jon haney Posted December 19, 2009 Share Posted December 19, 2009 I took the head off of the drag bike engine a couple of days ago. Valve clearances were all still could and the cams and buckets still looked new. After wiping up some excess oil and anti-freeze, I rotated the motor so that cylinders 2 & 3 were at the top of their bores. Below is what I found. In case it's not painfully obvious, the exhaust valves left some nice divets in the top of the #2 piston. The genious who did my big-bore kit put that piston in backwards. :icon_doh: It's been running like this for two years and it still pulled a 190 lbs. compression. (I hope that's a good number.) Question is: Can I just turn the piston around and re-assemble? Quote Link to comment Share on other sites More sharing options...
cbrxxquad Posted December 19, 2009 Share Posted December 19, 2009 Take a look at the ring gaps on that side, but yeah. It is not that hard, as they are not marking them anymore, and there is not that much difference in the cutouts for the valves. Quote Link to comment Share on other sites More sharing options...
HANKSXXX Posted December 19, 2009 Share Posted December 19, 2009 I'd be leery of the valves, especially if they are the stock one's. Stock valves are a 2 piece design and have been known to pop the head off with HD springs and no piston contact. As Stan mentioned, check the dimensions of the ring groove which I'm gonna guess will be fine. I'd be tempted to finish the job the valves started with a Dremel and not even split the cases, but then again, I'm kind of lazy... Monday morning quarterbacking here, but a leakdown test would have been interesting. Hank Quote Link to comment Share on other sites More sharing options...
Slim99XX Posted December 19, 2009 Share Posted December 19, 2009 Agreed on junking the valves. I'm assuming the pistons are forged, if so they shouldn't be hurt. Quote Link to comment Share on other sites More sharing options...
JB4XX Posted December 19, 2009 Share Posted December 19, 2009 I'm sure you going to show that picture to the shop who did the kit for you. Wow. Definitely be checking those valves out while you have it open. :icon_duh: Quote Link to comment Share on other sites More sharing options...
tomek Posted December 19, 2009 Share Posted December 19, 2009 What a retard.Squish does not look so bad on intake side and on the sides but there is a loooooots of carbon on exhaust part of the piston.You may have to machine piston crowns in order to get nice 360 deg squish. I`m wonder what valve seats look like on those 2 cylinders. Quote Link to comment Share on other sites More sharing options...
jon haney Posted December 21, 2009 Author Share Posted December 21, 2009 The exhaust port has evidence of oil, so I'm sure the valve guides are crap. I was planning on having the same guy do the work on the head, but I'm not sure now. I figure anyone can make a mistake, but the measure of a man is how they react after the mistake has been revealed. I have not talked to him yet, but I'm hoping he will at least offer to pay for new valves and valve guides for that cylinder. I'm splitting the cases anyway to shave a little material off of the block, so I'll deal with turning the piston around. My goal with this project is to reduce the squish area. In searching some old threads, someone posted that .7mm is the minimum safe squish. Using a dial indicator and a little math, I came up with 1.7mm using a stock head gasket. If I have .020" shaved off the block and use a .018" head gasket, I get .86mm squish. Stan and Tomek, I would love to hear your thoughts on this. With a couple of squirts of oil in each cylinder my compression readings were 1=200, 2=190, 3=180, 4=200psi. Are those decent numbers for a stock engine? Thanks in advance for your input. Edit: I just remembered that I rubbed off most of the carbon residue (with a shop rag) from the squish area of the piston tops before I took those pictures. It makes sense that there would be less residue with tighter squish. Quote Link to comment Share on other sites More sharing options...
cbrxxquad Posted December 21, 2009 Share Posted December 21, 2009 Valve to piston clearances need to be measured before you take any out, or you will have to cut valve pockets. Cam timing will effect too. There is a thin gasket you know? Quote Link to comment Share on other sites More sharing options...
