Topic: Vintage sidecar rebuild - new video

[scottly]

Where do you have the idle mixture screws set? Have you tried turning them in a bit to see if it helps? What are your impressions of the new accel settings so far?

[Tintop]

Where do you have the idle mixture screws set? Have you tried turning them in a bit to see if it helps? What are your impressions of the new accel settings so far?

Mixtures (new style) are @ 2 1/2 right now scotty.  Tried turning them in (lean), and then out a bit.  Didn't make any noticeable difference either way.  The 50 idles are in right now, may try the 45's.  The engine needs to break in more, so tomorrow I'll heat cycle it a couple of times, then get down to setting up the idle.  As for the accel, 3 twists of the throttle, then hit the start, and it fires.  So that's a good sign.  Did do an easy short pull up to 4K, and didn't notice any flat spot or stumble, also a good sign.  The old plugs are a bit ratty so I have some Denso iridium's coming tomorrow.  I'll install them before I get serious about adjusting things.  Must say though that it already sounds sharper than last year.

Right on Brian....unless you change your mind about Laconia. 

Can't tell you what a relief it was to hear it start Brent.  After all the extra expense(s) getting to this point the race budget has taken a serious hit.   So we'll be staying close to home this year.  That is unless a sponsor with $'s shows up.

[scottly]

Mixtures (new style) are @ 2 1/2 right now scotty.  Tried turning them in (lean), and then out a bit.  Didn't make any noticeable difference either way.

Interesting. I found with the 40 idles that the mix screws had no effect once out past more than 1 1/2 or so. You might try turning them in until they start to have an effect? Have you seen the 2 1/2 figure anywhere in a manual?
When will you be able to actually ride the rig? That will be the true test of the accel pump.

[Tintop]

The 2 1/2 turns comes from Pierce Manifold scotty.  My mixture screws are the newer style with the long taper.  As was explained to me, most (all??) the books about tuning these things were written in the 60's / 70's.  So they all refer to settings based on carbs without air correctors & the more blunt (original) mixture screws.  If I have to go less than 2 turns then the idle jet is too rich, more than 3 1/2, then it's too lean.

1st ride will be at the track.  Would like to get over and setup Friday PM, so I can cruise around the pit area to help break in the engine.  I've also got new tires that need to be heat cycled.  So 1st couple of times out Saturday will be 70% max.  That should however give a good idea how the jetting & accel are working.

[scottly]

Try turning the screws in, until you regain some control of the idle mixture; if they have no effect, they are out too far in my experience, and indicate that the idle jet itself is the limiting factor. If your idle mixture is too rich, don't try to add more air before leaning the mixture screws.
So the track will be this coming weekend??

[Tintop]

Try turning the screws in, until you regain some control of the idle mixture; if they have no effect, they are out too far in my experience, and indicate that the idle jet itself is the limiting factor. If your idle mixture is too rich, don't try to add more air before leaning the mixture screws.
So the track will be this coming weekend??

That's basically the plan.  I'll install the new plugs, then work on the idle mixture.  Given that the adjustment range with these is 1 1/2 turns, they're not as sensitive as the original style.  That said, if I have to go less than 2 turns, I'll put the 45's back in.

[scottly]

Don't worry so much about the number of turns; if you can vary the range from rich to lean, then your jets are within range. Adjust your screws in until RPMs start to increase, then decrease, then back them out a bit. The sharper taper screws are uncharted territory....

[Tintop]

Don't worry so much about the number of turns; if you can vary the range from rich to lean, then your jets are within range. Adjust your screws in until RPMs start to increase, then decrease, then back them out a bit. The sharper taper screws are uncharted territory....

That's the main issue.   Tomorrow should answer the basic questions.

[scottly]

Anxiously awaiting results.. I have a feeling you are going to be very pleased on your first track day with the new setup.

[Tintop]

Day one results scotty -

Tried the 50 idles, but couldn't get any kind of reaction.  Had them turned in to 1 turn, which is below spec for these mixture screws.  Changed to the 45's, and reset everything to my baseline settings.  Ended up at 3 turns out, and a sync'd idle @ 1000rpm (3/4 turn).  Then opened the air correctors 1 turn......idle jumped to 3K+, used idle adjust to bring it back down (-1/4 turn) to 1K.

