Okay need some advice; my sons LT80 has the following mods done to it:
Milled head .030
Motor was board .050 over
Mild port and polish
DG 20 mm carb with 105 main jet
K&N air filter
2 weights removed from front roller
Lighten very little rear clutch
Work Shocks front and rear
FMF fatty pipe with a power core II silencer
Dougles wheels ITP tires
Midwestmini speed gear 13x25
Midwestmini chain tensioner
High rise Alloy race bars
Light Maier hood
LED tail light
Bottom end has been rebuilt

With all this motor work done I am still not satisfied with the top speed, it does well in low range and mid but I haven’t seen the speed hit 30.
Here are my questions it’s a two parter:

Question 1
Should I advance the timing since the motor has been mod? Will this give me more top speed?

Question 2
What gear ratio should I be running? I presently have 13 tooth up front and 25 in the rear that gives me a 1.9 ratio.
My son is 10 and is ready to move onto a larger quad, I am still trying to keep this for him. I believe if I can get more top speed then he can keep this at least one more season.

 

Timing-no leave it alone.
Sprockets-15 or 16 front.
"all this motor work" Sorry dude but you sure have been led in the wrong directions.[img]i/expressions/face-icon-small-sad.gif[/img]
You know you have a mild port job, and you found out that the FMF is a grunt pipe and doesn't rev well.
Gearing is the right direction or you can get a real motor kit and have your son be challenged with the power.
He'll smile once again. [img]i/expressions/face-icon-small-smile.gif[/img]

 

Okay I ordered a 15 tooth front sprocket, waiting for delivery. Will post top speed once I have a chance. All the work done on this LT80 did in fact wake the LT up my only complaint is the top speed. I had to think back when I first started the building process I wanted my son to be able to sit at the bottom of a dune and shoot straight up it. And it does! now I am looking for top speed, of course I hadnt a clue that the FMF pipe was such a disapointment on speed. never the less it is a pretty cool ride, he just needs top speed. I am hoping that the 15 tooth sprocket will in fact bring the top speed up. So I am assuming that i will need to modify the clutch a little more?
Real motor kit LT80 that hurts brother. On your motor kits what is the top speed?

 

We run a 13 front 25 rear 4 rollers and have great high end speed/power. I also have "real" motor and clutch mods from "LT80" but with any decent motor/clutch work you have to lose that FMF. We ran an FMF like yours with our mods and it goes flat at mid-range with no top end. Sell it and get a trinity pipe. Our top end speed is right around 50 but it gets there very fast. Good luck

 

50 mph seems hard to believe. List your work done on the motor.
Are we thinking to get better top speed I should have my other cylinder port and polish done. Ditch the FMF pipe and get a LRD or trinity pipe?
I have another cylinder that was port and polished mild. board .051 over has scars on the cylinder, I wonder if this can be fixed or if I am better off geting another cylinder and get the work done for top speed.
Give me your thoughts.
As for a real motor kit the list above list all work done on my motor.
It seems like the cylinder needs to be redone, or is there something else missing?
I do believe it is time to start looking for a better pipe. I might have the chance to get the stock pipe back, is the stock pipe better then the FMF pipe?

 

Okay LT80 ow much to mod cylinder, clutch and reed cage? PM me please with $ qoute.

 

Forum rules prevent that.
Lets just see what the sprocket gives you. It may be just what your looking for. [img]i/expressions/face-icon-small-smile.gif[/img]

 

Sounds good, we dont want to see any forum rules broken. But this other post of an LT80 that you worked on doing 50 is that possible with your motor mods? What is the top speed of these motors after your mods? I hear that stock they do 28/29 mph. What can one expect after your mods or just port and polish and gear mods? I am to a point now where I am considering ditching the FMF pipe...

 

At the Paducah TT race, I can guarantee the mini's were doing at least 60 mph. We gear up for that one.[img]i/expressions/face-icon-small-smile.gif[/img]
At Pine Lake my boy and another rider of mine was clocked at 52 and 53.
For MX, gearing is different and speeds will vary per track/gearing.
For the dunes, usually a 18" paddle is used with stock gearing, possibly 1 tooth up in the front (my motor).
The difference is rpm's stock is 6500, modded is 11,500+. HP is almost tripled.

 

The motor kits is there case mods involved in reaching this speed? Or is everything done to the cylinder, head and carb? I would assume there are extensive case mods needed. either way you are sick if you are getting these LT's at that speed. sick sick sick, Let me know what I can do or need to do to get that speed. PM me if you can for information only