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

[Meatball]

Im waiting for the post where you say it pops wheelies and goes 50.....ha!

[eclark5483]

Dyno test is scheduled for Thursday at 1:00. Also my last day of work for 2 months (HOORAH!!)

Gonna start dismantling my other Spree and prepare it for it's Iowa State themed makeover. Since my Hawkeyes themed one is up at the shop, decided to use the new one to test fit the hand guards I customized.

[Meatball]

You should get those lights to trace back and forth like Night Rider

[eclark5483]

OK, final results are in.

We did 2 runs, in the 2nd run, it died out, assuming soft seize. Aborted any more testing. Wanna give this new piston a proper break in and not beat it up like we did the first one. Got the RPM's up pretty high though, so a soft seize was not unexpected (DON'T TRY THIS AT HOME KIDS).

But anyway, with the added Polini carb, ported SB50 intake and reeds, it made a HUGE difference in how fast it took off on the dyno. Stoich air fuel was right where I was wanting it to be, and I'm pretty happy with the results. All that's left now, is put it all back together and give it a proper break in. Peak horsepower is looking to be about 2.47, max torque is coming in at 3.24. Looks as if it reaches it's peak at around 28mph.

I'll probably take it back up in the spring after its had a proper break in period and run it a little harder, see if we can get max speed posted for everybody.

So anyways, here is the final video.

https://www.youtube.com/watch?v=Xr3m1_i4g64

And here is the Dyno data.

[Meatball]

reminds me of my experience with that bore...hit the throttle and the speedo jumps up to 20...then 30...then 35-40!!...then 0

to sum it up in a word....buzzkill

[eclark5483]

Eh, I don't know about buzzkill, but for sure, we can conclude you have to be VERY, VERY, VERY gentle on the break in. Peak horsepower, I am assuming, is very different depending on the gear ratio you are using. I would think using a lower 13T or 12T gear, will yield you more horsepower. It's just a given that changing gear ratios to a higher gear will take away your total power.

So what would it output with no gear changes? Ya know, maybe I might just find that out as well. As I have said in another post, I have another Iowa Spree that I am doing in an ISU theme. I'm in the process of course of hunting down all the parts I will need for the transition, and I tentatively have the variated AF05E engine I want to swap into it. But.. after getting the results I have off this Hawkeyes version I am doing now, I am pretty tempted to just keep the original engine in the ISU restore, and even keep the original 12T gear so that when paired with the BBK, MLM, and Polini/SB50 Intake/reed combo my take off would just be insanely quick. Horsepower/torque values would also change to a higher value on the dyno (I am assuming).

So with that being said, I might NOT do that engine swap to the variated AF05E, I might just keep the stock engine for the other Spree and make that one into the beast it can be using stock 12T gears.

G9 predicted HP of about 4.5-5.5. I don't think he was wrong if you use the stock 12T gearing. The Taz gears show something much different. But then, that is what one should expect when they do a gear swap.

For now, the dyno testing of the BBK is officially over, and hopefully Taz has gained a bit of insight on his BBK as well. But I don't think the final word/judgement on it is over. He has an AWESOME BBK, and I REALLY, REALLY appreciate him sending me a free replacement BBK and sending me free pilot and main jets to test them with. Aside from the recommendation of being VERY VERY gentle with break in, I stand by what I had told the other guy on my feelings about the BBK.

If you are going to run a Tazland BBK on your Spree, break it in with the AIRBOX. Use 6 - 3/8ths inch holes drilled into it just past the inlet. Do NOT try running it with just a pump. If you want to keep your pump, use 96:1 in the tank. Better yet, 80:1 for break in. Without pump.. 32:1 in the tank. You absolutely CAN NOT run it without additional oil in the tank. I think these basic guidelines will help everyone have a more trouble free experience using the BBK without having to buy a Polini carb, or SB50 intake/reeds. Stoich air/fuel is what I am basing this opinion on. Not horsepower or torque.

[1man8scoots]

What was the og hp vs ported cage and intake? I'm inter3dted to know the % increase

[Meatball]

We know that an "unbroken" bore has an additional amount of friction which equals additional heat. Easily seen with the naked eye by looking down a new bore and seeing its criss-cross type markings on the inner walls. A break-in period is basically meant to "finish" the honing process by means of millions of strokes from the piston/rings, therefore reducing the overall friction (heat) created by said stroke. We also know this is why additional oiling is recommended during this process.

My question: are you saying that the only reason your final run ended in a soft seize was because the bore wasn't broken-in? Like the additional heat from it NOT being broken-in was the cause of failure? Or are you going to completely break-in the bore to 100% certainty before you confirm or eliminate this possibility?