jon haney Posted December 21, 2009 Author Share Posted December 21, 2009 Valve to piston clearances need to be measured before you take any out, or you will have to cut valve pockets. Cam timing will effect too. There is a thin gasket you know? Cometic just came out with one that is .018" They show it on their web-site. A friend of mine put one on his ZX-14 that he has raced for 3 years and he estimates about a 10 HP increase. Stan, I was hoping you could give me an idea what stock piston-to-valve clearances should be so I could determine my chances of having to deepen the valve pockets. I promise I won't hold you responsible for anything I fuck up. Quote Link to comment Share on other sites More sharing options...
cbrxxquad Posted December 21, 2009 Share Posted December 21, 2009 Well I start to get worried less than .060. Have done a few closer, but real specialized circumstances. Would have showed that problem Jon. But, your going to have to do your motor the way it is set up to know what it is. Spring pressures too, can allow closer clearances. Good springs will insure no float, but put a strain on valves and the two piece ones might fail. But, cam timing does the most to worry me. Valves need to be checked for interference between each other too. Quote Link to comment Share on other sites More sharing options...
tomek Posted December 22, 2009 Share Posted December 22, 2009 You can drop to 0.7 mm on squish (BTW I`m running 0.6mm on 14000rpm R1),that means removing 1.0 mm one way or another.It is gonna increase your C/R to something ridiculous like 14.2:1 ( claimed CR is 12.0 right ?).I`d say it is too high on pump gas,if you decide to go this way some material will have to be removed from piston tops to lower CR. I had similar situation with Wiseco`s kit for YZF1000,it opened squish to something like 1.5mm,I had to machine off compression bumps to bring CR down to about 13.5. 2mm on exhaust and 1.5 mm on intake is safe minimum on stock parts. Quote Link to comment Share on other sites More sharing options...
cbrxxquad Posted December 22, 2009 Share Posted December 22, 2009 One thing just hit me, make sure the rod is on right too. Might be backwards... Quote Link to comment Share on other sites More sharing options...
jon haney Posted December 22, 2009 Author Share Posted December 22, 2009 You can drop to 0.7 mm on squish (BTW I`m running 0.6mm on 14000rpm R1),that means removing 1.0 mm one way or another.It is gonna increase your C/R to something ridiculous like 14.2:1 ( claimed CR is 12.0 right ?).I`d say it is too high on pump gas,if you decide to go this way some material will have to be removed from piston tops to lower CR. I had similar situation with Wiseco`s kit for YZF1000,it opened squish to something like 1.5mm,I had to machine off compression bumps to bring CR down to about 13.5. 2mm on exhaust and 1.5 mm on intake is safe minimum on stock parts. What are these dimensions for? This info is exactly what I'm looking for. Thank you very much. Wiseco says compression is 11:1 for the kit I have. Removing .032" of total deck height will increase the compression by that much? I was hoping to be able to run 91 octane. I'm pretty sure I will have to deepen the valve pockets anyway so maybe I should take about .010" off the piston tops. What do you think? Quote Link to comment Share on other sites More sharing options...
jon haney Posted December 22, 2009 Author Share Posted December 22, 2009 One thing just hit me, make sure the rod is on right too. Might be backwards... I was reading my Haynes manual last night and saw a picture that had me thinking the exact same thing. Gonna try to split the cases tonight. This is a little scary for a guy who hasn't done this sort of thing in 15 years. Quote Link to comment Share on other sites More sharing options...
tomek Posted December 23, 2009 Share Posted December 23, 2009 You can drop to 0.7 mm on squish (BTW I`m running 0.6mm on 14000rpm R1),that means removing 1.0 mm one way or another.It is gonna increase your C/R to something ridiculous like 14.2:1 ( claimed CR is 12.0 right ?).I`d say it is too high on pump gas,if you decide to go this way some material will have to be removed from piston tops to lower CR. I had similar situation with Wiseco`s kit for YZF1000,it opened squish to something like 1.5mm,I had to machine off compression bumps to bring CR down to about 13.5. 2mm on exhaust and 1.5 mm on intake is safe minimum on stock parts. What are these dimensions for? P/V clearance This info is exactly what I'm looking for. Thank you very much. Wiseco says compression is 11:1 for the kit I have. Removing .032" of total deck height will increase the compression by that much? I was hoping to be able to run 91 octane. I'm pretty sure I will have to deepen the valve pockets anyway so maybe I should take about .010" off the piston tops. What do you think? You really have to close the squish to 0.7mm,0.86 mm won`t give you shit other then compression bump.When you adjust squish to the point that the piston is almost hitting the cylinder head at the peak rpm all the mixture from the squish band gets pushed inside of the combustion chamber improving efficiency and all fuel gets burned.Don`t be surprised if you actually gonna have to pull out some fuel ( lean out the mixture) afterward. 11.0 CR on those Wisecos ? What is the stroke,59 mm IIRC ? In this case removing 1.0 mm would give about 13 CR,I guess there is no need to touch piston tops. You can lay back valve pockets and smooth out all the edges on compression bumps. Quote Link to comment Share on other sites More sharing options...
