Well, your DJ144 properly fuels the top end of a "uncorked" 250 - so you may very likely need at least a DJ148 - but we have no data, at this point, to go on..

Running 1N, stock spring, stock lift port is all we can do to control the midrange AFR. Without data, I can only postulate that a BB would require much more fueling in the mid than a 250 - so perhaps the above measures produce an acceptable midrange AFR..


Your part throttle "flat spot" sounds more like slide stiction causing a "lean out" due to a "slow-to-respond" situation.. But I really have no information on part throttle issues..

 

In still waiting on my clutch springs so I can't get on the dyno yet, but I figure I'll toss in my 2 pennies. It seems that multiple are having midrange troubles with the big bore and open setup. My thoughts are that the increased vacuum caused by the bigger jug may be causing the slide to run full open earlier than a 250 would. That would explain a rich area in the mid range that would go away when the rpms get higher.

 

Well, only you are running DJ148/1N, only you are sensing something in the midrange @ WOT.. Jabara is not running your setup and, whatever he is sensing, is not occuring at WOT but at part throttle (%20)..

Nonetheless, you could be right - if so, there should be a "jolt" of increased power/pull as the engine speed rises enough to process the overly rich AFR ..

DynoButt setups have cost a lot of owners a lot of HP/TRQ, over many years..

You always start with the main jet and top end fueling when tuning the CVK - So top end AFR is all that's important right now.. Once that has been determined, the "stupid monkey" work can begin - the midrange fueling.. Once this begins, most of the options are already being used (1N, stock spring, stock lift port) so that doesn't leave much for a monkey to play with - smaller lift port sizing, stock needle reinstall, is about it.

 

I was actually wondering about the stock needle. It may be worth a try. Dyno first, though.

 

I kinda jumped ahead in the post above - but yep, if your top end is ok and your midrange is not, I'm going to present your options - test the stock needle - start going smaller on the lift port..

This is stupid monkey work that continues until the midrange is fueled correctly..

 

are you running the 148? all i have left currently is a 146, not sure if ill be able to feel much difference. i also need a 40 pilot badly

 

When I have good dyno data to analyze we should learn everything about what is actually going on - and tune accordingly.. Perhaps nothing needs changing at all. With a good AFR chart below good power curves, we can fix anything that needs fixin..

The concern is getting your clutch up to snuff.. You have about the earliest clutch failure ever reported on a 351 install - perhaps due to the lidless CVK setup making way more TRQ for a much longer span of RPM than "usual"..

 

I didn't have the mcm mod done. The bike does have 10,500 on the clock. The previous owner was around 20 years old so he probably alternated between wheelies and burnouts to warm the bike up.

 

Here's my plug after 300 miles on 144/1N, looks lean to me, I am putting in my 146 asap because that's all I have left, need not order more jets on Tuesday, what do you all think

 

Here's a better one, I guess it doesn't look too awful...

I also noticed the too if my piston is already brown/black with some light deposits, is that normal for 300 miles? Can't get my horoscope working till Tuesday.

Let me know what you think about 144 vs 146, I'll have it apart for a bit.