Maxxam 150 2r need some input please on top speed

[ItsjustT]

Looking for suggestions as to what speed I should expect and what to try next to get top speed up...

My son has a Maxxam 150 that was running about 45mph on a performance coil and performance cdi.

The piston and rings burned up so we replaced the cylinder and piston with the 155cc bore kit. At the same time we went ahead and installed the A9 cam, reset timing and valve clearances and replaced air box with 39mm pod filter. At this point the buggy bogged down around 1/2 throttle.

We installed a new 30mm carb and still had the same issue even with adjusting mixture multiple times, so removed carb and sent back to amazon after reinstalling air box. It ran well but still slower than prior to cylinder replacement.

Yesterday complete carb cleaning and went from stock main jet on stock 24mm carb to 120 main jet and pod filter. No longer bogging, idles and has faster acceleration but tops out at 28mph on flat or downhill. No bogging that is just the speed it will reach, was really expecting more for the upgrades

Again, looking for suggestions as to what speed I should expect and what to try next to get top speed up...

Current mods:

155cc Cylinder & Piston
A9 Cam
120 main jet
Performance CDI (No Rev Limit Blue Unit)
Performance Coil (Orange)
Replaced clutch with new stock unit
Variator replaced and installed 13g weights (14g stock)
Removed air box and installed pod filter

[ItsjustT]

Any help or suggestions is appreciated..

[JERSEYDEVIL]

this wont solve your problem but i see this alot. whenever upgrading stuff you need a reference point. always make changes in steps, this is how we would tweak my race car when we made changes to see what helped and what didnt. for example after a rebuild run everything stock to see where you are at. then add one upgrade at a time and test it. does it help/hurt? if it helps then keep it and try it w/ another upgrade did that improve thing more?. if you pile on with upgrades if youdo hit a hiccup you'll never know quickly where you might have gone wrong or which part does not work or might be defective. right off the bat the 30mm was too rich. remember bigger carb, leaner jet. as far as the top speed, not sure.

[ItsjustT]

We tried to do upgrades together as they made sense. bore and cam, air filter and jet etc. We had it running well on the cam and bore with the stock carb and stock air box just not as fast. When we did just the air filter it bogged so went back to airbox and then upgraded main jet on a stock carb with air filter, no longer bogs but not as fast as I would expect with those mods. Appreciate the input and just really don't know where to go next

[GX150]

1. Air filter requires a 6" intake tract between carburetor and filter
2. You need to check spark plug color to verify jetting if you don't have an air/fuel gauge
3. Try your stock CDI or coil to see if you have a bad performance one

[SYCARMS]

I doubt the 45mph. Most go by the speedo on the buggy. Not at all accurate. Most of the older buggies with exception of the 2004-2005 Carter will top out at 30mph stock and 35mph with a cam and open filter system properly jetted. The 2004-2005 (not all though) Carters would do 40-43 mph stock due to the gearing in the final drive. The downside was they would barely climb a bunny hill. The later buggies with internal reverse will do 40mph stock due to different cluster gearing in the transmission. Now being evident you lost speed this could be due to many different things, too lean a/f mixture, faulty cdi kicking in the rev limit too quickly or the cdi's timing map is not sufficient with your mods. The 30mm carb you installed actually hurts your performance since the engine will not produce the proper cfm's to efficiently operate the carb unless you had major upgrades like larger bore with at least a 3mm stroke, performance head with larger valves and runners and a custom cam with a higher lift and longer duration than what is currently offered in cams. Lastly not all cams currently offered are created equal. What I have found is that when I degree a cam I found that depending of where the cam came from, the lobe separation, open and close degrees of the intake and exhaust varied sometimes greatly. As JD stated above, this is the reason you want to do one mod at a time so you can determine as to weather it will help or hinder unless you have a supplier who you can trust knowing his product will achiev the results advertised. Recheck all your basics like spark a/f mixture, timing, valve clearance and compression. If all that checks out to be good try putting the stock cam in and see if results change.

[351mustanger]

^^^I agree with the above post. With the stock carb and no major jetting changes, the cam is where I would look first. Out of all the mods, the cam would be the most influential of performance. Next would be cdi. Double check that the new clutch and variator are torqued down correctly and not slipping.