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Message started by Andemon on 12/30/18 at 12:26:47

Title: Tuning info for stock carb airbox supertrapp ex.
Post by Andemon on 12/30/18 at 12:26:47

Hello all. Maybe someone can help me. I've got an issue with backfire when getting on the gas. Even happens when revving sitting still. Will almost stall out when revving, idle will come back with a slower idle sorta then return normal. I have a stock carb not sure the year but the slide needle is fixed, main jet was 145 and pilot was 52.5. Per the manual it looks like the 2nd carb they started using. I've changed the main jet to 155, pilot the same ( think I might want to go to a 55 ) Put an extra washer ( 2 times the size of original ) plus the original on the slide. I've got the mixture screw out about 3 turns. I think it's running lean. Haven't done a plug chop or looked at the spark plug yet, but it seems lean. The super trapp doesn't have a baffle, it's not wide open completely but it's missing something in the middle, at least that's what a buddy told me. I'm thinking maybe up the needle a little more and maybe the pilot size and main jet size. I can't really get on the gas when riding and the backfire is ridiculously loud and annoying.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by batman on 12/30/18 at 13:45:36

You lift the needle jet by decreasing the thickness of the spacer, not doubling it. Remove both spacers , and replace with 2 or 3 - # 4 steal machine washers.(either combo will be thinner than the white spacer) Right now your running super lean in the mid range. ( you've lowered the needle not raised it).Do this before changing jets or adding more plates to the muffler.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by Andemon on 12/30/18 at 17:28:39

Thanks Batman!

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by batman on 12/30/18 at 20:58:35

Your welcome! The reason I said 2 or 3 washers is that the number you us is based on your elevation above sea level, GENERALLY -it may differ depending on your muffler- 2 washers if you're below 1000ft to sea level ,and 3 if you're above or near 1000ft, maybe run the stock spacer if at 4 or 5,000 ft above.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by Dave on 12/31/18 at 04:36:51

If the engine is popping and backfiring when you are opening the throttle....then you have an ignition of fuel delivery problem. There really is no reason your bike won't run well with a #150 main and a #52.5 pilot jet with the stock air box and air filter. Removing the white spacer on the needle and using two or three #3 machine screw washers raises the needle a bit, and it corrects for a slightly lean condition that can occur at low throttle settings....the engine tends to surge a little bit when you use light throttle settings. (The white spacer is on top of the needle and making it thinner raises the needle and richens the mixture).

If the backfiring occurs when you have closed the throttle and the engine is slowing down........you are forcing your engine into a situation where it will always be noisy and backfire. This really isn't an engine that like to be revved like a fuel injected sport bike. The backfire is not nearly as noticeable with the stock muffler.....it is far more noticeable when you put on a less restrictive and louder muffler. A Supertrapp works fine on this bike when it is complete - if somebody has taken off the back plate and turned this muffler into a "glass pack", that is not an ideal situation for this engine and it may be impossible to get the carb tuned properly.

When the engine is at higher rpm and you shut the throttle completely - the butterfly closes, the slide and needle drops - so you have closed off all of the fuel supply except for the small idle circuit. The engine creates a high vacuum - and it pulls a lot of air past the closed slide and closed butterfly....so the mixture goes really lean the fuel/air mixture cannot be ignited by the spark plug. The unburned fuel goes into the exhaust system where it can be ignited by the hot header/muffler....the result is a lot of popping and banging. (The Transient Enrichment Valve (TEV) is supposed to provide additional fuel to correct for this lean fuel/air condition

You should jet your carb for how the engine runs when you are opening the throttle - not for how much noise it makes when you shut the throttle. There really is no good reason for you to be using #155 or #55 jets.......something is wrong with your carb (did you put the spring on the bottom and the spacer on the top of the needle when you put it together)? If you carb is correct than it sounds like there is something wrong with your ignition or your muffler setup.

The situation where the bike stalls....or almost stalls when going back to idle is a continuation of the "too lean mixture" as the engine is slowing down from being revved.....and it can also be a sign of an idle speed that is set too low - raising the idle speed a bit can help correct this condition.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by Andemon on 12/31/18 at 10:27:53

Thanks Dave and Batman. I used 2 washers on top after removing the white spacer (mine looks orange). They weren't #3 washers but equivalent to the thickness of 3 of the washer that goes on top of the spring. Still wasn't good enough. I removed 1 and now it's more equivalent to 2 washers. It's a little better. I know this isn't a sport bike. I'm not trying to get on it like a mad man. 5th gear 40-45mph and I can't really get on the throttle more than 1/2 it'll pop/backfire. I'm near sea level in central Florida. My last savage had a TM38 flatslide with a Jardine muffler. Ran a lot better with that set up and might try to get those parts again. I'm thinking a valve adjustment might help as well. I've tested the coil, stator and pickup coil. All well within spec. Spark plug is new as well as a new Duracell battery. The exhaust header is nice and evenly snug. I will be checking where the muffler attaches to the header pipe to rule out an exhaust leak. I have a bunch of the spacers on the rear of the supertrapp but not the center cap. I need to possibly source one or get another muffler. Thanks for the help! Much appreciated! Happy New Years Eve!

