Working toward getting the RE5 back on the road

[tom93gts]

Today I put in a new battery but she wouldn't start, so I pulled the spark plug and, well, guess I need a new one.

Need a new plug by tomBW, on Flickr


Luckily (or smartly?) I bought 2 last time so put the new one in and fired up right away, yay! After about 5 seconds though, fuel started leaking out the carb. I must have not put something together quite right a few weeks ago when I rebuilt the thing. I suppose I didn't get float or needle and seat right, maybe will get to that this weekend.

[charles]

Wow. Doesn't look like any A9EFP that I ever saw...

[tom93gts]

Feb 22, 2020 13:23:45 GMT -5 charles said:

Wow. Doesn't look like any A9EFP that I ever saw...

It's some other motorcycle plug, using the adapter from Jess. They are cheaper and easier to come by. I still have an A9EFP or two laying around just in case.

[tom93gts]

Got the needle and seat sorted out so no more fuel leak, but now I can't get it to rev past about 3500 without the choke on. Will look at all the cables to the carb and make sure everything is timed correctly next, eventually, when I get around to it.

[wayne]

Really sounds like that second throat is not working at all. Rev it with the air horn off and see if the secondary butterfly is opening as revs rise. If not, check the vacuum bell housing on top of the carb is actually working. Pull the hose that goes from the bell to the carby and suck on it. the little arm underneath should rise and fall. While you're there, is that arm correctly connected to the secondary butterfly? Does the butterfly open and close as you suck on the pipe? Replace the hose and check it's connected to the right pipe on top of the carby (see below).

If all of that was already okay, then undo the brass nut under the carby below the air horn (not the one on the side, the one underneath). Put a medium flat bladed screwdriver up there and remove the secondary jet (it should be a 180). Give it a clean, replace, try again.

[tom93gts]

Thank you Wayne, I'll probably get some time again this weekend to take a look at my carb. I'll check out the function of the vacuum actuator on the secondary throttle body.

[tom93gts]

The actuator actuates when vacuum is applied (aka vacuum hose with mouth suction). But the vacuum supply line to the actuator doesn't seem to supply any vacuum, at least I haven't been able to determine when it should supply any vacuum. When should that line activate and is there any way to test it? Maybe I need to take the top off my carb again and examine that.

[tom93gts]

Did a bit more diagnostic work and determined that the vacuum supply for the actuator seems to be working as when I increase RPM the secondary will start to open. But just as it starts to open at around 4k rpm it's like it hits a wall and absolutely under no circumstance will it go over that.
I disconnected vacuum to the actuator and sealed the vacuum leak with my finger and the engine will rev beyond 4k with no issue, so something is going wrong when the actuator begins to open the secondary. Is this a cable timing issue? Maybe I need to adjust the cable to the butterfly that's in the housing? This carb is so much more complicated than the Weber on my REPU, Suzuki must have used a lot of engineering resources to come up with this thing.

[wayne]

Don't have a pic of both passages referred to, only one. I'll have to pull the proverbial out and get one.

The vacuum to operate the bell housing is supplied by two tiny ports, one upstream of the secondary butterfly and one downstream.

I think the figuring is that as the port valve opens (it's set to start slightly before the secondary is due to open) the downstream one provides initial vacuum as it's opening that secondary tract to rotor induced suction. As the secondary starts to open, the upstream one is now exposed to the Bernoulli effect as air starts to move down the secondary throat. This additional vacuum assists in keeping the secondary moving (assuming the throttle is still open wide enough).

So if there's not vacuum or not enough, those tiny ports may be blocked.

The easy one: remove the carby. On the flat, engine-side face of the carby there are several holes. One of them contains a tiny jet. Remove and clean.

Now block this hole (I find an old O ring of suitable size, cut it and poke the end down into the hole the jet was removed from- Unfortunately a finger won't work, you'll see why when you're looking at it).

You can then use a syringe, maybe filled with Isopropyl alcohol or methylated spirits. Attach a short hose from the syringe to the tube on the top of the carby that the bell housing vacuum hose is normally attached to. Looking from the air horn side of the carby down into the secondary throat, give the syringe a squirt. A jet of the fluid should be seen to squirt out of the side of the throat in about the "2 O'clock" position mid way down, just behind the concentric venturi that sits inside the 2ndry throat. Hard to see the hole but the fluid squirt should be obvious.

If nothing comes out, there's a blockage in that vacuum port. You could try a blast of compressed air down the two accessible holes (carby top pipe and where the jet is seated).



