Bogging right out of idle

[SkunkWerX]

Hello gang, been reading here for a while, getting all the good info, finally decided to register and ask a question or two.

 

It's a 2003 Banshee we picked up used, that I suspect was never entirely tuned and jetted for the mods.

 

Toomey T5s, Reed spacers, Boost bottle, K&N airbox lid filter, breathes well and is unrestricted.

 

It ran "OK" when we first got it, of course what is "OK" when you have no benchmark?

It started easily, ran OK, nuff said. It began faltering getting worse, and that is when I discovered some whacked out carb air adjustments. Right side Air screw was almost all the way closed, left side was at 2 full turns out, whoa. Left side float valve leaked, knew that all along, also knew it would need the rebuild kit and new float needle/seat

 

Between my son and I we have owned Blasters, Warriors, i currently have a 660Raptor, the banshee is really my sons bike, so, we aren't strangers to mods and tuning, but this is the first Banshee, so we're getting our feet wet with Dual carbs and lots of jetting stuff.

 

Rough idle, hard starting, then pretty much no starting. Have remedied most of that stuff.

 

Did the normal outside checks, Checked for air leaks, ordered the Air filter adapter right away, we've owned at least 3 other Yamahas and know all about how crappy the Air filter fastening system is. Anyway, sprayed WD40 on intake boots, and reed spacers to make sure it didn't have an air leak.

 

From the looks of the tires, chains, sprockets, and eveything else this thing hasn't seen much riding. We swapped our Maxxis Razrs and Works shocks over to this bike.

 

Finally got inside the carbs, found 250 Mains and the stock 25 pilots. For the Toomey's and open Air Box lid 250s seemed pretty small. Toomey sez go to 280s, just for the pipes alone. I'm adding a little more for the open air box and cranked it up to 300's. Top End is WAY COOL now, just nothing but arm pulling power, butt sliding off the seat...you guys know the feeling. So we can't say anything bad about 1/4 to Full throttle range, it rocks!

 

Low end Bog has got us down, though. Starts first or second kick now, idles decent, but when you jump on the throttle is Bogs down, even will cut off if you don't feather it up.

 

With the stock 25s for pilots, we can start up, get it to idle, but it idles best with Air screws turned all the way in, maybe 1/4 turn out, max. Yeah, it makes sense tht pilots might also be too small. Turn Airscrews OUT more, runs rough, idle goes to crap, then at about 1.5 turns, cuts off. No surprise, figured Pilot was too small, also, just like Mains.

 

This evening placed 30's for pilots. Almost same indications. Bogs from 0 to 1/8th throttle, right off of idle, really. the warmer it gets, the more pronounced the Bog. If you can "feather" the throttle thru the Bog, it then takes off like, well, a Banshee.

It is now running best and holding best idle at 1/2 turn to 1/4 turn out on the Air screws.

 

I have 32.5 Pilots, in hand, so, is that the way to go?? Increase from 30 to 32.5s and see what happens to the Bog??

 

Added info:

-TORS is eliminated, followed all instructions, unplugged all, taped ends all that stuff.

-Has the idle kit and new Carb caps, no problems there, I synch the Carbs each and everytime I replace the caps. Set the idle per what i read, 2 turns Clockwise from where the throttle bodies bottom out and idle screws are just touching them.

-Cut outs facing toward the airbox, float bowls are left/right correct.

-Set float height and check them everytime carb is apart.

-Installed Carb rebuild kits , float needle, seats, Air screws, etc. Fuel is flowing fine, checked that.

-Even in the beginning, first time removing bowls, totally clean, not even any tiny grit.

 

Only about 300 feet above sea level, 68 to 80 degree temps, 50% humidity.

Running 93 octane at 32:1 ratio

 

I think I have gone over everything, and just asking, go ahead to 32.5 Pilots and see what happens to the Low End Bog?? If the motor didn't breathe so well, I would think 32.5s were overkill, but, since the bog persists, and turning the Air screws OUT makes it worse, well....that's where I'm at.

 

any and all thoughts welcomed.

