I'm making progress with the VP 105 fuel and floats/jetting. I just made a couple of blasts this morning and things are working as they should with the floats set to the mating line and the AF screws only 1.5 turns out. Now that it will run again, I can get back to fine tuning. Recent "problems" and fixes since last weekend, hope it helps someone else.

1) Water through my K&N filter was hopefully fixed by adding a water repellent outer wear. If I still have water problems, I'm getting an EHS lid or a whole new airbox. Under the right circumstances, a high compression Raptor will pump water out of the exhaust pipe almost as well as a fire truck:-) Removing the airbox lid should be done only if you understand the implications, a lot of water can get in there in a hurry and there is nothing you can do but pray once your engine starts blowing it out the exhaust. On a MX machine that will be raced rain or shine, the extra few HP may not be worth the reliability of removing the lid.

2) Loose positive battery terminal connection, a real bugger of an electrical gremlin when it's just a little loose.

3) Floats were way off with VP fuel, at least 1/4" above spec. Adjusted with clear hose to fill the bowl to the carb mating surface. I could not get the needle valve to work right if the fuel level was adjusted to just below the mating surface. I think this is going to be a recurring problem as I test different race fuels with different specific gravities. Anyone that adjusts these floats by measurement alone is lucky, the clear tube method is the shiznit.

4) After I got the above problems squared away, the 27.5 pilots were too rich by 1.5 turns or so. I could probably drop the pilots to 25 instead of 27.5 and add a couple of turns to the AF screws but it's all the same in the end. At anything over 2 turns, the quad wouldn't idle right and would blubber, backfire, and shut off after a short blast up the street.If I let it sit for a minute, I could make another short blast. I could get it to run a little by opening the choke half way. If someone can explain how shutting down air flow with the choke will offset rich pilots, I'm all ears. It still seems backwards to me. Anyone know how to connect a vacuum gauge to each Raptor carb? This hit and miss on the AF screws is for the birds.

5) Stupid carb boots weren't properly seated at least one time I tested a different float/AF setting. I'll bet they weren't properly seated one or two other times and I just didn't notice. I've found it 100% reliable to install and clamp the boots to the airbox first. Installing the head boots first would let just a little bit of the airbox boot roll under the clamp near the bottom and I couldn't get it to unroll without disconnecting the airbox boots.

 

It does sound backward. A lean idle mix. will be erratic. Do you have a tool to adjust the idle mix. while the engine is running? I would think 25 pilots and close to 3 turns out on the screws would be where I would start.
Here are a few signs of idle mix. out of adjustment:
Lean= popping on decel., revving in neutral and release the throttle and it revs a little high before returning to normal
Rich= RPMs drop lower than normal after releasing the throttle then recovers and idles normal.
Hope this helps.

 

Im pulling out the Dremel and going to town on that float stopper, so I'll let you know what I comes of this new modification.

 

Hiram - Let us know how that turns out.

Sixsixt - I do have a modified screw driver for adjusting the idle mixture while the engine is running but I burn my hand every time I try! I'm going to throw a new plug in it and check the color after just idling for a few minutes. Any ideas for a vacuum gauge port to monitor while adjusting the AF screws?

 

The only vacuum port I know of is the one on the left boot. I've always done it by ear with the engine running, turn it in so it's lean then richen it till it sounds the best and ad another 1/8 turn rich and try it. If I get alot of popping on decel. I turn each another 1/8. A little popping is OK IMO.

 

Went through everything again yesterday, I had those carbs off at least 10 more times! I could not get my Raptor to run worth a crap unless the AF screws were less than 2 turns with 27.5 pilots. I played with the floats some more and got them to adjust to slightly below the bowl mating line but no more than 1 mm or so. With the AF screws over 2 turns, I got bog at early throttle and sputtering/popping when I left off. The Raptor ran at 2.5 turns out without completely shutting off but it wasn't right. Just under 2 turns gives good idle, instant power to mid throttle and no carrying on after I let off the throttle. Once the bottom part of the powerband was working better, I had a little mid range bog so I went from the 4th clip on the stock needle to the 3rd clip. As soon as my GYT-R needles arrive, I'll be back in there. All my tuning was done with VP Red (105) fuel. Can't stress enough that the floats are #1 priority, I think they were my main problem and I just got wrapped around the axle with the loose positive battery terminal and last weekend's water sports.

Thanks for the ideas SixsixT, do you have a picture of the tool you use to adjust the AF screws while the quad is running? Also, I think I'm going to install a vacuum port on the right carb boot so I can adjust the AF screws properly and really sync the carbs. Anyone that's played with 4 cyl motorcycle engines (Vmax!) knows that carb sync has a lot to do with the way the engine performs. I don't doubt that you have an experienced ear, some of us need a little mechanical assistance:-)

 

What the hell?????? This thread has been going on for four days and I just now see it.[img]i/expressions/face-icon-small-mad.gif[/img]

I am in the SAME situation as ya'll two, kinda. I just can't get my floats to adjust. I wondered why the level was different than with regular 93 gas. I never thought about the specific gravity.[img]i/expressions/face-icon-small-confused.gif[/img]

UBETRUN, should the vaccume be the same on both carbs, since it is a single?????I guess the different size/shape/flow of the port would make it different.?.?
You can use some heavy gauge wire, like tie wire, and make a "T" shaped peice and sodder(sp?) it into your fuel screws, to adjust them while running.

I get my new needle and seat valve Monday, so I might be comming back here looking at some of ya'lls problems to fix mine.


[img]i/expressions/face-icon-small-cool.gif[/img]

 

Ubet like ward said the carbs share common ports and of course a common cyl. so a sepperate vacuum may not do any good not like a 2 cyl. with a carb for each cyl.
Look at motion pro web site they have a couple different tools for carb adjustment , I have a snap-on one myself.
Ward where have you been?[img]i/expressions/face-icon-small-tongue.gif[/img] And you were just talking about specific gravity in another post, but I don't know how much it would effect the float level. It would be easy enough for you guys to try each type of fuel while your doing this and see.

 

I'm still hosed but have an idea - intake valve lash. Be back shortly:-)

 

That was it, too little intake lash. I was less than .001 too tight on the intake valves. I am now running .008 intake lash with Hotcams Stage II. I can hear a little clatter again so I'll take that as normal.This thing is more powerful than when I first started getting on it, maybe that's the C12 instead of VP Red? Maybe all these tuning runs helped to break it in? Put 8 gallons of VP Red through it so far and am starting on a 5 gal jug of C12.

Anyhow, I buttoned it up tonight with 190/195, 2.25/2.75 turns AF, 27.5 pilots, stock needle on 3rd clip, floats set up according to the factory spec which is about 1/4" above the bowl mating surface doing the clear hose trick.