Mid Minarelli tune questions

I'm doing a mild tune on a General with a Minarelly V1. I put a 15 15 on there, with a 60 main jet. I took the cylinder to a shop and had them machine off 1mm from the top. (they took off a bit to much, but I think I can fix it with a gasket no problem). I have a stock exhaust on it and drilled out the first manifold at the back of the pipe with a long drill bit going through the end of the pipe. I have a two piece bi turbo that I have not cut up to make fit. Soooo...

1. It runs, but tops out real low, like at 23 mph, is it becasue I'm not getting enough exhaust out? Do I need to cut up and fit that bi turbo? It runs and idles better than ever, I just killed the top end.

2. Is a 60 about the right jet to fit on that setup?

3. If I put on the bi turbo, I'll open up the exhaust port to match the pipe, but do I need to open up the intake too, or will it really not be a big deal?

Thanks!

Quinton

Re: Mid Minarelli tune questions

Definitely open the intake port up to match your intake manifold. Then tune.

Re: Mid Minarelli tune questions

Open up the intake and exhaust port. Raise the exhaust port by about 1mm and drop the intake the same. WIden them both about 2mm-ish. I did alot of playing around with my 50cc cylinder before going to the 75cc kit and had it running at 33, up from about 25mph. Put on a pipe------>Best addition.

Re: Mid Minarelli tune questions

because of the machine shop bit, check your piston to make sure it is clearing the intake and exhaust ports correctly, if not correct it with gaskets.

for jetting, do plug chops and rejet accordingly. you may just be running too lean or too rich and thats whats causing your problems.

you don't have to open the intake if you open the exhaust, but like tim said, you really should.

are you running a 15mm intake? if not you arent using all that carb's potential. youre not going to see great performance improvements runnning a 15mm carb into a 12mm intake then a 12mm intake port.

Re: Mid Minarelli tune questions

general should have a 15mm side ways intake on it stock

mines all stock and goes over 30 so sounds like you have a problem prolly way too rich

Re: Mid Minarelli tune questions

I believe I have the 15 mm intake. I have the engine on the bike, then bought a parts engine. I did all the machine work to the cylinder I pulled off the parts engine so I wouldn't screw anything up too bad. The intake on the orriginal has a much wider opening and exits to the side of the engine, where the parts bike has a manifold on it with a much smaller diamiter opening, and it exits to the front of the bike. The inside diamiter is different on the two of them, but the outside is the same, and the carb fits nicely on both.

I don't think I changed how the piston clears the ports becasue I took all the extra material off the top of the cylinder, so the piston never reaches the area i modified.

I'll open both ports up, see how it works, then maybe move those ports down and up respectively. Thanks!

Re: Mid Minarelli tune questions

When you're talking widen the ports, are you going 2mm on each side, or 2mm wider all together? Thanks a ton! Port timing is not something I know a lot about.

Re: Mid Minarelli tune questions

Its a air pump. The ore in the more out.

Re: Mid Minarelli tune questions

Thats not much... its .080

Re: Mid Minarelli tune questions

if you are just widening you aren't messing with port timing just port area- do 2mm on each side. if you want to mess with port timing lower your intake window by 1mm and raise your exhaust window by 1mm. as long as your porting is consistant between the intake and exhaust (lower intake/raise exhaust) then you are golden.

for the 15mm carb i would put a decent puch pipe on that mounted on the other side versus a crappy biturbo. and yeah make sure that intake is 15 cause if it is not then all your efforts are wasted. good luck.

Re: Mid Minarelli tune questions

I think a #60 is too small. I am running a bored out 14-12 and I am running a #68.

Re: Mid Minarelli tune questions

60? 68? Seriously? I am running a 15.15 and a Mamba and I run a 59 jet. I might need to be a little higher, but if it was super lean I'd have seized already. I haven't done a real plug chop with a fresh plug, but a I got a nice brown coating last I checked. I max out around 33-34 and have way better acceleration than stock. Quinton I think you need a lower jet, I was doing a 56 when I had a 15.15 and a stock exhaust, I don't know what effect your drilling will have on the situation.

Re: Mid Minarelli tune questions

Although, could my advanced timing be making it run better lean than properly jetted? I am like 50 degrees past TDC.

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