due to the shorter stroke of the XS, possibly also valve sizes and cam profiles. I ended up cutting mine up, and I am now trying to convert them to a conventional perforated core, with fiberglass packing. The reverse cone will then have to be bolted or riveted on, using an internal adapter ring...
(A Norton Commando has 89 mm stroke and 1 3/8" headers as standard, where the XS650 has a 74 mm stroke)

 

[Buccaneer]

Thanks all.

Azman that seems like the perfect way, I was thinking of a bar with holes or slots in it for the bolt threads -and wondering how much hassle it was going to be to get everything in place... a tapped bar will be much neater, and easier!

Roger on the sound issues... will have to find out the only way! And certainly not weld or use any cement until it's right...

Will post back with findings!


Cheers, Buccaneer.

 

[5twins]

Yes, the drilled and tapped bar is the best method for mounting an aftermarket sliding track muffler. It spreads the load and clamping force along the whole track. Bolt heads will break out in short order, especially on our vibrating XS .....

 

[Buccaneer]

Hi 5twins,

OK got the first silencer mounted and I think these pipes are going to look nice on the bike - hope the sound will be reasonable too, although since this is a 180-degree 400cc, I'm not holding my breath on that one!

Having read further in the Tech section I now realise I was a bit hasty to just wade in and cut the first silencer off flush through without reading up on all the detail first .. .. anyway, hopefully I may have got away with this rash behaviour on this occasion ... but I do need to get some pipe adaptors so that the inner of the downpipe seals properly to the silencer...

Seen the pics here of that #548520 1-1/2 ID to 1-3/8 OD adaptor, however so far I have not been able to find anyone selling them this side of the pond. Since over here IDs are rarely specified and quite often neither is wall thickness, finding an adaptor that will work over here is maybe not going to be so easy!

Actually I'm also wondering if my XS400SE (1981) downpipes are the same size as the stock XS650 ones - mine are 1-1/2" (38.2mm) OD and a tad over 1-3/8 (actually 35.2mm) ID for the outer chromed pipes. The inners measure at 32mm OD and 29.2mm ID - approximately, becuaseI cant get the vernier in there very well, and the cut ain't too clean. Maybe tomorrow I can get in there and clean up, or pull the old can apart and measure more accurately. Anyway, can anyone say if these dims look about the same as the XS650 stock downpipes?

I did find out with a bit of web scouring that the #548520 pipe adapter is actually made by 'Maremont' based in Loudon TN (ha!) and is a current part on their website, I have asked if they could send some to UK... this part is specced as a 1-1/2 ID to 1-3/8 OD adaptor.

In case Maremont don't ship abroad, does anyone know if / where a suitable pipe adaptor can be purchased in UK?

I have attached a first quick pic to show how it looks. In reality there is more work to do yet and (depending how it goes with the pipe adaptor) the hanger bracket will probably need some modding to move the silencer forward a bit - at the moment it is just the stock Yam 400 hangers, they actually do virtually fit!




Cheers all,

Buccaneer.

 

[Buccaneer]

I've now finished the job and if anybody would beinterested, have some photos of dismantling the XS400SE exhaust system including cutting into the silencers at various points to find out how they are constructed internally, in particular around the junction of the downpipes to the silencers.

I did not investigate the far (output) end of the silencers much as yet. At posting date (23rd June 2013) I still have bits of / the old cans but at some point these will probably go down to the dump.

Remember the following is all actually for the XS400SE but I don't doubt the 650 is very similar:

To the best of my beginners knowledge, the bottom line was that I might as well have cut the silencers straight off at the obvious place just near the end of the downpipe and right in front of the little chrome cover that hides the weld between downtube and silencer.

After you cut here you are left with a downpipe that is dual-wall. OD is 38.1mm, ID of outer tube is around 35.3mm, inner tube OD is 32mm and its ID is below 30mm. NB: The outer tube has hidden vent holes up near the exhaust collet (near the engine). If you just fit the whole downpipe into a silencer designed for 1.5-inch inlet, (which was my naieve original plan), exhaust will flow back between the two tubes of the down pipe and exit through the drain holes near the engine. It will sound bad too.

So then, what you need are a pair of tube reducers to the following spec:

Downpipe side: 35mm OD, around 32.6mm ID (Mine used 1.2mm wall diameter stainless steel tube and fitted pretty tight over the 32mm OD inner tubes, might have fitted even tighter with 1.4mm wall... then again, since nothing's ever quite straight, if the numerical fit is too exact you might find it just would not fit on at all!).

Silencer side: 38.1mm (1.5in) OD. The tube I found also had 1.2mm wall thickness so these were 35.7mm ID.

