LT racing jet kit report...

[Radbuster]

Hi guys,

I'm trying to find Yamaha part numbers for the N3EG and N3CG.

I have been looking at optional needles on the fiche cards for the YZ250 from different years, but can't find them.

My LTR (modified DDK) is really weak from mid to top, even after trying all clips and MJ's and need to get it to work right. Right now it could compare to a good running 125 on top.

Coming off a YZ450, I really miss the mid to top for MX, but like the current calm engine from low to mid in the woods.

How much squirt does the CCK actually have from mid to top? Could it be good for vet-type MX? I'm no pro, but it's nice to have the juice when running against 450's on sandy mx tracks.

Any info would be much appreciated.

[GMP]

If its as bad as you say with the LTR needle on top you have other problems. Top is the easy part to get right.

[Loosenut]

Gasser and GG27, that low-end stumble may be fixed with a #8 slide. If you have a stock head, you might really like the extra pop it can give you.

[iancp5]

Radbuster,

I don't think you lose any top end with the CCK as that is determined by the main. It just smoothes out the transitions - personally and I admit this is just opinion, smooth transitions should help any type of riding. Even MX bikes are built smoother than they used to be they just have less need for bottom end. Provided you have enough power what good is hit - it just makes it harder to control. If you read the test reports of the top road race bikes, even MotoGP, the magazine testers are nearly always impressed with the smoothness of power delivery. After all the rider wants to control it not have the bike take over. Same for new MX bikes, they're always a smoother delivery than previous generations. For enduro or trail you want the same but better because you will use the bottom end as well. The CCK hasn't made any difference to large throttle openings on my bike at all, it still pulls like a train.

If you have a problem with wide open or large throttle openings maybe something else is wrong?

I used to race a friend on a 450 Enduro (KTM) and on sheer power he didn't seem to have any advantage. I bought the bike off him and it is easier to ride fast because it has a wider rev band and better bottom end torque but if I make good gear selections the Gasser will hold it up to 60 mph in a sprint. The 450 is ultimately faster in a straight line though. In the woods the 450 is more tiring and slower towards the end of a race. For sandy MX I imagine a 450 would be faster if you don't tire. But as is usually the case, once you have as much power as you can handle for a whole race every bit extra slows you down.

[Radbuster]

Hi guys, thank you for your answers.

I'm at the end of my wits at the moment and need help. The CCK seems to be the way to go, clean and strong all the way with smooth transitions sounds perfect. Agree fully that too much or too zippy power is only bad. I learned that lesson well with my YZ450 '03

Engine has only has about 20 hours. First 10 hours it was run by the previous owner with extremely fat jetting with the stock needle. Lots of smoke, spooge from the silencer, all black plug and drool from the PV drain.

I put in the LTR at #3, 178, 42 (#7, stock still in there) during the summer and cleaned up the spooge and put in a fresh plug. I have only ridden tight woods since then on low to mid throttle and thought it was perfect.

Lately I've had access to some more open spaces, and noticed it couldn't rev out. The engine feels as if the PV does not open and blubbers a lot with "normal jetting".

One possible problem area: The stock silvery pipe was finally smashed up and I couldn't fix it because of the heavy gauge. The bike was street legal and had a black pipe with an extra air pipe close to the cylinder. I had the pipe removed and welded shut. I'm now using that pipe. I assume it is otherwise identical to stock. Possibly, it's not and is more like the Gnarly with good bottom but lacking on top, or worse.

Could the silencer packing be saturated and messing things up?

I removed the PV covers to check if the PV was jammed. There is a thin film of black oil on everything, but the right side vertical pin from the crank can move up and down smoothly. Left side with the two bearings (both sealed, not as in the manual where one has open bearings) seems ok. I have not disassembled the PV and removed the cylinder. Can the PV still be jammed if the actuator pin moves smoothly up and down?

Air filter care was a little sloppy, so I cleaned the airbox to spotless, got a new filter (nice to have 2), a fresh bottle of Maxima FFT, oiled it lightly, let it set overnight.

I removed the pipe, looked inside it and seemed ok clean, cleaned out the mound of goop under and around the flange where it must have been leaking, put in 2 new o-rings and added a little high-temp silicon, and let sit overnight.

