| Author | Message | ||
     Bandito90 |
Well it looks like I'll be pulling the head sometime.Put some oil in the cylinder and the compression went to 210 pounds.I hope the jug and piston are salvageable and it just could use new rings. | ||
| Crackhead |
send the head out for porting then. EZ I didn't know if the b70 with the high comp piston would have interference issues. | ||
| Gearheaderiko |
Bandito: What happened? Any news on your problem? MY 80psi piston:   | ||
| Bandito90 |
Long time since I posted,But I pulled the top end today.And to my surprise it looks like gearheaderikos piston only worse.I'm sure the cylinder is trashed to.I have the stocker.So I'm probably just going to have it checked out and put a high compression piston The bad side is the intake side.Help me out guys what can I do to prevent this again.I assume it was running lean.But did notice material off the head gasket.    | ||
| Gearheaderiko |
Well, since the pictures a little blurry I cant tell for sure, but that piston looks completely TOAST. The skirting looks really tore up. Material off the head gasket is probably just transfer. My pistons skirt doesnt look like that. You only had 80-100 miles on it? I would send a good picture of that (or send the piston) to CP Pistons- I have the contacts name- since it failed just like mine did. (they say to go through the original vender-so you may have to go through NHRS- but I was only 10 miles away). The story I got (from CP) was that it looked like the engine was running too rich which washed away the cylinder walls and the resulting blowby caused knock and ping which overheated the piston until it "chunked" off pieces. Except for the major scuffing on the skirt, your piston looks the same as mine. What I know is that we had some pre-ignition problems and backed off the timing and it seemed to run fine after that. I did notice that the compression was decreasing with time. I did dyno the bike and mixture was right on. We got a lot of miles out of the previous XB set-up which was the same, just not the '515 nikasil'. We got 500 miles out of this 515 (this was racing too). My 10.5:1 CP is doing just fine on my streetBlast with a .015 overbore stock cylinder. I'm very interested why your piston failed the same way as mine. What the jetting was and what symptoms from first start-up you experienced would be very helpful. Also was this an iron lined cylinder (stock type) or 'Nikasil'? (The 2 have different piston skirt to cylinder wall clearances. Standard is .0035, Nikasil is .0015, so its possible it was too tight in the bore, but  ) | ||
| Bandito90 |
The bike started fine and seemed to be okay through the heat cycles.I checked the plug and it showed a good color.The cylinder is the lower dollar NHRS kit.Which is the iron lined as opposed to the Axtell.A friend of mine looked at the cylinder and said to have bore checked.It might be able to be saved.I did have problems with it when I bought it.The piston pretty much did not fit in.I had to ship it back to NHRS.They said there guy might not have honed it right?It could still be a little tight.Like you and my buddy have said.I can't remember the jetting anymore.But it was using specs off the forum.I mean this thing could have been dying slowly from the start.Not long after the heat cycles was when it started blowing major oil and eventually quit running.I still kinda think the cylinder was not machined correctly.I would post better pics,But my cameras are all broken and my phone is all I got. | ||
| Gearheaderiko |
How many miles? The jetting recommended could have been anywhere from a 150 main to a 180 main depending on what they (we?) thought you needed (its best to leave jetting 'as is' until you run the bike-for next time). That could mean barely running to running really well. Could you look in the carb?A compression test before you ran it would've helped too, but its sounds like it was bad right from the start. NHRS needs a phone call and maybe they'll help you out. If they set the piston clearance for the wrong type cylinder, then that seems the likely culprit. Did you check the piston ring end gap before you installed the piston? (from what I remember reading it sounds as if they sent you the piston already in the bore ready to go. They may have expected you to take it apart and clean it before final assembly. That would certainly have caused you problems if they did and you didnt). If you got a picture with the phone a little further away, the pics look like they'd be better. PM sent | ||
| Bandito90 |
NHRS re gapped the rings when I sent the cylinder back.From what I remember.They said it was ready to go.I slid the cylinder down and connected the piston to rod.I'm not really expecting to get anything else from them as I bought the parts a year ago. | ||
| Bandito90 |
I talked to NHRS today and they said I probably really detonated the thing.Bad thing is there are no overbore pistons for the 515.Also was told I could use a lightning piston,But it would be 10:1 not the 10:5.but again no over bore.Looks like I'm going to take the cylinder to my machine shop to see where it stands as far as measurement and roundness.I was told it should be 2.5 to 2.7 thousandst for the clearance.I might just go and have the stock jug bored and fresh piston put in. | ||
| Gearheaderiko |
