can't get top end 660 grizzly

[mike123]

I have recently replaced the piston in my 660 grizzly, after putting it back together it started right up, sounds good, lots of power I took it out for a ride down a stretch of road and for some reason I can't get it past 74 kph. I have plenty of throttle left and it feels like it wants to go faster but just starts to hesitate around the 70 kph mark and then will not go any faster than 74 kph. I have tried adjusting the carb, and the valves but no difference, before I blew my piston I could reach around 100kph so I know something is wrong. The bottom end is all there can lift the front wheels off the ground when I hit the trottle, starts great any time, I can't figure out why I can't reach top speed, could the timing be out?

 

[gforce]

did they give you the correct piston..ive had them give my wrong parts in the past..check yer part no on the reciept or box..s,,,it happens

 

[mike123]

All the parts are the right ones, i had the cylinder oversized up one size according to yamaha specs and a piston to match from yamaha. like I said it has lots of bottom end and it gets up to 65-70kph in no time but after that it looses its top end. Maybe I'm looking in the wrong places could be clutch I guess, but I did'nt touch the clutch...

 

[QMAO]

Sounds like you are running lean on the top end, it is a carbed grizz right, Might have to raise the needle to give more fuel. Someone with more experience might have better opinions.

 

[sledn]

Sounds like you are running lean on the top end, it is a carbed grizz right, Might have to raise the needle to give more fuel. Someone with more experience might have better opinions.

If it is too lean,a bit of choke should give more power.(Then check jetting)

 

[mike123]

ok, thanks for the tips but I figured out the problem, for anyone who decides to change a piston on thier own pay close attention to the timing marks, I had advanced my timing by 1 tooth on the cam sproket and that is why the grizzly acted the way it did, after setting it back one tooth on the cam the 660 still has the bottom end and reaches 94 kph on the straight away, maybe a few minor adjustments on the carb and I could reach 100kph, however I'm not to concerned I am running 28" mudlights on it.

 

[leonard]

break that in before you go hard on it for to long you will thank yourself for doing so.

do your first oil change after only afew hours "some say even 1hr" and then do it @ 10" then 50 and after your 3-4th change it wont be fully broke in but the initial should be getting close to done.

you will gain some kph when its broke in properly btw.