Malossi BBK for People 50 2T

[chaz35]

pace, post link to 21mm dellorto kit you keep talking about.  Cheers

[paceneedsstides]

I think I saw one at scooterpartsco.com under Malossi parts but you and I would be better of just buying the carb standalone only thing I think that doesn't swap from 19mm is the slide. Needles and jets should be the same on both.

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[paceneedsstides]

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[paceneedsstides]

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[paceneedsstides]

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[chaz35]

Interesting pics of your engine, looks similar to my engine.  Notice piston failed at exhaust port.  I remember a couple of guys saying looked like pre-ignition to them.  I decided it wasn't, but I am not so sure now.

I think barrels are the same for 19mm and 21mm.  Cheers

[chaz35]

pace, how does wrist pin bearing look?, check rod play.  Rod up and down play shouldn't feel any, side to side, very little, less than 1/32", maybe need new crankshaft?  You getting new BBK, or just new piston?

[paceneedsstides]

pin and crank are good this time around I had gotten a very beefy Malossi bearing has almost no play inside piston when installed. I'm gonna buy a whole new kit and install it if this one give me trouble soon then I'll probably need to crack open the case.

[chaz35]

pace, I was talking about testing the rod and big bearing.  I remember you getting special wrist pin bearing, just curious how wrist pin bearing looked.  Mine was in bad shape, but hey, you didn't run grinding compound through your engine, like I did, lol's.

Got in NGK BR9HS plugs, will test tomorrow and report back.

Have been reading some of 245luigi BBK posts, a lot of good info, like another guy verified CHT temps we have been running.  Cheers

[paceneedsstides]

Yeah I've read 245luigi posts and actually talked with him in messages a bit. Also ParaIndiana, Amish Sasquach, and Dr Frankenscoot I got them all on friends list and Club page on Facebook.

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[chaz35]

I know about Amish, but the other 2?  Guess I will have to check out your FB sometime.  Cheers

[paceneedsstides]

Para isn't active on here anymore but he has posted on Like thread and has a bike close to 245 and about what I want to finish with Dr is on 49cc

[chaz35]

I tested NGK BR9HS plug, seemed to be better, I definitely recommend it.  I still hit over 400f, but ran better and generally stayed a lot cooler.  I think something bad was happening with BR8HSA plug, I assume it was getting too hot and had pre-ignition.  I will not be running BR8HSA with BBK anymore.

With carb up to now, I am either too rich and runs bad or too lean and gets hot really fast.  With AU nozzle I can finally get jetting rich enough, maybe too rich?   Carb has 86 main, 40 idle, W9 needle set 2nd notch down.  I think needle a little too rich, so I will lower needle to 1st notch or try W7 needle.  I think main a little too rich, but unfortunately 86 main is my smallest jet, will have to place another order.

Was interesting how throttle response and load on engine effected performance.  Generally, 86 main was OK under a load accelerating or going up a hill, but too rich to cruise.  In the needle range, often better with less throttle, which indicated too rich condition.  I can see where someone racing wouldn't have the tuning issues you have riding on the street.  When I used to race karts, a tuned racing engine normally wouldn't idle, and once you got going it was WOT almost all the time, there was no cruising.

I still think engine needs to be detuned a little.  With different plug, I will mess with the carb a little more before I try detuning it.  Have more ideas how to detune.  I have damaged head from 1st kit I could enlarge combustion chamber a little at a time and test instead of 2nd cylinder base gasket.  Then wouldn't be changing port height, but would still lower compression.  Cheers

[chaz35]

Maybe 1st time did long run and didn't go over 400 degrees, max temp was 394F.

I need smaller main jet to test, but don't have anything smaller than 86, so tried using smaller idle jet.  Dellorto tuning instructions says idle jet effects jetting from idle to WOT and I believe it.  I changed idle jet from 40 to 38, and then to 35 and ran a little better each time.  Still not there, main jet too large, running too rich, but keeping engine cool.  I was consistently cruising at approx 80k/ 50mph, but engine was balking from time to time because too rich.  Max revs 9600 to 9770 as I recall, so was flying a couple of times.

I also noticed effect of ambient temp.  I did 2 long runs today, 1st run was hotter, then cooled down and rained.  Engine definitely running cooler with cooler air temps.

Believe it or not, I am still having a great time with this scooter.  I think have just about got Dellorto carb figured out, and really like it.  I will order some more Dellorto parts and keep trying to dial it in.  The BR9HS plug was huge.  Hopefully, can get carb tuned so engine runs like it supposed to and not overheat.  However, at some point it, if can't keep it cool when it's running right, will have to detune engine.

With a little less compression, engine should still run great.  I know how it's supposed to run, my Super 9 LC runs perfect IMO.  BBK should run the same way, except have more acceleration.  It's been long road, but I am still making progress, and having fun.  Cheers

[paceneedsstides]

I put new kit on lastnight will install engine later today and hopefully begin the breakin again. I may have to check out the cooler plug though I don't have the overheating issues. I think what the hesitation at WOT is is 4 stroking because of being to rich I have heard it can damage engines if happens to often

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