TOPIC:

I have a 81 KZ650-D4 with 81 KZ650-D4 and VM24 carbs.
4 to 1 exhaust and KM pod filters.

Main 112.5
Pilot 17.5

The needle high is one higher then middle (one step reache then middle).

Engine is rebuild, valve etc shall be according to speck.

Air/fuel (mix) screw is adjusted best I can and carb sync is done.

Today have I taken a longer trip and the bile is working fine in general, but I experience some load alternation approx +/- 50% throttle.
I think has nothing to-do with the RPM.

When I cruising with 10-20% RPM it goes perfect, and then I increase the throttle it response good, but when it comes to approx 50% it start to load alternation, not heavy like you need to-do something, but its should be better and you don`t have full propositional control over the throttle vs force.

These area is approx 10%, and I guess around 50% throttle, and if you crease further it disappear, but at the same time it disappear you feel more power also released.
And you have the proportional control back further 60-100% throttle.

The % is approx.

I can add one thing more, when you idle and if you are slow with the throttle you can kill the engine, if you are not so slow it goes okay.... just the second its picking up from idle when you give throttle are you really slow with the throttle it can die.. Don`t know of if these two thing are in relation?
Summary:
Good proportional / linear control 0-50%, 50-60% you have some prop. control, but you have load alternation more then I accept.and after maybe 50% it disappear and I have good prop. / linear control again.

When I was running with stock 750CC pistons, the bike was running fine, but I could feel the same load alternation, some times, in deep hills.
But it was fare softer and I was nothing doing anything with it. I`m running with the same jet setup now.

I have got a lot of help with my project and I have a other threat where I got help when it comes to start up procedure etc...
www.kzrider.com/forum/2-engine/607610-st...ter-rebuild?start=20
I just wanted to start a new threat for these specific problem, more information can be found there.

Nessism, have suggested jet issue?

KZB2 650, thing I`m close to the jet setting I shall have, rise the needle height one step?

I`m not in a hurry so just wanted to see if we all could agree on the next step

The stock setting on 24mm carbs for a 650 is on the 4th clip (one clip from the bottom) with your set up I would think the bottom 5th clip one step richer (raising the needle) would be what you need. Like I said some riders have reported approx the same thing going on in the mid range and have blamed the pods over the air box but you should be able to get it 90% there.

KZB2 650 wrote: The stock setting on 24mm carbs for a 650 is on the 4th clip (one clip from the bottom) with your set up I would think the bottom 5th clip one step richer (raising the needle) would be what you need. Like I said some riders have reported approx the same thing going on in the mid range and have blamed the pods over the air box but you should be able to get it 90% there.

Before the 810 upgrade when I was using the 750, it was much better so I assume we should be able to reach the same now also with 810.

Thank you,
I will try to change to clip 5 the next days and report back

Just curious, example if the size deviation for pilot and main jet was to big I would have the same issue? We are talking about the transfer perioed between the two jets?

I'd try one step up on the pilots.
Steve

SWest wrote: I'd try one step up on the pilots.
Steve

Since it had nothing todo with RPM, just throotle and in the mid range you think it’s the pilot?

I only have 20 pilot jet in spare and are running on 17.5 now. So I need to order 18, should I also order 18.5 just in case or?

What should I order to have something to play with?

Thank you.

SWest and KZB2 650, what is the differences between increase the pilot jet and raise the needle?

Try to understand the advise from you both, since you KZB2 650 suggest raise needle and SWest, increase the pilot?

Thank you.

SWest wrote: I'd try one step up on the pilots.
Steve

Some back and forth with me , sorry....

I have checked denniskirk.com and it looks like the next step is 20 (running 17.5 now).
So then I have pilot jets

Will try to install them soon and report back how it went.

The pilot jets control idle and off idle to 1/8 th throttle or a little more....... the needle controls mid range ....... thinking Steve was refering to were you said it was a little off off idle dying on you and not responding quite right but 20s sound too rich to me .......

KZB2 650 wrote: The pilot jets control idle and off idle to 1/8 th throttle or a little more....... the needle controls mid range ....... thinking Steve was refering to were you said it was a little off off idle dying on you and not responding quite right but 20s sound too rich to me .......

Ahh I understand, so try for improvement in the mid range is raise the needle as you had said before. Will try these the next days, and report back.

I have driven in the city for some hours today, and it`s annoying you need to give some throttle before you release the clutch if not you kill the engine.
You don`t have so smooth starts I had before with the original 750CC, maybe these has something to-do with higher compression also?

I understand it`s not much to-do with it then, if so must I try to gt 18 pilot jet or something? and not 20 because that is to large?

The biggest problem is the mid range so lets see what the needle raise give of effect, if that not helping, then I need larger carbs ?

Try the 20's. You can compensate with the air screws.
Steve

SWest wrote: Try the 20's. You can compensate with the air screws.
Steve

Increase pilot should improve off idle bevahior and raise needle should improve mid range?

Are you agree I should do both?

Is the best thing to test one thing at the time or shall install the 20 pilot jets and raise needle at ones?

Adjust the air/mix screw and do carb sync and then take it out for a spinn?

Thank you.

One thing at a time. Install the jets then if you feel you need a little more at midrange, raise the needle one notch and bench sync. Each time adjust the air screws for best idle. Once you're satisfied, sync the carbs.
Steve