 

Oh, also, verified needle clip is on 3rd position, so, it's right in the middle.

 

 

Thanks for reading and giving it some thought.

Edited September 22, 2006 by SkunkWerX

[Toomey Banshee]

280-310 mains with pro flow adapter and no lid. If you dont run in much water go to the K & N dual clamp on's with about 340 mains, I did this on my youngest sons 99 that runs T-5s and noticed a pretty good power increase. Pilots should be 27.5's with air screw some where about 1 and half turns out, give or take a half turn. Did you disconnect your parking break circuit yet? If not then square that away asap. This should put you in the ball park. Did you do a compression test yet? Plug chop? Clean and sync your carbs? Needle sounds about right. Its all trial and error, good luck.

[SkunkWerX]

Thanks Toomey-B,

 

No plug chop yet, as High End is not even my concern at this point, wanted to correct the Low End bogging, then would work on the fine tuning from 1/4 to Full throttle.

Bogging so bad it will die if you don't "feather" or "goose" it up into the 1/4 to full throttle range.

 

With the 30 pilot, it idles and runs best with Air screw almost all the way IN.

The more i turn it out (CCW) the worse the bogging gets.

With the stock 25 pilot, it was even more pronounced, leading me to thinking I was too lean on pilot.

 

Parking brake circuit is gone, cut off, heat shrink over the wire ends, same for throttle wires.

Tors box unplugged, totally, with connector ends (to & from) taped.

[dajogejr]

with your mods, temps, riding locale, etc....

You should not need bigger than 27.5 pilots for your setup, even if you remove the airbox and put pods on.

 

What kind of spark plugs you running? Gap?

As said, compression check time....

 

When mine had an airleak, WD 40 would not make a difference, I think it was too thick. But, carb cleaner saved the day...it almost died out on me...

 

You should be able to run 25s in there with a turn or so out running an air box....

You said you did the rebuild kit, but...did you just swap parts, or did you completely clean the carb bodies with all of the brass out of it. Pilot circuits are tiny as is...a spec of dirt can throw it off....

[SkunkWerX]

Thanks dagogejr

 

Yes, I did a full cleaning, made sure carb cleaner would blow thru all ports, orifices, etc.

Even replaced the little air jet (160 or 16 as it's numbered)

 

Thanks for your idea that it should run and get off idle easily on a 27.5, even a 25.

That's what I was thinking/questioning.

 

And, yes, after reading your comments, I am now thinking back along the lines of an air leak, loose reed spacer, /cracked/loose reed, or something in between.

 

I did a quick visual and vacuum test on the boost bottle itself, it is intact.

i don't have the stock crossover tube, or I could swap it just to be sure.

 

My compression tester won't fit in there, it's an older one, for autos,

so I'll have to call my buddy and try to borrow his sometime this weekend.

i did the thumb test Both "seemed" same/same and blew my thumb off with a good deal of force.

I know it's not the scientific way, but, I've got enough experience to feel if one or the other was that weak....but still, you are correct, it is a check that will need to be performed correctly if i don't find something obvious.

 

Keep the cards a letters coming.

 

I'll re-post, here, later tonite or tomorrow with any findings/changes. in it's behavior.

 

Oh also, What about simply too low of a mechanical idle?

I was thinking I may need to mechaincally raise the idle speed, but, I'll need to take more material off of the external bosses, where the idle kit screws are tapped an installed. They are tightened in all the way, and it seems like I may need to take another 1/8" off the material, so they can protrude into the carbs a little more, if anything, our idle speed seems a little bit low, not horrible, but probably could stand to be raised an additional 200rpm.

Thoughts on idle speed??

 

More info to follow, as I beat my head against solid objects.

 

STEP 1, tonite: remove carbs, boots, reed cages, spacers, and inspect ALL for leaks cracks, problems, etc. I do have a couple of spare intake boot gaskets, just in case.

 

Thanks again guys.

[SkunkWerX]

Back from the work shop.

 

Disassembled entire intake tract , cleaned all surfaces, inspected.

