04-05 Yamaha Raptor 50

[atvingnc]

CJ5350,

too bad on the piston. did the cylinder have any damage ? anything get into the crankcase ? I am presently reassembling the clutch side of the 80, once this is done I'm going to tear apart the top end (especially after your experience) and check the cylinder and piston and probably replace at least the rings. hopefully I won't find any surprises.


PatM

your saying that right from the dealer it would not idle right ? I understand adding all that stuff on
to get better performance, but not to just make it run, that's not right. (I'll bet those items where a
buck or two)

If you have to leave the choke onto keep the machine running (after it has warmed up) then your carb. is to lean. I don't remember off-hand (I did write it down buts its home) the number of turns for the air/fuel mixture screw from the factory but I'm thinking between 2 and 4 turns (#15 jet). however I also replaced my low speed jet with a #10 and after adjusting the screw it ended up being 1 1/2 to 2 turns to get it running correctly.


Most tuning articles I've read have said that for a given idle speed screw setting you are looking to adjust the air/fuel mixture screw to get the highest idle RPM. I turned my air/fuel mixture screw clockwise until the engine ran rough (about 1/2 turn from fully closed). then I started dialing it out while listening to the engine RPM and counting the number of ccw turns. as I dialed out it the RPM got higher until it flattened out. any further and the engine started to run rough (this is all with the choke off, the engine warmed up and the tranny in neutral). then I took the number of turns (from my starting point of 1/2) to the point where the RPM no longer increased or engine ran rough, divided it in half and added it to back to the 1/2. so lets say I went 2 turns from the 1/2 starting point then my air/fuel screw should get set at 1 1/2. this off course is considered a by ear (in the ball park) setting and you may find that 1 1/4 or 2 is better, but it should get you close. Now after that I played with the idle speed adjustment until the engine idled fairly smooth when sitting still in gear (I don't have a tach). I have had these settings since and the machine has run quite well.

I have read about other methods of tuning but this was the simplest and it seemed to work for me. Now another rule of thumb I've heard is if you have to adjust the air/fuel mixture screw more than 2 1/2 turns then you need to move to the next larger low speed jet. Now as far as I know there are only two adjustment screws on the 50 carb., air/fuel and idle speed.

do you find at wide open that the 82.5 jet works well. I replaced the original jet with a 78.5 and it seems to work well but with an 80cc on the horizon I was wondering about changing that.

There are some great websites that can explaine the carb. theory and the various tuning methods. just use yahoo or google and type in some variation of "carburetor tuning". I have read some great articles on tuning techniques and what is really going on in the carb. http://justkdx.dirtrider.net/carbtuning.html

[PatM]

Thanks atvinggnc. I got it to run better before I put the mods on. It was actually running great with just the cdi and pipe. You blip the throttle and it went with no hesitation. My daughter was ripping around the corners. After I added the filter and changed the jets that when it went back to its not running/idling state. I played with it this morning after I put my daughter on the school bus and have it better now. I have the stock pilot jet in there and closed the low speed screw then backed it out 1 full turn (2 rotations counting the notches). I then adjusted off of that. When I closed the screw from its factory state it was at 2 1/2 full turns out. I then adjusted the air/fuel mixture screw and have it much better. I don't know the amount of turns out it is but will check it. At least now it starts even with the choke off and stays running. There is still some hesitation but it is much better than what it was last night. Might just be my fat 225lb body on it that makes it move like a slug. I will see with my daughter on it when she get homes from school. Standing next to it if I just give it gas it seems o.k. but I will let her try it and see what it does. I will just take a 10mm wrench, philips screwdriver, pliers and a couple of other things along with the jets to try it tomorrowwhile up in the mountains and get it dialed into that elevation so she can ride.

Now as for not running right from the dealer I bought it from a private party. It is an 06 that I paid $1400. Kind of a steal for that year and shape it was in. It just didn't want to get out of its own way even with a tail wind.

Thanks again for the help and all of the useful info on this one thread.

[Verhovina6]

I was wondering if I buy the whole carburetor from Raptor 80 will I need to adjust idle and air/fuel screws at all. Dont want to get into this fine tunning. thanks

[atvingnc]

CJ5350,

haven't heard from you in a while. how goes the 80 project. how much work is it going to take to get the engine running.

I just got the clutch side of my 80 back together. I decided to pull the head and cylinder off and
found that the piston had some scoring so I just sent the cylinder out for machining, and ordered a new piston and rings.

