sianod,

I agree that it has something to do with the shorter slider. this is because different throttle positions have different fuel sources in the carb. With the longer slider the throttle would only open to an equivalent of 1/2 throttle. there would have minimal use of the main jet at that point, mostly the pilot jet, slider and needle valve would provide the fuel (see http://justkdx.dirtrider.net/carbtuning.html). I notice that going from idle to 1/2 throttle has no problem. I am going to try and raise the clip position on the slider needle to see if it will reduce the fuel delivered during acceleration. another thing I notice is that the needle taper also has alot to do with fuel delivery all the way up to WOT. unfortunately here there is no other needle valve available.
if it is a rich condition then going back to the original main jet 72.5 would probably also help.

From as best as I can tell the Raptor 50 carb. is identical to the one on the Raptor 80. I am going to be removing the carb. in the next couple of days I wil try make a closer comparison of the two.

 

Thanks for the info. I will try a few things this weekend and post my results.....please do the same.

 

sianod,

I didn't spend any time on the Raptor 50 this weekend (worked on the 80), but I hope you found a solution to this problem.

After looking over some of the carb. theory sites and thinking about what is going on I have come up with this hypothesis.

I think the problem with the 50 is not that carb. is delivering too much fuel when going from idle to WOT but not any at all. I checked the plug after a WOT and stall and it was dry. I also notice that the engine does not sputter and die but just dies immediately, like the run button was turned off or it was out of gas.

At idle the main jet is not delivering any fuel to the engine (as it shouldn't).

when the larger slider is installed in the carb. Opening the throttle all the way actually only causes the slider to half open. The fuel at this point is drawn through the pilot jet, needle valve and a small amount from the main jet. because the pilot was providing fuel already there is no delay in giving the engine fuel on the half throttle until the main jet comes in and you may feel a little delay but the engine will rev up ok.

However, when the smaller slider is installed, going to WOT causes the slider to open completely. this means that the main jet which prior to WOT was having NO fuel drawn through it must now start providing fuel. I believe that the combination of the small engine size and the time it takes to get the main jet to start providing fuel (build up of low pressure at the jet) causes a starvation condition.

The auto industry solved this problem a long time ago by inventing the acceleration pump in the carb. this provides a shot of fuel until the main jets can get going. I think that there are also small engine carbs. (ATV, motorcycle, etc ..) that have this feature. I think that larger engine displacements have much less of a problem becasue they draw more air volume through the carb. and can cause the main jet to start feeding fuel quickly.

I was going to try putting some gas in a spray bottle and upon WOT spray some into the intake of the carb. my suspicion is that the engine will rev up ok and not stall. I was thinking that riching the idle circuit some and possibly raising the level of the fuel in the carb. float bowl could help this problem. Also I am nor sure if increasing the main jet size can help this becasue at some point the machine will run too rich. I don't think that it is solvable with this carb.

I have wondered why the 50 runs a larger pilot jet than the 80. with the larger slider installed the pilot jet would be to some degree just about always be providing fuel to the engine whereas the main jet only at about 1/2 throttle.

keep me posted on anything you find

Thanks

 

Thanks ! I have also found some info that says what you are saying. These carbs are always going to have this problem. I did not have anytime this weekend to play around with the raptor; my wench died on my Quad and I had snow to plow.... I think my kids are just going to have to take it easy when starting before WOT. If I ever find anything out I will let you know. I have learned a lot about carbs from these posts.

 

I think a manual instead of auto clutch helps this problem because it allows the rider to rev the engine up before engaging the clutch. this allows the main jet to start flowing fuel so WOT works correctly

the one thing you commented about was the quad always stalls when shifting from N to drive. I never have this problem. I changed the jetts to 12.5 and 76.2 (Raptor 80 stock) and then adjusted the idle/air and the idle speed screws and it goes into drive just fine. does it idle good in nuetral (not low) ? if so than turn up the idle just slightly and try switching and see if that helps.

Snow plow !! I vaguely remember those days. where in NY are you ?

 

Raising the idle can help as well (as simple as that sounds)

It can help with the transition between the throttle circuits....

It will probable not fix your issue, but it may help a little

Just figured I would mention that as a last ditch effort to help

I had a similiar issue with my 2006 TRX450R..

 

About 40 mins. from the Catskill area. We recently got hit with a nice snow storm. I have a 2006 Kiodiak 450 Special Edition with a 50 inch plow and warn wench. This plowed a foot of snow like nothing. It also cut through about six in. of frozen ice mix too. Since this was the first time I used it I went crazy and did about 5 driveways until my wench stop working. It took me about 4 hours to find the problem which turned out to be a bad wire tap under the handle bars off the ignition switch. My dealer did not do such a great job routing the wire harness. I had them install the wench because I got it for free when I bought my quad with the plow.

 

I've been to the game farm a few times there. I grew up in Beacon, went to college in Rochester and worked in Buffalo for 10 yrs. (that\s where I really learned to dislike winter). I still get up that way every 6 months to see my sister in Marlboro.

 

I fought this issue for months on the Raptor 50. Have you guys replaced the stock CDI yet? The RMStator cdi I put in helped some also turning up the idle helped more than anything.

I got tired of messing with it and gave up on a good fix for it. Going from N to D posses no problems anymore, but it will still bog and sometimes die if you stab the throttle. My little ones have eventually learned to ease into the throttle.

 

Evasiveone,

I have a procom CDI. I tried turning up the idle but my daughter complains that the quad wants to go or continue to go when she doesn't want it to. I gues I could remove some of the ***** from the clutch basket and solve that problem.