Let's see, I did some performance mods over the winter and now I am getting some serious spits, sputters, and backfires when trying to start the engine cold. Before I started tearing it apart this winter I had 8,000 miles on the 2007 FLHX 96" TC with K&N AC, V&H Duals, V&H Ovals, and PCIIIUSB. It ran good with no problems, I just wanted a little more power (isn't that how it always goes). I replaced the headgaskets with .030 Cometics to bump the compression up a little and improve the squish. I Swapped in some Andrews 37H cams with SE quick install pushrods. Swapped out the PCIIIUSB for a TMAX w/AT. I used all new gaskets (cam chest, intake) and o-rings, torqued everything according to service specs. I setup the TMAX with a base map (map 396) that is close to my components and followed all procedures for initial setup.

Now for the symptoms: Starting the bike cold is rough going, it sounds like it is firing almost exclusively on the rear cylinder. After a lot of spit/backfires it will startup and run really rough and you can hear the difference as the TMAX tries to adjust. The rear cylinder has a strong ehxaust note/pulse, the front has a week mush note/pulse and appears to be dumping excessive fuel out the exhaust. After the bike warms up, it really starts to staighten up a lot and the exhaust from the front cyclinder gets stronger. Restarts on a warm engine go pretty smooth with light pop/backfire sometimes. If the engine cools completely it is a B!tch to get started again and all the symptoms repeat. I don't want to mess it up so I need some help on where to start to get this cleared up. I have one opinion from a wrench that said maybe I am a tooth off on the chain cams. PLEASE HELP!!![/align]

 

If you think you might be off a tooth, do a compression test of the front and rear cyls. They should match. You might also have a pushrod too tight and a whole host of other things including the t-max not operating correctly, but start with a compresssion test.

 

Thanks for the quick response Dalton. I will check the compression and report the results. On the pushrods, I used a SE quick adjust set. Everything I read about them said to adjust them out 2.5 turns. I however had 2 techs at the dealership tell me to adjust them a 3 full turns, so I did. Do you think having them to tight could cause this problem?

Joe

 

I agree with Dalton on the pushrod. Leaking compression out the valve when cold and as it heats up clearance will allow the valve to close. Easy check.
Ron

 

No,
3 vs 2-1/2 turns should not cause the problems you describe unless the lifters were not on the base of the lobes when you adjusted them.

Not at home so dont have my manuals, but guessing stock compression should be in the 140 to 150 range, maybe someone else can chime in with what you should find for compression.

 

Hey Dalton (YEEHAAAAAAAA), you called it man. I checked the compression and sure as **** the rear cylinder was at about 165 psi and the front was at 0-5 psi. So the front cylinder had no comression and the 165 psi was low for the rear because with the cometic .030 and the cams it should be around 178 psi. My first thought was the valves are staying open so it must be the pushrods adjusted wrong. I pulled out all the pushrods and started from scratch taking my time on the bleed down. I followed the directions going only (2.5) revolutions instead of what the dealership recommended (3). After all lifters bled down I did another compression check (178 psi) on both the front and rear cylinders. Put the plugs and wires back in and did a test fire. She fired right up and sounds sweet as hell. I got a big *** smile on my face; can't wait to take her out for a spin (maybe this week if the snow stays away). So, let me say thanks to you all for the help!

Joe

 

Glad I could help....Now go riding and enjoy it !!