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by batman on 12/31/18 at 17:03:11

Andrmon ,some owners at sea level have gone to a 55pilot and a 155 main jet ,but it sounds like the muffler being to open should be the next thing to deal before trying larger jets.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by justin_o_guy2 on 12/31/18 at 23:31:14

have a bunch of the spacers on the rear of the supertrapp but not the center cap. I nee

How many disks?
A picture would really help.
Just a link to the model would help.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by Andemon on 01/01/19 at 08:52:31

Had some aluminum laying around. Cut and drilled it. Started with 3 holes but it created too much back pressure. Still popping/backfiring but not as loud now. I've thoroughly cleaned the carb including that TEV, diaphragm was good. Kinda thinking the diaphragm is worn on the carb and maybe a 55 pilot would help. Better now but definitely excessive. Pic of the mod I did.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by justin_o_guy2 on 01/01/19 at 12:44:47

Supertrapp is designed to be tuneable, by adding/subtracting baffles in the stack.
Holes in the cap mess that up.
I had 14 on mine, using a stage one cam. Don't remember the jetting, pretty sure the 05 had the stock pilot, white washer was sanded to about half.
Had a K&N filter, which I would not do again, removed the intake snorkel and slightly enlarged air box. It spit and snarled beautifully on aggressive downshift, but could be ridden past horses and riders without spooking them without a problem. I would not buy a Supertrapp again, but if I got a bike with one, I'd call it a BONUS,, for sure..

How many disks are there.?

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by Andemon on 01/01/19 at 13:56:38

21 plates, can't get them off because one of the bolts just spins, another broke when trying to take off. I really do believe it's the carb and not so much the exhaust. I have a stock muffler, put it on and was still getting the same results except you couldn't hear it as much. I think the diaphragm is beat on the slide. No noticeable holes but it's rather worn and stretched. I think it isn't lifting high enough when accelerating or giving throttle when sitting.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by verslagen1 on 01/01/19 at 14:24:23

the stock carb runs just fine with 6 discs and an end plate with no holes.
with those holes you probably don't need any discs.
there are 2 bolts on the bottom of the can, remove those and you can slide the core out to do what ever you need to.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by batman on 01/01/19 at 16:39:17

I have no experience with the supertrapp , but if Vercy said it will run with six plates and a flat plate as a cap, then the 21 plates and 9 holes you're trying to run is like a straight pipe. We know that doesn't work . I'd follow his advise.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by Dave on 01/02/19 at 03:44:02

My Supertrapp had 6 discs when I got it....and as Versy reported the end cap was solid.

The bike ran fine.....the Supertrapp was just a bit too loud for me and my neighbors so I replaced it with a Harley muffler.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by Andemon on 01/02/19 at 12:47:39

Thanks for the help guys, I'm over the supertrapp, I found a cheap replacement that definitely works much better and is baffled but still not normal popping going on. When I decide to do the valve adjustment I'll dig into the carb again. Something isn't right and haven't figured out what just yet.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by justin_o_guy2 on 01/02/19 at 13:07:06

Sell it in the
Marketplace.
If I could get up and down without needing a chiropractor, I'd buy it.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by batman on 01/02/19 at 15:21:38

When you dig into the carb again , pull out the slide ,look down into it two things you should look for is that there should be two small holes in the bottom , that you can look through (Vacuum ports) and that the brass plate has a dimple very near the needle that should protrude downward. If you don't see these, the plate is positioned wrong (180 degrees out- blocking the ports) or upside down,( the dimple protruding upward toward you.) You should also be sure that the tongue on the outside of the rubber diaphragm is fitted in the slot , and that you seat the rib on the outside edge in the slot in the carb body before replacing the spring and top cap.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by Andemon on 01/03/19 at 05:33:12

That's exactly what I believe is wrong Batman, that's the answer to my problem I believe. I'm sure someone else at some point messed with the carb before me and set it up wrong. I'm going to dig into it and see. Thanks Batman!! Update check photos, think it's correct now. Putting it back on and checking.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by Andemon on 01/03/19 at 06:08:40

Here is what it looked like when I took it apart first. Dimple up and partially blocked holes.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by batman on 01/03/19 at 06:57:21

Yes top pic is correct! should work much better now.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by Andemon on 01/03/19 at 08:03:20