jon haney Posted December 23, 2009 Author Share Posted December 23, 2009 You can drop to 0.7 mm on squish (BTW I`m running 0.6mm on 14000rpm R1),that means removing 1.0 mm one way or another.It is gonna increase your C/R to something ridiculous like 14.2:1 ( claimed CR is 12.0 right ?).I`d say it is too high on pump gas,if you decide to go this way some material will have to be removed from piston tops to lower CR. I had similar situation with Wiseco`s kit for YZF1000,it opened squish to something like 1.5mm,I had to machine off compression bumps to bring CR down to about 13.5. 2mm on exhaust and 1.5 mm on intake is safe minimum on stock parts. What are these dimensions for? P/V clearance This info is exactly what I'm looking for. Thank you very much. Wiseco says compression is 11:1 for the kit I have. Removing .032" of total deck height will increase the compression by that much? I was hoping to be able to run 91 octane. I'm pretty sure I will have to deepen the valve pockets anyway so maybe I should take about .010" off the piston tops. What do you think? You really have to close the squish to 0.7mm,0.86 mm won`t give you shit other then compression bump.When you adjust squish to the point that the piston is almost hitting the cylinder head at the peak rpm all the mixture from the squish band gets pushed inside of the combustion chamber improving efficiency and all fuel gets burned.Don`t be surprised if you actually gonna have to pull out some fuel ( lean out the mixture) afterward. 11.0 CR on those Wisecos ? What is the stroke,59 mm IIRC ? In this case removing 1.0 mm would give about 13 CR,I guess there is no need to touch piston tops. You can lay back valve pockets and smooth out all the edges on compression bumps. I would think closing the squish to half as much would offer some measure of improvement. :icon_think: I'm only .006" shy of .7mm. I was just trying to be conservative. Stroke is what ever is stock. I'm doing full dyno-tune after re-assembly. Quote Link to comment Share on other sites More sharing options...
Crazy Dave Posted December 23, 2009 Share Posted December 23, 2009 Could be a lot worse.............. Quote Link to comment Share on other sites More sharing options...
jon haney Posted December 24, 2009 Author Share Posted December 24, 2009 Damn! That is why I'm staying away from nitrous. Quote Link to comment Share on other sites More sharing options...
jon haney Posted March 29, 2011 Author Share Posted March 29, 2011 I FINALLY GOT THIS THING ON A DYNO. Wish I had a print-out but I forgot to ask for one. Walter Sprout makes an annual trek to OKC to help racers with tuning their P/C and drag shocks, so I figured I would let him do it. Wichita doesn't have anyone I trust for dyno-tuning. Anyway...She made 153 BHP and 91 ft-lbs. This is with a heavy-duty chain that was a little too tight. Had 75 ft-lbs @4000 RPM. This thing makes great torque. Gained at least 3 tenths in the quarter-mile, but the trap speed only went up 1-1.5 MPH. I think it's safe to say that minimizing the squish and bumping the compression a little is well worth it. Had my best racing year ever. Quote Link to comment Share on other sites More sharing options...
