gusto

Do a pressure test and compression test before you do anything else

Try a 27.5 pilot

What your wanting and what your buddy is telling you are two different things. Your ordering a LP 421, NOT a hp 421. So your already not getting a drag engine. Therefore your 34mm carbs are actually a perfect choice and I would not consider changing them. if you want to build a drag bike, you need to switch your cylinders and then you can consider bigger carbs, although still not needed. 19cc dimes and vp110 is costly and unless this is a real drag bike (cut, stretched, and lengthened) you absolutely don’t need it. if your building a general purpose fast dune bike, your current choice is perfect.

What’s your budget? porting from a reputable shop will be 300-400 plus bore and pistons your 500-600. It will make a big difference in power, especially if you have good pipes and reeds. or Driveline 392 cc kit for 800 thats what if look into

https://static1.squarespace.com/static/5be4d5b35ffd2095efa9bdff/t/5bf1a09b6d2a7391b5a84730/1542561947962/KeihinCarbJetting-2015.pdf Study this, if you learn this you’ll know what to do. Sent from my iPhone using Tapatalk

Example, if you move your needle to create a richer position and the bog gets worse that means you’ll need less gas. So you will need a smaller pilot jet. And get your air screws to work perfectly from a half a turn out to 1.5-2 turns out from being fully seated. Sent from my iPhone using Tapatalk

Move your needle clip to determine your pilot. You’ll get it Sent from my iPhone using Tapatalk

Are you running stock carbs? Is it ported? Is it piped? Aftermarket reeds? Sent from my iPhone using Tapatalk

Your safe. The problem your describing is pilot jet. Raise your needles first (more air) and see if that makes a difference. If it get s worse or better change your pilot accordingly

Plug looks good and safe. Your main jet is good now change your pilot or move your needle.

DC Pro

check out my dyno graph in the dyno section. I tested them on the same engine, the description above is close.

says invalid link. How do I open the links?

Put in a 30 pilot, adjust air screw and report back

Here’s my serval with a good comparison between the pipes. It’s ported by Redline Racing. Other builders will have differing numbers I will say this about the three pipes, the Shearer has by far the best clearance for filters at the stinger and having the chambers further up front your legs are not going to get burned.

Taking off the lid helps it breath better. Take it off

Check if your pilot is clean how many turns on the air screw are you? buy one side larger pilot and one smaller, put one of them and see if it’s better or worse. If the larger is better, go in that direction

Ya, nut huggers on FB

John Long (JL Engineering) sells a 200 watt stator that he tells me has worked great with no returns. His dc battery/rectifier is an awesome unit also

Hahaha

Damn Claude there’s a search bar...

https://www.summitracing.com/search/part-type/die-grinders

https://www.summitracing.com/search/part-type/porting-and-polishing-kits

Summit when you cant afford CC

Also, your on your last bore, just run it and don't throw more money into it.