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Discussion Starter #1
I built a 2010 engine, +3mm bore +4mm stroker crank JE stroker pistons 2014 velocity ported head 2014 throttle bodies & round venturas back cut * polished transmission with ceramic bearings, so to be gentle i fitted the stock Gen4 cams on stock timing with a standard thickness 79mm head gasket put her on a dyno where a stock 2017 GSXR 1000 put down 190 RHP she put down 209 DIN power with 96flb torque. I go away inspect the bores etc decide its all good & fit Big Kent cams and dial emm in 112 112 go back dyno expecting bike to come alive and after bout 40 45 mins dyno time re mapping her pish starts spewing out expansion tank i got bubbles so most likely head gasket, well im gonna tear her down (American Slang:smile2:) tomorrrow have a look :dontknow:
 

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I built a 2010 engine, +3mm bore +4mm stroker crank JE stroker pistons 2014 velocity ported head 2014 throttle bodies & round venturas back cut * polished transmission with ceramic bearings, so to be gentle i fitted the stock Gen4 cams on stock timing with a standard thickness 79mm head gasket put her on a dyno where a stock 2017 GSXR 1000 put down 190 RHP she put down 209 DIN power with 96flb torque. I go away inspect the bores etc decide its all good & fit Big Kent cams and dial emm in 112 112 go back dyno expecting bike to come alive and after bout 40 45 mins dyno time re mapping her pish starts spewing out expansion tank i got bubbles so most likely head gasket, well im gonna tear her down (American Slang:smile2:) tomorrrow have a look :dontknow:
Ouch. Good luck mate. Hopefully it's something small, easy and inexpensive.
 

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yup, you have some issue to tend to, lol

did you upgrade the head bolts??

what was your cranking compression?? Lowering compression to a more manageable level. Keeping the cranking compression under 200-220 will help alot.
 

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Discussion Starter #7
yup, you have some issue to tend to, lol

did you upgrade the head bolts??

what was your cranking compression?? Lowering the 112 to something like 105 will drastically effect compression to a more manageable level. Keeping the cranking compression under 200-220 will help alot.
Hi bud, no i havent uprated the bolts but im gonna do that now anyhows wether it was pre det or not:crackup: Cranking pressure .....ummmm well you got me there :rolleyes: i figure the cam numbers need playing with.
 

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Discussion Starter #8
detonation-period. pic tells it all. blown hg/burned strap.
Absolutely mate i think 1157cc is a lot in a skimmed 0.6mm head but ultimately long low down pulls on the dyno gave a few knocks and blew her out im reckoning on adding 0.2 to the gasket. The ignition is fairly neutral throughout, with quality pump gas (american slang:grin2:) it gave me a little wake up call.
 

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Discussion Starter #9
To be honest i just found out that GSXR 1000 putting down 190 was with a slip on filter & flash. I may just put the stock cams back in and enjoy it for a while, the big cams can be difficult to get right.
 

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Absolutely mate i think 1157cc is a lot in a skimmed 0.6mm head but ultimately long low down pulls on the dyno gave a few knocks and blew her out im reckoning on adding 0.2 to the gasket. The ignition is fairly neutral throughout, with quality pump gas (american slang:grin2:) it gave me a little wake up call.
Your squish clearance will increase and detonation will get worse with a thicker head gasket, you might want to rethink your plan.
 

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yup, you have some issue to tend to, lol

did you upgrade the head bolts??

what was your cranking compression?? Lowering the 112 to something like 105 will drastically effect compression to a more manageable level. Keeping the cranking compression under 200-220 will help alot.
Lowering the intake from 112 to 105 will advance the cam timing, which will raise cranking compression even more.
 

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Discussion Starter #12
Your squish clearance will increase and detonation will get worse with a thicker head gasket, you might want to rethink your plan.
That doesn't make sense to could you explain that if you reduce compression ratio then you are reducing heat which causes pre detonation.
 

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That doesn't make sense to could you explain that if you reduce compression ratio then you are reducing heat which causes pre detonation.
Google squish clearance, there are 1000s upon 1000s of explanations and videos. I recommend reading some of them before you spend more money on your engine.

2nd. There is no such thing as pre detonation...............there is detonation and pre ignition.
 