Well all the pistons are probably the same price, except a stock Blast piston. Your cost difference would be on the bore and whether the 515 is salvageable (which is doubtful by the look of that piston). If you look at the 2 jugs side by side, my guess is the 515 is much beefier and probably a Sportster part. I'd just order the high comp piston and bore your stock cylinder, like I said I havent had any problems with that set up (and you may want to go with the stock cams until 500 miles are up. Just because of the previous problem). I'm still very curious as to why our pistons failed in the exact same place. Even though mine was an XB piston and yours a 'Blast' piston, it makes me wonder. I would definitely spend the money and send it to CP (get approval first). I'll give you the contacts name and you should definitely mention my name and include my above pictures. Still, we dont know what your jetting is at, that would be helpful. I thing EZ is running the B70's (or has), but since he also runs the "Dial-A-Jet" on his carb, it negates his jetting being the same as yours. Faulty piston design, bad head to piston fit (causing a 'hot' spot-laymans terms)? You may also want to do a Badweb search. You may find others who have used your set up but havent posted in years. I'm also sorry to say that I have been lackadaisical in contacting Revolution Performance (good people and a Badweb sponsor) about getting their opinion. Too much going on with the priority on getting bikes running rather than chasing mysteries. | ||
| Gearheaderiko |
PS: its a custom bore. I dont think there are any stock bikes that have ever used the 3.563 bore. You can bore out a stock cylinder to that bore also. | ||
| Bandito90 |
I believe my jetting is 180 main 45 secondary.I'm just wondering like you is the piston was a faulty design.Also it seems the cometic gaskets are kinda expensive.Can I use the stock gaskets with a high compression piston?And also I called Revolution and they only sell the piston for the 515.Is NHRS my only choice for a high comp piston or are there other places that have them? | ||
| Fast1075 |
Really BAD detonation AND preignition...the broken top land is from detonation..the metal burned away from the piston on the one side at the top is from preignition...the skirt is most likely scuffed up from the heat expanding the piston and/or burning the oil off the cylinder... When you put it back together, pay attention to quench, skirt clearance, timing, A/F ratio and be sure to deburr all of the surfaces in the combustion chamber and piston dome...lastly...make sure you are running a cold enough plug. And I seriously don't like that piston design..not much metal between the back of the ring land and the valve pocket on the intake side..that looks weak.. (Message edited by fast1075 on June 23, 2009) | ||
| Bandito90 |
I was running a stock plug as I didn't see any other listed to use.Correction on my jetting its 175/46 with the air idle screw out 2 1/2 turns.I adjusted the timing as in the manual.I'm still thinking my cylinder was not correct from the beginning.Any other piston available for the blast?Also will stock gaskets work for the head and base? | ||
| Swampy |
The top of the piston that is missing follows the curve of the valve pocket, that doesn't look right. | ||
| Bandito90 |
I ordered an overbore piston to use with the stock cylinder.Hope things go well this time.Also I found I have main jets from 175 to 200 if needed. | ||
| Fast1075 |
I'm sure not going to put one of those pistons in my motor...they BOTH broke in the same spot with no indication of mechanical interference...the valves didn't hit...the piston didn't hit the head...weak design.. | ||
| Ezblast |
Stick with Revolution. EZ | ||
| Gearheaderiko |
NHRS & RevPef both sell the CP pistons, but I prefer Revolution Performance (besides being a Badweb sponsor) since NHRS has steered me wrong on several counts. You can use the stock gasket kit. Did you order a stock piston or high compression? Jetting seems tolerable, but I dont know how the B70's flow and whether they would need that much different jetting (but I doubt it). FWIW: the difference in head designs between the XB and Blast is that I was using a 150 main with the XB and a 180 with the Blast! If the rings werent seating and you had a lot of blowby, then a richer mixture probably would have been needed. Spark plug with the high comp piston should be on the cold or race side. I ended up going two steps colder. On Quench, squish, clearance, etc. Fast, you know more about this than most. The thing is that the 515 is supposed to be a 'bolt on' mod. That means everything should have been worked into the design. Its really just a .063 over piston. Nothing experimental, no wild cams or valve timing, just basic run of the mill mods. Sure, they always tell you in the paperwork of any hi-po top end parts that clearance etc should be checked. With basic mods this shouldnt be necessary and most wont do it or wouldnt know how (but thats another discussion). The piston does look very thin at that point. The valve pockets dont need to be anywhere near that big. Apart from the missing piece my piston looks dam near normal. There arent any real signs of extended detonation or preignition. I've seen much worse on engines that didnt fail. But why did two CP 515 pistons fail? Coincidence maybe? I ran a high comp .015 over CP XB piston for 6000 miles before the rings finally gave up (racing). The high comp .015 over CP Blast piston is doing fine after 5000 miles and the last compression check showed 210psi. I'm very hesitant to buy another 515 piston. (The only reason I went with the 515 was that I had a week to do the top end for racing and buying the kit was the fastest way to get everything asap). I'd like to see us both get a heavily discounted piston from CP, but I think it would have to be really cheap for me to buy another 515! All this is why I like using the XB top end. Everything can be factory stock and you're getting SE550 cams (B70 comp), 7500 rpm springs, 10.?:1 compression, bigger valves and a better flowing head-all stock, made for every day usage and the parts are readily available from the dealer. I dont think I asked, but did you clearance the rocker covers for the B70 valve springs? Or did you use 'beehive' springs? Or did they fit without grinding (mine didnt on the Blast head. The XB uses beehive stock). | ||
