[larry0071]

I've put just under 1,000 miles on the 03 1K in the last 2 weeks and I notice a very distinct intake "pop" as if it is pre-igniting while the intake valve is still open. This is a smooth running engine that makes great power and can be run at 2500 RPM with no chugging or shaking. The throttle boddies are recently synced and it has the DynoJet USB electronic tuner under the seat and was dyno tuned by the original owner. 14,900 miles on the bike, all records indicate excessive/compulsive maintenance routines from both previous owners. Bike also has recently installed KN intake filter with around 1500 miles on since installing new. Also has aftermarket StainTune exhaust, the sound has been observed both with the sound baffles installed and without.

This is not something that happens regularly, it is totally random and in a 200 mile day will be heard maybe 2-3 times. Always while lifting the throttle and pulling the clutch to shift up or down, I have not experianced it while cruising on throttle.

My fear is that it may push the throttle body rubber boot(s) off as I have read many times on here of the boots becoming part way dislodged.

Is this a normal thing to hear every once in a while, or should I start to panic and tear apart the bike?

 

[EC90T]

The popping sound is from a lean condition that exists because modifications have been made since the bike was dyno tuned. The engine is a big air pump and anytime you change the breathing or exhaust characteristics you have to retune accordingly.

 

[larry0071]

Do you feel the KN air filter makes enough change to cause that? Is this what leads to blowing the intake boots off of the throttle bodies?

I guess I may need to find someplace around Northern Pittsburgh that can retune the thing, I know less then nothing about the PCMIII Dynojet tuner thing..... All I could do is make bad into worse, real fast!

 

[EC90T]

The K&N can cause this. This could also have to do with how dirty the factory airfilter was at the time of tuning. Say if the stock airfilter was 50% restricted at time of tuning then at some point down the road the filter was replace with one that would flow 20% more than a stock new filter, well you get the idea.

If the popping sound is light and it doesn't bother you, then leave it alone. if it sounds like a tire popping/shotgun then that can be severe enough to dislodge the throttle boddies from the boots.

I've got a notion that the DL engine suffers from a reversion problem at low rpms. The lean condition only exaggerates this issue. Only in the extreme cases where the throttle bodies dislodge that it causes any rideability issues.

 

[larry0071]

No, it is not a startling loud pop sound, but you know it happens. The bike does not really pop out the mufflers going down a hill using engine braking (like my stock ultra lean 09 KLR does) so I kind of assumed that it could not be crazy lean.

I guess I will just chalk it up to normal and acceptable... a trait of the bike.

Like that constant whirling sound from the engine..... or the clunky Harley like shifts..... or the exhaust on the left side setting my foot and ankle on fire (not literally!) in stop and go traffic.... or the fuel gauge that is totally non linear..... As long as I know it is fairly common and acceptable, I can add it to the list of things to not worry about.