Hesitation/Flat spot at 4K to 5.5K rpm's

[rojo]

I just got an LTD about a week ago as a non-runner on the cheap ($200) for a bobber project.   It does have a pretty big dent on the side of the take but that just gives me an excuse to buy a stud welder.   

Since then I've adjusted the valves, cleaned the carbs, changed oil, coolant, and break fluids.  The bike is running now after fixing an electrical gremlin in the run/stop switch. After wrestling with the air box a bit, I opted to go with pod filters.  So, I just put on some EMGO pods and using some instructions found on the site, I adjusted the pilot screw currently at 3 turns, clipped 3 coils off the spring on top the diaphragm, and shimmed the needles with 3 #4 washers on each side.  Went with 3 turns on the pilot screw as I thought it was still running a bit lean with some popping on hard deceleration.   Idle is set at 1200 rpm.  

The only real issue I have is a persistent hesitation at around 4000 to around 5500 rpm when rolling on the throttle (medium to hard throttle) up-shifting thru the gears.  Once it gets pasts the little flat spot/hick-up, the bike runs like a scalded ape.  I am debating clipping another coil on each side to help the slide move past that flat spot a little better.  I live in the Denver area so I should be running a little richer, so I don't think the main jets are the issue.  Once the bike gets past the flat spot ~6K it pulls hard and accelerates well.   Any other suggestions to eliminate the hesitation/flat spot?

Been reading, learning a lot, and getting ideas for my first bobber build.  


Thanks

Rojo 

[Blaine]

Feb 12, 2015 20:12:44 GMT -6 rojo said:

I just got an LTD about a week ago as a non-runner on the cheap ($200) for a bobber project.   It does have a pretty big dent on the side of the take but that just gives me an excuse to buy a stud welder.   

Since then I've adjusted the valves, cleaned the carbs, changed oil, coolant, and break fluids.  The bike is running now after fixing an electrical gremlin in the run/stop switch. After wrestling with the air box a bit, I opted to go with pod filters.  So, I just put on some EMGO pods and using some instructions found on the site, I adjusted the pilot screw currently at 3 turns, clipped 3 coils off the spring on top the diaphragm, and shimmed the needles with 3 #4 washers on each side.  Went with 3 turns on the pilot screw as I thought it was still running a bit lean with some popping on hard deceleration.   Idle is set at 1200 rpm.  

The only real issue I have is a persistent hesitation at around 4000 to around 5500 rpm when rolling on the throttle (medium to hard throttle) up-shifting thru the gears.  Once it gets pasts the little flat spot/hick-up, the bike runs like a scalded ape.  I am debating clipping another coil on each side to help the slide move past that flat spot a little better.  I live in the Denver area so I should be running a little richer, so I don't think the main jets are the issue.  Once the bike gets past the flat spot ~6K it pulls hard and accelerates well.   Any other suggestions to eliminate the hesitation/flat spot?

Been reading, learning a lot, and getting ideas for my first bobber build.  


Thanks

Rojo 

Your on the right track. You can remove the springs temporary to see if the bog goes away before you cut any more off them.Don't leave them out all together because the slides can hang up & not return to closed position.

[rojo]

Just got thru tweaking a bit more.  I took out the spring and ran the bike with little or no effect.  I ending up shimming the needle more, adding one more washer for each side.   This took out all but a very little amount of hesitation when I really get on the throttle.   Slow to moderate acceleration there is no hesitation at all.  Gonna try a little Seafoam as well.  I was told the bike wasn't run for "a while", I assume years.  I have no other history from the PO.  

One other question, still carb related, has anyone tried using a KLX needle in these carbs?  The reason I ask is that the KLX needle is tapered.  It's a fairly common practice to swap these out on a KLR 650 to get better low end - mid throttle response.  KLR's also use a CVK carb that looks similar to the LTD's. While reading through the forum, I did not see where this had been done.  But I could have missed it.  I may pick up a couple KLX needles and give it a go.  

Thanks for the assistance

Rojo

[Blaine]

Feb 13, 2015 13:49:04 GMT -6 rojo said:

Just got thru tweaking a bit more.  I took out the spring and ran the bike with little or no effect.  I ending up shimming the needle more, adding one more washer for each side.   This took out all but a very little amount of hesitation when I really get on the throttle.   Slow to moderate acceleration there is no hesitation at all.  Gonna try a little Seafoam as well.  I was told the bike wasn't run for "a while", I assume years.  I have no other history from the PO.  

One other question, still carb related, has anyone tried using a KLX needle in these carbs?  The reason I ask is that the KLX needle is tapered.  It's a fairly common practice to swap these out on a KLR 650 to get better low end - mid throttle response.  KLR's also use a CVK carb that looks similar to the LTD's. While reading through the forum, I did not see where this had been done.  But I could have missed it.  I may pick up a couple KLX needles and give it a go.  

Thanks for the assistance

Rojo

Never tried that.Post back with your results.It will help others.Thanks.