J-Madd Posted December 23, 2006 Report Share Posted December 23, 2006 I don't have pics right now, but heres a link click here. They have an added intake port above the two stock ones. The casting is chipped on one cylinder port exposing the steel sleeve. About 2 mm is exposed probably. The chip is where the port enters the cylinder. What is the significance, if any of this slightly damaged port? Quote Link to comment Share on other sites More sharing options...
wesw Posted December 23, 2006 Report Share Posted December 23, 2006 (edited) i dont see anything that your talking about. all stock ones have the boost port about the reg intake ports. is that what your talking about. Edited December 23, 2006 by wesw Quote Link to comment Share on other sites More sharing options...
J-Madd Posted December 23, 2006 Author Report Share Posted December 23, 2006 I don't have pics right now, but heres a link click here. They have an added intake port above the two stock ones. The casting is chipped on one cylinder port exposing the steel sleeve. About 2 mm is exposed probably. The chip is where the port enters the cylinder. What is the significance, if any of this slightly damaged port? You can't see it in the e-bay picture and I didn't realize that stock cylinders had that port. I haven't looked at a stock set in a while. Yeah that is the port I am referring to. Quote Link to comment Share on other sites More sharing options...
J-Madd Posted December 23, 2006 Author Report Share Posted December 23, 2006 Never mind. I'm a dumbass :shoothead: . The casting "chip" is just where the sleeve is exposed and it's on both cylinders. I thought I saw it on only one cylinder, therefore assuming it was a chip or flaw of some sort. However, I am open to suggestions on jetting for these with stock carbs (for now),K&N clamp-ons and +4 timing. I know it is highly variable with porting, but a safe place to start would be a help. Thanks. Quote Link to comment Share on other sites More sharing options...
J-Madd Posted December 27, 2006 Author Report Share Posted December 27, 2006 Ok. We got these pistons and cylinders installed. The used pistons were marked left and right. The compression is 60 psi in both cylinders, but compression feels fine at the kick starter and it starts on first kick. We put in huge main jets (410s) to be extra safe, and of course it runs like crap. I haven't rode it so I can't describe the running condition exactly. The pistons and cylinders both appeared to be in great condition. I e-mailed the seller and he said the topend was tight when he tore it down. Another reason to beware of e-bay. He told me that the rings had to be installed incorrectly or a gasket is leaking. I know the rings are installed right, hell you can't get the jugs on if they're not on correctly. We're gonna spray soapy water around the head and base gaskets and check for bubbles upon kick starting. We did re-use the gaskets (this is not my engine, I would not have done this), but the gaskets looked good. Note: The compression tester is accurate. We tested my Cub and got 160 psi. Quote Link to comment Share on other sites More sharing options...
sheefreak Posted December 27, 2006 Report Share Posted December 27, 2006 Something is going on w/the tester. At 60lbs you could drag it around behind a truck all day and it wouldn't start. Air leak at the base gaskets won't affect compression so I wouldn't concentrate there. I would try the compression test again and make sure you hold the throttle wide open and kick the shit out of it till the needle stops moving. Quote Link to comment Share on other sites More sharing options...
Dinner Posted December 27, 2006 Report Share Posted December 27, 2006 (edited) Maybe it's just me, but 60Psi is way to low IMO. You should re-ring it at least or something. Edited December 27, 2006 by Dinner Quote Link to comment Share on other sites More sharing options...
wesw Posted December 27, 2006 Report Share Posted December 27, 2006 60 psi sounds like they are junk or something is wrong. you need to check ring gap. and mic the jugs for straightness. i wouldnt run it unless it had 120 psi with the 20cc i see in your sig. jetting yeah thats way to big. try 27.5, 4th clip and some 360 work down my guess. but first fix your compression stuff. Quote Link to comment Share on other sites More sharing options...
sheefreak Posted December 27, 2006 Report Share Posted December 27, 2006 But wouldn't you guys agree it is not going to start on first kick if compression was actually at 60PSI. I wouldn't go diving into the motor yet. Quote Link to comment Share on other sites More sharing options...
