low rpm blues...

[AkBigN]

I have a little problem I wanted to run by you guys.

I have a 97 600 and I have put on
- Vance and Hines full exhaust
- Dynojet stage 3 jet kit
- K&N pod air filters

When I go to roll on the throttle the bike gets a real low pitch sound doesn't accelerate much and jerks really hard until it reaches 4k. Right when it his 4k it rockets forward as is smooth as silk. This happens in all of the gears and not just first. I'm thinking this isn't normal, just wondering if anybody has had a similar experience with these kinds of mods or knows what is going on.

[toobalicious]

normal... all three of the performance mods you did nearly always squelch low-end torque as they add high-rev hp, which makes the "problem" especially noticable on a smaller I-4 like your 600... aside from that, the vacuum operated carb slides will never fully open at low engine speeds no matter how far you twist the grip... i recommend that you tach to at least 5K before shifting on all but the laziest roads... lugging the engine wastes fuel and could potentially lead to engine damage from pre-ignition/detonation... in my experience, these I-4 engines are very happy at moderate revs... if you want that low-end grunt, get a harley 8)
a

[AkBigN]

Thanks for that, sounds about right. I am thinking about putting the airbox back on and going back to stage one jetting just to get a little of that low end back...and to save some gas.

[The CyberPoet]

You never said whether you had the carbs' fueling tuned after you installed all of this... Although it is true that all of these mods sacrifice low-end torque in favor of top-end performance, a proper tuning of the pilot circuit and idle set-up should give you a bit of smooth power back (not quite as much as stock in most cases -- that's the fault of the larger exhaust headers; less back-pressure sacrifices low-end-torque in favor of top-end speed).

The proper thing to do would be to find a shop that has a dyno and exhaust-gas analyzer and someone versed in handling such tuning, and have them tweak it to optimize the set-up. It's a common error with stage 3 items to think that you can just slap them in and have them work -- they must be tuned afterwards to compensate for differences between different brands of exhaust headers, etc.

PS - if you go back to the OEM air filter, you'll probably need to knock the jetkit down to a stage 1 kit or you'll run into just as many problems (just in different RPM ranges). And you'll still have to get it tuned because of the V&H exhaust headers...

Cheers
=-= The CyberPoet

[wilson1]

I had this same sort of problem with close to the same upgrades (V&H Exhaust, K&N, DynoJet Kit...don't know the stage tho?). I am that mechanically inclined, but a buddy of mine has a few drag bikes, and brought it to him to tear apart. I watched/learned/helped him out that afternoon and this is what he ended up doing on my bike, and I have 5 times more low end than before...and really didn't lose much in the mid/high range either...

On the sliders, it only had one of the correctors (I think that's what those little hollow plugs are called) from the jet kit. The other hole on the slider was untouched. So, beings I didn't have another corrector, he put epoxy (I think?) into the the slider hole, and then used this little bit to drill it back out. Also, he put the little ring on the needles, down from the top notch, to the second from the top. And then also turned down the fuel mixtures screws because he said it was running entirely too rich. Re-Synched up the carbs after all of that, (maybe something else...I don't remember sorry, I know, I suck)...and been driving it for a few hundred miles since, and runs like a dream!

Hope that maybe helps? Maybe not beings how techincal I was, haha. But I'm pretty sure that is the main things he ended up doing. Maybe it's the same sort of problem, maybe not? Good luck anyways!!!

TJ

[md86]

Hey , those holes in the slides .... I have/had BOTH of those holes open and was told by the shop I had it dynoed at to somehow plug one or both of them . I plugged one and it definately seem to run different . Dunno if that's a good thing or not though . What did you notice about plugging them . You did them both ? I need some details here , help a brother out !

[wilson1]

Yeah, both the plugs are in now. Except, they are not SOLID plugs. They have a hole through the center of them. Kind of just makes the holes smaller. Probably like 1/3 the size or so? But yeah, ran like crap until I hit about 3500-4000 with just one in....did all that and runs AWESOME in the low end, and very minimal loss in the middle/high end. I'm pretty sure all it does is let the slide open faster, but don't hold me to that.

[md86]

Huh , maybe I'll have to experiment with that some more . Wonder how hard it is to drill JB Weld ... How big would you say those holes are ? Like needle size , or maybe bb size ?

[wilson1]

Umm....I don't know. I would say like 1/3 the size they are now. So...maybe BB size, or smaller. I can try and get ahold of him and see if he remembers/knows what size he drilled the epoxy out if you want.

[md86]

Yeah , that would be tre cool !

[AkBigN]

Yeah maybe I need to see if that's the problem. I had Suzuki put the jet kit in and I don't have a lot of confidence in the Suzuki mechanics up here. There is only one dealer I can go to so there isn't many options. I would like to keep the power I have now and just fix that low end crap. I mean I can't even go fast off a stop light because it jerks and crawls forward until it reaches 4k. If I do put my airbox back in I know I will have to put a stage 1 back in but I would rather just fix the stuff that's in it if I can.

[wilson1]

It sounds like mine was a lot like yours. Sometimes if you didn't take of SLOW enough, it would even bog the engine down so much that it would kill it. Try that stuff, and I bet it will fix your problem.

I still haven't heard back on the size yet by the way, but hopefully will have some news by tomorrow.

TJ

[toobalicious]

if you are killing it at lights, you should slip your clutch more... the beauty of inline fours is their high rev powerband... at lower speeds, however, you must raise the revs and slip the clutch enough to keep them up there in order to accelerate fast and not bog it... a little harder on clutch plates maybe... clutch plates are pretty cheap and fairly easy to replace if you if you can wrench at all... they are therefore expendable wear-parts like brake pads--- you dont take it easy on your brakes when you need them, right? 8)
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[AkBigN]

I guess that's a good point. What's a clutch when you are having fun?

Well I decided to screw Suzuki and try to fix it myself. I opened up the carbs and moved the clip (not sure the technical name) on the needle one down to enrichen it. It bogged down HARDCORE. So then I moved it one up and now the bike runs like a champ. I can give it hard throttle in first gear and it doesn't bog down at all. I was wondering if it would effect the rest of the rpm range which was fine before, but to my understanding the fuel flow is taken over by something else at 4k, which explains why I was fine above 4k before. Hopefully I won't have to get anything else done to keep her working right. Hope this helps anybody else that's having this problem. Again everybody, thanks for the help. This forum is a lifesaver. If I never found it I would be stuck with the dealership breaking all my sh*t!!!

[The CyberPoet]

I opened up the carbs and moved the clip (not sure the technical name) on the needle one down to enrichen it. It bogged down HARDCORE. So then I moved it one up and now the bike runs like a champ. I can give it hard throttle in first gear and it doesn't bog down at all.

Maybe the idjit down at the stealership couldn't count clip positions correctly (started counting from the wrong end when did the install?)...



If the fix was that easy, then they definitely didn't put it on an exhaust analyzer to tune it after they did the install. Either way, glad to hear it's resolved

Cheers
=-= The CyberPoet