72cc Malossi BBK Installed [Questions Tho!!!]

[shiba]

So I got my BBK from Red Etf and after having some bad luck w/ the c-clip and piston ring...i got replacements and got them installed last night...and my scooter runs again!! yay!!

So I've attached photos of a brand new spark plug I've had in this new BBK for maybe a total of 30 min (mostly idle, occasionally giving it some throttle to rev it up a bit)...

Spark Plug after about 30 min use

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This is with an 82 jet if I remember correctly...which I'm guessing is expected since I've read that I should be closer to 90-110 range....sadly, the jet kit I ordered from daywot may not be in stock for quite some time...so i'm exploring other options (probably find a drill kit and hand drill the one i have a bit larger, sounds ok, right?)


In addition, how important is the shroud around the engine.... I noticed that the angle that the plug goes in is not as steep so the plug cover doesnt seat nicely (the shroud pushes against it and i'm sure it would pop off after riding for a bit...).... I've attached a photo for this as well....

Spark plug hole in bad location?

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Is it ok to just take a dremel and cut away some of the shroud to solve this problem....or what is the best solution?? I'm guessing its not ok to just remove it completely...

thoughts, comments...

glad to have a working scooter....its gonna be hard to wait while the thing breaks in...but i think 600 miles is only a few tanks..right?!

edit:
I suppose I should also ask...since I have a bbk now...do i need to step up to premium gas or anything fancy, or is unleaded ok still? same goes for oil (currently have the pump, should i premix as well...or only premix..or is just the pump fine?

any other precautions I may be forgetting since I'm excited to have a working scooter again?

thanks all!!!

[Wheelman-111]

Greetings:

The shroud is Critical. Reposition the hole, and seal the gap with tape or sheet metal so the plug wire donut seals well. Moving air is the only cooling, and leaks anywhere decrease it.

[shiba]

Greetings:

The shroud is Critical. Reposition the hole, and seal the gap with tape or sheet metal so the plug wire donut seals well. Moving air is the only cooling, and leaks anywhere decrease it.

Ok, thats kind of what I figured, but it never hurts to triple check!

Is a dremel the best way, or what other methods have people used?

[Wheelman-111]

Greetings:

Read one way to close up the hole here. I used a hacksaw and a sharp knife, but Dremel is more precise.

[Kevinstonge]

Personally with a 72cc bbk I'd ditch the injector and run 30:1-32-1 premix for the break in period. Others will have to chime in on jetting for a stock Carb for a 72cc setup. I do know that an 82 main seems kind of small, as my 65cc polini kit came with a 90 main and runs great so far(still breaking in).
Are you running a oem carb and exhaust?

[shiba]

Yup, stock carb and exhaust...

Random side question about jets... Does anyone know of any local stores that may carry small enough drill bits for me to drill the one I have out a bit bigger??

As for the plug cap... Turns out the head gasket from the stock bore was a similar size, so I dremeled some plastic off and tapped that on top so the boot sits nicely with few if any gaps for sure to really step out...

After riding around for a total of 15 min (not exceeding 25mph... usually around 15mph) the highest I saw the temp get was 277f... and that was when I let of the throttle, which I'm guessing was just because not as much air was being pushed through to cool the head... Is this temp good? I can set two thresholds on my trail tech vapor... but I'm unsure what a normal temp should be for this ATM :/

Thanks again all!! Super excited to be rolling one again :p

[paulpauly7]

you want to be between 300 and 360

[shiba]

you want to be between 300 and 360

ahh ok, very good to know...i'm guessing that i'm not getting that hot because i have an improper jet size currently? i think so far my max temp i've seen was about 324F or so...

[maddog]

I would change that 9 to1 gear ratio to a 7 to1, this will keep the engine running cooler, also go to a larger carb, the stock carb will fuel starve at high speeds.

[shiba]

Quick update... I just hit 400 miles today... Shooting to get another 100 in before the weekend is over... 500 miles enough for breaking it in??

I've been keeping a log with photos of my trail tech gauge with max rpm and max temp and duration of my runs... May post if it's interesting to someone...

I'm going to try and pull the plug tomorrow and get a photo since I got a 90 jet in there right now...

[deuce217]

Glad its running. What BBK? MHR? Are you running stock pipe and carb? 324 temp is fine. If it climbs above 400 keep you eye on it. Mine will get to about 425 if I am WOT a lot and on lots of hills.

[shiba]

Glad its running. What BBK? MHR? Are you running stock pipe and carb? 324 temp is fine. If it climbs above 400 keep you eye on it. Mine will get to about 425 if I am WOT a lot and on lots of hills.

i just got the normal cast iron, no mhr... stock pipe and carb (jet is 90 tho).... my max temp so far has been 351 i believe...and that was after booking it for just under a mile (rpms were prolly close to 7200 for that period..and the temp spiked when air was no longer being pulled in at that rpm...

besides that, my temps have stayed fairly close to 300f during normal operation...sometimes a bit above...most of the time below due to air...only when i lay of the throttle does it 'spike' up in the 300's...

my max rpm's so far were 8310...and that was only because i had 5/6 weights in...i've since put in 8g's and my max has only been in the 7800 range...usually lower for my runs...

[shiba]

Spark Plug

2013-07-07 12.09_small.jpg (231.99 KiB) Viewed 11523 times

this is the current color of my plug after about 300ish miles, maybe a bit less...all w/ a 90 jet...thoughts? too small of a jet, or?

also, the last few tanks i've started using premix(32:1) along w/ the oil pump...

[shiba]

32:1 mix with 50:1 or whatever the pump pushes, which is 3 ounces per gallong. and yoru mixing, waht 8:1? 16:1?

i have my gas mixed at 32:1... not sure where your getting 8:1 or 16:1...

edit: unless you mean that 32:1 mix in my gas + what the pump is putting out (at 3oz per gal)... if thats the case, then i have 7oz per gal which is like 18:1....which i'm guessing is way too much... so i should probably cut the amount i'm putting in my gas mix some... (say to only 1oz of oil, which would give me 32:1....right?)

i think that makes sense...can someone confirm?

p.s. i've got about 40 more miles until I hit the 500 mile mark...

[shiba]

yea.. the pump, pumps oil into the gas. it mixes for the motor. thats how you have oil and gas mixed.

yea like 3 ounces per gallon. fill that quarter bottle up, and 5 tanks later yo8ur out of oil. its going into the motor. 3 ounces, with yoru 3 ounces you threw in there too.

yup, i knew how the oil pump works never knew the exact amount it put out per gallon tho...so thats always good info

was just confused on where you were getting 8:1

p.s.....down to 16 more miles... should hit that tomorrow on the way home from work