Filter is new.
I took the air filter out, put in a new spark plug gapped to .6mm, tried a spare ignition coil and even flushed out the gas it had in it (wasn’t old)

Still same misfire under load at about 1/4 throttle and 4krpm

I opened the air filter and that isn't what I found in mine.

Hahaha hopefully you had something in there

I removed the carb to check the reeds
Lot of fuel/oil on it. Look ok?




I’m really thinking it is just running too rich. But I don’t know if it’s too much fuel or oil from the autolube pump.

Here is a pretty good video on the oil injection pumps. It helped me understand how to set it up. Hope it helps.



Jim

Boyesen reeds run rich. It's even in their instructions. It's no secret I'm not a fan of Boyesen reeds although many love them. But if you don't have the stock reeds, there's not much choice. I have a couple of bikes with them.

If it's happening at 1/4 throttle, you could try dropping the needle one notch. (Move clip one groove higher in the needle, which lowers it.)

Thanks for posting the video Jim.
Great explanation of the auto lube pump.
Im going to do the test to see if I am getting too many CCs. The alignment on the autolube pump on mine is right on.

I tried moving the clip and lowering the needle but it didn't make a difference.
I was noticing way too much fuel/oil on the new spark plugs.
I took the head off again and noticed a lot of fuel/oil on top of the piston.

Verified the specs on the pump.
All seems to be within spec.
So what could be the reasons I am getting too much fuel?
This is driving me mad Hahahah

Had to go through the entire thread to see if we had dealt with the carb earlier .
As I see we haven't , strip out the carb and see what is actually in there , as opposed
to what should be in there .
A previous owner may have fitted a carb kit . These frequently cause running issues
due to the brass hardware often bearing only a passing resemblance to OEM Mikuni parts .
Jet needles , which are usually brass in kit form , are the biggest culprit .

Thanks swoop

I have been using this carb on the bike
yambits.co.uk/dt175-carburettor-p-94263.html



I do have the oem carb for the bike but the previous owner told me it needed a new one so I bought the one off yambits for $40usd.

Below is the oem carb and the jets off of it



Should I just rebuild the oem carb?

Try the std reeds. Bit of a story but modifying the porting on my 100 road race bike 'bucket racer' a lifetime ago, i ended up with a rich like blubber at 1/4 throttle. Couldn't carburate it out without going so lean it killed it. Smart mate of mine who worked on 'proper' race bikes said 'reed flutter'--double up the reeds==Damn it it foxed it straight away. Was an RT2 reed block housing welded into te back of a TS/TF100 Suzy cylinder with wild porting. Blubber was about where the pipe kicked in hard so maybe a bit above 1/4. I was still using the std Yam steel reeds so just added another set to stiffen them. Anyway--was just a thought from my experience.