When do i need a new piston???

[GIXXER1KR]

Hey guys i got a few questions?I have a year of trail riding and a few races on my 06 motor.I do all my maintenance regularly and keep it running in excellent condition.I have heard a lot of guys say its a high maintenance motor.I checked my valves recently and they were all in tolerance.The biggest question i have is when do i know its time for a new piston and rings.And what else should i do.i wouldnt mind getting a port and polish job and maybe a better piston.I was think Curtis Sparks or Baldwin.Any info would be appreciated!!!!Right now i am running the HRC Cam and header with a Yosh Slip on.I would like to keep this if possible ....What would be the most reliable bang for the buck????

[pro-rider46]

you have a preety good setup. i would recomend a port and polish, because the stock piston compression is 12:1 on 06+ models. anything above that is running race fuel and close to 6 bucks a gallon. you can get the port and polish and still run on pump gas, but if your okay running race fuel i rocomend a baldwin 14:1 or one of chad502ex's pistons. his are 15:1 to 17:1.:macho

[GIXXER1KR]

Yeah i want to stay on pump gas so ill have to stay at 12.1...Who do u recommend on port and polish and what kind of piston.I am thinking better valves when i do the port and polish..

[pro-rider46]

well i would recomend a wiseco piston at 12:1 but is lighter, i believe there called pro-lite. i really dont have any experiece with porting other than reading, but chad knows his stuff and can probably do oversized valves and porting and flow test it, but i have also heard good things from wpp/wicked racing port and polish and oversize valves.

try a new thread in the powertrain section about the best port and valve jobs. if you make a dicision post it up here, im interested in finding out more.

[chad502ex]

thanks pro-rider46. I appreciate your words.

my pistons are custom 15:1 pistons that permit additional head machining for compression ratios up to 17:1, if desirable... This requires running race fuel though,...

I do porting and use flow bench validation of the porting I do using anti-reversion technology that is not just smoke-and-mirror show,.. just ask any of my customers who run my work. anti-reversion has been proven to work in physics from pipe organs to engines to microwave radio frequency transmission. again physics is physics in any application.

But,... I will just say this,... just do your homework and research the builder you decide to use... be sure to internet search for actual proof (dynos) for the power they claim, and be sure the builder can consistently and reliably build what they claim. Price and being able to deliver what is talked about and agreed is extremely important.

Just food for thought...

Hope this helps.

[CHEVYZ]

As said, I wouldn't go much more on the piston. I have heard that you can run 13:1 on pump, but it is pretty risky and I would much prefer to know for sure before I buy something-so where you are at is fine.

For port and polish, it can make a big difference. There are alot of good builders out there, and it really varies. You really have to research it yourself to see what you like personally, and what fits in your price range. Keep in mind that with some of these builders what you see isn't always what you get, however. I have seen some people get incredible engines, and others that lose power compared to stock from the same builder.


And just to share my experience, I have some of Curtis Sparks' porting, and it is garbage compared to many others I have tried. C&D Racing is VERY inexpensive, and does a hell of a job for the price. Just throwing that out there as well.

[DEVINF450R]

I have a wiesco 13.1:1 in my R and I mix race gas with 93 octane. you can run pump gas no prob but it doesn't put out as much hp. I have put most my hours on that piston until I changed it last week. if you change rings every 20hrs or so (race) and prob every 6mos (trail riding etc.) you should be fine. HONDA'a are NOT high maintenace compared to Yamaha or even most other brands. Definitely go with the wiesco... the only reason I changed mine was preventitive maintenance and it was in my race quad for 13months...still looked great

[Flynbryan19]

Buy yourself a compression tester and once it goes below spec its time to change the piston/rings. Anything before then is simply a waste of money.

Rings every 20hrs or even 6 months also seems way too high, but then again I don't know how you ride. It all comes down to how hard you are on your equipment and the quality of the lubricants you keep in it.

[GIXXER1KR]

I have a comp tester.What should i have for comp and doesnt the decompression lever during starting afect it???Not sure i did mostly 2 stroke rebuilds b4 this!!!

[trx450jason]

I know with the decompressor a compression test wouldn't an accurate test at all. But I'm still running my stock '04 piston with no problem at all.

[chad502ex]

the decompressor mechanism can be disengaged for a compression check or leakdown test.

[DEVINF450R]

I am very hard on equipment... better safe then sorry. 120 for a piston or 800 for a jug, piston and crank....or worse if it kills valves or the head:ermm:

[GIXXER1KR]

How can the decompression lever be disengaged!!!I know i remember seeing it on the side opposite the timing gear.It has a little arm.

