Getting the Tazland BBK, GEARS, + MLM ran on a dyno

[eclark5483]

I say a goal of testing and reporting configurations that will make it pain free for anybody who wants to do one is always a good thing. Personally, I'd like to see the carb pilot issue resolved by SOMEBODY. It's too bad there isn't a $30-40 new carb on the market that works with the Spree and is easy to change out the pilot just as it is a main. Or an aftermarket intake on the cheap like you can get for the 139QMB engines on hundreds of websites. But I guess that's the game you play when dealing with a vintage scooter.

[MrJumps]

Spree needs more exhaust options, something its always lacked. After the manifold adapters any carb about can be used.

[PolishMoFo]

Thanks for that i will try that for the break in before getting a new carb setup

[eclark5483]

OK, replacement intake adapter from G9 came in today, fits well. Still no intake/reeds from 1man8scoots, so I'm proceeding forward without it.

New piston is in, Polini is pretty much in, should have some more dyno runs coming up soon...

In the mean time, just wanna share a couple images of what beating the heII out of the piston using various oil levels, lean conditions and what not have done to it.

The piston has a bit of scoring on it as you can see in the image. The cylinder itself, is not too bad. Though could use a good honing.

It's still going to Jumps if he wants it.

[Meatball]

Aluminum piston VS Steel bore...we all knew who'd lose that battle...It actually looks like my piston did after a handful of soft seizes. Surprised it never locked up on you even once...I bet it was close tho.

[eclark5483]

Actually, it DID lock up.

Check out this video at the 30 second mark:

https://www.youtube.com/watch?v=Qnf-bt6L3Bo

You'll hear the back wheel lock up.

That run we got a loss in horsepower from what the 2nd and 3rd run showed. Peak horse when it did 40mph was 3.04 or something like that. And that was WITH a scored piston. So I'm betting there is way more horsepower then that, that can be made.

[Meatball]

Its a tell tale sign of heat spikes. As temps rise very quickly, the softer metal (piston) expands faster than the harder (steel) bore which causes the piston to become tight in the cylinder and begin to bind. Thus, causing scoring on the walls of the piston until ultimately it seizes. Its pleasing to know that the connecting rods are over-engineered in a sense that you rarely hear of rod failure.

If temps were to rise/lower at an acceptable rate, the steel bore would be able to "catch-up" with the much quicker expansion of the piston and never bind or score. Its the heat spikes that are the killer with these.

My bbk experience with a cht showed very normal temps all the way up to full throttle. Once there, temps shot up faster than my wrist could react. My cht was actually skipping big gaps of numbers while trying to catch up with the rising temps. Im thinking now how I should've recorded it to see exactly how it all unfolded.

[Meatball]

Not sure what different set-up you had for those runs opposed to previous. Was it just an oil mixture change? I would love to see what the temps are doing during these runs.

[eclark5483]

Hopefully, the new Polini, along with Jump's deleted oil pump, will address that. If not, there is nothing else to do but swap the engine I suppose.

[eclark5483]

Not sure what different set-up you had for those runs opposed to previous. Was it just an oil mixture change? I would love to see what the temps are doing during these runs.

The first set of runs,(1-5) it was 64:1 in the tank plus oil pump. In those runs the plug was fouling which I'm sure contributed to the lean conditions.

[Meatball]

Well, since these so-called "air" cooled engines are, in fact, cooled by liquid (fuel) then you may have some success in a different carb. We've tried to up-jet the stock carb to the point of muddy rich and that didn't help so maybe the stock carb is inadequate NO MATTER the main jet size? Time will tell...in the meantime I will be

[Meatball]

Just a thought for you, eclark. Taking into consideration your ultimate goal of your Son's enjoyment with this build, have you considered:

Adjusting the throttle to limit its functioning range? Have it set so even at full twist its only pulling about 3/4 actual throttle. The bbk seems to run fine at 3/4 throttle and if high speeds is not what your Son needs then I believe it will hold up at that level just fine. It may limit him to only achieve 30-33mph but it would stay in a safe operating temp for him with all the benefits of the added torque. Just a thought.

[eclark5483]

Actually to update on THAT, my boy has finally been using the blue TaoTao. He still wants the Spree home, but I'm hopeful now that he will stick to the blue scooter. If he does I'll be able to do what I want to do with the Spree and finish the restoration and use it as a show bike. Have already had an offer of $3000 for it that I promptly turned down.

[MrJumps]

How is that battery box lid looking? I shipped it pretty hastily, had no choice but hope it showed up intact.

[eclark5483]

Haven't put it on yet, been too busy at work to bother. I'm gonna try scanning that sticker on it so I can have the guys make me a new one... might just paint it too. Actually, I'm still in the market for a complete set of stickers. And that's the thing... if it wasn't so hard to track down a bunch of holy grail parts, I probably would have taken the dude who offered me $3k for it up on his offer and just used the money to fund the other Iowa Spree I'm looking to do with the variated AF05. At least this one has the petcock cover on it so I won''t have to spend upwards of over $100 from some rip off artist on eBay looking for a premium payout. So yeah... THANK YOU for the cover. Considering what I've seen other's charge, it was a steal.