 

Looked inside intake ports: looks real clean, no scorching, no build-up, cranked it, pistons go up and down :biggrin: But seriously, it all looks very clean, newish, inside and out.

 

Found Boyesen Rad Valves with Pro Series Carbon fiber reeds installed. Figured i'd find some after market reeds, as I have one of the stock cages and reeds, as well as the 2 original intake boots, in the parts box he gave me.

I would have picked Delta-V, but, the RAD is what is in there, so that is what I'll deal with.

They look new. Very clean, tight, no visible gaps, bends, tears, no scorching, no brown edges, none of that. Retaining screws were all tight.

 

It all looked OK, *except* for previous owner placed a couple of thin raggedy gaskets between the intake boot and reed cage. I checked the Clymer manual, it does NOT show a gasket there, as the boot itself has the rubber sealing surfaces. Took care of that as a preventative measure.

 

Replaced with new gaskets, reassembled, torqued slowly, in an x-pattern, made sure it all sealed down correctly.

 

Intake Port--[gasket]--Reed spacer--[gasket]--Reed Cage--Intake/Carb boot.

 

Re-assembled all.

 

Bogging is still similar, maybe a little bit better, but still bogging off the line. 0 to 1/4 throttle.

 

Idles best right after start-up with Air screws turned almost all the way IN.

Starting is not a problem, First or 2nd kick, 1/2 choke when cold. Re-starts easy.

 

Pilot=30 Main=300 Needle clip=3rd groove. (verified again tonite).

Float height is correct. Carbs are synched.

 

No air leaks.

Tried Wd40, Carb cleaner and Starting fluid, no changes to idle as I went over all the connections. These are the Stock Mikuni Carbs, just to be clear.

Tors Removed, idle kit installed, Toomey T5s, K&N, Open Airbox lid.

Using Mikuni brand jets with the little [-] symbol on them.

 

After start-up, can't keep it running at idle with Air Screw more than 1 turn OUT.

The more the Air gets screwed IN, happier it is. This is when the Bog is at it's least problem.

 

After running it up and down driveway, Bog becomes more prevalent, let off to turn around, start to get back on the throttle (downshifting properly, of course, Not in too high of a gear).

Can feather thru the bog, but barely.

 

Then pull it into the shop, and it won't idle, or idles very poorly, one more small goose on the throttle and it Died.

 

That's where it stands. Bog gets worse when warm, idle gets crappier when warm.

This has been consistant, no matter what Pilot is installed.

 

No excessive smoking or anything noticeable like that.

Maybe a little popping in the exhaust, very little, here and there, when revving 1/4 to 1/2 throttle.

 

 

OK, back to the Idle Screws for a moment. With the idle screws all the way IN, it is barely lifting the Throttle Bodies from their "at rest" bottomed position.

 

The Idle still seems to be rather low RPM, even when it's dialed to the best Air mixture.

 

Could it be I just don't have enough "lift" on the throttle bodies to achieve a smooth idle with "normal" Air mixed in (~1.5 turns Out)?

 

With 30 pilots in there, you would think it would be starving for more Air, right?

It seems like it should be Rich as hell right now at idle, with 30's and Air cut all the way to 1/4 turn OUT.

 

That's about all the behavior it exhibited, that I can remember.

 

All thoughts and suggestions are greatly appreciated.

[Jfranke]

I'm in the same boat as you with low speed bogging, I have little compression (not tested but you can REALLY tell when you stand on the kick start and it falls down easily). Have you tested your compression yet? It seams like you've done EVERYTHING you can with the carbs.

 

Just a suggestions from a rookie with the same sounding problem. I am going to be rebuilding my top end with pistons, hoaning (possibly boreing), rings, etc. Well see when I get 'er apart.

 

Good luck with it. Josh

[SkunkWerX]

Thanks Josh.

 

I have to borrow a comp. tester. When kicking it still has that "resistance" that you expect from each piston reaching TDC. When I lean on it, with my hand, it will support me, not sag.

 

Did the "thumb" test again, pops my thumb off with force. I've tested basic compression this way for 30 years, so i have a little idea what "good" and "bad" feels like.

