jetting??

[rbm33]

i just replaced the piston in my 300 six days and now it seems my jetting is really off.

before my jetting was always spot on but now when i ride it it seems like i have given up some low end and moved it to the mid range and top end. i dont think i have lost power, just moved it around quite a bit.

i wonder what could have caused this with the piston replacement? i went back with a stock piston.

thanks in advance

[(F5)]

Should have posted in intake section, but try adjust idle mixture for a start off. A bit more suction can mean you're too rich. But should only be a bit.

[Jakobi]

I'm going to pose the question and ask about the gasket stacks. Did you put the same sized gasket in or did you add extra to time the piston level with the exh port at bdc.

Other than that like f5 said. Could just be running a bit richer with the added efficiency that fresh rings offer.

[rbm33]

Originally Posted by Jakobi

I'm going to pose the question and ask about the gasket stacks. Did you put the same sized gasket in or did you add extra to time the piston level with the exh port at bdc.

Other than that like f5 said. Could just be running a bit richer with the added efficiency that fresh rings offer.

hey Jakobi

i was hoping you would respond to this. i went back with a stock piston and gaskets.

my jetting has always been about as close to perfect as you can get and i have been running the same jetting since the bike had about 4 hours on it up to the reubuild at 75 hours.

i guess maybe it is carburator related but the change is very significant.

what would you suggest trying first on the carb?

[Jakobi]

Leaning it out again

If I recall you started off running something like 40 N3CH#3 175 and then eventually ended up at 42/45 N3CH#3 180 didn't you? There was a change from the FMF silencer to a house of horsepower/cannon too?

I'd start where you're noticing it most, which from post above is the smaller throttle openings. Come out on the Air Screw to 3-3.5 turns and see if its a leap in the right direction. If so go one smaller, start at 1.5 turns and let the judgement begin.

Also quick checks, any adjustment to PV during pull down? Is it operating smoothly? Good preload? especially at rest/idle? If its got slop it'll eat your bottom end out big time. How'd the reed petals look? You've got to be getting a few hours on them now too. I found one frayed pretty badly at some point. Think it was around 85-100hrs but would have to check records to be certain.

[rbm33]

Originally Posted by Jakobi

Leaning it out again

If I recall you started off running something like 40 N3CH#3 175 and then eventually ended up at 42/45 N3CH#3 180 didn't you? There was a change from the FMF silencer to a house of horsepower/cannon too?

I'd start where you're noticing it most, which from post above is the smaller throttle openings. Come out on the Air Screw to 3-3.5 turns and see if its a leap in the right direction. If so go one smaller, start at 1.5 turns and let the judgement begin.

Also quick checks, any adjustment to PV during pull down? Is it operating smoothly? Good preload? especially at rest/idle? If its got slop it'll eat your bottom end out big time. How'd the reed petals look? You've got to be getting a few hours on them now too. I found one frayed pretty badly at some point. Think it was around 85-100hrs but would have to check records to be certain.

correct on all accounts.

i didnt make any changes to the power valve adjustments that i konw of but maybe i messed something up there, because like i said earlier the difference between now and before is huge.

i need to check my reeds, it has right at 80 hours on it now so they could be getting a little rough.

ill also try the air screw adjustment.

are there any tricks i need to know about when checking the power valve??

[rbm33]

i think i have it working now. i pulled the power valve cover and it looks like i over tightened the nyloc nut and was causing the powervalve linkage to bind up. it would only close about half way. i backed the nut off a bit and everything moves smoothely now so im betting that was the problem.

[Jakobi]

Originally Posted by rbm33

i think i have it working now. i pulled the power valve cover and it looks like i over tightened the nyloc nut and was causing the powervalve linkage to bind up. it would only close about half way. i backed the nut off a bit and everything moves smoothely now so im betting that was the problem.

If it was only half closing that would significantly affect your bottom end performance. Hope thats hit the nail on the head. If not have a look at the PV sticky thread if you haven't yet. It covers all the ins and outs and some kind folks have even posted pics and vids of how it all works.

Cheers

[rbm33]

thanks Jakobi, i just read every post in the sticky, i should have read that before i pulled the cylinder off!! lol

i havent gotten to try it out yet but i bet its going to work!