Hey guys, got my 71 AT1c and 81 DT running pretty good and getting into more fine tuning etc. Both bikes seem to bog or fall on their faces at around 6500 rpm, 3rd gear at WOT. Both carbs have been cleaned meticulously, float height set, new fuel line/filters and clean tanks. They both had pod filters and I just swapped to dual stage UNI with no change in response. Both idle screws set at factory setting. Is in all the way more rich, out more lean? The DT is better, rips way harder (reed valve) but they both do it, the AT1 is just worse. On that bike I tried 1 turn out, up to 3 with no real difference made. Is this just kind of the end of the power band saying shift the damn thing or what for a 125? Acts almost like it's suddenly choked. I did notice the intake manifold on the AT1 is cracked pretty good at the bolt mount, tried to seal it up with sealant with no significant change after. I may just be getting TOO meticulous at this point but wondering what ya'lls feedback is. I thought maybe main jet clogs...nope.

I'm also gonna attach pics of the DT carb, vm22 and am curious of the black port and the one with the hose with a screw in it (not my work) those breathers or ??

Pod Filters are less restrictive than stock airboxes , in my opinion .
You may be experiencing a lean mixture , as you get up in the rev range .
Fiddling with the idle circuit won't have any significant effect in the range you
have described . You could try lifting your needle one clip . That's putting the
circlip down one notch from the top . That may show an improvement .
If it does , you still may need to lift needle higher , and still may need to increase
the size of your main jet .
I think the port you have capped on your DT carb may be the breather for the float bowl .
Before changing anything , uncap that , as it may be stopping your float bowl from refilling .

The capped fitting is that way stock and must remain capped. The fitting on the other side is for the oil injection. If you are premixing must also be capped.

Exhaust on both is my first thought if falling over on full song. Limited by a restricted muffler--carbon in the spark arrestor trick, lumps of it, down where you can't see easily.

That's it, if you're WOT and it bogs that is ALL main jet, high speed circuit, so do the clip thing on the needle, start at #4 from the top, try it, and if no better go to the 5th from the top. Don't even mess with the air bleed/Mixture screw or idle speed, that has nothing to do with your problem.

And RT is right, if the spark arrestor is plugged/restricted then you'll also get this result. I'd start with the needle, and go from there.

You guys all rock. My head from day one was main jet, was thinking just upjet and now that I've ran both a shitty pod and a dual cell foam UNI on both bikes I don't think there's much difference in the 2 as far as restriction goes. I thought maybe the UNI would be a less air situation than a shitty pod but I agree 100%, move the clips and see...will probably help or fix and then move to bigger jets as needed. I don't think the arrestors are an issue but it's a good reminder to check as I know the DT was ran with real rich premix. The AT1 sat for years without the exhaust even on it so ya, will check. Maybe that's why it came off in the first place. I'm pre-mixing both at like 32 :1. On those pics basically all need to be capped? There's the "blue" port in the pic, the brass which had the oil injection line hooked up with no oil tank and the angled black in pic 2, what's that? Having a hard time finding a good in depth resource for the VM22SS.

Also...where's the love on my DT lighting thread?!??? I got a couple number plates for side covers and am thinking maybe about the Acerbis Elba 2 headlight with a simple round tailight but have never done any lighting mods from just using the wiring that's there. There's pics over here:
yamaha-enduros.com/index.php/forums/1977...ighting-improvements

The black one is the vent. Do not plug that one. The other two go right into the carb throat and will cause a bad vacuum leak if not plugged.

On the lighting... I can't speak for others but it's been such a tedious topic for me lately... it seems everyone wants to run modern 12v LED's and/or high wattage bulbs which is fine... if you want to replace the stock system.

If you just want a basic headlight and taillight all you need is use yellow off the stator to power the lights, keep the wattage load close to stock, use 6v incandescent bulbs, and use a stock Yamaha one-wire AC voltage regulator.

Nailed it MarkT, I'm not one of those guys and I think I'm headed in the right direction.

Well shit, I got in a hurry when I went to move my c clip down and didn't pay as much attention as I should've on how it all came out. I moved the clip down 2 notches and it ran like shit so I moved it up again and then a 3rd time back to the factory setting and I'm just not putting it back together right. The slide seems to only go all the way down 1 way but I think I have that plate that the cable seats into wrong. Uhhghh. I'll do a search on it...if I can get it right I think moving the clip down 1 will do the trick.

Kind of a "Duh" reminder, but be sure you have the slide in correctly when you reassemble the carb. There's only one way it fits in and moves and operates correctly, so that the small pin inside the chamber fits into the recessed slit that runs the vertical length of the slide.