The V-force reeds should still be fine. I run synthetic at 50:1 with fresh pump gas. Our normal pump gas is stated as 95 octane, but have no idea if it's RON or other rating. We also have 98, which I think is the same but with no alcohol or other "negative" additives.

Gearing could be too tall at 13:48. Maybe 3rd,4th,5th,6th are so tall it just seems slow, but I doubt it. Next change will be to 13:49.

I've gone up and down all clips and tried all MJ's from 180 to 160 on the same evening on paved roads at a desolated industrial area. Low to mid is wonderful, mid to top is very dissapointing.

Weather is slightly above freezing, dry, high pressure, right above sea level. Jetting changes have surprisingly little effect compared to 4-t's with FCR carbs. On my little WRF or big YZ, one clip or one MJ too high or too low, or quarter turn on the fuel screw became way off. On this one I can barely tell a difference except that at 178 or higher it just blubbers, under 168 it starts to get the hollow intake sound. 175 to 160 still pull almost the same

The transition from a good mid to a weak top seems better with the least stumble with the clip at #1-3 from top, ie. middle or all the way down, ie. leanest.

Shoot me! Right now it's a 42PJ 1 turn, LTR #1(!), 168MJ(!) slide #7.

Sorry for rambling. Would a CCK cure this situation?

Any ideas?

[GMP]

I'll bet your using the Euro catalyst pipe, which would explain everything. Get the other pipe fixed, or replace it. Don't even try to work with the cat pipe.

[Skidad]

[QUOTE=Radbuster;14490]
One possible problem area: The stock silvery pipe was finally smashed up and I couldn't fix it because of the heavy gauge. The bike was street legal and had a black pipe with an extra air pipe close to the cylinder. I had the pipe removed and welded shut. I'm now using that pipe. I assume it is otherwise identical to stock. Possibly, it's not and is more like the Gnarly with good bottom but lacking on top, or worse.

Could the silencer packing be saturated and messing things up?

QUOTE]

This black pipe could very well have a catalytic converter inside and will not run correctly on top at all. It's all designed for street legal Euro emissions and the CAT will be in the big belly part of the pipe. Euro KTM 2 strokes were coming with them also as well as having a throttle slide limiter. Externally you could not even tell the KTM's had the CAT but the air pipe is the give away. Try snaking something down into the pipe from the stinger end and see if you hit an obstruction in the belly section. The guy in Europe with the KTM actually cut his pipe open and removed the CAT and welded the pipe back up. The air fitting as well. This could explain it as well as your other pipe being smashed to the point of non repair would kill top end. Do you not have someone over there who fixes smashed pipes? We have a number of places available to us in the US for pipe repair.









Skidad in MA

[iancp5]

Sounds like the Cat is the problem.
I'd also try blocking a rad off with cardboard in front at temperatures around or below freezing. I usually have a bit stuck out the top so I can pull it out without stopping if it starts to overheat. Below freezing I once covered both rads and it didn't overheat until 2 hours later when the air temp rose!

[Radbuster]

You guys are the best!

I'll check the pipe first thing.

Maybe we have pipe repair over here, but haven't found anyone yet.

OT:
With thinner gauge steel such as with an FMF Fatty I suppose it's easy to "blow it up" with hot air. I have seen a kit with plugs to seal the ends for this. I'd guess it's not possible with the thick steel of the stock pipe. Problem two, dents aside, how to straighten out the pipe after it has been pushed back towards the frame rails and left water hose so it can align with the mounts and exhaust flange. When "blowing it up", does the steel "remember" the original form and solve this?

I have an E-line pipe guard for dent protection, but the bending the problem. A possible solution would be to stop crashing. I'm working on that one, but the problem comes back from time to time.

Thanks for now. /F

[skid jackson]

Rad
If you are just popping out a few dents the pipe can get pressurized and the dents will pop out. If the pipe has been bent or kinked you need a jig to get it back to normal. There are quite a few folks in the states that can pop out dents. Not many have the jigs to get them back to proper bends.

these guys are very good but far far away from sweden
http://www.piperepair.com/

I gotta think there is a similar outfit in sweden,norway, finland.

I've also heard of some riders using a big azz pipe and heating the stinger end of the exhuast pipe and bending it over to get the stinger to line up.