Malossi BBK for People 50 2T

[chaz35]

Raising carb needle made difference, think all needs now is larger main jet.  Still had high temp >400f, but very controllable, running a lot cooler, takes awhile for temp to build now and cools off fast when back off throttle some and let revs come down.  I may order some larger main jets or enlarge what I have when torch tip cleaner set gets here.

Scooter really fun to ride, has huge acceleration, great top speed, high rpm was >9700.  Top speed should get better if I install Malossi torque driver, which I probably will.  Going to be really fun after I get it dialed in a little better, and ride with son-n-law's PCX150, I think may surprise him.  Cheers

[paceneedsstides]

My Engine Blew up on me circlip came out and tore top end up not pretty at all. 1000 miles on BBK have ordered new one and other stuff plan to install next weekend.

[mclark999]

That's a bummer

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[chaz35]

pace, sorry to hear about bad luck, will be very fortunate if same thing doesn't happen to me.  I checked circlip several times, but who knows?  2nd one should be a breeze to install, after practicing on 1st one.

If mine blows, probably would do it again, BBK's rock!

[paceneedsstides]

Yeah I need the staying power the BBK provides for hills here on every damn road in Charlotte. I think internals are ok can't see any damage ain't cracking case just gonna go with it. If it don't work and I got to crack case will just build some nasty awesome fast thing lol. But yeah up until it blew with 1K no issues at all great power and still not tuned good lol I bought some more stuff than just BBK so hopefully will have oil pump operating again and a cutom cable eith 90 degree bendy on top of Dellorto Carb. I KNOW CHAZ WILL WSNT GO SEE THAT INSTALL LOL. Plus I got a different needle and a couple jets to try to get 2T atomizer and bushing to work in carb eith out running too rich

[chaz35]

Torch tip cleaner set came in, I bored out main jet some, and went for ride.  Still not there, but slowly getting there.  I am still getting >400f CHT, but I am pushing it harder and harder.  My goal:  cruise at approx 80k or 50mph without overheating.  I am cruising 60 to 70k no problems, with huge acceleration and >50mph top speed, much above 80k/ 50mph just seems thrashing engine, doesn't sound good, probably way past carb size.  This scooter is different ride than my Super 9 LC,  which I ride WOT most of the time.  This one can't ride WOT nearly as much, would have too much speed.

I got the WYPO Standard set Tip Cleaners for <$6 shipped.  The #17 tip cleaner was the next size larger than the 108 main jet installed (the largest Keihin equivalent main jet available from jetsrus).  I can buy 110, 115, and 120 Keihin OEM main jets, but thought I would try the tip cleaner 1st.  The #17 tip cleaner is equivalent to .043-.045" or drill size 57.

Was still running hot, so I bored it out to the next size #18, ran better still, but still not there.  So, next will try the next larger tip cleaner #22.  Hopefully, #22 will do it, because the tip cleaners start getting really large, difference between #22 and next size #24 is a lot, looks like would be too much, but I don't know.

I think part of the problem is gearing is too low for the HP this BBK is making.  It feels like I have power to go 70mph, but I just run out of revs, 9700rpm max so far, don't really like to turn that much.  I can tell CVT varies rpm depending upon how much throttle I give it.  If I go WOT engine will turn more revs at 80k than if I accelerate to 80k with less throttle.  Still gets there fast either way.

I did some more reading on max temp and think 400f is OK.  There's not much out there about it, same motorized bicycle info, and some ultra light plane info too.  I am consistently hitting over 400f briefly, highest last ride was 414f, and no problems.  It always happens when I am on a long run, with a car behind me, so I push it a little more than I would like.  I think main negative, probably have more engine wear at higher temps, but makes more HP, runs better.

I have also started keeping track of oil consumption and gas mileage.  I was surprised mileage was initially approx 66mpg, which indicated lean to me.  As I have enlarged the main jet with the tip cleaner mileage has dropped, <60mpg now, probably approx 55mpg.  Hard to know exactly, but have enlarged 108 main jet from approx .040" to >.050" and next tip cleaner size #22 is approx .055", that's a big difference.

Today air temp was cool, approx 50f, next few days will be warmer, will be interesting to see effect of warmer air.  Jetting should be relatively richer, so should run a little cooler from that effect, but don't know if will be offset by less engine cooling effect from higher air temp?, we will see.  Cheers

[chaz35]

Bored out main jet with tip cleaner from approx .044" to .048" and went for long ride.  Engine was really staying cool, so I did my country road ride.  Went >400f once, just backed off some and cooled down fast.  Was cruising 80k/ 50mph at high 8000revs, low 9000revs, sounded great, ran great, max rev's >9700.

Ring flutter sound less noticeable, I guess caused by lean condition, I am glad it's going away.

Will bore out main jet one more time to approx .050".  I am getting comfortable with the tip cleaners, but will probably buy some mini drill bits, probably size 56,55,and 54, to bore out jets faster, tip cleaner takes some time to enlarge the bore.  When hot weather gets here, may need smaller jet, I don't know.  Next time I order something from jetrus, will get the 120 main jet to compare, I suspect it's too small?

I am very pleased with it now, seems like all the trouble was worth it.  This thing runs fast, is blast to ride.  Cheers

[paceneedsstides]

sounds like you're dialing it in nice man I got BBK instealled again and about 70 miles on her so far so good so seems like case and crank are ok . I'm glad you're getting that temp down I ordered parts for my carb when I got BBK and got beefier needle bearing so far so good. I got W7 needle for casrb and installed the 2T bushing and atomizer have lowed my jet to 40 idle and 92 main but still tuning as I don't take it over half throtttle yet. Idle seems good I will be upjetting on main try  96 or so the 2T stuff makes you go way down on jets on the Dellorto compared to 4T aomizer. The W7 needle is supposed to better for 2T and it's definitely alot fatter so less fuel going to engine. I also bought new parts to connect a splitter and started running oil pump again instead of premix. I know we both had issues now but looks like we're getting them dialed in too bad you ain't out this way we could ride together the Malossi/tecnigas crew lol.

