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Post by scootwerkz on Apr 3, 2012 22:16:17 GMT -5
Sorry guys, I've been busy with work. I did get the engine. At first glance, when I opened the box I thought it was used. It was so dusty and dirty, but after cleaning it and opening it up, it's definately new. So far what I've done to it, was take the head and cylinder off, so I could get the oil pump out and remove the gear from it. After my original pump took a crap. I figured I'd go with premixing now. While the cylinder was out I was going to chamfer the ports, but to my surprise they already done! Then I installed my 70cc head. After reading all tech posts from 90gtvert, which are super helpful. Thank you 90gt! I went on to the exhaust and cut my flange off and port matched it, and also made a slightly bigger diameter header pipe and installed the exhaust. Oh and I drilled a port in the crankcase so I can use the vacuum fuel pump which uses the pulses in the case to operate. That's what I've done so far. Hoping to install the engine this weekend. Oh b4 I forget, I do have a question. I recently bought a koso 28mm carb. And now I'm wondering if it'll be too big. Can I still use it, or has anyone ever used one b4?
Dave
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Post by reveeen on Apr 4, 2012 3:03:33 GMT -5
Koso/OKO, same difference.... PWK copy. You might want to have a few jets around to dial in the carb. It ships with: main jet 138, idle mixture jet 38, not sure if you got one with a "power jet", or not. (most seem to plug the power jet as it is kinda unpredictable) Picture of one with a power jet: www.minimotoscene.co.uk/forums/showthread.php?50906-Has-anyone-tried-a-PWK-carbs-on-a-minimoto(the tube from the float bowl to the air inlet horn on the air filter side of the carb) Jets can be a problem, both the physical getting, and the price. Any Honda dealer can order you PWK jets (CR250), the "problem" being they likely don't stock them, as new bikes are all fuel injected, and they will likely charge you $16 EACH. I have bought (in the past) jet assortments from this guy: stores.ebay.com/Autotech355-Performance-Parts10 different in a box for $20... usually you get them in 10 days, or so. Depending on the air filter you use will dictate the jet you need. For example: on a 70cc vertical, slightly ported, modded chamber exhaust, 6 petal reed block, K+N air filter, 24mm OKO with power valve, I'm running a 112 main/40 idle. I would consider a 138 too big, but it may not be for your application, so try it I guess? This guy seems to have his "stuff" together about OKO carbs: www.miniriders.com/carby-tuning/23986-those-about-rock-buying-oko-flatslides.htmlBUT: remember... these folks are talking 4 stroke engines (you are pumping at least twice as much air).
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Post by 90GTVert on Apr 4, 2012 11:59:14 GMT -5
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Post by scootwerkz on Apr 4, 2012 18:03:30 GMT -5
Thank you reveeen and 90gt for the great info. Definately answered my question and then some. I was wondering about the jet size too. Wasn't sure if, because the carb is bigger and letting more air in, then the jets would be bigger than using a smaller carb. And I found that answer too. Thanks again. Well I'm excited about trying to get it running this weekend and I'll let u guys know what happens.
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Post by reveeen on Apr 5, 2012 2:55:41 GMT -5
Probably, if the truth be known, we are both running too big a carb. As with a car, you have to be careful the bigger you go, as they tend to lean out quick @wot (that is kind of the idea behind the "power jet" thing bodged on the front of that carb picture I linked to). So, really no harm will come of running too rich (other than it will run like crap), but crossing over into lean unknowingly @wot, for extended running, WILL hurt stuff.
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Post by racerbugg on Apr 7, 2012 11:36:47 GMT -5
scappy says this is no longer avail. guess you got the last one
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Post by scootwerkz on Apr 11, 2012 1:34:21 GMT -5
When I called to ask about the engine they said they only had 2 left. I guess they weren't lying. Well I finally got it running, but having a hard time tuning the carb. The carb came with 3 jets, but they dint have any size markings on them. And I don't have any jets bigger then a 115. But after reading more of project 90 and the carb tests that were done. I decided to order a 21mm dellorto. Sometimes I wish I wasn't so impulsive. Lol.
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