HANKSXXX Posted March 29, 2011 Share Posted March 29, 2011 I FINALLY GOT THIS THING ON A DYNO. Wish I had a print-out but I forgot to ask for one. Walter Sprout makes an annual trek to OKC to help racers with tuning their P/C and drag shocks, so I figured I would let him do it. Wichita doesn't have anyone I trust for dyno-tuning. Anyway...She made 153 BHP and 91 ft-lbs. This is with a heavy-duty chain that was a little too tight. Had 75 ft-lbs @4000 RPM. This thing makes great torque. Gained at least 3 tenths in the quarter-mile, but the trap speed only went up 1-1.5 MPH. I think it's safe to say that minimizing the squish and bumping the compression a little is well worth it. Had my best racing year ever. Probably your best tuner ever too... Walter has a great reputation.. Nice job on the motor.. Quote Link to comment Share on other sites More sharing options...
Warp11XX Posted March 29, 2011 Share Posted March 29, 2011 91 octane pump gas and anything over 10:1 will be just asking for a big pain in the ass. This doesn't account for shitty ethanol fuels at all. ECM and electronic retard/anti-knock might be able to help out some, but I've tried everything under the sun to fix this problem and nothing less than 100 octane has ever come close. My application started as 12.30:1, lowered to 11.25:1 and -15 deg static timing...still pings like a bitch on hot, humid afternoons. Runs like a raped ape on 100LL from around 11pm until about 8:30am though..... Quote Link to comment Share on other sites More sharing options...
jon haney Posted March 29, 2011 Author Share Posted March 29, 2011 91 octane pump gas and anything over 10:1 will be just asking for a big pain in the ass. This doesn't account for shitty ethanol fuels at all. ECM and electronic retard/anti-knock might be able to help out some, but I've tried everything under the sun to fix this problem and nothing less than 100 octane has ever come close. My application started as 12.30:1, lowered to 11.25:1 and -15 deg static timing...still pings like a bitch on hot, humid afternoons. Runs like a raped ape on 100LL from around 11pm until about 8:30am though..... Using 91 octane at 12.3:1 compression should not be pinging. That is about where I am at. No pinging even on 87 octane, but I do have an FI Bird. I think you have some other issue causing your pinging, but I lack the experience to give any advice on what to look for. Quote Link to comment Share on other sites More sharing options...
partsman Posted March 29, 2011 Share Posted March 29, 2011 My 91 600 ran 13.5:1 JE pistons on pump gas,had the head off last year and still looked great.Did a comp test a couple weeks ago and still have over 200 psi.That motor has seen about 3-400 passes and close to 20,000 km of riding. I tried the poor mans way of raising comp on the 1100,took the middle layer out of the head gasket.Ran it for 2 years,had the head off last year and noticed a little blow by between 2 & 3,put the normal gasket back in and ran the same #'s as the year before.What I gained on comp I lost on leakage. Quote Link to comment Share on other sites More sharing options...
tomek Posted March 29, 2011 Share Posted March 29, 2011 91 octane pump gas and anything over 10:1 will be just asking for a big pain in the ass. This doesn't account for shitty ethanol fuels at all. ECM and electronic retard/anti-knock might be able to help out some, but I've tried everything under the sun to fix this problem and nothing less than 100 octane has ever come close. My application started as 12.30:1, lowered to 11.25:1 and -15 deg static timing...still pings like a bitch on hot, humid afternoons. Runs like a raped ape on 100LL from around 11pm until about 8:30am though..... 13.7 C/R on my R1 track bike , runs like a raped monkey on pump gas . You can only compare fuels and C/Rs for given engine , otherwise it is absolutely , positively , pointless . Some of the main things that effect permissible C/R : bore size , combustion chamber design , squish band , cylinder hear design , camshaft duration ,etc . Quote Link to comment Share on other sites More sharing options...
Warp11XX Posted March 30, 2011 Share Posted March 30, 2011 ECM and electronic retard/anti-knock might be able to help out some Using 91 octane at 12.3:1 compression should not be pinging. That is about where I am at. No pinging even on 87 octane, but I do have an FI Bird. I think you have some other issue causing your pinging, but I lack the experience to give any advice on what to look for. I guess that the difference lies there...I've done it with an engine that isn't electronically controlled by a computer. Maybe I'm missing something but it just seems to defeat the purpose when the ECM has to dial the spark back so far that it basically nullifies the potential gains on the mechanical side for lack of a stable fuel. And the loss could really be transparent except in direct comparison...bet you could dump a load of VP or high dollar Sunoco in there and pick up significant gains.... Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.