300 running issues

[rosco]

I wouldn't go any leaner on the main. I was kinda thinking you are probably a little on the lean side all ready. I would think at that elevation you should be up around a 178 or 180 main. I really like that N3cj or cw needle. I would think with a 42 pilot and that needle in the third clip position you should be in the ball park. I am totally basing this off of what we run at our elevation so who knows I maybe way off. I think it would be worth giving it a try though.

 

[snailspacejase]

A reed check is immanent
Na I'm not going to go leaner. It was a daft idea.
Have noticed the spark cap was a bit loose, and on inspection is quite eroded and black inside.....
Also it's 5k ohm and I'm running a resister plug so no need for two suppression resisters. I'll swap it out and try again.

 

[(F5)]

nah, best to leave suppression stuff in place these days of digital ignitions, you won't lose any spark performance.

 

[snailspacejase]

Good call.
I changed the cap out (for a 5k ohm one ) and put a new plug in. Still the same.
Reeds next.

 

[snailspacejase]

I've just looked at the reeds and found the carb stub gasket was upside down so it shielded about an 1/8th of the opening into the reed block. That can't be good. The reeds looked ok, no frayed edges, cracks ect. Two of the outside petals were not sitting flat though. Maybe half a mm high so you could see a good chink of light through there. I was thinking of flipping them.

 

[snailspacejase]

Reeds now perfect and gasket corrected. Flat spot fault still there. I tried increasing the main to 180 and it became much worse. Hmmm. Might try a 170.

 

[snailspacejase]

I tried a 168MJ. Yuk. Flat spot still there but bike is too aggressive and pinks loads more. Didn't run it like that for long.

 

[lgr]

What spark plug are you using?

 

[snailspacejase]

I've tried
BR8 EIX
and
BR8 EG

 

[lgr]

I have experience similar problems on my snowmobiles if I tried running non resistor plugs

 

[snailspacejase]

I think these are both resister type plugs.

 

[Swervin]

What needle are you using?

 

[snailspacejase]

Currently an NEDJ
Previously a N1EF
Fault the same for both. It happens at WOT only so I'm thinking the needle may have less of an influence. The chap at Gas Gas UK said the silkolene oil I was using was bad for gumming so maybe I'll go through the pv again. Also the exhaust.

 

[Swervin]

Mine had a giant hole in the middle of the power band with original needle, so I put a CCK needle in it.
That solved my issue.
You say yours has a flat spot on WOT (wide open throttle)??

 

[lgr]

Your reed cage isn't installed upside down is it? Sounds stupid but mistakes happen. The intake passage is offset to one side by a few mm. If it is installed this way it will not want to hit wot without a good bit of nursing

 

[snailspacejase]

I wish it was that. Yeah it would be miles out of alignment upside down.

 

[eviljim]

I wish it was that. Yeah it would be miles out of alignment upside down.

How do you know what is the right way up?

 

[Jakobi]

How do you know what is the right way up?

The hole in the reed block matches to the spigot the carb joins to (and is located off center in the reed block). Put it in upside down and the ports won't match, even though externally everything will.