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Discussion Starter · #1 ·
I just rebuilt my 01 raptor 660. Just honed stock bore and put in a 9.9:1 compression pistion. no other engine mods. After the new pistion my raptor doesnt seem to pull as hard as before at mid to high rpms. Im still running stock jets all around and havent messed with the carbs yet. By putting in a new piston do I need to rejet or just adjust?

My brother has a 2000 DS 650 and my raptor is suppose to walk all over his up to 50 mph at least but if we take off he always pulls away when mine starts hitting the high rpms. How do I fix this?!?!
 

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Master of the Electron
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I don't see how a near stock Raptor is going to pull a DS650. You need to open up exhaust and airbox, then rejet accordingly.
 

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I am unique
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I just rebuilt my 01 raptor 660. Just honed stock bore and put in a 9.9:1 compression pistion. no other engine mods. After the new pistion my raptor doesnt seem to pull as hard as before at mid to high rpms. Im still running stock jets all around and havent messed with the carbs yet. By putting in a new piston do I need to rejet or just adjust?

My brother has a 2000 DS 650 and my raptor is suppose to walk all over his up to 50 mph at least but if we take off he always pulls away when mine starts hitting the high rpms. How do I fix this?!?!
Are you sure the cam timing and valve lash is all good.........:)
 

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Discussion Starter · #4 ·
Are you sure the cam timing and valve lash is all good.........:)
As I reassembled the top end I made sure everything was in spec. I ended up also replaceing my valve seals, all 3 intake valves, and also lapped my two exhaust valves as well. Everything else was within specs determined by the repair manual. I am sure the engine internals are build correctly and in spec so I am thinking it might be some form of carbuator adjustment.


If my brother and I line up the two atvs right off the start its pretty close but when he starts hitting the high RPMs mine starts to fall off so I need to grab the next gear to keep up. By the time I hit 5th gear he has about 2 lengths on me. So I am trying to get more power out of mine.

The other thing I forgot to mention was if Im running steady rpms at low and mid rpms and just quick snap the throttle wide open it studders before it starts to pull most of the time but if I roll on the throttle it doesnt studder. Would that be the jets or do the carbs just needs some pilot screw adjustment??
 

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As I reassembled the top end I made sure everything was in spec. I ended up also replaceing my valve seals, all 3 intake valves, and also lapped my two exhaust valves as well. Everything else was within specs determined by the repair manual. I am sure the engine internals are build correctly and in spec so I am thinking it might be some form of carbuator adjustment.


If my brother and I line up the two atvs right off the start its pretty close but when he starts hitting the high RPMs mine starts to fall off so I need to grab the next gear to keep up. By the time I hit 5th gear he has about 2 lengths on me. So I am trying to get more power out of mine.

The other thing I forgot to mention was if Im running steady rpms at low and mid rpms and just quick snap the throttle wide open it studders before it starts to pull most of the time but if I roll on the throttle it doesnt studder. Would that be the jets or do the carbs just needs some pilot screw adjustment??
You may need some carb adjustment, what jetting are you using presently, pilots, needles and mains.........
 

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Discussion Starter · #7 ·
Everything is still stock. I havent changed anything in the carbs. I believe its a 22.5 pilot, 140 and 145 mains. Stock needles and spings and needles are set to the middle clip. Pilot scnew is set to 2.5 turn from fully seated.

Carbs have been recently cleaned with all new o rings and gaskets.
 

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Stock Raptor will not walk a Ds650. I have both raptor and DS650 and the DS will beat a stock 660 with no problems but when modded the 660 will beat a stock Ds but I have never modded any of my DS's past a slip-on to compare after that though. IT is more or less about how good of rider and how well you know either machine though.
 

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Master of the Electron
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I'd consider upping the mains to 150L/155R - it may be starving for fuel a bit at top end.

Of course, I'd suggest full exhaust, open airbox and 160L/165R jets, then you should have no problems with the DS.
 

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Discussion Starter · #14 ·
Spent some time getting the jets and carbs put in last weekend. turned out I went with 155/160 with needle clip on center clip, 22.5 pilots and pilot screw at 2.5 turns out. Not it hauls ass. Took it out on the paved road and from idle in first gear with 22 in tires on the back and stock gearing it wheelies through 1st (actually cant go full throttle acceleration cuz itll flip over) and picks the tires up halfway through 2nd gear. It was freaking awesome!! Thanks for all the help everyone!!
 

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Master of the Electron
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Glad you got it dialed in!
 
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