Topic: First time starting new engine, 2 & 3 not as hot

[jakec]

Hey guys I just finished rebuilding my 400 engine and Bike. I warmed up the bike rubbing up and down. Then I went to go ride it and it couldn’t get me up the driveway.  So I parked it and felt the pipes. And two and three are significantly less hot but still hot.  Just totally rebuilt a bike so pretty much everything is new in carbs are totally rebuilt. I checked both condensers with a battery before installing them in the bike. And I just did the timing. I also have four new spark plugs in for Nui and GK cabs. But the coils are original.

 I did finally get it to get me up the driveway and I went up and down the street but it definitely felt just like a bike that’s not running on all cylinders. Where the bike will run sluggish and then suddenly surge at times. I’m pretty sure it’s not the carbs because they’re freshly rebuilt and there is only one fuel line for the whole rack.

[jakec]

 Also I had to rev the bike pretty high to get it to move me. But I didn’t go above 5000 RPM. Once I got a few blocks away the idle got stuck at around 4000 RPM and won’t go down. So now I’m letting the bike cool off.

[jakec]

Also, this is the problem I was originally having when I decided to take the bike apart. One day it wouldn’t run right and I think it was a two and three cylinder problem. But I Try to diagnose it then and it didn’t seem to be electrical so everyone thought it was the carbs. But I ended up taking the carbs apart and they were messed up so this is actually a new set from a 350 but with the correct jetting.

[Alan F.]

Check float levels.

Just because parts are new or newly assembled doesn't mean they'll be problem free and without errors, stuff happens so don't let it get you down. Just pretend it's a musical instrument out of tune.

[jakec]

I just rebuilt carbs and corrected float level. Unless you mean to do the clear tube method. I would like to try anything else I can before removing the carbs though since it's a big job on this model.

Since it's cylinder 2 & 3 doesn't that point you toward coils? especially since all the other variables are theoretically taken care of.

This was my original thread from almost 2 years ago.

http://forums.sohc4.net/index.php/topic,174470.msg2030865.html#msg2030865

Theay said my ignition issue was solved.. but all I did was confirm i had the plug leads correct. Also I have a different set of carbs than in that post.

[jakec]

Here are the plugs. If lack fuel was the problem wouldn’t 2 & 3 be lean instead of rich, as they’re showing?

Also concerned why 1 & 4 are showing leans

[scottly]

The fact that the 2&3 plugs are carbon fouled mean that you were getting spark, at least until the fouling shorted the spark-plugs, shunting the high voltage to ground. No spark=no carbon.

[toma]

Buy yourself  strobe and quit guessing. They are not that expensive and tell you if the plug is firing under compression.

[jakec]

I should get a strobe although I don't think it would help me with this specific problem?

When i started the bike I think it was running on all 4 in the beginning but then cut out to 2 & 3 eventually when I tried to load the bike (with myself).

I tried again once engine was cool this afternoon, removed plugs and cleaned them, reinstalled, started it up, running on two cylinders, soon jumps up to 4k rpm and stays there (no throttle). Also, 2 & 3 are warm but not hot. So I am just repeating the experiment.

My friend Kevin is telling me to check the points which I will do. I can remove carbs if needed, where do people buy the clear tube for the float test?

[scottly]

How did you clean the fouled plugs? Wire brushes, carb cleaner, and sandpaper don't work. You need to burn off the black with a propane torch, or replace them.

[Alan F.]

My thoughts are to collect as much data as possible by measuring coil primary, secondary and plug cap resistances, verify float height with clear tube, even fish tank tube will work. How old is your battery? Have you brought it to an auto parts store and had them load test it? Have you cleaned and added a little dielectric grease to every electrical connection on the bike? What position are your air screws in? Stock airbox, yes?

I'm no expert but these things are important to be sure of as you move forward with your troubleshooting.

This can be fixed, don't give up.

[jakec]

Yeah I just cleaned them like you said with alcohol and a brush.

What I have done just now is check points, they are ND branded.
Check drain screws and all have fuel
Check air screws and #4 was a little to far out. They’re all good now.

Battery is a couple months old and full charge.
No grease on connections but everything is clean and working as of now.
Stock airbox, stock everything and brand new Honda air filter as well.

The good news is it didn’t leak a drop of oil!

[Alan F.]

The good news is it didn’t leak a drop of oil!

And there's oil in it?  Just kidding. Good work making sure of those things. How many turns out are your air screws?

[scottly]

I tried again once engine was cool this afternoon, removed plugs and cleaned them, reinstalled, started it up, running on two cylinders, soon jumps up to 4k rpm and stays there (no throttle).

I suspect when the RPM jumps to 4K it's because it starts running on all four cylinders, and the idle is set for when it's running on only two?

[jakec]

That is an interesting theory. Although the plugs came out looking the same as the first start up (and pipes were still not as warm).

I did just realize I made a mistake, I misinterpreted the manual so my air screws were 2 1/2 out. I have adjusted them to be 1 3/4 out now, per some posts I read on here.

[jakec]

Do I need new plugs in order to get further diagnoses, or just in general? Can I throw them back in a couple more times until I get it to run on all 4, then get new ones to diagnose fuel mixture?

[scottly]

You are pissing into the wind trying to troubleshoot with carbon fouled plugs: even if you fix the problem, the plugs are still fouled, and the motor won't run right. Like I said before, either replace the blackened plugs with new, or burn the black off with a propane torch.

[jakec]

Ok, having corrected the air screws, does that affect anything other than idle? Just wondering if I should put new plugs in and try starting it again. I will back out the idle screw.

[scottly]

Only the 2&3 plugs are fouled, so replace/burn them off and try starting it.

[Alan F.]

Air screw position will eventually come into play at low throttle in higher gears, but your bike would have to be very well tuned to notice the minute difference then.

[jakec]

If it's true that the idle jumping up to 4k is because all 4 are firing, that would mean that the problem can be fixed easily by adjusting idle.. which is optimistic I think but would be nice.

Also, I think the tank needed to be switched to reserve when I was trying to ride the bike, because the tank was about that level when I inspected it last night, and the fuel line was vapor locked. I am using an inline filter which makes this worse.

[Alan F.]

Is this the setup you have?

Stock was an in-tank filter with a single outlet petcock.



How old is your online filter? I've had them clog up quickly enough to surprise me.

[jakec]

Like I said everything is new, brand new inline filter as well as new petcock internals with sock screen over the inlet tube.

[Deltarider]

... brand new inline filter as well as new petcock internals with sock screen over the inlet tube.

Then the inline filter is redundant and can be abandoned.

[jakec]

I would like to do that now but there are two things stopping me, 1. don't have a single line long enough, and 2. it's pretty much impossible to install a line on the carbs when in frame.