I'm going to leave things as they are until I can drive it around the pits Friday PM for 10 to 15 minutes.  Engine should loosen up, and the piston will have expanded.  I'll recheck settings then.  Figure the mains should be close, even a bit rich now with the accel jet adding high speed enriching. 

[scottly]

I'm going to leave things as they are until I can drive it around the pits Friday PM for 10 to 15 minutes.

While you are tooling around the pits, play close attention to how the motor runs at small throttle openings, when the progression holes are in play. If you sense any hesitations, switch to the 50 idles.

[Tintop]

While you are tooling around the pits, play close attention to how the motor runs at small throttle openings, when the progression holes are in play. If you sense any hesitations, switch to the 50 idles.

One of the reasons I want to take it for a drive tomorrow, is it will mainly be at small throttle openings.  Given the way it's currently acting it's to bad Weber doesn't make a 47.5 idle.   One thing that occurred to me was maybe going to a different 'F' - eg F8.  A 45F8 should be richer than an 45F9, but not as rich as a 50F9.  Got to check my books, as I'm not sure exactly how that works given Weber's numbering system.   As it is, the current combination works, just not sure it's the perfect solution.  I'm still running the same main / air / emulsion combination from last year.  So I expect that to be a bit rich now, what with the pump jet now adding high speed enriching.  One of the things this weekend will also help sort out.

[scottly]

My gut feeling is that 45 idles are going to be too small when running through the progression holes. As long as you can get the 50s to idle properly and reliably, regardless of the screw settings, I would rather err to the rich side than the lean, especially after the piston damage from the last outing. Like I say, that's my gut feeling..

[Tintop]

The pistons were toasted because of heat, these sidecars run very hot.  It wasn't from running lean, my exhaust pipe & plugs can attest to that.  One of the changes I'm making is to add more cooling holes in the dustbin, especially for the head area.  The only reason I'm spending this much effort on getting it to idle is to make life easier during warm-up & gridding.  I won't have to keep playing with the thottle.  Once the flag goes up (red light comes on) for the start, the butterflies never get closed enough for the progression holes or idles to have any effect.  The reality is at any given track if the solo's spend 40% of their time @ WOT, the sidecars will be at WOT 70%, and they're carrying twice the weight.

[scottly]

The pistons were toasted because of heat, these sidecars run very hot.  It wasn't from running lean, my exhaust pipe & plugs can attest to that. 

You can't go by your old pipe and plugs when you were injecting massive amounts of fuel with each twist of the throttle. I realized the 40's were too lean for my bike after it got so hot I couldn't kick-start it after a 90 mile run at 70 MPH. Even at that speed, I was running on the progression holes, where the size of the idle jet is the main factor, not the screws.

[Tintop]

Do understand that in a 'street' application you are running at small part throttle openings most of the time (idles & progression).  It's why Webers can give increased fuel economy, and it's important to get it right.  I just want to be able to pull up on the grid, have it idle (hands free), so I can start the GoPro, adjust gloves etc.

I use a quick turn throttle, and only partially close it to shift gears.  Otherwise I'm on it at 1/2 throttle+ to keep the bike sliding in the corners, or pinned at WOT.  The idles & progression holes stop flowing (from venturi air pressure) once the butterfly gets open about 1/3rd.  Even if the throttle closed enough during a race for the idle & progression to come back online, it would be for only a split second.  Certainly not long enough (like cruising down the highway) for any lean condition to have a heating effect.

[Retro Rocket]

Do understand that in a 'street' application you are running at small part throttle openings most of the time (idles & progression).  It's why Webers can give increased fuel economy, and it's important to get it right.  I just want to be able to pull up on the grid, have it idle (hands free), so I can start the GoPro, adjust gloves etc.

Fuel injection.?...

[scottly]

Updates?