Well it's still happening. Lol. Maybe valves off or timing? I'm guessing valves, I say that because they are noisy. A lot noisier than I remember my other savage. Did a quick video. https://youtu.be/a3LuFRRayb4

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by batman on 01/03/19 at 11:23:38

Idle speed sounds a bit high, but you haven't told us if you 1)adjusted the fuel screw 2) removed plates from the muffles, 3) adjusted the valves
generally you tune the carb to the muffler,not the reverse.So start with the muffler, then the fuel screw (1 1/2 turns out is a good starting point), then rejet if needed.
You really should ride the bike when testing, blipping the throttle with no load on the motor isn't a good test, when you ride the bike and close the throttle the rear wheel "drives" the motor so rpms drop more slowly,and the motor and oil are fully warmed (after a few miles).

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by Andemon on 01/03/19 at 14:10:29

I'm done with the supertrapp, already trashed it, wasn't in the best of condition anyway, tons of rusty metal falling out of it from the inside, it was junk. New muffler is much better. I will probably be getting a Harley muffler this Saturday, local guy posted on craigslist for $10, he's got 2. Anyway, carb specs, main jet 155, pilot 52.5, mixture screw is currently at 2 3/4, I'll dumb it down to what you suggested batman but think it'll make it worse. I'm going to dive into the valves tomorrow when I can. I think they're a bit off which is helping with this issue. I tested the coil and it's right in the middle of the specs, same with stator, pickup coil was on the lower end of the spec but within spec ( possible issue? ). I did ride it and still getting the issue. I did read valves or timing could be causing these issues. There's no intake leaks around the rubber manifold but I'll double check that, could be something going on there. Thankfully I've become very quick at disassembly, lol, I'd say 50 times I've had the thing apart. I got 2 savages recently, made one, used parts from 3, traded parts for what I needed. 2001 frame forks wheels etc and electronics mostly, 96 bottom end, 87 head and valve cover. I'll get it for sure. Thanks for the help, definitely need it and it's helping me!

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by batman on 01/04/19 at 07:38:11

OK.just take care ,loose valves make noise (an increase mid rpm performance) but aren't causing any damage . tight vales won't close and will burn. Our valves always make some noise ,it's the nature of the beast. What are you using for an air cleaner?

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by Andemon on 01/04/19 at 08:07:14

Was quick to put this together, valves looked good but wish I would of lapped them before I slapped the head on. I usually do but I've been bikeless for a few months and it sucks. I'll put them on the higher side of the specs, I know Suzukis like to breathe. Had a gs850 that did well on the higher side of vavle clearance. I have the original airbox and filter. Going to dig into the valves before it rains.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by Andemon on 01/04/19 at 13:44:10

Exhaust valves were below .003 set them to .005 what a pain to do this vavle job but got it done. I couldn't get the timing cover off, so had to take the entire cover off. Haven't ran it yet. Need to get fresh oil tomorrow and give it a go. How close is the DeComp supposed to be to the valve? From what I read on here and a picture I seen I'm thinking my lobes are worn.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by verslagen1 on 01/04/19 at 13:57:47

The decomp cam will hit the rocker when the lobes or rocker are worn.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by Andemon on 01/04/19 at 14:47:26

It's not touching it now but it's close. I'm thinking this is partly why it is running the way it is. Hoping this valve adjustment clears it up. Verslagen1 mine is a lot closer than the picture you provided in the valve adjustment write up.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by Andemon on 01/04/19 at 14:49:40

Guess it's what I get for cutting corners to get it done fast...sigh, it figures because the time I choose not to measure things and get in depth with a build things are out of wack. First and last time I do that.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by batman on 01/04/19 at 21:51:18

Andemon, You might also check and adjust the decomp cable ,you may have it to tight . do you have a Clymer book ? If not the solenoid should only move out 3-5mm. , if you bike is worn setting it to 3mm may help.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by Andemon on 01/05/19 at 06:20:36

Batman, yep I got the erroneous Clymer. There's slack in my decomp cable. I really didn't see much info on setting the solenoid. How do you do that?

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by verslagen1 on 01/05/19 at 08:25:07

there is supposed to be a lot of slack in the cable.
the measurement is taken on the solenoid.
remove the rubber cap and measure the depth of the center piece.
if you hear a clack when you push the button followed by a click of the stater relay a half second later, it's probably ok.
too tight and the lever won't pull up.
if you're not sure, looser is better.
when starting, it should start on the second or third rotation and should never stall.

Title: Re: Tuning info for stock carb airbox supertrapp e
Post by batman on 01/05/19 at 08:46:09

I place a finger in the back side of the solenoid (there's openings) and gently push it out , then measure the brass stem length ,adjusting the length at the bracket holding the cable end at the arm,