On Friday night I installed a full HMF system (sweet by the way), a 175 main (suggested and provided by HMF), and a Pro Design kit with a Uni foam filter. Also removed the intake snorkel and still have the lid on. Sat I was adjusting the mixture screw, 2.5 turns from dead bottom is what HMF suggested (that means from all the way in?). It was popping a bit, so I turned it out half turns til I got to 3.5 and there was no popping. Rode at Ocala today and it ran great the first few hours, then (didn't change/adjust anything) it starting popping LOUD. Why?? Popping is lean or rich? I thought lean because the prong on the plug gets pretty white, and the threads are black/dry. But by the end of the day, I was getting nearly one foot flames. It also smelled like fuel, so I assumed rich. What the h*ll man. Oh, and it started bogging a bit at the end of the day on the top end, and now it's hard to start/keep running when cold. Sorry for the very long post, but a lot of things happened/changed that are relavent. Someone please help, I'd like not to blow up the bike!


Oh- also got a Outerwears lid but didn't instal because I was unsure of its fuel condition. Think I should run with no lid and see if there's a difference? Also running 89 octane if that's a factor of anything stated. Thanks again.

 

Popping on throttle let off, means the idle circuit is too lean.
Check to see if the mixture screw came out, 3.5 is getting to the limit of travel, and it could have unscrewed an come out. if you go one up on the pilot jet, the mixture screw will be able to be closer to 2.5 turns out. The turn count is from lightly seated.
An exhaust leak, and/or an intake leak will also cause popping. recheck the tightness of the intake and exhaust pipe.
Octane wont make any difference on the lean or rich.

 

You said your airbox lid is still on,did you drill 3-5 1" holes in lid like hmf recommends? I don't think it says in the instructions but I noticed this on a HMF website advertising the system. I also have popping on decelleration sometimes. I called manufacturer and was told it is normal for a performance pipe. Also, my setup is 175 mikuni main,2 1/2 turns out, lid off with outerwears lid cover in place of lid, and uni filter provided with system,snorkel still inplace, and it runs perfect. Good luck

 

I went through all of the same problems and I ended up needing new rings. I had like 50 lbs of compression and it would take forever to get it running but once I got it warm it would run good, it also popped like you were saying. Maybe, mine was just a wierd situation but it also happened right after installing my jet kit. You may want to check your compression.

Also, how far away are you from Brooksville, FL(it is about an hour or so north of Tampa)? Just wondering cuz I found a kicka** place to ride with tons of jumps (not just sand and whoops).

 

Well, I live right under Daytona and Tampa is roughly 2.5 hours away. We are willing to ride to Ocala anytime, so if it's as cool as it sounds, the trip is not a prob. How large is the riding area? Is it a track, or just a place to ride? Been having no luck finding jumps and such without going to a track. Get back to me, we ride every weekend.

Yeah, since I have such a large main, and I can SMELL the gas now, I don't think it's lean. It could be that there's no exhaust gasket that I know of. Where does the gasket sit? I didn't find one when I removed the stock head pipe. And does anyone else's HMF headpipe leave no thread on the studs after tightening it to the cylinder? Almost seems as it's not fitting in there right. And yes, the mixture screw is still there, but I think I'll look for a leak, then remove the lid and adjust accordingly. If anyone can help me with the exhaust gasket/headpipe fitment issue, I'd appreciate it!

 

I didn't find any gasket when I took my stock headpipe off either. Must just be an error in the installation instructions from HMF. I went to the garage and measured stud thread sticking out beyond nut and it is just over 1/8". You may want to loosen up pipe and wiggle around, then retighten both nuts evenly so you don't bind it up. Hope this helps. [img]i/expressions/face-icon-small-smile.gif[/img]

 

Thanks for checking the studs for me. Yeah, it must be leaking from there because the stud wasn't even past the bolts. For now the exhaust and headpipe are off and I'll fix it tomorrow. Also put the mixture screw at 2.5 turns out and took the lid off, and we'll see if it helps tomorrow. One more question kawzuki, was the end of your stock headpipe that goes into the cylinder hole wider than your HMF? Because my HMF has about 1/16" play and isn't snug around the hole. I think the exhaust hole is small enough that this may not matter, but just wondering if yours was the same. Thanks again.

 

I think the stock pipe was snug coming out and the HMF was loose going on. It's been a few months since then so I can't remember very good.

 

Well we are considering going there this sunday. I dont know if that is to short of notice or not but I will let you know for sure by like friday. The property is only like 15 acres but it has what look like the sand traps(or whatever they are called) on a golf course only they are pretty deep and they are everywhere. I've never seen anything like it and am not sure where they came from or how they got there. I think it is private property and we dont know who the owner is. I would hate for you to drive that far and we get kicked out or something but it is up to you. Let me know if you would still be interested to go this week and about how many you think would be coming with you.

 

My z-450 does the same thing with the popping real loud when you let off the throttle and it a bit7ch to start when its cold. Try the idle jet, that has to be the problem. Do to the fact that my engine is getting rebuilt i never had a chance to change the idle jet. Also as for the exhaust, when i had to put my yoshipipe on for the second time it seem like it was loose and was leaking big time. I just add some washer to the stud and its worked out for me.