[chaz35]

pace, thanks for update.  Can you post link to beefier needle bearing?, wrist pin needle bearing?  Yes, too bad not closer, we would have some good times riding scooters, for sure.

I hogged out the main jet again to approx .050", changed the slow jet to 45 from 48, and had my best run yet, max temp stayed under 400f, was 399f lols.  I was running it pretty hard, only slowed down a few times to keep temp under control.  Air temp seems to be more critical than jetting in keeping engine cool.  As weather gets hotter, will probably need to run larger jets to control temp.  I ordered some mini drill bits to drill out my jets, and they also might come in handy to measure what I have (sometimes the marking on the jets is very hard to read, for me anyway).

High revs is staying around 9600rpm.  Runs really nice, just roll on the throttle, and pulls great.  Idle is funky, varies depending on how hard engine was working before I stop.  Sometimes, wants to do fast idle for awhile, maybe 3000revs plus, then will drop down to 2000 or so.  If I turn down the idle, then will idle too slow, less than 2000, like 1700rpm.

Have another idea to cool off engine, decrease compression a little.  Can add another cylinder base gasket to raise the cylinder, which will lower the compression ratio, and raise the ports a little, which may help it run higher revs.  As the engine wears in, compression will drop off anyway.  Probably won't do this adjustment unless I have to, because carb jetting appears to doing it now.  Cheers

[paceneedsstides]

still seems to me that you may be running lean still especially at idle I had that same issue when I went down to 40 idle jet but on Dellorto you can asdjust idle fuel and air and I was able to fix that I like to idle about 1850 to 1950rpm. The bearing I got is longer than stock it sticks out on both sides of crank and just fits inside piston with a very small amount of free space. to me seems like less chance of slapping back and forth and so on here is link.

https://scooterpartsco.com/malossi/malossi-master-part-list/malossi-wristpin-bearing-for-piaggio-12x17x16?zenid=tgj268mrdj4ugsvhlqee02llm2

[chaz35]

Thanks for link to wrist pin bearing.  I was looking for one wider like that.  Downside, a little more weight going up and down with piston, but don't have to worry about small end of rod running on less than full bearing surface.  I will definitely get one, next order to scooterpartsco.

Yes, I am still running lean.  It's amazing I haven't damaged the engine, I bet it has zero carbon buildup lols.  If I had more $'s and time, might try running it hotter up to 450f to see if can take it, but not that brave, 400f is pretty scarry IMO.  Without CHT probably would have stuck it long ago.  Will bore out main jet again soon, plus try dropping needle some, and install next size smaller slow jet 42, I think running too rich at less than mid throttle now.

I ran it WOT for awhile couple of times last ride and seemed to hold steady 380 to 390F.  Headwind and hills put more load on engine and it responds with heat.  With tall wind, no heat problems.  Cheers

[chaz35]

I checked my gas mileage and oil consumption.  I kept records for 8 fill-ups, almost 9 gals gas.  Mileage was approx 50mpg and oil approx 2.2oz per gal of gas or ratio of 59 to 1, a little surprising.

Fortunately, I add approx 1oz per gal each fillup at the gas pump, so I am running over 3oz per gal oil.  After I thought about it, makes sense oil pump would be delivering less oil relative to gas.  It's pumping the same quantity of oil, but engine is using more gas, mileage went from approx 60mpg to 50mpg.  Also, since only getting 50mpg, I often have to drive slow to make the gas last to the next gas station, which causes the oil pump to pump less oil.  If I wasn't driving slow from time to time, I guess mileage would be less, and maybe oil consumption a little more?

I reset the oil pump so it bottoms out at WOT, set it to pump the max quantity of oil.  I will test again to see what difference it makes, if any.

I am waiting for mini drills to come in and I will bore out main jet to .052" from .050" and see how it goes.  Cheers 

[paceneedsstides]

My guess is you're gonna run oil rich doing that and gunk up kit and exhaust. It happened on my OEM kit the dealer either didn't know how ot tune it or did thst for breakin and I was getting way to much oil. Have you put the Dellorto on yet?

[chaz35]

You may be right about getting too much oil.  I will monitor, see how it goes, easy to adjust back.  What oil do you run?  I like to run good quality full synthetic, have found with experience quality of oil makes big difference.

Haven't installed Dellorto yet, still messing with my OEM Keihin.  This thing runs like a scalded cat, as is.  I am very happy with performance, if can just keep it cool.  Horsepower makes heat, mine is making heat.  I suspect won't really run any better with Dellorto, except probably make higher revs which would be good I guess.  Also, Dellorto would probably get better mileage, better carb over the full range from idle to WOT.  Cheers

[paceneedsstides]

I run Castrol TT RS I think is the name of 2T full synthetic it's one of the cheaper good brands and as many miles as I put on my scoot can't afford the $15 or higher a quart stuff. I was in Houston and working for Royal Purple still like I did in my mid twenties when they were a small start up I'd be set I see they make an injectable 2T but I like Castrol never had an issue with them. I think it would help cool you down a tad if you put that Dellorto on I never had an overheating issue with BBK since Dellorto was installed before BBK and with 4T stuff struggled to get it around 375. Now with 2T atomizer and bushing and W7 needle instead of W216 that came with it I got it almost dialed in just running rich on top half of throttle but at half throttle can get good RPMS and 50ish top speed flat.