adnoh wrote:
I Miss typed on my phone. The (J) seams odd (lean) to me. ( CO, The needle chart I was referring to is this one.)
Most pilots with the 39 mm carb uses a (G) or (H) for dia. Not saying yours does just an observation. Now for the dirty filter that is a jetting no no. You will chase your tale around and around or eat another piston when you do clean it.
This chart gives an idea of what needle does what in what range compared to what one might have or want to do in way of change for tune.
If you
Engine hits hard now with that (J) wait until you put good air to it. Again not saying change it just keep it in mind. why you ask?? Well as most of us know and CO knows quite well is the Engine will have a tendency to detonate on throttle closure when running hot on hard pulls if your not fat enough on slow jet and needle dia of choice. Hench the question on slow jet. Week mixture strength at high rpm and heat load after TDC (Top Dead Center) (Top Dead Center) it will or could knock. Think of it as a quick lean out and it makes since. This is another reason most of us run our petcock on reserve and pull out choke right after hard pull or sustained
WOT (Wide Open Throttle) (Wide Open Throttle). Cheap insurance since we are NOT EFI based.
I would go back and read what CO post a link to at Duncan and read some more of it my be applicable.
You intake velocity is a high velocity type set up.
For a comparison ONLY. The needle choice for a over bored stock pipe pilot is the standard EEG in clip one or two or DGG or DGH clip two through four. Please remember this only what I have done. I use a lower velocity (denser) intake than most which requires a richer all around setting base off of velocity
Choose wisely grass hopper !
Lot of good info here - "pull out the choke right after a hard pull or sustained WOT (Wide Open Throttle)" - to the best of my recollection, it seems this is when my pistons melted. Will do some more research on the needle situation and see what my next step will need to be
canadian oddy wrote:
Try it without the pre-filters as well please.
Basically looking at running it with no lid and just a single filter.
This thing may be choking for air a full throttle or high load.
Once that is determined will decide what has to be done.
Did some WOT (Wide Open Throttle) runs after cleaning air filters, first with lid and secondary filter and then with the secondary removed. Seemed to be good with the secondary filter on and even better with it off. Here is the plug pic (sorry but a bit blurry):
Attachment:
Plug color looks pretty good.jpg [ 23.86 KiB | Viewed 369 times ]
The really good news here is that I have been through 10 gallons of fuel (5 of 110 race and 5 of 100LL) with some heavy riding and a lot of WOT (Wide Open Throttle) runs and no melted piston! Not sure if the extra octane is masking a problem or if the lack of octane was the problem but either way works for me.