Anyone having trouble with warm up issues related to air leaks on there 58mm TB. I just had a 103 screaming eagle stage 4 race kit put on my 2007 SG from the dealer. I allready had a Thundermax ECM on the bike .All the data that is collected by the system states that there is an air leak in the tb. Thundermax says that the 58mm's are problematic and I should take it off and put the oem one back on. I dont want to the kit came with it and the bike seems to really rip, but I am at wits end with the dealer who says that there is nothing wrong with the tb and I should just dump the TM and put the SERT on that came with the kit. I want to keep the 58mm on with the TM if there are problems with the 58 how do I get the stealer to replace the 58mm TB
Gregg

 

I don't have any problems with mine or the two I put on other bikes

 

I have a TMax installed also, I have a 58mm TB but have been advised by a few builders that the 50mm I already have is good enough for a 107 and the 58mm may give me more power on the high end, but I would probably loose some low end torque. Long story short I had the TMax throwing a code last month, and the bike wouldn't go over 3k rpm, I took the TMax out and put the other ECM back in and the bike ran fine, so of coarse I'm thinking something is wrong with the Tmax, decided to try the TMax one more time, same thing. This time I decided to troubleshoot, ended up finding a bad connection on one of the TBW wires, secured the connection and everything worked ok, my question is why did the TMax find the problem and the HD ECM didn't? I would work with the guys at Zippers, the TMax may be trying to tell you something.

 

You have to decide who you are gonna work with. Who is doing the work? I would either let them do what they believe is best to correct the issue or take it to the other guy that has the conflicting theory and let him work on it. I have had the 58mm TB for 3 years and don't have or have ever had an issue with the TB. Oh and judging by the lack of 58mm TB's , you will not get a 58mm TB replaced under a defect warranty at this time, there aren't any available.

 

I have been trying to work with TM I have sent them data at least 6 times with some adjustmests to the IAC I made. I dont believe the data Im sending is false the numbers dont lie. I called the owner of the dealership and told him that Im sick of being the middleman relaying information back and forth. He had the service manager call me to make an appointment , I brought the bike up and of course they want to put the SERT in again I told him the numbers dont lie and there is deffinatly an air leak. I wanted them to put on a new TB which they had but they said it was fine. The tech put the bike on the dyno made a few afr adjustments bike seemed to run worse but said that I need to ride it so it would autotune. Im sick of the bs I wish they would at least try a new TB ,thats a start. Again the data is not lying about the air leak.

 

the larger TB will have less air velocity than before with a smaller TB, especially at low rpms

( the 58mm is about 30% larger in area than the 50mm- 2641 square mm vs 1,962 square mm )

depending on cams/overlap/pulses from the exhaust etc.

the air may be reverting..


and it is possible that the TM is reading this ( interpreting) this as a leak.

an actual intake leak is pretty easy to find, and if nobody has found one yet, look elsewhere.


I'm guessing that low rpm operation is not going to be good on this motor.


Partially covering the TB opening ( like with a hand) at idle, may give an indication of whether the velocity is a factor

mike

 

My '07 103" is making 114/120 with a stock throttle body and injectors. A 58mm throttle body on a 103 seems like overkill to me, but I'm sure the engineers at HD know more than most.

Seems to me like there are people trying to help you diagnose the problem, but you aren't willing to listen to anyone unless they offer you up a new 58mm throttle body.

Zippers is telling you to put the stock TB back on. If it idles and warms up fine then you might be able to trace the problem back to the 58.

The dealership is telling you to ditch the TMAX and try a SERT. If the bike runs fine with the SERT then you might be closer to tracing a problem back to the TMAX.

Like QTR said, you need to pick which direction you want to go and let them do it. Nobody is just going to give you a new 58mm throttle body because you said it's bad. They are going to want to verify that is the problem first.

Sounds like you are getting good advice from both Zippers and the dealer but you don't want to listen.

Zach

 

Great explanation. You might be on to something.
I have a 58mm tb. My 106 makes 107hp/115tq.
It hits 100tq at 2300 rpms and stays over that until the rev limiter shuts me off.
So I'm not so sure about a bigger tb costing any torque,well not me anyways.

 

I don't believe the 58 TB costs tq either. Now when you get too big, yes. But the point is 58 is not too big. HD put a 50 on the 08 Touring bikes which need more tq than the other bikes HD makes. Why? If the 50 made the engines lose tq it would have cost HD not 1 dime to continue using a 46. I believe bigger, up to a point, adds tq. These are not carbs that need airspeed to pull the fuel and atomize properly.

 

expanding, and this is theory;

IF reversion/pulses are suspected to be the problem, tuning the exhaust tract ( or changing cams) may "tune this out" tuning the exhaust is easier and cheaper and can give a quick indication, either length or diameter need only be changed to see if there is an effect.


the beauty of the Keihin CV carb ( and the SU carb) was the Constant Velocity of the intake charge. The diameter of the intake varied depending on air density and motor demand.

another interesting system was the intake manifold on the Vmax which normally ran on 2 of the 4 carbs at part throttle, and would run on all 4 carbs at high motor speeds. "gates" within the intake would open/close to keep intake velocities high(er) at low speeds

this is not dissimilar to the 4 barrel carb with 2 small barrels for normal operation, and a secondary 2 larger barrels which open under correct throttle and vacuum conditions, it is to keep intake velocity high

high intake velocity is not only used to pull fuel from a carb's float bowl, but on an efi ( or any motor) to get a complete cylinder fill.
Cylinder fill can be over 100% with tuning of the intake and exhaust tracts.

another example: the 60's Cadillac 429 motor had real problems with shaking at idle due to uneven intact runner length, while not a mechanical problem, this unsettled the typical Cadillac customer of the time. Leading to a complete change to the 472/502 design. The 429 ( and i have 3 of them) was a great motor making 360 HP, but was killed off after only 4 years.
Interestingly, installing an MSD really helps to smooth out the idle on these


- there are reasons that top fuel motors don't run well at low speeds- these motors are built to run ( for minutes) at high rpm with clutch slip used to control wheel spin



mike