Lost power with Supertrapp slip-ons?

VMAX  Forum

Help Support VMAX Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

texas-ss-tornado

Well-Known Member
Joined
Oct 18, 2008
Messages
941
Reaction score
32
Location
Lexington, KY
Just put some Supertrapp slip-ons on my 90 VMAX. They were used, but in excellent condition, the guy I bought them from had them on a 2005 model, and he told me he had put 4 or 5 discs in each side, they sound GOOD! However, my "seat of the pants" dyno is telling me that I have lost power. I will know for sure this weekend when I go riding with a buddy of mine, but what are the chances I actually lost power by going to these mufflers? I have more discs to put in if I have to, is it more likely to increase horsepower with more discs or less? I'm assuming more, because I'm building back pressure, it might be quieter, but should increase performance, right? Or am I thinking backwards? I kept my stock exhaust just in case, but I'm hoping to at least get equal performance from these Trapps, they do sound great! Any input would be greatly appreciated, thanks! :punk:
 
Oh yea, and I have the closed end caps. I just found a thread that "kinda" explained it, I'm still thinking I need to add a few discs and see if the performance increases. Let me know if this thinking is logical! Thanks!
 
If your all stock, I would put 8 on each side, shim the needles a hair, and take off your Y.....
worked for me...........
but others will soon chime in with their thoughts also.
 
when I ran trapps, I used the closed endcaps. I ran between 10-12 discs per side. When I replaced the main with a mikuni 147.5 and readjusted the a/f, things woke up. I didn't remove the "Y", but shimmed it about 1/4".

Generally slip-ons wont increase your power, I've found out that basically the only people who make noticable gains are the manufacturers. But they will give you a better sound and remove about 20+lbs of weight off the bike.

Another thing I noticed was if you want to buy more discs or different endcaps it's cheaper to go through JEGS, or Summit than a motorcycle store.

p1020400.jpg
 
Thanks for all the responses, I'm going to add a few disks on each side and see how it responds. Am I hearing this correctly, adding disks will make it LOUDER?
 
Yes it will, as more disks = bigger hole = more noise.

An A/F screws adjustment may defo help getting back to where you were.
 
Yes it will, as more disks = bigger hole = more noise.

An A/F screws adjustment may defo help getting back to where you were.

I've never messed with jetting, airbox or anything on this bike, and have had it for about 5 years. I was thinking about getting a K&N filter for it too. I hate to sound dumb, but do you need a special tool to change the A/F mixture? I've done this same adjustment on a V65 before, but not a VMAX. Where are the screws located??? Thanks for the help!!!
 
On the max they are visible just under the slides covers on the carbs. At the very bottom on my picture.

If they have never been tampered with, the holes will be sealed at factory, and you need to very carefully drill the caps and pull 'em off with a small hook or similar.

Also, if they haven't been moved before, you MUST record where they are FIRST! Simply screw each one all the way in carefully counting the number of turns required until it hits its stop. Gently - you don't wanna be heavy-handed with these lil' guys.

P1030901.jpg


P1030908.jpg
 
Well, I just took them off and there were actually 6 per side, I added 4 on each side and will ride it later this morning and see if there is a noticable improvement, it did get a little louder, but it sounds GOOD! I just looked at my A/F screws, and I don't see a screw in that hole, so it has never been touched. I'll see how it runs before I start messing with those! Thanks for the help!
 
By the way, what SHOULD be the factory settings as far as turns out? 2.5 ???? I definitely have that stock plug in there, what's the easiest way to get it out? If I drill it, will it just disintegrate and fall out in pieces???
 
Drill the plug with a SMALL drill bit. Just large enough to get a drywall or sheetmetal screw started in the hole. Then, put a screw in the little hole you drilled and yank them out with the screw.

The A/F screws will most likely be all over the place and no two the same. Yamaha set them with by measuring EGT from the ports on the stock pipes.
 
Drill ahole on it being very cateful not to hit the screw whith the drill bit whenit goes threw the plug, then screw a sheet metal screw in the hole and pull the plug out using the screw.
 
Well, I won't have to worry about the A/F mixture, just adding those 4 disks to each side made enough difference to think I'm back to "normal". Thanks again for all the tips!
 
Yep you drill it but go easy, I thought the same when I put on supertrapps I had the comp open end caps and then added 6 disc to each side man it ran different sounds bad to the bone and was out goofin of testing it and this kid pulls up beside me with 600 ninja talkin how badass his bike was and everything he did with the none stop revving of his motor. When we left I. Smoked him so bad he had nothing to say and finally shut up about his bike . But the more disc adhp and sound less adds torque and quiet
 
I think most people would suggest drilling a small hole big enough to screw a screw into the hole, clamping onto the shaft of the screw & giving it a good yank, it should pop right out. You just don't want to bury the drill bit deep into the plug, or the screw into the hole you make in the end cap, just a couple-3 threads, so you get a bite on the pressed-in plug. Some people use a small angled pick in the hole instead of a screw.
 
I used a small drill bit, I wrapped a piece of tape a little less than a quarter of an inch from the end to use as a marker.

Made a self tapping bolt real quick ( just file a "V" on the end ) threaded it in and pulled out the brass plug.

I think it took a whopping 5 mins.
 

Latest posts

Back
Top