Starting point for Western Washington?

[pscook]

Hi, all-

I am just getting my 2002 XC300 ready to ride, and wanted to run my jetting past the "experts." I bought the bike last month and spent the last few weeks sorting out some issues, but now I'm about ready to ride it in anger. A couple of spins in front of the house do not provide accurate jetting, but it does upset the neighbors a bit.

Here's my current set up-
50:1 Premium pump/Amsoil Dominator
Carb is stock, as far as I can tell. No obvious modifications to any external points or functions.
Needle- Don't know. The only markings are "CC" (maybe GG?). Nothing else indicated.
Clip- was on second from top (lean), now in middle (it's what I do to set baseline on my other bikes)
Main- 170
Pilot- 38
AS- Now at 1.5, was at .5

Any suggestions from those who ride Walker Valley, Tahuya, and Capitol Forest? I don't mind buying a handful of brass, but I do want to make sure I am going in the right direction. I don't want to make any broad generalizations or assumptions, but previous experience with this bike in my riding area is preferred. The main reason to question the current jetting is that it's a former California bike, and I think it was set up for hot weather high-country riding. The piston looked kind of lean (lots of carbon), and I want to make sure I don't melt anything my first time out.

 

[PEB]

I am by no means a jetting guy. However that is lean compared to what is in mione for the same areas. I think I have a 42 and a 178, which i run from sea level to 8,000' Which one is the air screw and what does it do?

 

[cascade_crawler]

With the cold weather around here your probably gonna want to richen it up a bit. Our carbs are different but this gives you an idea of what worked well today...42 pilot, 178 main.

 

[HydroDog]

Jetting is all depends on how you ride. Are you going to ride 1st gear single track well then that 38 pilot might work for you; I run a 38 in my 07.
A 170 main could be OK unless you hold it wide open for long periods. Since you opened the air screw out that means you wanted it leaner. I've been riding a few years now and I have never seen anybody seize their bikes because of a lean pilot or needle; bad jetting = bad throttle response at lower RPM and a poor idle.
A rich main jet will run like crap (spit and spudder but never clean out when pinned) at high RPM but a lean main will sound good but will toast your motor, so it is better to be rich on the main and then slowly back off just to the point where it runs clean for the area you ride at.

 

[pscook]

I plan on riding slow single track to fast fire roads, mostly second and third gear open trails. Walker Valley is closest to me (Shoreline), but my riding buddy lives near Tahuya and we go to Capitol Forest more often now. I hope to be on the trails more than last year.

Regarding the air screw, I simply opened it per the manual to start jetting. I haven't even heat cycled the engine yet in my neighborhood, hopefully later this week will provide an opportunity. Heck, maybe even today if I get the chance.

I plan on taking a "mental health day" on the 16th to Walker and really sort it out. That's two weeks away, but it's the best I could plan for.

Now, what's the easiest method to swap jets and pull needles? I have a desert tank that surrounds the carb, do I need to completely pull the tank and carb, or can I get away with pulling the tank and rotating the carb in the boots to access the float bowl? Oh, and any suggestions on float height? I never measured that, probably do that later today, too.

 

[pscook]

I warmed the bike up and gave it a couple of spins down the road. I was running really rich off idle, AS is at 2 turns out with needle at 2nd slot from top (lean), jets as listed above. Runs better, was very rich off idle before. I can not wait to give it a proper trail ride and sort it out. Also, I was able to change the needle without too much effort, the main will be a bit more trouble as the desert tank won't allow me to rotate the carb to get access to the float bowl.

Anyone have float height suggestions? I still need to measure mine, but I would rather get in there just once rather than several times.

 

[pscook]

Okay, I am absolutely frustrated right now. Cleaned the carb like it swore at my mom. Fresh gas. Fresh oil. Same result. Doggy on the bottom and just not running right. Runs "best" (relatively) at 1.5 turns on the AS with needle at leanest clip. As I have a 170 and 38, should I just go big and see if that clears it up? Should I go for the NEDJ needle, 175 main, and 40 pilot? Different ratio? Different oil? (Amsoil Dominator at ~50:1)

If anyone around the North Seattle area wants to come over, or have me come over, I am down with that. I really want to ride this bike over the holiday break, and I want it to run properly. Heck, maybe my problem is that I don't know what "running properly" is? Therefore, if someone wants to help me out, there is food/beverages/gas money in it for you.

Anything at this point will be helpful. Don't make me go back to my YZ426, did you see what that four-stroke did to Jakobi? Don't make me do it!

Phil

PM for email/phone number/address. Make sure to name your flavor of beverage or food favorite.

 

[PEB]

What do the reeds look like? I think you would need to pull the carb so set the float. Not a big deal, easiest if you swing the sub frame up and away by pivoting it on the upper bolts.

 

[Jakobi]

As above. Whats the state of the engine?? Compression? Spark plug? How many hours on the top end? Any chipped reeds? Float height? Has the head been modded at all? Squish gap?

Then variables. Elevation, temp, relative humidity,

 

[pscook]

I pulled the carb (I had to clean it, after all), float height is 19mm. Float seam not level with carb seam (closes early). Reeds were interesting. They did not seal, about a 0.030" gap from totally closed. I took them off to flip them, thinking I was so clever, but after I flipped the top one the gap was worse. So I returned it to original. I know it sounds like I'm from Planet Stupid, but shouldn't the reeds seal? But no chips or cracks.And yes, pivoting the subframe helped immensely.

As for variables, about 45F, 250' above sea level. 92% humidity. I'll check compression tomorrow. Decent sparkplug. I think stock squish (not measured).

