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Post by scooter on Nov 3, 2014 23:24:52 GMT -5
I have been eyeballing one of these case boring tools. Although I have not found instructions for using one, it looks rather simple. I believe the idea is to set or bolt down the tool onto the case using the holes in the tool,  then adjust that tool insert, in the center, to your bore diameter,  and then use a slow drill to bore out the case.  It looks super easy and probably only takes a few minutes. It's a little pricey at $150 but, if you are handy with a bench grinder, you could probably make that tool bit last forever, but they have new bits for under $20. The drill powered case boring tool. Have you tried one? Do you want to? Well, do ya?  |
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Post by rcq92130 on Nov 4, 2014 0:57:44 GMT -5
My ex-wife was a boring case, to be sure.
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Post by tvnacman on Nov 4, 2014 7:18:33 GMT -5
I have and have used it . The one I have is a little different . It's tricky at best to use .
John
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Post by toddmaples on Nov 4, 2014 7:40:05 GMT -5
I have and have used it . The one I have is a little different . It's tricky at best to use . John Would it be easier to split the case and grind on it if I'm already installing a stroker crank? |
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Post by tvnacman on Nov 4, 2014 8:33:37 GMT -5
The connecting rod will be in the way if you do not remove the crank .
The shavings get everywhere , if you were to do it free hand I would still split the case to clean out all the passages .
John
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Post by dmartin95 on Nov 4, 2014 17:35:43 GMT -5
Do these things work for the crankcase and the cylinder?
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Post by tvnacman on Nov 4, 2014 17:59:39 GMT -5
Do these things work for the crankcase and the cylinder? look at the jug , the round cylinder sticking out needs to fit inside of the lower case . When referring to boring out an engine it means enlarging the hole that the topend and block meet , the topend/jug slip into the block . John |
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Post by rcq92130 on Nov 4, 2014 21:15:44 GMT -5
Mr Martin Just to make sure - here is what we are talking about. When you get a BBK, you get a set of parts including a jug (cylinder liner), a cylinder head (where the valves go), a piston, etc. :  The jug - the part housing the piston when it travels up and down (driven by the crankshaft and connecting rod that are inside the crankcase - is the part that must fit inside a hole in the crankcase. The problem is the hole that is standard in a GY6 engine is pretty small, and most serious Big Bore kits will not fit into it:  So the hole must be enlarged so the BBK jugs can fit in the hole. THAT's what is meant by "bore". When you buy a BBK you get a cylinder lining (jug) and piston that are already the correct size for what you buy. You do not need to do anything to the jug you buy other than install it ..... presuming the hole in the crankcase is large enough (bored out, if you are getting anything larger than a 60mm BBK). You don't need to bore the jug. What is required to bore out the hole to a large enough size is either: (a) take it to a machine shop; or, (b) get a tool, remove the 4 head bolts (I think), attach the tool, spin it with a drill ... and the tool cuts a slightly larger hole. The big job with either (a) or (b) is you need to open the crankcase halves and remove the crankshaft, etc --- cause aluminum shavings will go all inside and they will need to be cleaned out. Hope this helps. |
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Post by dmartin95 on Nov 5, 2014 1:59:48 GMT -5
Mr Martin Just to make sure - here is what we are talking about. When you get a BBK, you get a set of parts including a jug (cylinder liner), a cylinder head (where the valves go), a piston, etc. : The jug - the part housing the piston when it travels up and down (driven by the crankshaft and connecting rod that are inside the crankcase - is the part that must fit inside a hole in the crankcase. The problem is the hole that is standard in a GY6 engine is pretty small, and most serious Big Bore kits will not fit into it: So the hole must be enlarged so the BBK jugs can fit in the hole. THAT's what is meant by "bore".When you buy a BBK you get a cylinder lining (jug) and piston that are already the correct size for what you buy. You do not need to do anything to the jug you buy other than install it ..... presuming the hole in the crankcase is large enough (bored out, if you are getting anything larger than a 60mm BBK). You don't need to bore the jug. Hope this helps. Yes, that is quite helpful..... Is the only way to get a bigger piston is by purchasing a BBK? Is it possible to get a new jug for my existing cylinder? I was thinking I would just bore out my existing cylinder (jug), but apparently that's not how it's done....?? To further expand on this topic, if I decide to go with a stroker kit - do you know if they sell tall cylinders for A-case scooters (54mm stud spacing)? The stroker Kits I have seen come with spacers.... I have seen some BBK's listed as "tall cylinder", eliminating the need for spacers.... However, the only tall ones I've seen have been for the B-case (57mm stud spacing)..... My ideal find would be a 63mm, water cooled "tall" BBK..... |
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Post by rcq92130 on Nov 5, 2014 2:14:02 GMT -5
Screw boring out the cylinder liner! A new jug + mated piston + rings + wrist pin costs about $70 delivered (and that for a decent high compression piston. Why fark around with anything else?