[Tintop]

RR - Can't use fuel injection unless the engine came with it (rules).  XS's never did.

scotty - Test day report.  Carb settings are very close.  Doesn't seem to pull the same rpm as before, but the mid range is better (cam timing?).  Plugs are running cleaner, and the exhaust has a nice sharpness now.  Transmission is sh#t.  Just not down shifting well.  Too many times it wouldn't shift down, and the rpm's were then too low exiting.  Good news was that it would pull out of it, although slowly.   Lots of time lost.  Changed the pivot point of the shift pedal (drilled new hole) to get my foot deeper.  That improved things somewhat.  Will have to go through the clutch before the 1st race.

Biggest issue was the front end.  I'm now sitting back about 1 to 1 1/2", and deeper.  I've taken weight off the front end, and it's pushing badly on rights.  Lefts are only slightly better.  Still pushes, but I can spin the back wheel, and get it to rotate.  Have some other shocks, and am going to try a longer one, to shift weight back onto the front.  The bottom bushing(s) aren't quite right, so hoping I can reuse the ones from the current shocks.

Added some venting to the front (letterbox slots) to try and cool the head area better.  Photo tomorrow.

[scottly]

scotty - Test day report.  Carb settings are very close.  Doesn't seem to pull the same rpm as before, but the mid range is better (cam timing?).  Plugs are running cleaner, and the exhaust has a nice sharpness now. 

So the accel pump is in the ballpark? No farts or sneezes when whacking the throttle, even when coming out of the turns at too low RPM?
The higher RPMs might be a bit soggy with your mains plus the added high speed enrichment?

[Tintop]

scotty -

No pulls OK, just like if you tried to pull away from a light in 3rd gear and the carb(s) is right.  When it's in the right gear it's very crisp.

Yeah that's my thought re the mains.  Might try the 190 air, and see what happens.  If that helps could go step down to 135 main, and maybe 180, or 175 air (from 185).  I'm also going to index the plugs, but later.

[scottly]

scotty -

If that helps could go step down to 135 main,

Are you currently running 140 mains? If so, I would try 135, with no other changes..

[bear]

[quote author=Tintop link=topic=102875.msg1372

Biggest issue was the front end.  I'm now sitting back about 1 to 1 1/2", and deeper.  I've taken weight off the front end, and it's pushing badly on rights.  Lefts are only slightly better.  Still pushes, but I can spin the back wheel, and get it to rotate.  Have some other shocks, and am going to try a longer one, to shift weight back onto the front.  The bottom bushing(s) aren't quite right, so hoping I can reuse the ones from the current shocks.
[/quote]

If you have some front end adjustment increasing your trail a little may help if you want to maintain your ride hight with the shocks.

Cheers,
Brian

[Tintop]

So Day 2's report.  Was on track with the SRA's sidecar school.  About 8/10 bikes, split between F1's & F2's, all with rookie passengers.  I was the only vintage for most of the day.  Eat them up in the corners, but got left on the straights.  Made passing somewhat of a challenge.

Changed the top P/U position of the rear shocks.  Made them more vertical.  Seemed to help.  Front end works well (for a sidecar ) on turn-in when I can get some weight transfer, either with quick app of brakes, or throttle roll-off.  Problem is  when I get back on the gas, the front end is unloading.  Had my passenger change his foot position in rights which helped.
Heat cycled the other new rear tire through two short 70% type sessions.  Then did a 5 lap hard session.  Tried slowing down my shifts, and being firmer with shifter pressure.  Helped somewhat, but still not what I want.  Did get through turn one with only a slight roll off on the turn-in, then back on the gas.  Pinned in 4th before the apex.

Now that the engine is broken in , I'll reset the idle.  Checked plugs a couple of times and much better than last year.  The Iridiums definitely burn cleaner.  Did get a backfire on over run in the last session, I'll have to check out the source. 

New letter box openings I did at the track.  Need to touch up the paint edges.

[Tintop]

Was a good thing doing the 'test & tune'.  Probably would have had issues at the first race weekend, but found them early.

Looks like I found the chain alignment & handling issue.....swingarm play, needle bearings & sleeve worn.   Replacement kit ordered.   Checked through the clutch.  Two clutch rod parts were worn / damaged, replaced them from stock parts on hand.  Steels are OK, checked on a glass plate.  Do need new frictions, as minimum is 3.1mm, and the best one was 2.95.    New EBC friction plates & springs should be here Friday.

Took some photos of the spark plugs, will post them later for advice.