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coupe is exactley correct. detonation is the result of unburned fuel, sometimes called end gasses, that burn late and violentley after the combustion burn process should be finished. loose squish especially on a big bore with larger squish area will definatley promote detonation. need to always set squish tight as safely possible to avoid pth contact at high rpm for max power and quick burn. practically all engines power made in first 15 degrees engine rotation atdc so end fuel gasses rob power also. t he quick burn flame front does not penetrate the squish area well and fuel vapors are trapped there that burn/explode later as piston travels downward opening up squish area. tight squish forces the fuel mixture out as piston is practically touching head into the chamber under the plug to burn quickley/completley. the turbulence produced forcing this mixture out of the squish also better atomizes fuel to burn quickley. just one cause of detonation, several other factors cause detonation. although tightening squish will raise compression, it will reduce chances of detonation. not a preignition problem, that destroys hp before clean burn combustion even occurs, ur making too much hp/torque for that to be a factor. checking cranking compression after fire up on a new build will always indicate fuel requirements necessary for power/reliability. i think u have some more power to make, but gonna have to adjust some things.
 

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Some good knowledge here man... these folks are giving you some good info.

...and FWIW, pump gas by itself is a pretty evil thing to tune on a high-specific output motor, at least here in the states with our gas. You never really know what you're getting out of the nozzle when it comes to blended fuels, and you have to be pretty conservative with timing and mixture if you don't know what your fuel is going to do.
 

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pump gas will absolutley limit hp, dont fool yourself into thinking u can work around your chosen fuels limitations, when building a engine, fuel, intended usage are first considerations. i limit pump gas street engines to about 190-200 lbs max cranking compression after longer duration higher lift cams degreed, heads milled/squish minimized. bigger bore bikes, busa/zx14 i can pump 225-230 same cam/compression mods on stk pistons but pump gas senerio gone as it is unsafe. also cant lower cranking compression to what seems safe on pump gas by moving cam timing higher, that compression returns at high rpm's. cant get it all on pump fuel, especially street ridden where heat becomes a factor. fuel/tuning become critical on high compression engines running top end for any distance. lower compression motor safer, practically as fast, just lacks the torque to get to top speed as quickley from less compression factor. google hp vrs compression charts, some surprising info results.
 

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Discussion Starter #17 (Edited)
Google squish clearance, there are 1000s upon 1000s of explanations and videos. I recommend reading some of them before you spend more money on your engine.

2nd. There is no such thing as pre detonation...............there is detonation and pre ignition.
Thank you for explaining mate iv been having a look i appreciate the help theres not so many around willing to do that lately.
 

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Discussion Starter #18
Google squish clearance, there are 1000s upon 1000s of explanations and videos. I recommend reading some of them before you spend more money on your engine.

2nd. There is no such thing as pre detonation...............there is detonation and pre ignition.
Thank you for explaining mate iv been having a look and im getting involved with this now so need all the help i can get. :grin2: There are fewer around willing to help these days.
 

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Discussion Starter #19
coupe is exactley correct. detonation is the result of unburned fuel, sometimes called end gasses, that burn late and violentley after the combustion burn process should be finished. loose squish especially on a big bore with larger squish area will definatley promote detonation. need to always set squish tight as safely possible to avoid pth contact at high rpm for max power and quick burn. practically all engines power made in first 15 degrees engine rotation atdc so end fuel gasses rob power also. t he quick burn flame front does not penetrate the squish area well and fuel vapors are trapped there that burn/explode later as piston travels downward opening up squish area. tight squish forces the fuel mixture out as piston is practically touching head into the chamber under the plug to burn quickley/completley. the turbulence produced forcing this mixture out of the squish also better atomizes fuel to burn quickley. just one cause of detonation, several other factors cause detonation. although tightening squish will raise compression, it will reduce chances of detonation. not a preignition problem, that destroys hp before clean burn combustion even occurs, ur making too much hp/torque for that to be a factor. checking cranking compression after fire up on a new build will always indicate fuel requirements necessary for power/reliability. i think u have some more power to make, but gonna have to adjust some things.
Nice one mate look at all the time you took typing that in :thumbsup: Im getting the idea now :grin2:
 
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