Lowered Base Gasket from .5 to .3, now bog at WOT

B

brads1725

New member
Hi All,
New to the GG community here, only owned one for about 6 rides.
Bought a 2014 EC250 Factory Replica, was going great all around. Engine has 96 hours on it so pulled the cylinder out and threw a wiseco piston in it. While I was at it I dropped the base gasket from the .50 to the .30.
Bike runs great bottom end, idles fine, pulls up the front wheel as you roll the throttle on. But now if you dump the throttle to wide open it bogs.
I got the bike at 81hours and it was a little boggy revving, it had an old B7ES in it, changed it to a BR8EG and went great for the next 15hrs - nice tan colour.

Now with the new piston and the WOT bog its looking black.
Does any one know of any jetting changes that must be done when dropping the base gasket?? only 0.2mm difference, wouldn't have though it would change much. Didn't check squish with solder (lockdown) just a bit of blutac, so will be a bit inaccurate but was something along the lines of 2.0-2.3.
It has sat with motul 800 in the tank and carb for 3 weeks, so I will pull the carb and clean it in case its and issue with old fuel/oil separating. Will put a new BR8EG in it tomorrow to make sure that isn't the issue.
Everything was going good before, bit of wear on the piston but good for 96hrs. Only trail riding at sea level. Everything is stock otherwise.
Power Valve operating freely, ran it with the cover off
New coolant, dumped it and clean.
Oil Level fine, no sign of water
Im not going to get the head machined or anything, everything was all good before so worst case scenario i will roll back to the .50 gasket. Just be good if there is a known jet change to get the best of both worlds

Cheers all
 
Def clean the carb including breathers. New piston is change too, better pumping.

WFO is mainjet. Try 1 size down and see if it is better.
 
Put a new plug in, no change.
Pulled the base gasket out and switched back to a .50, same as what came out.
Bog at WOT still there. Its fine at half, pulls hard but if you dump it to full it just gurgles.
Pulled the choke out and its the same bog, little worse so must be too much fuel.
Think I will swap that 188 main jet out for a 175. Seems to be all I can find in stock.
 
Thats an enormous change of 5 sizes. I wouldn't do that without being sure others are running that on 250s. My 300 runs smaller still but that counts for nothing.

What is stock?
 
why change out the base gasket again instead of just the MJ?
188 seems very large, just look in the jetting database to get an idea.

did you think of the powervalve operating correctly?
if this problem started from when you took the cilinder off...
 
Im starting to think the problem was there before but I ride trails and never dump it to WOT. It's very spoogey out the back end
It's got a 188 in it and the manual calls for a 175. Apart from that I don't think the engine had been played with.
I ordered a main jet kit with 10 options so ill start tinkering and keep you posted.
 
Usually 250?s like a main one or two sizes larger than a 300 and a pilot one size larger. I?ll guess a 178 will be good with that needle on clip 2 or 3.
 
You change your base gasket because the bike bogs? :eek:

The 188 is far too big, even for a 250 that's ridden heard in deep sand. As the guys suggested get a 175 or 178...
 
Dropped it progressively from 188 to a 178 then down to a 175. Still got the same issue. Might be an ignition problem, new plug and gapped correctly.
Some one has been mucking about in this carb though so it is throwing me off the scent - to go with the 188 MJ they had the needle clip on position 1 for leanest. Also running a N1EH needle which looks like its for altitude, manual says it should be running a N1EF. Although I am not sure if we are talking massive difference here
I have switched back to 175MJ, 40Pilot, Clip 3. Still bogs with a wrist full to WOT but idle and low end up to 1/2 it runs great.
Anyone had coil or lead problems causing a WOT misfire? What is the best diagnosis route?
 
Hi,
I agree with Hanesd regarding the power valve.I had a similar issue after a top end.I had not assembled the power valve properly.Muppet.
 
Yeah i was thinking that too so I pulled the side cover off the exhaust side, then put the exhaust back on, all moves freely when you rev it. rod moves up and down and the assembly rotates when the rpm comes up
 
Good work.That would have been too easy.Did you check if you turn the power valve actuator by hand & look in the exhaust port,is the centre valve opening fully & the left & right rotary valves are opening & closing at the right time? ie calibrated correctly.Lay the bike down on the left side when doing this so the centrifugal balls don't fall out. haha I said balls.
 
If it's a stator coil it will get progressively worse as it heats up.
Check muffler isn't collapsed.

Does it rev out at moderate light load running?

The std N1EF needle will be junk, but it should at least rev out. I'd look in jetting thread, not sure on those series if H does much. Wonder if it's too thin at WFO and main is still too big.

Look up a decent needle and try again before going too small on mj
 
Took the bike out over the weekend and it is running mint, no bog at any stage. The previous owner has put and inline filter in the fuel hose. After pulling it I could see how terrible the flow was through it. I think after riding a bit the bowl would drain down and not leave enough fuel, it really was just a trickle coming out under the gravity feed.
With that out and the jetting back to manual specs its going great. Too good in fact, shot me off trail a few times
 
Ahh. That's my pet hate. Inline filters. Someone needs to invent a curved one. I've seen, used a right angled one but it didn't seem to cure all faults.
 
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