The easy one, the jet. The hole it comes from is immediately above where I'm holding it (the lower of the two that look like keyholes):

[hudson]

To me this sounds like a lean condition, I would check the secondary main jet and its passageway for blockage ( #62 in the Carburettor Exploded view located in the resources tab ) This jet is located in the bottom of the carb and would be susceptible to dried fuel blockage. Also would check #36 secondary pilot jet. I suspect lean because Tom describes seeing the secondary opening and the engine stops accelerating ( adding air and possibly no fuel ) and revs past this point by keeping the secondary closed and just opening the primary.      The service manual located in the resources tab is a MUST READ for all RE5 owners as we have to become are own mechanics.  Just my one cent worth.                                                         Regards, Brian

P. S.  Please follow up with what you find as to the cure.

[wayne]

Yes, I mention checking the 2ndry main jet in an earlier post but Tom hasn't reported on that as yet.

[tom93gts]

I did inspect the secondary main jet and verified it is clean, so that one isn't the issue.
Thanks for the suggestions, guess it's time to remove the carb again. Hopefully this next weekend I'll be able to come up with the time for that.

[timpa136]

Tom,
I don't hesitate to tell you I have had to clean the Carb twice, Once to get it running and again to fix it after I figured out

which circuit was clogged. Maybe you got a tank full of California gas. Unlike conventional Mikunis, most deposits dry up in the bowl.

In the RE5 carb, those passages are hidden in the body to clean out.

Good Luck

Tim

[wayne]

I agree with both HUDSON and TIMPA136. There probably is (as well as any other issues), a lean condition occurring. So all this vacuum stuff is just trying to narrow down and isolate any other issues. And re TIMPA136 and the multiple carby cleans, unfortunately, I believe this, at day's end, is the awful truth for the RE5 carb.

Mar 1, 2020 14:37:28 GMT -5 tom93gts said:

I haven't been able to determine when it should supply any vacuum. When should that line activate and is there any way to test it?

To answer the question:

You can clearly feel the actuation of both the AP and the Port Valve in the throttle grip. However, if you're unfamiliar, I'd advise removing the port valve cover (easy to do) and observe when the timing plates touch and actually start the port valve moving as you twist the throttle grip. Get familiar with what that feels like on the throttle grip, it makes cable adjustment so much easier.

The point where the port valve starts to open is is the earliest that vacuum should occur to the bell housing. In theory, it's 35 degrees from the fully closed position of the primary butterfly (note, fully closed is still 8 degrees from vertical. That 8 degrees is disregarded by the factory and considered "Zero". All degree settings are referenced to this.

That's the start of the vacuum but the secondary butterfly can't start to open 'til 41 degrees as it's limited by a factory set plate. In reality, that 6 degrees is a barely noticeable turn of the grip. Once the secondary butterfly starts to open the other hole down in the throat also adds vacuum.

Where your PV and/or AP are actually set is open to the variables of previous owners and their fiddling and whether the dealer enacted Bulletin 9.

[tom93gts]

Mar 2, 2020 2:12:36 GMT -5 wayne said:

The easy one: remove the carby. On the flat, engine-side face of the carby there are several holes. One of them contains a tiny jet. Remove and clean.

Now block this hole (I find an old O ring of suitable size, cut it and poke the end down into the hole the jet was removed from- Unfortunately a finger won't work, you'll see why when you're looking at it).

You can then use a syringe, maybe filled with Isopropyl alcohol or methylated spirits. Attach a short hose from the syringe to the tube on the top of the carby that the bell housing vacuum hose is normally attached to. Looking from the air horn side of the carby down into the secondary throat, give the syringe a squirt. A jet of the fluid should be seen to squirt out of the side of the throat in about the "2 O'clock" position mid way down, just behind the concentric venturi that sits inside the 2ndry throat. Hard to see the hole but the fluid squirt should be obvious.

If nothing comes out, there's a blockage in that vacuum port. You could try a blast of compressed air down the two accessible holes (carby top pipe and where the jet is seated).

So this passageway was definitely a problem with my carb. At first when I plugged the jet hole I could not get any air at all to blow through the vacuum nipple that connects to the actuator. I was finally able to blow compressed air through to clear the blockage. Put the carb back on, and now it runs even worse. Actually I think I just might have the idle too low and need to set the idle set screw. But aside from that, I am still not able to get it to rev past 4k.

Hopefully tomorrow evening I get some time again and I'll check out Hundson's suggestion with jet #36.

Thanks for the help, one step closer!