[CJ5350]

Originally posted by: atvingnc
CJ5350,

haven't heard from you in a while. how goes the 80 project. how much work is it going to take to get the engine running.

I just got the clutch side of my 80 back together. I decided to pull the head and cylinder off and
found that the piston had some scoring so I just sent the cylinder out for machining, and ordered a new piston and rings.

Gday Mate, still going....ordered a 3mm oversized wiseco piston kit, found a full gasket kit in far north Queensland (Australia) The head has a mushroomed valve on the intake and local yamaha wants $58 for one..Anyone one wana post me one?????

Still trying to find the rest of the old piston in the case and found lot of meterail in the pickup screen and looks like a crack in the clutch basket...Some ebay bargin....

[atvingnc]

why is the valve so damn much ? I was looking on ebay at vesrah valves. For $30 you can get both of them. 3mm over (big bore) wiseco piston was a couple of $$$ I'll bet. that will give you a 90+cc. cracked clutch basket. what where they doing with or to the engine. I had to remove and install my clutch basket. for removing it an air impact wrench worked awesome. I bought the clutch removal/installation tool from pitposse to put it back on. do you plan on putting new valve guides in the head or are you just going to just install new valves. everything I've read about valves says that new guides should be installed. I just want to replace the valve(s) and do some minor lapping, without having to go through the guide removal and installation and reaming (especially since I don't have the tools for that). you have any experience with valve replacement, what problems can or will occur if guides aren't replaced.

[CJ5350]

Atvingnc, sent ya a PM....no idea why they want so much for the valve??? the vesrah ones arn't stocked local for the 80cc engines here...the piston kits was on $120 Aus..

There is no play in the guide so I don't see the point of changing it....just going to have the valve seat cut again

[motobob]

i first want to thank everybody for all the great knowledge on the raptor 50. after reading this forum i paid a visit to raptor 80 racing. I picked up a pro circuit t4 pipe, k&n filter, 80 main jet, dynatek cdi(no rev limiter), 80 slide and throttle arm, and a 12.5 pilot jet. this bike runs awesome except at idle. it wont idle without the choke on. I have been reading other post and i am thinking of going back to the stock pilot jet which is a 15. I have adjusted the air/fuel mixture and the idle but can still not get it right. are there any other adjustments on this carburetor. I read something on this forum about a low speed screw with possible notches. does anyone have any knowledge on adjusting this or any suggestions on what else i can try. The dynatek rev limiter that raptor80racing has is awesome. it does have a rev limiter but is set at 16,000.

[bugme]

Hello, and I am in the middle of something similar. I replaced the main and pilot jet, the slide, the throttle arm. I also moved the circle clip down to the last position and then played with the air/fuel and idel screws to the point that it runs great with the exception of idel where it will still idel for about 30 seconds and then die. I received the new gaskets last week but still haven't installed them. I also bought a new nozzel (same as stock Raptor 80). Hopefully, installing these two new items will correct this idel issue. I have a question for you: You mentioned a 16000 RPM rev limit? Are you sure of these numbers as I was told that stock cuts off at 8000 and the Pro Com I installed lets it run out an additional 1000 RPM'S to 9000 which creates enough vibration to shake a tooth loose, I can't imagine 16000?
Anyway, let me know.

Thanks
Jon

[atvingnc]

motobob,

man you just about went the whole 9 yards. A set of ITP holeshot tires and rims and a turbo charger (just kidding) and that'll be a serious butt kicking 50. Obviously if you need to have the choke on then you are not supplying enough fuel at idle speed. I have the 12.5 jet and my idle air/fuel mixture screw (under the rubber cap) is between 1 and 2 turns out from closed. I found that anything less than 1/2 turn from closed the engine will not run and anything over 2 or 2 1/2 the idle is rough. after I got this correct then the idle speed needed adjusting because the idle was too low. Make sure that you are adjusting the carb. when the machine is warmed up. also make sure that the slider cover gasket and the intake tube gaskets (rubber "O" rings) are good and the bolts are tightened well. any air leaks in these places can also cause this problem. After changing the jets have you found any problem when the throttle is hammered full open while at idle (stalling).

As far as "a low speed screw with possible notches" I don't know of any but I do know that some carbs. have notches on the slider needle valve that allows for adjusting the air/fuel at mid to high engine RPMs. I don't remember seeing any notches or clips on the slider or needle valve for this carb. The replacement slider that you put in does have the notch cut out on the bottom ?. Putting the 15 jet back in will give more fuel at idle but you will still have to adjust the idle air/fuel mixture. However the adjustment should be whatever the factory had it at.