As for top end, the seller told me that it had ~10 hours on an Eric Gorr top end. Which is a lie, unless Eric uses wrong fasteners, strips threads, loses washers, and is a general incompetent. Which he may be, but beyond that, it's a bit tired. I'll get proper numbers tomorrow.

After some deliberation, I'm thinking reeds are causing some issues. Same as 1996 YZ250, yes? Boyesen reeds, if there is any question.

 

[PEB]

I'll bet a nickel its the reeds.

 

[pscook]

Here's another question that may end up being blindingly obvious- I have a Boyesen block in there, so only Boyesen reeds will fit, correct? I'll try the local Yamaha shop and Tasky's today, see if they have anything in stock. Really don't want to have to order right now. If anyone has an extra set of reeds I'll take them off your hands.

 

[boyscout]

Yes you will need Boysen pedals to fit a Boysen block. My Vforce were the same as a cr250, not sure about the Boysen though.

 

[pscook]

As an update- Boyesen Reeds are for a 1996 YZ250. PSR-21 (current PN) or PRO-21 (previous PN). That is for the Pro Series Reed (PSR). Otherwise it's RL-91 for the 2002 EC300.

For fun (after ordering new reeds), I did a little test. The joke is that I am extremely frugal (read: cheap), but I like to think that I am creative and want to solve issues without spending lots of money. Okay, I'm cheap. Anyway, a friend jokingly suggested that I wrap a rubber band around the reeds to get them to close. We had a good chuckle, then on my ride home yesterday i thought about it a bit. Here's what I came up with-

First picture is reeds as delivered. Note the gap. Second and third pic are with the rubber band under the tail piece of the top reed, thereby preloading the reed into position. I'll give it a test this afternoon. I'm not expecting this to permanently cure my problem, but it will help remove one variable.

 

[djroggen]

How did that work out for you?

 

[pscook]

How did that work out for you?

It proved the reeds were the least of my concerns. I bought new reeds and there was no change from my cobbled together "test" modification, or even prior to the repair. The new reeds seem to work as well as the old warped set. But the rubber band shim certainly did help to preload and seal the reeds, no question. The gap was gone, and the bike ran all day without any change in performance (read: it ran poorly all day).

The bike has been rebuilt from the tires up (including every bearing and seal in the engine), cylinder plated to match a new piston, and I just haven't made the time to ride and test-n-tune. New piston, rings, reeds, exhaust o-rings, and other errata do wonders for these things.

 

[Bryan]

It proved the reeds were the least of my concerns. I bought new reeds and there was no change from my cobbled together "test" modification, or even prior to the repair. The new reeds seem to work as well as the old warped set. But the rubber band shim certainly did help to preload and seal the reeds, no question. The gap was gone, and the bike ran all day without any change in performance (read: it ran poorly all day).

The bike has been rebuilt from the tires up (including every bearing and seal in the engine), cylinder plated to match a new piston, and I just haven't made the time to ride and test-n-tune. New piston, rings, reeds, exhaust o-rings, and other errata do wonders for these things.

Check your silencer. IT may be all clogged up with spooge. My '01 was really lazy until I repacked the silencer and I reset the float level. Not sure which fixed it, but it sure woke it up. Just a thought

 

[pscook]

Check your silencer. IT may be all clogged up with spooge. My '01 was really lazy until I repacked the silencer and I reset the float level. Not sure which fixed it, but it sure woke it up. Just a thought

First thing I did, before any ride, was repack the silencer. The bike was running poorly from the beginning, so I went through everything that I could before I started tuning it for me. Now I just need to make time to give it some miles and see how it's doing. I love the way that it handles, now I just need to get it running well enough to enjoy it. Soon, I keep promising myself.

 

[Jakobi]

Sorry I'd fallen off this thread.

IMO the key to jetting these bikes is all in the needle. A rich pilot will burble just off idle and a lean will give poor response. A rich main will burble up at WOT and a lean will fall a bit flat. The needle is the key. It covered almost the entire rev range and has the most variables. It also overlaps both previous mentioned circuits.

I think the older bikes prefer to run a bit richer than the new. I would definately suggest spending some coins. Get an NEDJ and a N3EJ, both should be happy with around a 42 pilot. NExx 172/175 main, N3xx 178/180. Start with the clip in the middle. If you experience more burbling at 1/4 throttle than you are happy with lift the clip 1 pos and try again. Shouldn't cost much more than $30 in parts.

You could probably borrow a N3EJ/N3EW off a mate if you know anyone with a YZ250

 

[pscook]

Sorry I'd fallen off this thread.

IMO the key to jetting these bikes is all in the needle. A rich pilot will burble just off idle and a lean will give poor response. A rich main will burble up at WOT and a lean will fall a bit flat. The needle is the key. It covered almost the entire rev range and has the most variables. It also overlaps both previous mentioned circuits.

I think the older bikes prefer to run a bit richer than the new. I would definately suggest spending some coins. Get an NEDJ and a N3EJ, both should be happy with around a 42 pilot. NExx 172/175 main, N3xx 178/180. Start with the clip in the middle. If you experience more burbling at 1/4 throttle than you are happy with lift the clip 1 pos and try again. Shouldn't cost much more than $30 in parts.

You could probably borrow a N3EJ/N3EW off a mate if you know anyone with a YZ250

I have a stack of Yamaha and Suzuki needles and a fist full of jets standing by for my first run at the trails. The needles have been on my bench for about 6 weeks now, but my schedule has not let me test anything yet. Your posts in particular, Jakobi, have helped me set my performance goals. I have a nice little spreadsheet which provides the habits of the NXXX needles. Changing jets on the trail sucks, but needles are easy. I hope to find a simple solution with jets and tune with needles. With my current selection it shouldn't be too hard.

I'll get there, I promise!