Killing the bike

40 NEDW/NECW#3/#2 175/172 should have you very close to what you need for a 250. If it needs number 1 to run clean then thats what it needs. I don't think you're flame out issues will be related to clip position though, that was just an observation. If anything it will be pilot circuit which may be rich/drowning. The way the carb sits in the bike titled slightly forwards makes it prone to running rich both during steep declines, or hard on the brakes. If you haven't set the float heights up I'd suggest doing that as per the sticky in the 2T jetting section and then hitting the jetting again. You may find it then puts your needle closer to where its expected to be.

The head mod will also get you everything you want. More power everywhere. If they bump the compression a bit you'll get some more bottom end too, and as a bonus you'll get some better economy as well.
 
I'll check the thread out again about the float level. When I checked mine it was right where it should be according to spec, but if I remember correctly some people seem to think it is better to run it a little lower than stock.

It makes sense considering I can chug it incredibly low when just playing around.
 
Easy check. Pull the front brake and dip the forks a few times with the fuel on. Does it slosh out the overflows much?? Out the overflow is just wasted fuel, but straight into the guts of the monster is sure to make the bike act unpredictably. Being a fast bloke I'd imagine you're coming into the corners pretty hot and hard on the brakes. Makes sense to me.
 
I decided it's time to send the head to RB, so I sent it on its way today. It may not have any affect on the stalling, but it should be better all the way around. The squish was about 2.05mm at the edge and approximately 3mm at the end of the taper. My compression is already 190-191psi (checked cold), so I doubt if he will raise it much. I also checked the piston against the bottom of the exhaust port and it is flush. My bike came stock with one base gasket, probably 0.5mm.

I am tempted to adjust the jetting a little, but I know I should only make one adjustment at a time so I know whats what.

Thanks for all of the advice.
 
I just got my head back from Ron last night. Put it on the bike, squish is now 1.2 - 1.4mm from up to 3mm like yours. I have the side cover off and its on the stand with the forks off so I couldn't kick it to measure the new compression, but I requested a 10 PSI bump. Its all relative to your gauge. Mine measured 180-182 stock, my RBD modded '07 is 192 PSI and that bike rips on pump gas so I said give me the head volume for 10 more! Hopefully I'll get what I need to put this thing back together tonight, test compression, and ride this weekend.
 
Its a typical GG250, not bad at all, much like my '07. Flexxbars take a little more out as well. My '03 buzzed more than average, but I found that to be weld slag on the frame boss where the swingarm bearing sleeve contacts, so it was never making full contact and actually cracked the bearing sleeve. Better after I cleaned that up.

Worst bike I ever had was a KTM200, in fact it was so bad at higher revs I couldn't stand it and short shifted it. I hated that bike.
 
You guys were right about the needle being too lean.

I got my head back from RB today, so I put it on without making any other adjustments. The squish is considerably less now (1.1 - 1.3mm), but the compression is nearly identical to what it was before the mod, 190psi. It seemed a little crisper at first, but there wasn't as big of an improvement as I expected until I adjusted the needle position. I changed from the #1 position to #2 and finally #3. I also increased the idle a little higher. The bike is running much stronger now! The 40PJ is close, but when the temps drop down 70 F and below I will probably opt for the 42. I killed the bike one time today, and that was definitely rider error. I'm still going to switch to ATF to see if that changes the feel of the clutch any. I'm not able to modulate it as well as I should be able to.

The next race will probably be a good indicator of whether the dying problem is mostly rider error or if some of these adjustments are making a difference.

Thanks for all of the suggestions.
 
Last edited:
Another update......

I still killed the bike several times in the Leadbelt enduro. It could have easily cost me a couple of minutes. The bike ran great, so no complaints there, and the suspension was good as well.

I've decided that the issue is probably related to using too much rear brake. I never shortened the rear brake adjuster like most people do. Heck, I never even touched the adjuster, but it occurred to me that having the pedal too high could be my problem so I cut about 1/4" off of it and adjusted it lower. I also adjusted the idle higher than I normally run it.

One more week until the next enduro. I hope I'm getting this worked out.
 
You can only adjust the pedal so low. I made a new tip for the pedal that is flat and lower. I also made an offset pedal height adjuster that attaches to the pedal with a heim joint like a KTM. The steel pin in the alloy pedal is a joke and only makes things worse as it wears.
 
No, I'm an engineer, primary job now is software development for process control applications, but I've been involved in all all aspects over the years. Basically I get paid to solve problems of all kinds. I wish I had the space for a few machine tools. Almost all of what I do as far as bike parts I design so that it is easily done with hand tools or limited machining that I can have done at work, and with off the shelf materials.
 
Impressive.

Most parts that I make are made with a saws-all, dremel, drill, vise and file. High-tech stuff coming out of my barn for sure.
 
And what I do is not much different. If I need it, it gets made one way or another. I was ready to start cutting HDPE for a link skid and then a Scorpion turned up. Still might do that anyway.
 
One last update.

I raced a 60 mile enduro yesterday after adjusting the brake pedal and the idle, and I only killed it one time all day. Luckily that was in the warm-up section that wasn't being timed.

I'm pretty sure the problem is solved.
 
You must log in or register to reply here.

Similar threads

M
Engine surge/runaway?
Replies
4
Views
147
Mustyeddie
M
N
2005 EC200 Continual RH Crank Seal Failure
Replies
3
Views
289
(F5)
(F5)
M
2011 ec300 pipe and other recommendations
Replies
1
Views
2K
(F5)
(F5)
Anders
Bad smell from gear oil
Replies
3
Views
23
webmaster
webmaster
S
Not hitting powerband properly and bogging after service
Replies
2
Views
2K
swazi_matt
S
Back
Top