As for stroker stuff --- ask Alley. I know nothing about that; he nows everything about everything scooter related.
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Post by dmartin95 on Nov 5, 2014 5:33:15 GMT -5
Screw boring out the cylinder liner! A new jug + mated piston + rings + wrist pin costs about $70 delivered (and that for a decent high compression piston. Why fark around with anything else? As for stroker stuff --- ask Alley. I know nothing about that; he nows everything about everything scooter related. Does anyone know what the stock height of a gy6, 150cc "jug" (or maybe it's technically called the cylinder) is? I've been trying to find out by looking up "stock parts".... From what I've discovered, the stock 150cc overall height if the cylinder is 89.5mm. Now, some of the high quality BBK stuff such as Hoca and Taida I have seen has an overall height of 93mm...... That gives an extra 3.5mm.... In addition, the stock cylinder may have an extra mm or two........ Not sure, hoping alleyoops or someone else knows..... I like the idea of a stroker, I don't like the idea of shims......... |
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Post by scooter on Nov 5, 2014 6:28:39 GMT -5
The "Bore" in "Big Bore Kit" means the cylinder bore is larger. That is not the same "bore" as boring out the case to accept the larger cylinder.
As it was explained to me at one shop I visited, they would add spacers, or shims if you prefer, between the case and cylinder to make room for the longer stroker crank. We're talking 8mm here. A little over 1/4 of an inch. Closer to 5/16" really. (.315") That's all I know about it.
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Post by scooter on Nov 5, 2014 6:33:21 GMT -5
Do these things work for the crankcase and the cylinder? No. It is made to bore a very short hole. |
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Post by xyshannen on Nov 5, 2014 12:58:03 GMT -5
I have to admit, I've never really looked at these things. Figured you either need a lathe to use it or it was a gimmick. If it's as simple as bolting it to your case and using a slow drill, and it works, it's well worth the price. That is if you plan on running the GY6 platform for any real length of time.
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Post by RapidJim on Nov 6, 2014 10:00:26 GMT -5
I wish this tool was around when I did Alleys motor, the machine shop hit us for over $120 to bore the case. Scrappy also sells this tool www.scrappydogscooters.com/125_150cc_Performance.html . Now mind you, the machine shop I used took their time and made sure everything was jigged straight and custom fit the cylinder to the case. They also hot tanked the cases when they were done, saving me the time of cleaning it myself. As far as stroker cranks go, a lot depends on how wild of a stroke you go over stock.. The smaller strokes only require adding a base gasket or two. I have seen where people do all the measureing and math and get a machined spacer. I didn't see where they got it from. You have to be sure that you have the correct clearance between the piston and valves otherwise you will not like the results when you crank it, bent valves, cracked pistons ect. As RCQ stated, boring the cylinder to fit a larger piston is a waste of time for the average consumer unless you have a machine shop full of tools. The price of Big Bore Kits is very reasonable and and saves a lot of time effort and cost. We are not talking boring a car motor out here LOL.A 59mm replacement piston, with rings, wrist pin and gaskets will run you $50, the complete kit (good quality) will run you $100 (reference www.scrappydogscooters.com/125_150cc_Performance.html) A machine would charge in the neighborhood of $125 just to bore out 1 Cylinder because of set up time. |
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