| Bandito90 |
Thanks for all the info.The springs I got were crane cams.They were bought with my 515 kit.I do know the box said they were for the twin cam.There were also four spiring in the box.I thought they might be barely hitting when I put the motor back together.So I took the rocker cover off and it looked ok,But I clearanced it anyway.It still looks the same know as it it when I put it on the last time.I did order the piston from NHRS.I call Revolution and the person I spoke to said they only sold the 515 kit.I know it was not the same person I talked to like a year ago that seemed really knowledgeable.I might put the 180 jet in this time. | ||
| Fast1075 |
The huge valve pockets are so it will clear the valves no matter how big they are...it's a common one size fits all approach...Bandito's piston has most definate indications of preignition..the burn pits on opposite sides of the crown show it...maybe the ignition system went whacky...Erik's piston looks like detonation...excessively rich fuel mixture along with large quench will detonate like that... | ||
| Gearheaderiko |
Bandito, without trying to sound insulting: Clean the cylinder very well with soap and water. Check everything out thoroughly before and during installation. Make sure everything is lubricated well, before starting. Do the recommended heat cycles. Do a compression test, before starting after first start and as often as possible after that until its broken in (appx 500 miles). If you do have a problem you'll know when it started and for how long. Pay attention to any signs of 'knock and ping' and close attention to the A/F mixture. (avoid pulling the spark plug out of a hot engine, and use antiseize on the threads.)(from a previous post) While this may seem like overkill, since you dont know exactly what caused the failure, its best to be cautious. I would still follow the torque sequence guide they gave you rather than by the manual. You can also install the piston in the cylinder and install it as an assembly instead of installing the piston on the rod first. I like installing it as an assembly. Good luck and let us know how it turns out. | ||
| Gearheaderiko |
Fast: The one size fits all is what I was getting at and that might be why it failed in that spot. Whats interesting is while we did have initial rich problems (stuck choke) and detonation, they were solved early enough in the 500 miles (LOL) and it was dyno'd after that to be sure everything was on the mark. Hard to imagine a 150 main jet being lean! A mystery which I'm not sure I want to spend another $300+ to maybe figure out. 15 extra cc's isnt worth it and the potential gain could be gotten somewhere else! I appreciate the input. | ||
| Bandito90 |
Erik thanks for the advice.I was careful the first time and will even more cautious this time.I got my piston today,But it did not come with any instructions or the clearances to to give to the machine shop.I'll just have to get in touch with CP.I still need to get my head and base gaskets.Will stock ones be adequate? | ||
| Gearheaderiko |
Stock gaskets will be fine, just follow the NHRS torque sequence. I use copper high tack on the base and head gaskets. Your gasket set may or may not come with O-rings for the 'dowels'. They've seem to have done away with them, so a newer kit may not need or have them. An XB kit will have 2 sets (if you see a deal on e-bay)! | ||
| Gearheaderiko |
Someone else with the same failure: http://www.badweatherbikers.com/buell/messages/384 2/253592.html?1170087496 Hmmm.... | ||
| Crackhead |
I am picking up a blast with the 515 kit that is not running for $600. He said that it was only running for 5 hrs after the kit was installed and it sounded like it lost compression. Hopefully i can diagnose the bike next weekend. I am thinking a track bike. (Message edited by crackhead on September 17, 2009) | ||
| Gearheaderiko |
I assume since you posted that here you've read the whole thread! hhhmmm 5 hours running, sounds familiar. Possible the rings didnt seat or it was improperly assembled and I'm betting you'll need to take it apart. At that point you can assess damage and see if the 515 is still usable. If not, I seriously recommend going back to stock (overbore) bore (but I think thats a given  ) with a high compression piston or the XB top end and cams and......... I have opinions on making it a track bike too-great idea-but I can help you avoid some of the pitfalls (mistakes) I made. Congrats! Sounds like a good deal  PS The more I read about bad 515's, the more I'm suspicious about a "bolts right on" 600 kit  Really would like to find a factory parts option for a big bore Blast (short stroke). | ||
| Bandito90 |
Well,its been a long time and right at this moment I'm assembling or at least trying to my motor.I have the rings gapped and can get the first two rings in easily.But the oil ring is being a bear.My ring compressor is not helping either.Any tips that might be helpful? | ||
| Gearheaderiko |
Lots of oil and go slow. The oil ring is the least critical so sometimes you can work it in. The ring compressor that has worked best for me is the kind with a corrugated edge. The smooth sleeve kind hasnt worked so well. I prefer putting the piston in the cylinder first and you can do that right on the work bench, then mounting the cylinder on the engine and pushing the piston pin through (dont drop the clips). Easier to do and less chance of gasket contamination. This way is very difficult if you're using a used piston though (but you're not). Keep us posted. |