[Meatball]

I ask this because I went through the break-in process very carefully. Heat cycled 10 times with full cool downs. At least 70 short trips of about 1 mile each at varying speeds, never going over about 3/4 throttle. This process was painstaking and consumed a lot of my Summer to complete. Lots of putting around at 10-25mph. My bore looked smooth as glass when I decided it was ready...

[eclark5483]

What was the og hp vs ported cage and intake? I'm inter3dted to know the % increase

Page 1 there is an image of a stock Spree on the dyno. I'll have to look at back pages and find the image with what it was just the old carb and intake.

EDIT: Here ya go, top image is stock Spree,middle image is with stock carb/intake using a 90 main. Bottom image is Polini/SB50. No idea what's up with the power/torque discrepancy .vs Polini/SB50 setup, but the curve is more consistent..

[eclark5483]

We know that an "unbroken" bore has an additional amount of friction which equals additional heat. Easily seen with the naked eye by looking down a new bore and seeing its criss-cross type markings on the inner walls. A break-in period is basically meant to "finish" the honing process by means of millions of strokes from the piston/rings, therefore reducing the overall friction (heat) created by said stroke. We also know this is why additional oiling is recommended during this process.

My question: are you saying that the only reason your final run ended in a soft seize was because the bore wasn't broken-in? Like the additional heat from it NOT being broken-in was the cause of failure? Or are you going to completely break-in the bore to 100% certainty before you confirm or eliminate this possibility?

Yes, I think the problem was the rings & piston was too new. The run was the very first time it was started after the piston swap. Lots of potential for heat, especially since we revved it up to almost 10k. I wanna give it a decent break in before stressing it out like that ever again. Stoich was CLEARLY perfect. Oil was 32:1 with no pump. It started right back up, popped right off, idled fine. I was able to rev to about 5-6 grand and it went back to idle just fine, no noted A/F problems. So aside from dying after taking it to almost 10 grand, it ran/runs like a champ. So by process of elimination, I have to rule it as a soft seize attributed to not being broken in at all. Keep it cool!! I have a CHT gauge on it. If it gets over 280 during break in, I'll shut it down just to play it safe.

[MrJumps]

What does your plug look like? If your stoich is right your jetting is probably a little lean for a 2 stroke. Actually some guys say to run the oil amount you always will run because if you over oil than 32:1 during break in your not lean the airfuel mixture then your gonna be over oiling the bore, so when you finally switch over to 32:1 or lower than your "break in period amount" its gonna be running with less oil and still breaking in again. Ive been told many times to avoid using anything difrent then 32:1, and I think Jennings even said to run what gas and oil mix you run throughout the life of the bike from day one. If you wanna run extra oil, you need to jump both jets up a size to compensate for the leaning out it will do, that would be the safer way to add oil, but I feel the regular friction is needed to break it in, if you "cheat" and take away friction during break in, I feel you are only making the bore either weaker or it will break in very slowly and you will think youve broken the bore in but it still spikes. Ive seen this first hand, easily 20 heat cycles out of the way and a few light rides, went to lean into it the first time with fat jetting and my temps soared. Scary sight but killing the motor wont help either. When you kill a motor thats over heating you remove its coling source and if your moving (oil) will be cut off too. I would stay running and blip your throttle and come to astop and watch temps if they dont drop fast your jetting is too lean if they drop fast back down and the bike never stalls your better off then taking the chance of killing it and letting the rings stick. Again been there done that, scars the bore, ruins your rings imo, rehone and rings at least if not a piston since the old one probably is now pinged up from the heat.


Your heat seize is a lucky one, normally on a new bore that sizes it locks solid, ruins the crank, makes the rider go down hard. Never fun to hear about a new motor seizing. Imo I would pull the plug and scope it to look at the piston at least and if you have a 90* lense give the walls a look.

[eclark5483]

Ya think I should jet maybe a tad higher then? Can't remember what size of jet G9 said ships with the Polini. I'm thinking he said it was a 102, maybe it was 108. So I suppose I can grab a set of 100-118 jets from SSS. Stoich was right, at least when looking at where a 4 stroke should be and going lower. 4 stroke would be best in the low 13 range, 2 stroke needs to be a bit lower. I suppose I could shoot for a more lower 12 number like 12.1-12.4.

[eclark5483]

Thanks, I'll remember that next time. From looking at the video and comparing it to the chart which has speed at the bottom, I did a freeze frame, and I believe you are correct about peak RPM power.

[eclark5483]

Guess I'm not especially worried about over revving, my son ain't gonna go but 15-20 on it tops. Least not right away. It will take alot of time to progress him to going faster.... but....

Almost done