I'm still chasing what I think is an intake leak that shows more at idle and low rpm. I chased everything mechanical I could think of with about the same results. I had the flanges machined back due to crowding which helped, but judging from the log it still appears that I have a leak. Maybe I need to get the air cleaner in more of a neutral position. The induction manifold has a good 10 thousandth gap on each side and lines up with the ports. The idle always seems to fluctuate integrator on both cylinders at different times and just off idle. The rpm's hang up just a little bit on decel. Bike's parts are as follows

06 dyna
95 inch 9.8:1 compression
80cc decked street port heads with .030 head gasket
thunderheader
37h cams and stock manifold
25 degree injectors and HPI v2 air cleaner with external vents



https://www.dropbox.com/s/dcdt1ug339...x-r01.dm3?dl=0

 

Take the idle rpm area out of closed loop. See if the idle/off idle improves.
Unless you have stock muffs there may be enough exhaust reversion to send bad o2 readings which causes fluctuations.
Bob

 

I tried it with the idle and off idle out of closed loop. I still get a choppy idle. When I block off the iac while running it stalls. When I spray carb cleaner around the intake flanges it does drop the idle. I am going to try and take the manifold off again and remove some material .005-.010 from the feet on the flanges and use some yamabond to see if that helps the seal

 

It's leaking past the inner seal of the intake seals. Between the manifold and the seal. How the hell do I fix that?

 

You say you have 0.010 clearance a side on the manifold.. Did you check it by installing the manifold and rings with no seals and see that you can move the throttle body up and down say say 1/2 inch from centered on the AC. This will verify that the manifold has sufficient clearance..

I would also make sure that the manifold bolts that you are using do not touch the manifold. If the do cut away the manifold with a Dremel until they clear.

One thing I don't like about HPI throttle bodies is the manifold rings that they use.. They are made out of aluminum and bend when you torque em down. Check em by placing the flat side against each other and you like find that they are not flat. They are a special size mainly because they want to get away with using stock manifold seals with a 1.91-1.92" manifold spigot (check this on yours). Stock comes in around 1.81-1.82.

While it sounds like you've checked that you are using the right HPI manifold flanges for the heads you have they are probably bent. I bought an HPI used and when I got it I fount them bent. I used stock ones You need to make a couple changes when using stock one tho.. Since the stock rings are used on a 1.81-1.82" spigot and the HPI is about 0.1 larger you need a smaller seal. SnS makes one got their manifolds which have the same OD as HPI and use stock sized rings.. Cometic makes them also. You can also use HD number 27035-05 seals which HD made for one of their SE manifolds.

Stock manifold rings may be too tight on the HPI spigots. You can probably run a dremel tool with a sanding drum or tootsie roll on the inside to get the clearance but I do mine in a lathe..





Once you get this stuff done you need to check to make sure that the air cleaner backing plate spacing is correct I shoot for less the 0.005 clearance difference. I've got an assortment of shims over the years that were left over from previous installs. I end up using them or make custom length spacers..

I recently swapped heads from early TC to 06 up TC heads and even tho the early TC heads were milled 0.060 and the 06 only 0.005, I still had to trim the manifold spigots on the HPI to get a good fit..

 

Thanks max but just the air cleaner is Hpi. I am running the oem intake manifold

 

Well if they decked the heads you still need to make sure that the manifold swings up and down.. You don't have to worry about the ring fiasco. Stock rings and seals.. Backing plate spacing still needs checking.

 

I did what you said max in it hits when it swings up. I will remove some material and report back with some pics

 

It was tight



I removed some material with a belt sander and wet sanded it to get about .015 on each side

 

It can now swing up this much


And down this much


I shortened to feet on the intake flange brackets by about .005