New Guy with an old Raptor 660 - Yamaha Raptor Forum
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post #1 of 30 (permalink) Old 01-26-2017, 11:11 AM Thread Starter
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New Guy with an old Raptor 660

Hello Everybody,

I'm the new guy here and am looking forward to keeping in touch with other Raptor owners/riders/fixers.
Maybe, just maybe, I could help somebody out too!

I've done some searching here so as to try to not bring up a dead horse. If one of you experienced guys can give me a link to the answer I need, that would be great. Or perhaps you just know the answer. Hey, I'm happy either way.

My son's '04 Raptor 660 has an interesting issue. For several years it ran just fine. But in the fall of '16 a new problem popped up.
After running the engine at any riding speed (above idle), it will either take a long time to idle down or it won't idle down.

My first thought was sticking cable or sticking valves in the carbs. WOA - Welcome to CV carbs! New since I was a kid!

When we run the engine with the air box and boots off, we can see that the SLIDES (aka throttle valves) DO slide down as soon as we let off the gas.
The butterfly valves shut too. So nothing is sticking!

When running at speed, I think one heck of a lot of gasoline is spewing out of the jets into the venturi's. A lot! This is both carbs. It is my belief that so much gas is spewing out that even with both valves in each carb shut, the engine runs fast.

I will tell you the spark plug is black and sooty. And - this bike is all factory. No Mods.

I did check for air leaks in the carb boots. none.

Here is the real question I have. When we rev the engine up, the slides do move up, and come back down when we let off the gas.
BUT when we rev the engine, the slides pulsate (or vibrate) up and down like CRAZY! Like in tune or timing with the piston! Is this normal?
Or should the slides stay in one spot, only moving up or down as you give it the gas, or let off the gas?

Looking forward to hearing from you.

Thanks

Dale
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post #2 of 30 (permalink) Old 01-27-2017, 12:05 AM
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Welcome to the forum!

What you are describing sounds like 'slow return to idle' which, believe it or not, is usually caused by being too lean on the pilot (idle) circuit.

As your quad ages, fuel varnish builds up in the pilot jets, causing the idle circuit to operate leaner and leaner. The proper way to fix this is to remove the pilot jets, clean them out with spray carb cleaner and copper wire strands and reinstall.

A temporary fix (and to verify this is the issue) is to turn the fuel screws out (CCW) 1/4 to 1/2 turn each. Does it return to idle now?

Of course, the other issue may be a stuck throttle cable - you can see if this is the case by removing the throttle cam cover (triangular on the left side of the driver's side carb) and see if the cam returns to zero immediately when you let go of the throttle.

Another possible fix for varnished pilot jets is to add Seafoam (2-3X what is recommended on can) to your fuel tank and ride, ride, ride... often the Seafoam will remove the varnish, as long as it hasn't gotten too bad.

Good luck and let us know what you find!

BTW, slides are vacuum operated, so at open throttle you will see some modulation due to the pulsating vacuum of the single cylinder.

'01 660 Raptor, Burgard +2+1 arms, YFZ Shocks, LSR anti-vibe, CTR pipe, jetted, K&N
'01 Polaris Scrambler 400, K&N
'02 Honda 400ex, Big Gun pipe, jetted, K&N, Lonestar +2 A-arms, Lonestar anti-vibe
'02 Honda 400ex, DiamondJ +3 A-arm widener, Lonestar anti-vibe
New Toy: '16 RZR XP4 1000 Turbo

Last edited by QuadManiac; 01-27-2017 at 12:09 AM.
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post #3 of 30 (permalink) Old 01-27-2017, 07:13 AM Thread Starter
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Thank you QuadManiac -

I won't be able to get at the bike for a few days, but I will post a reply with the results.

I am happy to hear of another Seafoam advocate. While there is no magic potion for a completely varnished up carb, Seafoam has worked for me on engines that have just started to exhibit a lean run condition. Specific example is my 2 year old snow blower that needed one or two clicks on the choke to stop the engine from hunting/surging. A few tanks of treated fuel cleaned that right up.

I will check back in a few days and let you know what I find.

Thanks again,

Dale
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post #4 of 30 (permalink) Old 01-27-2017, 11:06 PM
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Originally Posted by Dale_W View Post
Thank you QuadManiac -

I won't be able to get at the bike for a few days, but I will post a reply with the results.

I am happy to hear of another Seafoam advocate. While there is no magic potion for a completely varnished up carb, Seafoam has worked for me on engines that have just started to exhibit a lean run condition. Specific example is my 2 year old snow blower that needed one or two clicks on the choke to stop the engine from hunting/surging. A few tanks of treated fuel cleaned that right up.

I will check back in a few days and let you know what I find.

Thanks again,

Dale
Yep - I've got 4 quads, two bikes, two scooters, a riding lawnmower, a motorized mountain bike, a rotary mower and a couple of weed whackers, all carbureted... without Seafoam I'd be cleaning carbs just about every week!

