Ok. Some of you have followed my looooooong drawn out top end rebuild. Finally got it put back together over the long holiday weekend and a couple of vacation days to boot. Again its a 99 400L Sport. Rebuilt top end w/a port and polish, factory bore. New dual petal reeds. Rebuilt went fine and it fired right up. Let it run for a few minutes take a ride up and down the road a few times. Really has top end! However, no bottom end at all. Just don't know if that's because of the 40:1 pre-mix I'm running right now including the oil injection or what? If I run w/the air filter on, it will run like crap! Guy who helped me put it back together says that once I know the oil pump is working correctly, drain the pre-mix out and run some 93 in it, and this should clear everything up? He says that is why it bogs down on the bottom end so bad because w/all the oil running through it, the motor is gasping for air and that is why it runs great on the top end?

I know this, that once I get this all figured out and dialed in, this thing will fly!

I know the factory pipe is killing it too. Soon, when I get the money, I want to get Rick's pipe, clutch spring, and jet for it.

 

ttt

 

yea its probably running very very very rich right now like you said so it will bog it down.

 

Cool. Just need some confirmation on my thoughts-thanks.

 

Port jobs dont work well with a stock pipe. Who did the port work? Did they raise the exhaust port and if they did how much? That alone could have a huge bearing on no bottom end. I never had additional premix cause any lack of bottom end. Extremely rich fuel to air ratio could cause it, but if you are running the same jetting then that shouldnt be a problem.

 

Thanks Bubba. I was hoping for you to join in. Yes, same jet setting. However, 40:1 in the tank along with the ratio of what the oil pump, pumps. I know my oil pump is working because I have noticed the tank line receeding.

I used the Race Logic Sport Port Kit template. My friend is a machinist and he scribed it and then used a die over the scribe to follow the cutting of the template. Yes the exhaust port was raised-based on the template and scribe seems as if maybe an 1/8" or so or that is how much was cut out? I know that is alot when machining, but we checked twice and cut once.

 

Oooooohhhhhh![img]i/expressions/face-icon-small-shocked.gif[/img] Is there any way you can confirm that with him? 1/8th inch is about 3mm, and that is a mile when it comes to porting. I have had my hands on race logic porting templates, and they did not raise the exhaust any when I checked it. The reason for that is to increase power across the board and keep the bottom end strong. Just FYI, a trail port job usually only recieves 1 to 1.5mm raise in exhaust height. Again I would double check. Now if this is the problem not all has to be lost. A bump in compression by taking .020 off the head will help a lot, as well as an aftermarket pipe and clutch change. A different clutch spring will help stall it up better and get a little more into the rpm range. Porting takes years to understand and I am still learning things everytime I do one. A scribe line is fine, but .040 (or 1mm) is easy to remove. Lets just take it one step at a time. Hope this helps,Bubba

 

Let me confirm this w/him. Maybe the more I think about it, the exhaust was not raised. The template was laid at the top/even of the exhaust port, however I need to confirm this w/him. I know that on the exhaust side the template showed quite a bit to cut out on the bottom end the more I think about it. Now I'm confused[img]i/expressions/face-icon-small-blush.gif[/img]

 

Allright, let me know.

 

Hey Bubba,
Just talked w/Mike who did the porting. The EXHAUST was not raised or lowered any, the template did not call for that, and he further stated that he would not have done that because it would have killed the motor. The only thing he did w/the exhaust was widen them, very little. Most of the cutting/porting was done on the intake. Then he just flow ported all the factory blemishes/castings out in the rest of the head.

He believes that once I dump the premix out of the tank and get some good gas (93 ocatne) everything will be good, but to really get the most out of this combo I should do the jet, clutch kit, and pipe. He said the pipe and jet will make another big difference and could be acting as a restriction now.