We've got poll threads for 47mm and 50mm+ bore 139QMBs already, as well as a stroker thread, so I wanted to see if we could gather some info on the "qaulity" crank equipped setups from people that have used them. Things like the Naraku HD standard or stock Taiwan made cranks (Kymco for example). This thread is for standard (stock) strokes, not strokers.
Please only vote if you have personal experience with a 139QMB/GY6 50 with a standard stroke crank upgrade.
It would be very helpful to include in a post :
-Crank used -Bore size -Any other details of the setup known -Any idea how/why it failed -Do/did you run the scooter hard or just cruise -Was it "de-tuned" (commonly using heavier rollers to keep RPM down)
You are able to vote twice on this poll, but please only vote once for each upgraded crank equipped engine that you've built. The option is there in case someone has experience with more than 1 build.
Thanks to all who participate. These threads can help us gather information to make better educated decisions in the future.
I had a Naraku crank installed on my 72cc big bore kit. It came from ebay and I noticed it stated 106 or 116 (I think) teeth for the oil pump compared to the other one they do and the chap who built the engine up for me said he had to machine the case to fit the new pump. This was on an old model from 2005. I shall keep you informed how the crank does in the future as only done about 60 miles on it at present.
Last Edit: Nov 15, 2018 16:38:14 GMT -5 by milly: correction
Violet the Vespaclone (lml star 2t 150cc 4speed) with sidecar. LML Cut Down 125cc 2006 It's TYRE'S not TIRE'S A reminder to self, do not buy anymore damn scooters especially Peugeot's ever!
I just put Naraku HD Crank in my QMB139,With 47mmBBK and 47mm head. I was going to use stock head to increase compression but was worried about starting issues. I need the bike to be reliable since its a work commuter 28 miles daily on average.
Post by donaldsonta on Nov 24, 2019 12:07:22 GMT -5
I don't know if mine counts as an "upgrade"?
$50 Goofit from Amazon. Made more sense to replace it two or three times than to trust one of the "high quality" vendors, as I've got burned on a couple NYC and similar parts that end up being the same trash with a nicer package.
My stock lasted about 10k miles being subject to significant abuse (no air filter, torn out rings, ect ) Probably 8k of that with a bbk.
So far I have 2-4k miles on the Goofit with a 72cc piston with stock head, A9 cam, foam filter and straight pipe exhaust with a 100 main jet. It's not super detuned, but I keep the RPMs under 8k. I run 6g rollers in a NCY copper colored variator to a stock clutch with stock springs in it. Stock gears in the back, although I replaced the bearings in the back about six months ago.
I think my compression was around 150mmHg or more when I checked it after crank replacement. I used the same piston and cylinder. I think my Chinometer is sitting around 24k, with that piston having been in since around 12k. (Also a goofit)
Needless to say most of the abuse too the crank, and the scoot in general was sub 12/15k range while I was getting everything worked out. It's a 2007 that I got for free beside a dumpster with a garnished carb and 300km on it.
I'm 6'2" about 190lbs and usually ride with 20 lbs of stuff, 20 mile commute in temps 9°F up to 95°F. 35mph on little hills, 25 in big hills, 45mph on flats. Longest single trip was about 300 miles in a day (2 legs of about 150miles)
Basic sunny style Mando Matrix 139qmb with aftermarket windshield and trunk added.
**2007 Manco Matrix** 72cc cyclinder, stock head, stock carb Foam filter, straight pipe, 100 main 6g rollers, stock clutch and spings, vented CVT cover 10 inch rims Kenda 3.5R10 K329s 23k on the Chinometer, another few thousand unaccounted for.
Not installing stiffer contra springs and installing the taller final drive has saved both belt replacement and cranks on my 52mm BBK build. I have roughly 5k on the odometer since a TOTAL rebuild. I can cruise @ 40-50mph. I do have a 2k stall/compression spring. I strongly recommend this trans setup for riders in hilly areas!
I Bought a taotao pony and i pulled the motor right off the bat and installed the naraku HD crank and a 101octane 72cc 47mm jug and a non egr stock 64mm valve head with a naraku racing cam. I am waiting for a set of rocker arms because the motor came with a 69mm valve head, so when i get that taken care of i can report in how well the motor does. I also used a 101 octane bolt kit, so every bolt is higher quality and torqued/blue loctited. It "should" last a while.
Naraku HD crank 101octane 47mm jug 101octane non egr 64mm valve head naraku racing cam pd19j carb 100 jet stock exhaust K&N cone filter NGK cr7hix plug
Mileage 100km (atm)
Last Edit: Sept 20, 2020 20:44:55 GMT -5 by shizly
Senna1Rossi: Thanks renagade281!
May 23, 2016 14:59:12 GMT -5
Fox: I don't really know how to say this but straight. I am Dave's Girlfriend Kellilee and bluntly and VERY SADLY he passed away early Tuesday morning. I know he would want ya all to know this. Thank You Brent for befriending my love he was very happy on here!
Jun 18, 2016 16:26:04 GMT -5
Fox: www.gofundme.com/29mgf6b8 I hope it is ok to pass on his gofundme page link. If not you will un-post it I'm sure. Thanks again all!!
Jun 18, 2016 16:31:18 GMT -5