New exhaust, bike acting up?

HalfLiterBeater · 08-20-2004, 09:50 PM

I just got the Hindle 2-1 system on my bike...it sounds great. It's a big difference over the stock 2-2 system also....loads of weight reduction.

My problem is this: The shop installed a K&N drop-in also, and tuned the bike. They said they didn't need to jet it, so no jet kit was used. I've gotten it back and riding it I noticed a few things: Off the line SUCKS. It bogs on takeoff so I have to give it extra gas and slip the clutch until I get into the 3000-4000 rpm zone, where it rips wide open. AWESOME low-end past the bogging....but the mid-range feels flat. It pulls hard up top like it should, but the mid-range just doesn't feel right. Could it possibly be running rich, due to the mid-range issues and the bogging?

FYI: The shop told me they spend more time REMOVING jet kits here than installing them due to the hot weather most of the year around. That's why it hasn't been jetted, just retuned.

My other question, which is really my MAIN question is...if I let it idle for more than, say 20 seconds, if I rev the throttle, it will fall back to WELL BELOW idle. I'll rev it up, and instead of dropping back to an idle of 1100 rpms, it falls to 400 or 500 and sputters there for about 2 seconds, then climbs back up to normal. If I rev it several more times, it will be fine...but if I let it sit at idle and rev the throttle, it almost shuts off. Could this be from bad tuning, or is it a carb problem?

THANKS to anyone that can offer any help here...these little quirks are starting to bug me.

ZeuSeason · 08-20-2004, 10:25 PM

When they said they 'tuned' what the hell did they do to it? Any idea? I'd take it back and tell them to tune it again cause the rpms are all over the board and the bike practically stalls. I don't know what would cause those symptoms that you are getting but it sounds like you took it into the shop for a mod and it came out all f@#ked up.

HalfLiterBeater · 08-20-2004, 10:37 PM

Well they have a dyno and an exhaust gas analyzer......but I have a funny feeling they didn't use either.

I'm just wondering what they could have done to make it want to shut off after it's idled for a little bit, but be fine when you've revved it a few times. The idle never gets unstable or erratic, it's just if you rev it like normal, it will dip back to well below where it should be. Almost like it's not wanting to fill the bowls in the carbs and is struggling for gas.

Jackal79 · 08-21-2004, 01:35 AM

You should proabably take the bike back to them and ask them why it is doing poorly. You paid them to tune it afterall.

It might be normal though. With it tuned for that free flowing pipe and air filter, I wouldn't be surprised to see it idle not as well and to loose low-end/midrange power. Seems to be the trade off when you install a pipe - loose idleing, low-end and midrange and gain top end power.

ghillie14 · 08-25-2004, 12:04 AM

Quote:

Originally Posted by HalfLiterBeater

I just got the Hindle 2-1 system on my bike...it sounds great. It's a big difference over the stock 2-2 system also....loads of weight reduction.

My problem is this: The shop installed a K&N drop-in also, and tuned the bike. They said they didn't need to jet it, so no jet kit was used. I've gotten it back and riding it I noticed a few things: Off the line SUCKS. It bogs on takeoff so I have to give it extra gas and slip the clutch until I get into the 3000-4000 rpm zone, where it rips wide open. AWESOME low-end past the bogging....but the mid-range feels flat. It pulls hard up top like it should, but the mid-range just doesn't feel right. Could it possibly be running rich, due to the mid-range issues and the bogging?

FYI: The shop told me they spend more time REMOVING jet kits here than installing them due to the hot weather most of the year around. That's why it hasn't been jetted, just retuned.

My other question, which is really my MAIN question is...if I let it idle for more than, say 20 seconds, if I rev the throttle, it will fall back to WELL BELOW idle. I'll rev it up, and instead of dropping back to an idle of 1100 rpms, it falls to 400 or 500 and sputters there for about 2 seconds, then climbs back up to normal. If I rev it several more times, it will be fine...but if I let it sit at idle and rev the throttle, it almost shuts off. Could this be from bad tuning, or is it a carb problem?

THANKS to anyone that can offer any help here...these little quirks are starting to bug me.

K and N airfilters usually make bikes rum a little lean...a jet kit would fix that right up. If you feel like they are dicking you around take your business else where.

hybrid · 08-25-2004, 02:53 PM

FACT: all motorcycles are set lean to pass emisions from the factory.

If your bike dipps below idle value when revved in nuetral and the engine is fully warmed up, it is rich at idle. If it hangs and then drops to idle it is lean. I would think that the shop doesnt have a mechanic that knows how carbs work so they take out the jet kit. What do they put in? Factory parts would eat a repair bill up. Needles are around $30 each so on an inline for (not yours of course) that would cost 120 with out the stock jets and the labor. I wouldnt buy a dynojet jet kit if I had to. Factory brand jet kits are way easier to tune and the numbers they use are exactly like oem numbers eliminating confusion. They probably just richened up the idle air screw so it wouldnt back pop on deceleration. It needs to be leaned up and the bike should feel linear in acceleration an explosive power hit means that it has a big drop in power then is jetted close to right

HalfLiterBeater · 08-25-2004, 04:12 PM

Quote:

Originally Posted by hybrid

FACT: all motorcycles are set lean to pass emisions from the factory.

If your bike dipps below idle value when revved in nuetral and the engine is fully warmed up, it is rich at idle. If it hangs and then drops to idle it is lean. I would think that the shop doesnt have a mechanic that knows how carbs work so they take out the jet kit. What do they put in? Factory parts would eat a repair bill up. Needles are around $30 each so on an inline for (not yours of course) that would cost 120 with out the stock jets and the labor. I wouldnt buy a dynojet jet kit if I had to. Factory brand jet kits are way easier to tune and the numbers they use are exactly like oem numbers eliminating confusion. They probably just richened up the idle air screw so it wouldnt back pop on deceleration. It needs to be leaned up and the bike should feel linear in acceleration an explosive power hit means that it has a big drop in power then is jetted close to right

Yeah, I understand the BASICS on carburetors... But mostly the rich lean stuff just from dealing with that type of stuff for my motor. I know fuel injection, that's what I've been playing around with for the past year or two..but I know the principles are the same. Dip is rich, hang is lean....

Although it doesnt dip during a normal idle rev, just if you let it idle for 30 seconds or so, THEN rev it. My only guess is that, its rich, and at idle it's loading up the cylinders...so when I rev it and it dips back down, it bogs til it gets rid of the extra fuel. Then the cycle starts again.

The guy who worked on it wasn't there, but the shop owner didn't even know if they had tuned it or not. He asked me. I said "I was under the impression that you guys did...? You were supposed to!"

So anyways, I'm getting an appointment to bring it back in and to have the thing set up again. I'm telling them it stumbles off the line, pulls like an SOB til around 4000-5000. Then hits a mid-range flat spot, and feels spongy and flat all the way til redline. No explosive power from 6,000 rpms to redline like before...now it's all mushy. I'm paying an extra $60 for a dyno tune also, so I can SEE what they did and not just go by my butt dyno. I'm ok with this because all the mods were paid for out of an accident...which also put $475 in my pocket. Best accident I ever had! ;)

I'm thinking too much gas at low rpms, not enough up top? Sound right to you guys?

omen_child · 08-25-2004, 04:39 PM

If you just asked them to change the filter and the exhaust, then that's probably all they did. In my experience, most aftermarket exhausts take a little bit out of the bottom end and midrange and give a little more up top, and require some jetting to get exactly right.