[Aussiecrf230]

Honda is not the only brand to have imperfect factory jetting.
The 2 stroke KTMs in the 90's and 2000's were jetted very rich down low resulting in black spooge running out the muffler. A whole generation of riders went through running expensive oils in smaller and smaller amounts in their fuel.
This actually made the problem worse as it was excees fuel the was causing this mess.
It was the first part of the needle that caused the problem and a change away from factory needle profiles resulted in crisp performance and a clean back end.
There was still sufficient fuel so running lean wasn't a problem.

I think the factory needles were this way as a simple fix for traction control.
This was before Map switches were even thought of.

Big bores often have similar jetting to the standard bore engines simple because they suck the air in harder resulting in more fuel being sucked through the jet.

[Leardriver]

I have heard Honda jetting referred to as bug sprayer jetting, due to Honda's tendency to put extremely rich jets in them.

An engine is an air pump, and the more efficiently you can move air in, via better flowing heads, higher lift and duration cams, freer flowing exhaust, whatever, then the more fuel that can be drawn throw a given jet size due to more air flow, also known as vacuum or carb signal.
When the nation MX race at Thunder Valley is held, back in the carb'ed bike days, the factories were running a 152 main. Their engines were hopped up factory versions, and super efficient at flowing air. You would think that you would need a richer jet for hot rodded engines, but many times, the opposite is true.

In Denver at 6,000 feet, mere mortal 450's take a 158 main jet.

[08ISGR8]

Alright you guys definitely convinced me that I’m not going to slap in the stock 178/42 combination.

I think the concept that was eluding me was the fact that if you add more airflow through the engine it translates to more fuel through any given jet size.

I have seen a lot of people saying they start better with a 45 pilot and it’s only 50f here currently. I think I’m going to try a 170/45.

I’ll let you guys know how it goes if the dealer ever gets my jets in.

[JimDirt]

Yes , Keep us posted on what you find with the changes ....

[08ISGR8]

Quick update:

The washer that came with the fuel screw wasn’t even close to fitting past the threads. I had to turn down the washer with a dremmel arbor and a drill/ sand paper.

I also had to find another o-ring and sand some off the edges to make it fit because the one that the screw came with tore almost immediately.

So now the bike seems to run better but still takes about 3 good kicks to start once it’s warm. (It doesn’t seem to pop on deceleration and it idles better)

It bogs a tad when if you give the throttle a really quick twist (maybe normal?) and also it will die the odd time when you go from neutral to first (clutch drags a bit)

The fuel screw I can turn the entire way in without the engine skipping a beat once it’s warmed up. It will start to skip though if I unscrew it 2 3/4 to 3 turns.

I did give the carburetor an unreal cleaning while i had the bike apart. Everything was apart basically but I didn’t fiddle with the accelerator pump timing. It does seem to give a good squirt when the throttle opens though it seems to me.

Maybe I should put the 42 pilot back in?

It’s 170/45 currently as a reminder

Thanks

[JimDirt]

A little concerned about it still running with the fuel screw all the way in , it should die ..... so possibly a air leak somewhere

The bog is most likely AP timing or the Pilot jet needs to go to the 42 (try it and leave all the settings as is and see if it takes away the bog) ... the squirt timing should be adjusted so the squirt just barely misses the slide , if it hits the slide that might be the bog , if the pilot change does not take away the bog , then check the P Timing ...... a lot of us used to take a small O-ring and wrap it around the AP screw so it had no delay , this also helps with the bog .... so a few things you can try ....

[08ISGR8]

I advanced the accelerator pump and added the o-ring mod today.

I also had no idea that these bikes have a stock idle RPM of 1700 +\- 100. I have been trying to do all of my tweaking around 1200RPM. I can’t imagine that not being part of my problems.

With the pump advanced and the idle increased it does seem to bog less.

What I really need to do is ride the bike and see if the problems persist or I’m just making excuses not to ride lol.

It’s getting boring in Ontario with the lockdowns happening. All of the tracks are closed and travel is supposed to be “essential only”. It’s a great way to drive yourself nuts and get paranoid that you will have a $3000 engine repair Bill.

Thanks for all of the help. It’s been greatly appreciated

[JimDirt]

No problem ... Also , a important thing .... when revving the bike on the stand , there is a good chance it will bog or crackle because it revs so quick it will hit the limiter , and if you try to free rev it hard/fast , it takes a second for the fuel system to catch up.... when turning or rather , fine tuning , it is best to do it while or in between riding it , so you get a honest evaluation of what it does while in riding conditions , there are too many variables while on the stand ....