[chad502ex]

Originally posted by GIXXER1KR
How can the decompression lever be disengaged!!!I know i remember seeing it on the side opposite the timing gear.It has a little arm.

loosen the lock nut and back the set screw out as far as possible so that the lever mechanisn never pushes on the exhaust fork while cranking.

[GIXXER1KR]

It should be ok to crank it over with the valve cover off right or will it make a mess?:DAnd when u say screw the little screw your talking about the lock nut that u adjust to set decomp clearance on the exhaust !!!Just back it out so it dont work..I think i got ya!!!So what should my comp be i looked in the 06 manual and its like 51-56 so i think thats the specs with the decomp working!!!This is all new to me.Ill get it down and thanks and chad shoot pm me some prices.Like the work u were talking about with the web 943 cam!!And what kind of fuel would that be and power?

[chad502ex]

Originally posted by GIXXER1KR
It should be ok to crank it over with the valve cover off right or will it make a mess?:DAnd when u say screw the little screw your talking about the lock nut that u adjust to set decomp clearance on the exhaust !!!Just back it out so it dont work..I think i got ya!!!So what should my comp be i looked in the 06 manual and its like 51-56 so i think thats the specs with the decomp working!!!This is all new to me.Ill get it down and thanks and chad shoot pm me some prices.Like the work u were talking about with the web 943 cam!!And what kind of fuel would that be and power?

it will make a slight mess with the splatter of oil slinging off the cam on rotation.. LOL!

i set the 06 to about 75psi on cranking with the decompressor disengaged. anymore than this its hard on the starter clutch sprags and the starter itself.

[sandmanblue]

Originally posted by GIXXER1KR
Hey guys i got a few questions?I have a year of trail riding and a few races on my 06 motor.I do all my maintenance regularly and keep it running in excellent condition.I have heard a lot of guys say its a high maintenance motor.I checked my valves recently and they were all in tolerance.The biggest question i have is when do i know its time for a new piston and rings.And what else should i do.i wouldnt mind getting a port and polish job and maybe a better piston.I was think Curtis Sparks or Baldwin.Any info would be appreciated!!!!Right now i am running the HRC Cam and header with a Yosh Slip on.I would like to keep this if possible ....What would be the most reliable bang for the buck????


Do yourself a favor and buy a CP 12:1 replacement. Sparks and Baldwin don't actually make their own pistons, they are either made by CP or JE. Of the two, CP would be my suggestion. You will also need to check your bore. After this much time on it, it is possible that it's out of spec. If that's the case, you're looking at a bore/replate and a larger piston - either 97 or 98 mm. It's quite important to have the bore sized to the piston and have the clearance set to 0.0008 to 0.0010. Honda recommends 0.0015, and that leads to a lot of piston slap (as anyone with a stock motor knows). Make sure the rings are gapped properly. CP advises WAY too much of a gap. Something like 0.020 for the bore size we have. If you do that, you'll be blowing oil. Most builders will set the rings to 0.014 on a single compression ring and 0.015 on the oil rings. This is best done by a qualified shop.

I won't post personal builder suggestions here. If you want some ideas, PM me.

[GIXXER1KR]

Chad u lost me there.U set the comp to about 75 psi with the decompressor disengaged!!!:confused: How can u set the comp i thought u could only adjust the starting compression with the decompression lever active!!!Do u me when engaged.And to do that u adjust the clearance right!!

[Dave400ex]

Check out Moto-Xperts for head porting. He did mine and it has made a huge difference. He had a TC head at his shop and I couldn't believe what the port job looked like. He has also had a Sparks and said it wasn't much better. Plus he is priced very well and quick. Tell him Dave sent ya... Moto-Xperts (http://moto-xperts.com/page6.html)

[chad502ex]

Originally posted by GIXXER1KR
Chad u lost me there.U set the comp to about 75 psi with the decompressor disengaged!!!:confused: How can u set the comp i thought u could only adjust the starting compression with the decompression lever active!!!Do u me when engaged.And to do that u adjust the clearance right!!

setting up cranking cylinder pressure with the valve cover removed will have a different procedure than performing a cylinder compression check or a leakdown check.

Setting cranking cylinder pressure is performed with the decompressor engaged and adjusted to about 0.018" if memory serves me,.... the compression test or leakdown check to evaluate rings is done with the decompressor disengaged...