'01 660 Raptor, Burgard +2+1 arms, YFZ Shocks, LSR anti-vibe, CTR pipe, jetted, K&N
'01 Polaris Scrambler 400, K&N
'02 Honda 400ex, Big Gun pipe, jetted, K&N, Lonestar +2 A-arms, Lonestar anti-vibe
'02 Honda 400ex, DiamondJ +3 A-arm widener, Lonestar anti-vibe
New Toy: '16 RZR XP4 1000 Turbo
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post #5 of 30 (permalink) Old 01-27-2017, 11:21 PM
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Check to see if the choke plunger is stuck. Some times they stick and can cause issues too.

2003 Limited Edition Raptor
Kenz 720cc 11:1 stroker, +1 valves, Mega Cycle X-4 Cam, Sparks 6x Big Core, Keihin 35mm FCR's. 158 mains, 52 pilots, fuel screws 2 turns out.

97 Banshee
F.A.S.T. Dune Ported 4mill, CPI Inframes, Keihin PWK33's, Direct Drive Lockup. 158 mians, CEL needles second clip, #48 pilots, air scews 2.0 turns out.
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post #6 of 30 (permalink) Old 02-02-2017, 07:42 AM Thread Starter
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Found the answer to the slow return to idle. At least I think we did.

You know how the floats should be at 13mm? These were set at like 3. OK maybe not that bad, but way off. WAY too high of gas level.

I set the floats to 13mm, then did the clear tube check. 3 mm above the crack.

When I had the carbs apart (one at a time) I cleaned the heck out of them.

*I could not budge the air/fuel mix screws. The manual calls this the pilot screw.

Put them back together. The only parts I used new out of the Chinese carb rebuild kit were a few O-rings.

The bike starts and idles fine.

When you give it the gas, it no longer has gallons of gas spewing up through the needle jets into the venturi(s). I suspect this is because the floats are no longer set for a super high gas level.

And, the slides no longer pulse wildly, just a bit now. Most important, the 'slow return to idle' is gone.

But, the engine runs pretty rough now, and backfires through the carbs some.

Any thoughts on that?

UG, and another question. The raptor manual does not show the part, but each carb has a little part that sits above the needle jet. It protrudes a little bit into the venturi. The needle slides down thru this part and into the needle jet (emulsion tube?).

This little part has one end that is countersunk in, and one end that us cut off flush. I put the countersunk end in to the top. Is that correct?

Thanks

Dale
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post #7 of 30 (permalink) Old 02-03-2017, 07:02 AM Thread Starter
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So yeah, another question. This one will be easy for the pro's.

At this point, I have the carb's attached to the engine, but the tubes and airbox are sitting on the garage floor.

I *think* the engine is running too lean.

Are these things so dang fussy that even putting the stock air filter, box, tubes, cover all back on could richen it just enough to get it running right?

Thanks

Dale
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post #8 of 30 (permalink) Old 02-03-2017, 07:24 AM
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If you take the lid off you'll need to up the pilots.

Sent from my SM-G930V using Tapatalk

Joagaca suspension,gytr frame skid,yfz calipers,powermadd hand guards,prodesign shifter,fasst flexx bars,rox risers,t.m. design chain guide,+2 lonestar swinger,billet dash,x-rex rears, klaw xc fronts,ebay bumper,prodesign case saver,primary drive sprockets and chain, all balls wheel bearings,+2+1 lonestar a-arms,+2 g force axle,vitos jet kit,ac pro peg nerf,amradillo swinger skid,sparks exhaust,prodesign intake,foam filter,outterwear,no lid

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post #9 of 30 (permalink) Old 02-03-2017, 10:02 AM Thread Starter
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Thanks JSANDERS347
That pretty much answers my question. DUH. My son has a new filter on order.

Since he will be running this bike all factory, I better put all the pieces/part back together before I make another move.

Makes sense. I have read where others have removed the lid or put holes in it, and had to increase jet size.

again, thanks.

I will let you know how it turns out.

D
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post #10 of 30 (permalink) Old 02-03-2017, 02:38 PM
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Quote:
Originally Posted by Dale_W View Post
So yeah, another question. This one will be easy for the pro's.

At this point, I have the carb's attached to the engine, but the tubes and airbox are sitting on the garage floor.

I *think* the engine is running too lean.

Are these things so dang fussy that even putting the stock air filter, box, tubes, cover all back on could richen it just enough to get it running right?

Thanks

Dale
They are not necessarley fussy. The vacuum slides and the hoses going between the carbs and air box is part of how they operate. With out those tubes there it can cause problems.

As for removing the air box lid yea you have to rejet because its a pretty big increase in air flow. Stock raptor with stock exhaust is around 36hp. Just removing the lid is around a 3 hp gain. On a machine that's only 36 hp that's a pretty significant gain in power.

2003 Limited Edition Raptor
Kenz 720cc 11:1 stroker, +1 valves, Mega Cycle X-4 Cam, Sparks 6x Big Core, Keihin 35mm FCR's. 158 mains, 52 pilots, fuel screws 2 turns out.

97 Banshee
F.A.S.T. Dune Ported 4mill, CPI Inframes, Keihin PWK33's, Direct Drive Lockup. 158 mians, CEL needles second clip, #48 pilots, air scews 2.0 turns out.
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