 

Screwed with it a little more this morning, same/same.

 

Today something electrical did happen that was stange.

We had it running, I was mvoing air screws 1/4 turn In and Out, and same for idle screws, just tyring for best running. Goosed the throttle, and it started "taking off" RPMs going up, even when releasing the throttle. That wasn't the strange part, I hit the Red OFF switch, the slide switch, and it continued to "race"....I grabbed the choke pull it out FULL and bogged it dead.

 

How did it keep running even after sliding the OFF switch closed??

 

Seems like I will be on to an electrical journey to verify it.

 

Also made me think, COuld it be the CDI? (I'll call it "CDI" til I die).

The blackbox under the seat area.

 

Could the CDI be defective and be screwing with me?

 

(TORS gone, parking brake switch cut off, wires taped, throttle swtich cut off, wires taped, TORS box unplugged, connectors taped).

 

I'm going to a Pig Roast, drink some beer and eat some BBQ, I'll get back to it tomorrow.

Edited September 23, 2006 by SkunkWerX

[Toomey Banshee]

In looking at your mods I see you have reed spacers with stock carbs on the stock air filter. I would look at your carb boots real close to see if they have any holes/cracks. There is a lot of pressure on the boots with the stock carbs and reed spacers on the stock air box. I would take the spacers out and remove the boost bottle. Neither do anything performance wise. I had both and didnt notice any difference with both being on or off. I know the boost bottles will develop holes on the top caused by the cables rubbing on top over time. Is the boost bottle seated far enough into the top of the rubber manifolds? How do they look where the boost bottle is connected? My guess is you have an air leak somewhere. What about the rubber hose connecting the carbs? Did you check that out yet? Maybe a slight hole/crack. Is it secured properly on the carbs? As far as the hush kit is concerned I have no knowledge with that. Did you take it off and see if anything changes? I would take the spacers, boost bottle and hush kit off. Clean your carbs real good and then clean them again, then sync them, keep your 300 mains, 27.5 pilots, air screws at 1 and a half turns and needle in the middle. Go from there.

[SkunkWerX]

Thanks ToomeyBanshee,

 

I have K&N filter and the filter adapter plate. My most restriction on the Filter side is the outerwears attached to the PowerLid. When you give it throttle you can see the outwears getting sucked down to the lid.

 

I pressure tested the boost bottle, no pin holes.

I don't have the stock cross-over, or yes, I would have swapped it out just for S&Gs.

 

The carb boots are newish, they come with the Boyesen Rad valve, they look fine.

My shop has a sink , so, I washed them with mild soap, warm water, toothbrush.

Did same for boots between filter and carbs.

 

Carbs have bee totally dismantled and cleaned twice if not 3 times. All needles, jets, removed, compressed air run thru, then carb cleaner. All orifices are open, carb cleaner passes thru air, pilot and Main jets. Air screws are new. Float valves are new. On saturday I removed float bowl gaskets, used dial caliper to set the float height, it was close, but, at this point I'm checking and making sure everything is perfectly adjusted.

 

Replaced the choke tube ebtween the two carbs, it fits tight, no leaks.

 

99.9% positive I have no leaks, now that I took it all apart, inspected and re-assembled

properly.

 

Hush Kit doesn't rob power, per Toomey, but, yes, I did try with and without, no change.

 

-Tried it with and without spacers, ran OK before and spacers were in place, but, took them out for a test, no change in symptoms.

 

When it runs, no matter what Pilot 25 thru 32.5 , it always runs best with air screw closed down to 1/4 turn out. So that makes it sound like a leak, but, I've ruled out leaks.

 

Still need to do the Compression Test, first, if that shows up good, then I'm going over all wiring and electrical. It acts like a TORS related problem, but TORS is removed.

 

Even starting to wonder if the CDI (ignition module) has a hicuup? IF i had a spare that would be a quick check, but, $150 to do a "what if" swap is a bit hefty.

