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Post by ryan_ott on Feb 2, 2015 21:55:51 GMT -5
Long time lurker figured I would put up my current build. I've built a few of these around 2008 but life got busy sold everything off and took care of the family. Things have settled in so back to one if my true loves. Started life as a $200 Vento Triton that is in good shape just needed a rebuild. So why not rebuild it the way it should of started life as. I'm planning on 45mm stroke with 54mm Hoca 8 port cylinder.
Cases were 50cc opened up using wire wheels, carbide bits and flap wheels. Finish came out very nice for what I used. Also did some port matching while I had it open. Checked port timing and they measure 196/ 136 squish is right at 1.2mm. I'll get some pictures up soon.
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Post by 90GTVert on Feb 2, 2015 22:13:41 GMT -5
What exhaust have you got for it? Port timing is pretty aggressive you if it's not a high rev exhaust you will benefit from trying to drop the durations and adjust squish/compression accordingly.
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Post by ryan_ott on Feb 2, 2015 22:18:59 GMT -5
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Post by ryan_ott on Feb 2, 2015 22:31:06 GMT -5
I'm hoping 190mech can help in the exhaust department. This in by no means meant to be a daily driver, I don't think I could fit all my tools in it for work. I'm just looking to see what kind of performance I can get out of it.
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Post by 90GTVert on Feb 2, 2015 22:37:16 GMT -5
Nice. Peace Pipes are great for the beyond sport 90cc+ stuff.
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Post by 190mech on Feb 3, 2015 6:45:18 GMT -5
Looking good!I agree with Brent,perhaps try a super thin base gasket to lower the cylinder which will bring down the durations and decrease the squish too.Is the piston dome flush with the bottom of the transfer ports at BDC?
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Post by ryan_ott on Feb 3, 2015 9:08:57 GMT -5
I have another head that will give me about 2.1mm squish, the transfer ports are a little higher then the piston at bdc. They would be closer if I used a thinner gasket. The bottom of exhaust matches with piston at bdc.
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Post by 190mech on Feb 3, 2015 10:16:55 GMT -5
Ideally the piston should be flush with the bottom of the transfers,this greatly adds cooling to the piston crown as the fresh mixture rushes over it..Exhaust port doesnt need to be flush..8 to 1mm is the squish you want if all the parts are of good quality.
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Post by nelson on Feb 3, 2015 20:34:52 GMT -5
Nice! Cant wait to here it run!
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Post by ryan_ott on Feb 3, 2015 20:57:54 GMT -5
Well after measuring, checking and rechecking my timings are closer to 192/132. I think the cylinder I have is meant for a longer stroke crank. The edge of piston at TDC is about 1mm below deck, the piston is also about 1mm under the transfer ports at BDC. So I either need to get some material removed from bottom of cylinder (anyone up for some machine work) or get a different cylinder. This one was the tall version but PFS had it listed for 45mm stroke. I think it's actually for 46mm.    That must be why the head that came with it had so much squish clearance. Well if Its 1mm to long and the head has a .72 lip on it, head gasket is .5 I should get somewhere between 1.2-1.4 removed for a .8-1.0 squish. |
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Post by nelson on Feb 3, 2015 23:33:58 GMT -5
I shaved the head down 2 mm on my 90 build. My crank is 43.5 and my port timings are very close yours. I have .8 mm squish with 175psi. My cylinder was made for 45 mm stroke but without base gaskets and set up like it is it runs great. Maybe the tall is for a longer rod. I did shave down the crown of my piston to get the timings closer to where I wanted to be.
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Post by birdman on Feb 4, 2015 3:55:21 GMT -5
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Post by 190mech on Feb 4, 2015 5:11:49 GMT -5
Have you tried checking it with no base gasket like Nelson said?That may bring it very close in all dimensions..
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Post by ryan_ott on Feb 4, 2015 6:13:12 GMT -5
I shaved the head down 2 mm on my 90 build. My crank is 43.5 and my port timings are very close yours. I have .8 mm squish with 175psi. My cylinder was made for 45 mm stroke but without base gaskets and set up like it is it runs great. Maybe the tall is for a longer rod. I did shave down the crown of my piston to get the timings closer to where I wanted to be. What did you seal the cylinder with just liquid sealant. I'll have to measure it that way later. |
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Post by 2TDave on Feb 4, 2015 6:32:06 GMT -5
To get my tall Hoca 54mm 45 stroke timings and squish near where you are I had to shave the head, no base gasket and raise the exhaust port. I used threebond for sealing the cases and cylinder.
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