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Post by Elektrey on Dec 22, 2014 1:10:16 GMT -5
I wanted to do some other things to my scoot while I had it apart as well.
I wanted to paint the crankcase. Will the outside of the case get hotter than 200 F ? or will I need heat resistant paint.
And is it as simple as unbolting the wheel and sliding it off, or will I need an impact/more tools for removing the wheel? the disc brake is already removed.
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Post by Jwhood on Dec 22, 2014 1:32:46 GMT -5
Wheel should come right off,as the temp of engine case im unsure of!!!!
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Post by 2TDave on Dec 22, 2014 6:06:55 GMT -5
I use engine paint rated at 500-600* on my cases. The auto parts stores have a good selection. I'm not sure of actual case temps but my cylinder head temps have reached into the high 300s.
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Post by Elektrey on Dec 22, 2014 18:30:01 GMT -5
Does anyone know if the "JOG Minarelli 1E40QMB 2stroke performance intake manifold reed valve" listed here fits on an r50x/morini engine? www.scrappydogscooters.com/50cc_2stroke_Performance.htmlTwo more Qs: Will I need to switch to a higher grade of fuel for a BBK because of higher compression? Running 87 now, no knock. Will I need to switch to a cooler plug? Running BPR7HS right now. |
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Post by Jwhood on Dec 22, 2014 22:35:30 GMT -5
no that will not fit,polini is the only one that makes one for the morini that im aware of
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Post by 90GTVert on Dec 23, 2014 9:17:02 GMT -5
Will I need to switch to a higher grade of fuel for a BBK because of higher compression? Running 87 now, no knock. Will I need to switch to a cooler plug? Running BPR7HS right now. Not sure about that specific kit or Morini timing. Most end up over 150psi cranking compression for me and require premium. You could lower compression or ignition timing if running regular is a must, but you should get more out of it with higher compression and standard timing. 7-9 is the common range for these small 2Ts. 9 to me is reserved for high end/racing kind of builds. 8 has worked well for me in anything from stock 49cc to I guess midrace 103cc and I'm WOT on long stretches a lot. 7 will likely work, but if you notice spark knock try an 8 (and/or higher octane fuel if you're using 87). |
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Post by Elektrey on Dec 23, 2014 19:38:30 GMT -5
I don't mind buying premium it's just that I already have a full tank of regular and hate to waste it. Might as well buy premium though it's so cheap now. I'll have to find a gas station with multiple pumps.
As far as spark plug I might as well buy a new one anyways as the one I have is pretty dirty and I can't be bothered to clean it. Probably will get the 8.
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Post by Elektrey on Dec 26, 2014 21:24:15 GMT -5
I'm wondering what to do about the crank.
Is it RPMs that would cause a crank to fail, or the sheer amount of horsepower going through it? Because I'm pretty sure I wouldn't go past 10k with the gearing I have. 10k would probably be 55 or somewhere near and I don't ever go that fast on roads around here (if I can achieve that with this kit).
Stock crank I've read was "weak" and could take 10k rpms, thats where redline is.
Scrappydogscooters sells a crank kit for $110 shipped that is unbranded. Asked them about RPM and they said that it depends on the setup but they wouldn't recommend running past manufacturer redline.
I can get a naraku crank and seals shipped from europe for $140 and I read somewhere that it can do 12.5k RPM.
My problem is I'd hate to spend almost as much as the 70cc kit cost me if I'm not going to need an upgraded crank.
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Post by 190mech on Dec 27, 2014 5:29:25 GMT -5
Like all 2T engines the rod big end bearing cage wears causing the rollers to get crooked,then stuff goes to poop real fast!Some of the racers comment on just routinely changing out the cages and not anything else on high end road racing 2T's..Every shot crank I pull apart has worn/broken cages and slanted rollers...If you cant find a quality crank,maybe try to find a known quality rod kit and have it installed on a stock crank.
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Post by RnDmoto on Dec 29, 2014 4:27:19 GMT -5
maximum speed of a crankshaft/engine is dependent upon reciprocating mass EG. the weight of the piston/rings/rod etc. The heavier the reciprocating mass, the more weight it must stop and accelerate up and down per revolution. a big bore kit would bring down the maximum rpm allowed, but usually the porting and expansion chamber tuning will not allow an overrev anyways as power will drop off before exceeding redline (unless you are over revving going down hill or gassing it on the centerstand) Cranks usually fail at the big end bearing. The bearing does not spin in one direction, it actually changes direction for every turn of the crank. This causes skidding and heat. Race cranks usually use silver plated big end bearing cages which dissipate heat. Main bearing failure is almost non existent anymore with quality bearings and lubrication. TGB cranks failed in the past because the press fit tolerance was too loose and they simply came apart, no matter how they were revved. ScrappyDog worked with an exclusive factory in china and developed a tighter, yet more economical crank that does not come apart like a stock crank does, and are less expansive than tgb cranks. I cannot speak for a Naraku crank as I've always used our crank for testing and builds.
I think the most important thing is to watch your revving on downhills, always use the best quality 2stroke oils, and keep good maintenance.
as a last note, i thought r50x's used a different crank than the standard tgb 2stroke?
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Post by Elektrey on Dec 29, 2014 16:51:23 GMT -5
Interesting info. my crank seems to be in perfect shape so far so maybe it is a different one. I will install the BBK on it and pay close attention to it. I think with the kit and pipe it shouldn't exceed redline but I will see.
On a side note, I got the new BPRH8S plug. It's funny because I found this:
lmao
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Post by 90GTVert on Dec 29, 2014 22:40:08 GMT -5
Maybe if there were an additional bit of info added, like 75-100HP per liter.
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Post by Elektrey on Jan 3, 2015 0:33:17 GMT -5
  Kit came in today. No need for chamfering there were no rough edges everything seems really well made. Ring was gapped at 0.20mm so no need to change anything there. I installed the whole thing just need to check squish. It was actually really easy to install. It came with 2 base gaskets one thick one thin, and a metal head gasket and a rubber ring gasket for the head. I put the thick base gasket and the rubber ring on. |
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Post by 2TDave on Jan 3, 2015 7:45:44 GMT -5
What kit is that? Sport pro MKII? If so it looks like it's changed since I got mine. No small bearing? S6 recommend a 9 plug for mine and it came with a few aluminum and a copper base gasket along with a thick paper. I think I used 2 of the thin ones to get .7 squish.
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Post by Elektrey on Jan 3, 2015 18:23:39 GMT -5
I got somewhere around 0.65-0.75 squish with the thick gasket and the rubber head ring.
It's the Sport Pro kit, I don't think there exists a MKII for the morini. Pretty sure they don't make it anymore and this is very old stock I got. No small bearing, I just reused mine since it was in really good condition.
Threw it all together today and ran it.
115 Jet - no starting
110 Jet - starts but doesnt rev
105 Jet - starts and revs but doesn't get very high, no accel
100 Jet - better revs but still rich
95 Jet - better power got it to 49mph full throttle, when I slowed down it wouldn't rev again. Pushed it home and spark plug was black, probably fouled, need to clean it.
Will continue tuning tommorow. It shifts 7-8k and still feels like it wants to wheelie from a start, I feel like with rollers it would do it.
So far so good.
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