Some ZS167FML questions for racing sidecar

[Jibberwobble]

I'll sort a photo today.

Yes I have a nice selection of small drills but didnt have them with me. I know jets are supposed to be more than just a roughly drilled out hole but as you say in desperate times these little tricks can get you out of the dog doo.

I'm going to head for a selection around 140 kinda size which seems rather huge to me but hey! If I can get it on a dyno with lambda sensor I'm sure it would be a quick excersize to get it right.

Also do these gearboxes play up when very hot? There's a number of other small issues with the gear change that could be messing it up but sometimes not even a running drop kick would get it into 5th.

[Weldangrind]

They certainly can. With punishment like you dish out, I'd probably try synthetic 20W40.

[Jibberwobble]

Bloody hell time flies, I need a time machine! Life got in the way again.

At the last round we settled on a 135 main jet after a 137.5 showing just a hint of over rich at the end of the straight. we are lapping a little quicker now and only half a second or so behind the quickest lap of the weekend, with a small power increase we will be right up there at the sharp end.

The bodywork is completely fubar now after a visit into the scenery and burying the front end in the tyres to the point where the bodywork was squashed flat onto the forks and breaking the front brake lever off. Going to have to blob it back together for the one remaining round this year.

The gearbox worked without fault all weekend.

The exhaust is not very pretty but hasnt snapped off yet dispite breaking an engine mount thumping the chair wheel over the curbs. If you get it right the chair wheel is up in the air before reaching the apex and completely clears the curb.





I stopped looking for a carb after a 32mm unit came my way, unfortunately when I came to start looking at dealing with the manifold I realised it wasnt a 32 at all but was a 28. I feel I need to go up to at least a 30mm so will get back on it soon. Been told that the longer u-shape manifold that I have planned will be good for bottom end torque which is a good thing as pushrod motors are never gonna be screamers.

Hoping to make some updates and repairs over the w/e to the old bucket.

[Weldangrind]

That exhaust looks pretty good from my perspective!

I've been giving some thought to a perfomance cam for the pushrod motors, and it occurred to me that reducing the base circle would have the same effect as increasing lift. Do you know any old-school machinists who could grind a cam for you?

[Jibberwobble]

I had a similar thought myself after remembering doing something like this as a teenager on an old honda engine in a go kart, my mates dad helped me out, he built vintage racing Austin Seven's for a living. I do have a couple of potential candidates to do such a job so it can go on the further investigation needed list.

Cant decide if a 32mm carb is too big or just get a 30 like the one you pointed out. There are KOSO 32's (Keihin clone) on ebay uk for a good price, not sure if a chinky carb is the way to go though hmmm!

[Weldangrind]

That last pic is priceless! "I've knocked a bloody filling loose!"

[katoranger]

I don't think I want my head that close to the ground.

[SpudRider]

Originally Posted by katoranger

I don't think I want my head that close to the ground.

X2!

[Jibberwobble]

Me again.....

Chad (my passenger) has quite a few grazes on the top of his lid now! I remember when I was passengering, the grass would be whipping the top of my helmet and visor with the sky visible by looking down not up. The problems start when the outfit behind makes a late lunge up the inside, hits you and takes your passengers head off. I like my passenger with his head on, its made of solid oak and the low down ballast is very usefull

Just sorting some photos..................

[Jibberwobble]

OK done a little work with the carb side of things, after sorting through some boxes of hoarded junk I came across some lengths of nicely bent ally tube with 28mm ID.

After some investigation, the carb I have been running would appear to be a Mikuni TM28 although it actually measures 27mm at the venturi. The other one I have been donated is a Keihin PWK28 and is 1mm larger. As far as I can tell the PWK is a two stroke carb but so I think is the TM28 I'm already using which runs very well.

However the PWK (pictured below) is physically smaller even though it has an extra 1mm venturi so is the preferred choice out of the two due to the carb being in the way where ever I put it.

Have measured the intake port of the engine and it's also 28mm so I'm thinking to just get by with one of these 28mm carbs for the last round and do some manifold experiments to work out if I'm on the right track before enlarging everything including some work to the intake and exhaust passages.



So I have chopped up some sections of tube and eventually found a shape that puts the carb in a place that less bad than everywhere else I've tried it. I dont know if this manifold will be too long though so have temporarily joined the bits together with some semco hose for trials. The manifold could be shorter with the carb behind the cylinder but would require some impossible bends!



Here you see the TM28 sitting where I've been running it on a tight elbow manifold and the new trial manifold heading off in a new direction.

[Weldangrind]

I'm interested to see the final placement of the carb. Do you intend to have the tubing TIG welded?

[Jibberwobble]

Not sure what is best really? weld the middle yes, rubber sleeve on the carb end obviously, engine end is a quandry. I'm thinking the tube may be a little on the light side to put up with the vibration and jarring.

As it happens the OD of this tube is 32mm so I could potentially use it as a pattern to mould a CF heavy weight tube for a bigger carb once the inlet has been relieved to the same size.

This is with the TM carb that I've been using. if it runs ok with this one I'll put the PWK on as it's physicaly smaller and will be less in the way.

[Jibberwobble]

A little development.

Had a tidy up of the birds nest of wiring thats been cable tied to the battery all year, now lives in a little CF box I made along with a battery tray (still to be secured). Gotta admit I dont understand the wiring, red wires turn into black wires, yellow and green connect to red, and yellow and red connect to green etc etc!! I'm sure the guy that chopped this loom up and attached it to this outfit in it's previous life commented that some things like the on/off switch were working backwards so he changed some things around. It all works though so have just connected it all back the same but in a slightly more organised fashion. Moved to coil and rectifier out of the way too.







Right so I've tried running the engine with the long manifold. It runs but needs some fiddling. This carb has always suffered a bit from a cloud of mixture/vapor chuffing back out of the carb mouth at wide open throttle and it seems to be worse now with the cloud reaching out in front of the handle bars, I can also feel it cooling my hand on the throttle grip as it passes by. I can pretty much pin the throttle with it in neutral and the engine doesnt reach very high revs so the first hunch is that it's now running much richer than it was with the short manifold. Secondly I think I should try disconnecting the power jet pipe on the TM28 carb. I'll have a play with it tomorrow afternoon when I get up, cant ride it at home though so it will just be static testing. Now running short on time as our last 2013 round is at the weekend and the bodywork n mounts are still very broken and need fixing, we may be able to get out on practice day on friday for some testing at speed.

Work calls.... back later

[Weldangrind]

Brilliant box! It should certainly keep the electrical bits cool.

[Wild_Alaskan]

looks like a very interesting racing series!