How many plates in YOUR Super Trapp...?

[81xsproject]

For folks running Super Trapps, I was wondering how my plates people were running and their results experimenting with more or less.

[Pat Kelly]

I have a SuperTrapp baffle in my RC Engineering 4 into 1 exhaust. I had 10 discs in it and it ran fine. I added 10 discs (20 total) and it runs good (but loud) when it warms-up. It takes a long time to get warm enough to keep it from dying. I have the 1196 kit. I went from 110 jets all across to 125's. I dropped back to 120 mains and 10 discs and it is better. If I remember correctly I read on the SuperTrapp website that a stock 1100 with the 4" discs would take 8 discs.

I did get two 3" SuperTrapp mufflers that I will use to make a 4 into 1 into 2 system. This will be Jet Hot coated (black). I want to do this not for performance but to get back to the stock appearance on my LG.
It will go from the four 1 1/2" head pipes to the 2 1/2" collector to a 'Y' pipe that is 2 1/2" in to two 1 5/8 out. The mufflers are 15" long with a 3 1/2" outlet (3" discs sit inside the muffler body).
The bike still has issues warming-up. I think this is an issue with the head (PO had buggered-up #2 in a bad porting job), dialing-in the carbs, and maybe pick-up coil wires.

[bikerphil]

I'm running 6 discs in my 4" Supertrapp behind a Mac header on my 79. 42.5 pilots and 142.5 mains. I initially was using all 12 discs and it ran fine but suffered a bit in the low RPM range. Using 6 discs pepped up the low R's just fine.

[Dan Hodges]

SuperTrapp Exhaust

I have one of S/T's 4-1 headers that was designed for the Eleven and I have two different mufflers. One muffler contains the mechanical baffle and is somewhat restrictive no matter how many plates you use and about 15 plates will flow as much as the muffler will. I have another S/T muffler that I removed the mechanical baffle from and in it's place I installed a 2.5 inch ID ceramic wrapped core that S/T special made for me that has provisions for the installation of plates or you can run it sans the plates. I'm using 22 plates with a competition open end cap. I have a Dyno Jet kit installed but use #120 Mikuni mains straight across rather than the main jets that came in their kit. I used the Mikuni mains because during my dyno test I had access to the Mikuni's and didn't have the next step up in the DJ mains. My engine is a "Wiseco" 1179 with a head ported by Nigel Partick and a set of welded hardface Mega Cycle cams which have 257 degrees of duration @ .040 lift and .375 valve lift and are installed @ 108.5 degrees centerlines. These cams are a "special" grind and you won't find them in the XS Eleven section of Mega Cycles catalog. With these cams I used a set of valve springs made by Kibble-White with Yamaha valve stem seals, keepers and retainers. I use the stock airbox with a drop in K&N filter and 4 1 inch holes drilled in the bottom of the filter tray. On my initial dyno test I had problems with my AF ratio and I never did get the stock needles to work properly but it made 95.58 horsepower and 70 ft. lbs. of torque with that set up but had some bad glitches at 2500 rpm and 4500 rpm. I put the Dyno Jet kit in and changed the centerline settings on the cams and with some fiddling with the main jets I made 98 horsepower and 73 ft. lbs. of torque with no spikes or glitches anywhere from 2,000 rpm up. It starts good cold with little choke and once it hits you can push in the choke and it will idle fine. On a very cold Missouri morning it requires some choke but only for about a couple minutes after which you can ride away even though I let it warm up untill I can feel heat in the cases before I hit the road. Over the years I've had three different sets of 4-1 pipes on it but other than going up one size on the mains the carbs remained stock and it ran perfectly. When I put that big bore kit in it and those cams I had a hellva time getting those CV carbs to work right but I knew that going in and figured I could make it work which I eventually did.

If you are running the SuperTrapps with the mechanical baffle and only 6 to 8 plates, you probably aren't making any more horsepower than you would with the stock pipes and even less torque....... ditto for a 4-1 with a 1.5 inch core muffler, it simply doesn't flow that well, just makes noise for your ego.

Reading spark plugs these days on a motor burning pump gas is diffulcult because the porcelain portion of the plugs tend to run whiteish and so you have to focus on the first couple of threads or invest in a illluminated probe that you can insert into the combustion chamber via the spark plug hole. A lazer temp gun works good too because it enables you to check the pipe temps.
If you have a combination that has several modifications, trick carburetors in particular, the only way you will ever get it right is with a sniffer on a dyno but if the motor is stock with maybe just an aftermarket pipe, a stock tune up with maybe a simple main jet increase will do it for you.

There are several different carburetors that will go on an XS and actually run but because of an infinite number of reasons they will require divine intervention to get them dead nut on. The 36 mm carbs from an FJ are by far the easiest to adapt to an XS but they varied from year to year and even Cody G. and Bobby Pugh had a diffulcult time getting them right on Bobby's dyno but once you get them right they work good on a big bore XS. I like the ones from an 84 FJ because that model has the vacuum pickup on the # 2 carb like my XS and the others don't.

If you call Super Trapp, they will design you a core/cores for your application
that will make you happy.

Dan