Not running quite right

[aerologic]

Hi All,

It's been a while. I've been riding my RE-5 but I do need/want to get it running just a bit better. Here is where I'm at. I can accelerate through all the gears up to highway speed with pretty good acceleration with no hesitation going through the normal flat spot RPM. So I feel like the I have the flat spot pretty well in hand. But, If I just cruise at some speed, RPM above the flat spot or below the flat spot, I get some hesitation, or jerkiness. I'm not sure how else to describe it. It sort of feels lean to me. I want to solve this.

I have messed with the port screw some but to be honest, I don't really feel any difference after turning it 2 or 3 or more turns. This bugs me. Does this make sense?

Sam did overhaul this carb.

I have experimented with jets. I'm going by memory but I think I have a 100 or 105 in it now. I could check.

It does seem to run better with the choke at the 50% level. This must point to something??

I do make sure it's warmed up before I adjust anything.

It idles great.

Any suggestions as to what my symptoms sound like?

I think I'm close to a perfect running RE-5.

Thanks in advance!

Dave P

[ziggystardust]

Bit big those jets, 87.5 /90 is standard.

90, 92.5 or even 95 can give good results.

I run a 90 in my M model and a 92.5 in my A.

Z

[aerologic]

Thanks Z. I bought 6 or 8 of them and have tried most of them. I can't say that I saw a lot of difference. This confused me as much as the turning of the pilot screw did not seem to change things much. I was hoping that this was the MO of some fault in the carb.

Dave P

[aerologic]

Here are a couple followup questions:

1) How would one expect the engine run with the wrong size jet? What characteristics?

2) How would one expect the engine to run with the pilot screw several turns opened or closed from ideal?

I'm just trying to get a feel for what engine/riding characteristics I should expect with the above two items off kilter, so to speek.

Again I think I have the flat spot handled but I'm having difficulty getting past the jerkiness at constant speed. It not terrible but I know it can get better.

Thanks again!

[ziggystardust]

If I fit too big a jet size then I experience 'lumpier' running on over run and some surging, I try for a compromise to use the smallest jet with the smoothest running.

With the pilot screw I turn it out from bottom about one full turn, then with the engine hot and ticking over at about 1250 revs I turn it either way and listen to the engine, I can just about hear the change as I run the screw up or down so I aim for when the engine just picks up. About 1 1/4 to 1 1/2 out works for me.
I then road test the bike, then I look at the plug to see if the colour is of dark sand.
All of this after I'm convinced I can't get the port valve timing any closer.
Other owner's may have a different approach but this works for me.

Z

[supersaki]

The first thing I would do,would be to check engine compression.Worn engines with low compression run better on a rich mixture.If the compression is within service limit,then check ignition and port valve before changing jets.Use your plug color as a guide.
Regards,
Roy