 

Compression check before gonig any farther. I'd suspect compression a little more, if it weren't so easy to start. Low compression usually shows as hard to start, and low end power loss.

I have "easy to start" , bogs zero to 1/4 throttle. From 1/4 to full it pulls as strong, even stronger than ever before with the 300 mains.

 

 

At this point, I'm thinking a lot, and listening to everyone, thanks for the ideas.

Edited September 25, 2006 by SkunkWerX

[dajogejr]

Werx....you need to do a leakdown test.

I just went through this...no matter what pilot, needle clip on two different needles, or main i put it...it would start and idle perfectly.

I put it under load and blaaahhh...fell right on it's face.

 

A leak down test will test the "innards" of the motor. Head and base gasket, crank seals, etc.

 

From what I've read, you've done a complete tear down and cleaning of the carbs and intakes...but, there's more to it than that.

 

It's either electrical or an air leak...and I'm gunning towards an air leak at this point.

 

PM Machwon on this board, he sells an inexpensive and complete leak down tester kit....

Before you go spend a TON of money on electrical and ignition parts, test for "other" leaks first....

[SkunkWerX]

I can get enough "plumbing" parts to build a leak down tester, between my air compressor fitting and scuba gear, I'll be able to put something together.

 

Leakdown is when you set the cylinder at TDC and shoot a given pressure to it, and meaure leakage rate, right?

Gonna start from scratch, and do a "simple" compression check first.

 

I know electrical and electronics well, I can also do all the ohm tests on the electrical system, takes time, but otherwise it's free.

Won't start swapping elec. parts until something leads me in that direction.

 

Thanks for the info.

I will advise with more info. as it happens.

 

Thanks.

[dajogejr]

It doesn't matter if the pistons are at TDC or not...

 

You're testing all seals..

 

Be very, very careful when using your air compressor. You only want to put in 6lbs of pressure, and it should hold for 6 to 10 minutes.

 

Much more PSI than that...and you will pop something...so, just be careful!!!

 

Good luck!

[SkunkWerX]

Oh cool, thanks, piece of cake, I have a Low-p regulator and a small needle valve, I use for air brushing, that will get it down in very, very low psi range.

 

Good deal, can do basic compression and leak down tonite, then i should know exactly where I stand .

 

(up to my @$$ in alligators, most likley).

 

 

again, thanks for all the help. I have the compression tester in hand, i can use those fittings for the leak down test. Piece of cake.

[SkunkWerX]

The float bowls are on the correct sides. The small hole in the left bowl is what allows additional fuel to be communicated to the right side in choked condition, I do believe.

 

The slides are in the correct carbs. The cut-out (angled bottom) goes to the rear, facing the airbox.

 

The first time I took everything apart I labelled the bowls with an engraver.

The silver Caps also have an "L" and "R" on them, makes it so much easier when re-installing everything, and I did verify Left vs. Right like 3 times, at least.

 

When I work at my bench, I keep things Left/Right separated. And check additionally when reassembling just to make sure.

 

But, thanks for the advice, you never know when a little thing will trip you up.

 

- - - -

 

Right now I'm looking for some rubber to block off the exhaust ports. Intake is blocked.

getting ready for the Leak Down test. I gotta find some thick pieces of rubber today.

They make rubber expansion plugs for plumbing pipe, I can probably shave them down to size?

 

Straight-up Kick, Compression test, showed an average of 118psi on Right and 120psi on Left.

Kicked 3 sets of 3, recorded, and averaged. all the samples were within 3 psi of each other, and both sides are within 2psi (less than variance 2%). On the surface it looks like it should run.

I'm guessing it's probably 60% used up, in terms of these pressures, but probably still has some serviceable life left in it.

 

After "kicking it up" , I let it sit for a few minutes, with no bleed down, so, doesn't that mean the piston has no holes , and rings are OK?

 

I've heard 100psi is the defacto "Rebuild" red line , right??

At or below 100psi your rings are shot? right?

 

Last thing, like dummies, we didn't hold the throttle open while kicking, oh well, live and learn.

So these readings are probably conservative, which is fine.

 

In search of rubber.