I got my reducers made from the bits of 38mm and 35mm OD stainless steel tube welded together. There is probably little point in using stainless, it just happened to be available in both diameters and short lengths from the same supplier on eBay and the total cost was GBP 5.00, or USD $ 7.50, not a problem.

Tubes were first cut down to four (in total) lengths of 125mm. The larger and smaller ODs fitted loosely together. In an ideal world it probably would have been best to jig or chock them to be precisely coaxial, but I'm fairly sure the welder just balanced them and started with some tack welds to hold everything in place... I wasn't there to check. Tube overlap was specced at 50mm.

After welding the join was turned down to make it nice and smooth and make sure none of the welding would foul the exhaust tubes.

The reducers had to be cut down at both ends to fit the exhaust, yes it might have been better to plan it more carefully so that no cutting and dressing would have been needed, but I was feeling cautious by this stage and wanted plenty of chances to measure, measure, measure before cutting.

So far I've assembled everything without any compound (we have gun gum / fire gum by Holts over here which seems aimed at these sorts of repairs)... it is almost but not quite 100% gas tight with just the assembly pressure plus a stainless steel hose clip round the outside of the silencer inlet done up tight. There is in practice no room for the pipe reducers to move around inside and the fit is so tight that even if there was room, they wouldn't move. It may well be best to leave it like that for easy future disassembly, but if the tiny gas leak ever seems to be a problem I could try the compound.

Have not put it through MOT test yet, but as it stands it should be fine. Modulo the straight-through silencers which are a bit too loud, not sure what the rules are for a 1981 bike, but will find out very soon!..

So, how does it sound? So far, a little bit disappointing bearing in mind the steep cost of the Commando silencers, and certainly does not sound as good as my old XS650 which had AFAIK the same setup. The 400 does not have have enough cylinder capacity, stroke or the 360 degree crank required to get the 'right' sound. So far this is all based on low revs, waiting for the test and a new lid so I can get on the road.

Next steps will be to play around with wire wool and other materials in the silencers to see if the sound can be tweaked. Pretty sure some extra damping will be required to get through the MOT anyway

To my eyes at least it really looks the biz, will post some photos if anyone is interested.

 

[Buccaneer]

*PS*

The Yamaha silencer hanger brackets did not need any modification at all!

I did need to source a strip of steel (10mm wide and I found 2mm thick x 1m in stock at local B&Q DIY shop) to go inside the channel on the silencers to give a really firm foundation for the nuts holding the silencer on. Decided not to tap it as 2mm too thin for this.

Drilled two 6.5mm holes in this for my (new) M6 bolts holding silencer channel to hanger bracket. Used two different types of square nut inside the channel. Ones removed from M6 'cage nuts' (used in telecoms / broadcast racks) are the thickest at 5mm thick, perfect for the bigger end but will not fit in small end. 'Roof Nuts' obtained from local Nut and Bolt Store (Namrick, excellent!) are 4mm thick and just right for smaller end of the channel.

Using M6x10 stainless bolts with penny washers, everything fitted just nicely and bolts do not chew into silencers.

 

[angus67]

sounds like you did a very good job mounting them. As far as packing for MOT, I have the small glass packs on mine, and when I pulled the baffles out, the packing was so minimal, u could see thru it in spots, and was non-existent in others.
I need to repack with some glass I can yank from under my house, get it as stuffed as I can, and wire tie the hell outta it. That's the plan, and I'm sticking to it.

 

[Buccaneer]

Hi Angus, do you have peashooters on your bike? How did you open up the silencersto get the baffling in? Mine are straight-through peashooters, and the only baffling I figured I could add is some wire wool pushed through from the back to half way up, then a balled-up chicken wire plug to stop the wire wool shooting out under pressure. Has improved the sound a fair bit, and so far nothing has moved! But spose the wire wool won't last long ... is stainless available?! Cheers, Buck.

 

[Buccaneer]

I've added the wire wool and it does help the sound a fair bit, I'd say it now sounds reasonably good (& not as loud of course) ... especially bearing in mind the typical XS400 sound on youtube demos.

 

[angus67]

http://www.mikesxs.net/product/07-0010.html
I have these.

 

[gggGary]

I had been making the inserts but Mikes sells them now, and the commandos include them. I got a set and they are nice, you still need to shorten the bolts so you don't cave the muffler when you tighten them. Hint thread the bolts in the steel bar then cut/grind them shorter unthread from the bar and the end of the thread will start easy.

Steel Exhaust Bracket with Bolts
Steel Exhaust Bracket with Bolts Photo Steel Exhaust Bracket with Bolts. 4 1/2" Total length, 1/2" wide.
Part #07-0116 $5.50 USD Ea.