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Post by Enviromoto on Jul 29, 2009 9:54:36 GMT -5
This winter I hope to launch another business idea. Custom race motors fully built ready to install. Then only then after I test and tune one will I sell it. Ill let all the other fly by night guys sell the stuff that makes your motor go boom. I plan on sticking around for awhile and I care about my reputation more than I do money.
If things go well I will be setting up shop in gasoline ally and I will be building custom scooters for all the race teams pit bikes.
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Post by 2strokd on Jul 29, 2009 22:13:01 GMT -5
That would be sweet!
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Post by felliott on Aug 20, 2009 15:56:14 GMT -5
We have replaced several crankshafts with the 80+cc kit on them. One with less than 2000 miles and one with only about 500 miles on it. The 2000 one used synthetic oil and the other one did not. Both rode them like they stole them. I personally have not had any bearing problems with the 72cc kits.
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Post by wildfire on Sept 10, 2009 8:56:08 GMT -5
I installed a 80cc kit on my qmb139 49.5cc. This was done after the original crank bearings went bad after 9000 miles. It ran good for a week then I lost compression and it wouldn't start. So I reinstalled the 50cc top end and it ran good for about 2 weeks until the crank began making noise. I fear that the 80cc was too much for the crank. I decided to stay with the 50cc, increase to a #80 jet, and 10g rollers. Before the crank started to go, it wolud cruise at 47mph. I didn't have the same take-off as the 80cc but it still is good performance.
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Post by 90GTVert on Sept 10, 2009 9:06:20 GMT -5
Thanks for the input. It's nice to have some real experiences documented rather than just hearing not to use the 80cc+ kits.
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Post by wildfire on Sept 10, 2009 16:43:32 GMT -5
I was thinking of using a 72cc camshaft instead of the factory 50cc. Since I cannot get compression with the big-bore kit, can I substitute the 72cc as a performance cam, and if so what should I set the valve clearance? I would think .002 intake/.003 exaust should be fine?
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Post by 90GTVert on Sept 10, 2009 19:07:21 GMT -5
There shouldn't be any difference in the cams that wouldn't let you use either. I used .003" and .004" for valve clearance.
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Post by wildfire on Sept 11, 2009 6:46:24 GMT -5
Thanks for the gauge info. I have also found out that a #85 jet will idle but , with a load put on the 50cc it is too much fuel. I haven't decided to fiddle around with the airbox yet. I Thought about putting both a hotter coil and CDI along with an iridium spark plug. A good balance between dependability and performance is what I am shooting for. My downfall is I haven't found the ideal combination. I love to tinker with my scooter!
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kliff
Scoot Junior
Posts: 5
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Post by kliff on Sept 15, 2009 5:37:47 GMT -5
Everything I've heard on these bearing failures, 72cc or 80CC plus traces back to crankcase clearancing with a dremel tool, WITHOUT taking the engine apart. Then praying to the gods it was completely cleaned. And when the bearings failed, we'd NEVER blame it in installation procedure, but on overstressed parts.
I'm going to pick up a new 50cc scooter this morning, I will be building 2 engines, a 72cc street/strip, and an 85cc strip only. But mine will be completely apart, then clearanced with a fly cutter I custom made. If you're gonna do it, you gotta do it right. If you didn't do it right, think twice before labelling weak parts.
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Post by 90GTVert on Sept 15, 2009 6:04:40 GMT -5
Welcome to the site Kliff. Thanks for stopping by.
Anyone that's tried them have any rebuttal for Kliff's statement about clearancing? I know my 2 stroke will be clearanced for the crankshaft and cylinder bore by a machinist. Of course it has to be apart to clearance for a crankshaft anyway. Like Kliff, I don't trust all those particles that could get into anything.
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Post by 2strokd on Sept 15, 2009 6:22:03 GMT -5
Yea, i agree with Kliff. Nobody goes to the beach for a mouth full of sand...
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kliff
Scoot Junior
Posts: 5
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Post by kliff on Sept 15, 2009 17:48:59 GMT -5
Thanks guys, and I ain't trying to start nuttin.'
Jeremy knows my stand on clearancing for BBK's, LOL....we've been there before. It's just that when I have a part failure, I've got to rule out all variables, before I can say defective part, or over stressed part. Whether I can see the particulate or not, near microscopic fillings can be as damaging, sometimes even more so that 1/8th swarf floating around... that's why we clean freshly machined and deliverred cylinder wall, huh Vert? It the stuff you DON'T see that will jump up and bite you in the arse!
How many times did you scub that Stangs cylider walls down? use everytyhing from soap and water, to solvent, to clean motor oil? Then start all over? been there, still do that. There really is no such thing a a plug & play engine.... just cause it bolts together and runs, don't mean it couldn't run a lot stronger, a lot longer, with the proper TLC.
OK.....I'm sorry, I'm off my soap box.....sorry.
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Post by 90GTVert on Sept 15, 2009 17:56:59 GMT -5
No need to apologize for making good points. We need a a group of dynos so we can test a couple of 70s and a couple of 80s side by side in the same conditions and see which ones give up first.
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Post by 2strokd on Sept 16, 2009 7:36:47 GMT -5
That would be fun! Then we could see hoe long one runs using conventional oil, then see how well a castrol oiled one runs lol. J/K, you are very right Kliff. I made a intake adapter out of aluminum the other day and had shavings all over the work bench. So what do i catch myself doing with the carb and intake adapter with little metal shavings all over? I stopped and thought you dumbass, mide as well shoot my foot while im here. I stopped and got the shop vac and some cleaner real quick. I could have sucked in some metal and not even known it thinking i didnt get any in the carb. Sorry to ramble just saying you have a good point Kliff. Cant be to clean...
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Post by 90GTVert on Sept 16, 2009 8:31:13 GMT -5
That would be fun! Then we could see hoe long one runs using conventional oil, then see how well a castrol oiled one runs lol. Now that's thinkin' with your dipstick. |
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