|
|
Post by drawkward on Jun 10, 2010 22:34:01 GMT -5
I think it's got 50cc specs when it comes to the crank. I have a 90cc crank that was cut down to fit 50cc parts. Kind of a shame, really.
I am pretty confident because I got a variator fan that was meant for a QMB that fit right on.
I just got a quote from Carlos on a combined purchase of a 54mm cyilnder kit and a 42mm crank kit. $276.00 including the piston return I just made. That's without shipping (not cheap either). I'm thinking real hard about that link you just showed me of that jog 90cc crank. Really curious. I really want to see if it would be cheaper to just put all stock 90cc parts on it than to buy the upgraded crank.
|
|
|
|
Post by 190mech on Jun 11, 2010 5:02:37 GMT -5
Whats the diameter and spline count on the vari side of the crank?My 90 crank is 15.7mm with 15 splines and the flywheel end is 16.8mm at the big end of the taper...
|
|
|
|
Post by 2strokd on Jun 11, 2010 8:09:48 GMT -5
I think it's got 50cc specs when it comes to the crank. I have a 90cc crank that was cut down to fit 50cc parts. Kind of a shame, really. I am pretty confident because I got a variator fan that was meant for a QMB that fit right on. I just got a quote from Carlos on a combined purchase of a 54mm cyilnder kit and a 42mm crank kit. $276.00 including the piston return I just made. That's without shipping (not cheap either). I'm thinking real hard about that link you just showed me of that jog 90cc crank. Really curious. I really want to see if it would be cheaper to just put all stock 90cc parts on it than to buy the upgraded crank. Almost be worth giving one of these a try outta the box? www.partsforscooters.com/90cc-2-stroke-1PE40QMB-Engine |
|
|
|
Post by 90GTVert on Jun 11, 2010 8:14:31 GMT -5
Good point. It would be pretty close after shipping and additional parts.
|
|
|
|
Post by drawkward on Jun 12, 2010 0:07:11 GMT -5
I just need to go ahead and make what I have work. The only problem that I'm worried about is the gap around the cylinder skirt between the skirt and the carters. I have a feeling that it is not letting it seal properly.
My new plan is to get the existing cylinder shaved down at the base to be the right height. I believe that's my only problem. The piston is just about the same distance below the ports as it is below the cylinder top (~3mm). I'm going to get 4-5mm shaved off. I don't want to have to go back and pay again to get it cut down more. I can always double up base gaskets. I'm also considering NOT shaving 3mm all around the cylinder skirt to help it seal to the carters properly. Do you have any guesses of what this should cost to get it done professionally at a shop? I've never done anything like this and I have NO idea what to expect.
|
|
|
|
Post by 190mech on Jun 12, 2010 5:18:28 GMT -5
Cutting the cylinder base will alter the port timing,making it milder.If youre gonna have it done,I'd take the time and put a degree wheel on to see exactly what your port timing is now,then cut the proper amount for best performance.Should have 182-185 degrees on the exhaust port and 127-130 on the transfers for good street performance..
|
|
|
|
Post by drawkward on Jun 12, 2010 16:52:26 GMT -5
I made a degree wheel, but I was having problems using it. I'm guessing because I was trying to use it on the variator side of the crank. I'm having difficulties taking off the flywheel after removing everything else already  I guess I could just pick up one of those strap wrench things I keep seeing at HF Tools and impact the nut off while holding onto the flywheel with the strap wrench. So yeah, it's impossible to use the degree wheel on the variator side of the crank... no? |
|
|
|
Post by 2strokd on Jun 12, 2010 17:07:56 GMT -5
Just center it up and bolt in on the flywheel with the fan screws. You can make your own start stop
(0 degree-what ever degree) points on the wheel. The total open duration of the ex and trans is all you really need.
|
|
|
|
Post by drawkward on Jun 12, 2010 17:16:44 GMT -5
Good advice! Thanks.
|
|
|
|
Post by 2strokd on Jun 12, 2010 17:22:38 GMT -5
No problem, your welcome :cheers: |
|
|
|
Post by drawkward on Jun 12, 2010 17:43:01 GMT -5
Exhaust is open just about 203 degrees, transfers for about 160 degrees or so.
Now if I cut down one mm, how much does that change my timing? This is all very new to me, by the way.
|
|
|
|
Post by drawkward on Jun 12, 2010 17:49:30 GMT -5
I just raised the cylinder 1 mm and checked the timing difference. It seems 1mm is about 5 degrees or so. So I'm thinking if I cut down 5mm (and use a base gasket) that I will end up with 183/140. But this doesn't seem right. Mech, you said I should have 127-130 on the transfers. Now how would I go about fixing that problem??
|
|
|
|
Post by 90GTVert on Jun 12, 2010 19:18:56 GMT -5
You can't really just say 1mm = x Degrees. Try marking 5mm below the top and bottom of the ports and then see what numbers you get when using those marks as your port roof and floor.
|
|
|
|
Post by 190mech on Jun 12, 2010 20:55:02 GMT -5
The transfer ports are the guys that must be set up right!Exhaust port is easy to mod once the transfers are dialed in.Like Brent said,mark the cyl at the points and see what you have,another way is to zero the degree wheel,run it down to 90 degrees,make a small scribe mark(using the top of the piston as a straight edge) next to the exhaust port,then go on down to 115 degrees and make a mark next to the transfers.Measure how much the transfer tops are above the scribe mark,that should be ABOUT what needs to be machined off.
|
|
|
|
Post by drawkward on Jun 13, 2010 0:14:36 GMT -5
You can't really just say 1mm = x Degrees. Try marking 5mm below the top and bottom of the ports and then see what numbers you get when using those marks as your port roof and floor. What is a safe way to scribe the cylinder, without having to buy expensive cylinder ink? Could I just use a pencil if I clean it out nicely? |
|
I guess I could just pick up one of those strap wrench things I keep seeing at HF Tools and impact the nut off while holding onto the flywheel with the strap wrench.