mopeds


Derbi SL build pt2
January 9, 2011, 12:35 pm
Filed under: Projects | Tags: , , , , , , ,

Got the beast running today. We had some little troubles with a bad head gasket then the wrong base spacing, but we got it all dialed in and it fired right up. Runs like a beast! Pretty quick, especially for a 12.12 sha. I can’t wait to get something bigger on there. We have some minor things to do still, but basically its all there. Score!

Sean got his new build fired up and its looking good. Obviously need some more little things, but hey, almost there and it sounds great.

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magnum stuff

So hopefully you say gabe’s awesome polini guide, and I thought I’d show you mine. I’ll be honest, the quality of my work is subpar. The exhaust port is nice, but the intake embarassing. Regardless, it runs really well, and its done stupid speeds, and It’s going to only get dumber.

In the cylinder (exhaust raised a lot, widened a lot, intake opened completely) The little scuffs, one at the rear of the port and the other 2 in front were me not good at using a dremmel.

The intake, again opened up all the way, and I filled it a bit with JB because the malossi 4-petal has a lot of wasted space in there

Transfers opened up just a bit. The most important part is opening up the upper transfers. Plenty of meat on the cylinder, so its un-tapped potential. Also, remember you MUST open up the outer portion of the exhaust port to to actually match the flange of your exhaust. Polini’s are tiny, just a bit bigger than stock, but much smaller than 99% of expansion pipes (except proma circuit, they are a perfect match).

Paz originally built my ZA for some other fella in SF. He didn’t go super deep with the upper transfers, but everything is nicely done. A roller rod was pressed in at the same time. The crank has 2k+ miles on it, so super solid!

Thats my ugly polini. I’d like to get another one in the near future as I worry this one may be slowly heading out. It was seized before I bought it, and there is now a fair amount of discoloration on the nicasil around the exhust port. All the cross-hatching is gone. Compression is OK, but not as good as it could be. That, plus I’d like to re-port another with a lot more care.

So in semi-related news, I’m going to make this thing rip harder than it ever has. Either selettra or HPI ignition (selettra is a few OZs lighter, but I think HPI has a little better curve), and my flatslide mikuni.

I want to race something come april, and even though this probably won’t be competitive, with the right gearing (N8P forever!) it should have really good pull. I don’t want to scrape up my LTD seat or tank, so I’m going to be using a freespirit pan and my spare C5 tank. That plus my disk brake EBRs. My goal is to have it running and semi-tuned by tomorrow. I’ll keep posting. Whistler from the 20th to 27th!



cuperteens race-prep

so while all the other teams seem to be doing all this crazy stuff, we’ve been keeping it pretty low key. I’m just going to accept derbi how it is. I know I could get a lot more out of it with a little porting, but I want to make sure it survives the weekend before I tear into it further. I also would like to mod the clutch more, but can’t afford another broken shoe, so that will also wait. The cdi and zen pipe paired with the disks already make it a fair amount faster than its last appearance in may (in which it earned the 3rd fastest lap time), so maybe it will be alright.

MagnumX is also going to be coming along and has received its own upgrades. 64cc of piston port magic make for some amazing torque. The pipe we made totally limits its top end, but its loud, and pulls pretty well throughout. I’ll probably ride it in at least one practice just for fun.

My brother is upgrading his tomos as I type, polini, 4 petal, etc. Again, won’t be the fastest bike, but it should rip pretty hard.

Justin (blasto) is riding the polini maxi which has a polini kit on it. I think its slow, and his pipe is going to scrape, but it has some amazing throttle response. Tom (broke dan’s arms) I think is just going to be riding speed racer again, but this time better tuned and a tad faster. He has some other builds in the works, but he’s all hush hush and I don’t know whats happening with them. Matt should just be riding his garelli/derbi monster. HPI, zen pipe, 75cc metrakit and a lomat 4 petal with a 24 mikuni makes a super blaster. My bike has more low end, but his mid-range/top end is insane. True blaster steez. No kinked fuel lines this time.

So thats it, no super hobbit/derbi/puch builds or whatever, although I kinda wish we were. I think Tommy and Jimmy should be ripping, but i know choke is working on some stuff too, so we’ll see. Everyone is upgrading and adapting very quickly. I do have leathers and plan to race as long as I’m healthy. I couldn’t walk yesterday, but spent most the day wrenching today, so I should be fine by friday. Either way, I’m super excited for the weekend. A long lost cuperteen returns!