Moarpower wrote on 05/17/23 at 22:51:06:
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The slide gets pulled open by vacuum pressure.  Moving it by hand won't tell you much.   You need to test it as described below.  

And you are definitely throwing way too much poo at the wall.  This isn't a jetting or performance issue.  Those don't just pop up out of nowhere.  So throwing parts (especially the dreaded "carb rebuild kit") isn't going to fix the issue and you are just wasting your time with them at this point.   

This is a mechanical problem.  It could be the slide or a blockage of some sort.  Start with the slide and make sure it will get to WOT as Mike instructed.  If it goes WOT but the problem persists move on to the next item on the list.   #problemsolving101  




DragBikeMike wrote on 05/18/23 at 02:32:28:

Update.
Removed carb and cleaned the emulsion/needle jet. It wasn't blocked but gave it and the whole carb a good clean. Plastic spacer is shot as you can see in the picture
So temporary use of 2 needle shims  very nearly matched the size of the original spacer. I'll try to find another spacer.

Installed new spark plug gapped to 0.85mm.

Started the bike and let it warm up for a bit before revving and inspection of the slide. I will attach a video link here when it uploads.

The slide had full range consistently. Did a quick and dirty test and it totally hauls all the way up to 135kmph. No sputtering.

Now here's the weird part. I attached my air filter, more sputtering but nowhere near as bad.
I even attached it with the long tube that was running perfect prior, and it is still sputtering but only just. I made certain to not block the oval hole, removed material and made certain it was not blocked in anyway.

So I'm guessing the rich co dition has fouled the previous plug.

From here, where should I go? What kind d of filter will provide me with enough air? I'm using a 155 main jet but have others coming. 155 is the smallest I have on hand. Should I drop down to 150?

Could the now much less severe sputtering be the the removal of the damaged Plastic spacer ?  

I don't want to use a velocity stack as they are rubbish.

"The slide had full range consistently. Did a quick and dirty test and it totally hauls all the way up to 135kmph. No sputtering."


So, now you have a good idea that your problem most likely resides in the filter/plastic tube setup.  I suggest you get rid of the current filter & plastic tube.  It would be most beneficial if you could post photos of the filter and plastic tube.  Try and take a few and post so that we can all see exactly what you were running.  I'm particularly interested in the plastic tube.

"Could the now much less severe sputtering be the the removal of the damaged Plastic spacer ?"  



Yes, it could, but IMO your problem was more likely related to the air filter setup.  You do too many things at once.  Had you simply removed the air filter and left the needle alone you would know conclusively.  Now you don't know for sure what corrected the WOT sputtering (filter or absence of the spacer).  Only make one change at a time.  

In regards to the elbow I should use, I am using my stock airbox to hide electronics, would a sharp 90 degree elbow like this be ok? Or would the angle cause issues. I am only asking, as the gradual bend elbow with the filter attached wont fit in the airbox anymore unless I redid my electronics.

Mike, The filter you linked has a 64mm flange inner diameter. What did you do to make it fit the 2" pvc elbow ?

I am riding a bobber setup from Bluecollar

Today I purchased an air filter that Ill try to make work. Its much larger than motorcycle filters but Ill have to ditch the airbox I was using for electrics.

Today I went for a 30-minute ride and used a PVC tube and 2 layers of nylon stocking material as a makeshift filter. No this is not ideal and not something I will do again. I just really had the itch for a ride today and wanted to make sure it would work.

Acceleration was great. On the way home I rode it a little harder and found slight stuttering at WOT as it neared the top of the rev range in each gear. This is NOTHING like the issue it had with the severe bogging. It would accelerate, stutter a little then keep accelerating and stutter a little more

It topped out at 130kmph at was sputtering a little. Maybe its the stock needle settings or the 155 jetting?  

Im curious as to what the top speed in each gear of my 4 speed would be. Riding it hard, Id get to around 70kmph in 2nd, and third would get to around 100kmph

You can see that there is nothing on the filter that will interfere with the oval air entry in the mouth of the carb.