J-Madd Posted December 27, 2006 Author Report Share Posted December 27, 2006 This is not any of the motors in my sig. It has a milled head (0.020'') that gave another motor 150 psi, K&N clamp ons, Toomey T5s and +4 timing. As far as the compression test; the throttle was held open. In fact, we first tested it without the carbs even on it. The tester would have to be good. Immediately after we tested this motor for about the 5th time, I tested my Cub motor and got ~160 psi. I'm thinking now that it may be the ring gap, but as mentioned, why the hell does it start first kick? Keep the thoughts coming!! Thanks. Quote Link to comment Share on other sites More sharing options...
J-Madd Posted December 28, 2006 Author Report Share Posted December 28, 2006 Ok, put in 350 mains (what we had in with stock cylinders) and same shit, no power. Every thing mentioned above is still true. Could these cylinders have a bore that tapers toward the top whereas they pull through the carbs then lose compression around the rings at the top? I do not have any explanation for this shit. We're taking it back apart and to a machine shop to check it out. Quote Link to comment Share on other sites More sharing options...
J-Madd Posted December 29, 2006 Author Report Share Posted December 29, 2006 I'm trying to give the seller the benefit of the doubt as best I can. Here's his response. Please comment if any of his statements may be true. If this is something stupid I'm overlooking that would be great. " have no idea what you are doing wrong. These came off my personal drag banshee. I ONLY reason I took them off, is I bought a cub. These ARE high compression cylinders!!! The piston to cylinder clearance is LESS than .002!! This is IDEAL! This has to be an air leak! Head gasket, base gasket, & CRANK SEALS, or leaking between case halfs. Check these thing out. If its not the gaskets, its probably the crank seals. Hope this helps. Chad" And my response: "A crank seal would only affect one cylinder at a time, unless it was both crank seals, in which case crankcase oil would enter the right cylinder, which has not happened. Crank case seals would not lower psi to 60. Base gaskets would not lower psi to 60. The head gasket is not leaking. This was a perfectly good running motor before we swapped top ends. I have posted on Bansheehq.com and no one has answers there either. I believe that the cylinders have been bored more or honed too much since you took the motor apart. There is no ring groove, so I'm sure they have been honed since then, which is normally ok. Are you sure your machine shop or whoever honed it didn't take too much out? I'm no mechanic, but I've put together my share of Banshees. I have a stock stroke 68 mm Cub, and am currently building a +4mm 68 mm Cub. These cylinders were purchased for a friend who was to pay me back. If I get these to a machine shop and they check out, I'll quit hasseling you about this. Thanks" Please help me argue my case or prove me wrong. Either way I just want to know what's up with these pistons/cylinders. Quote Link to comment Share on other sites More sharing options...
sheefreak Posted December 29, 2006 Report Share Posted December 29, 2006 Have you checked the squish? What about ring-end gap? I still cannot understand how it will start w/that low of compression, it just doesn't add up. Quote Link to comment Share on other sites More sharing options...
FredMW Posted December 30, 2006 Report Share Posted December 30, 2006 Any chance the pistons are for a long rod (795 series) and you are using them on a stock rod and stroke? Quote Link to comment Share on other sites More sharing options...
J-Madd Posted December 30, 2006 Author Report Share Posted December 30, 2006 Any chance the pistons are for a long rod (795 series) and you are using them on a stock rod and stroke? Finally the guy says "I was thinking last night. What crank are you running with these pistons. The weisco pistons are 795 series, witch are for a 4mil stroker crank. If you are running stock stroke, this is whay you have LOW compression." But I sent him a message a few days ago that said: " The rings are installed properly. I will spray soapy water around all gaskets and kick it over to look for a leak. You can feel plenty of compression upon moving the kick starter, it just doesn't show on the gauge. The gauge is good, we checked another motor and got 160 psi. We even have put a milled head on your cylinders. This is with a stock stroke crank, if that matters. Thanks so far for your help. I'll let you know how the gaskets test out." He never responded in regard to the stock crank. Maybe he didn't read it. But it was not listed in the description. Should we: - Try to get money back and go ahead and go with Cubs and new pistons - Keep the shit and buy +4mm crank Quote Link to comment Share on other sites More sharing options...
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